JOURNAL OF THE ROYAL MICROSCOPICAL SOCIETY: CONTAINING ITS TRANSACTIONS AND PROCEEDINGS, AND A SUMMARY OF CURRENT RESEARCHES RELATING TO ZOOLOGY AND BOTAN YW (principally Invertebrata and Cryptogamia), MICROSCOPY, Gc. Edited by BL FRANK CRISP, LL.B. B.A, One of the Secretaries of the Society and a Vice-President and Treasurer of the Linnean Society of London; WITH THE ASSISTANCE OF THE PUBLICATION COMMITTEE AND A. W. BENNETT, M.A., B.Sc., F. JEFFREY BELL, M.A., Lecturer on Botany at St. Thomas's Hospital, Professor of Comparative Anatomy in King’s College, 8. O. RIDLEY, M.A., of the British Museum, asp JOHN MAYALL, Jun,, FELLOWS OF THE SOCIETY. ser. II—VOL. III. PART 2. PUBLISHED FOR THE SOCIETY BY WILLIAMS & NORGATE, LONDON AND EDINBURGH. 1883. ae ale RAN 4 SSR ee etre 2 vol 3 | Pee tears . 7 ih ae Th - > « : de 3 b ehii a) , ws 4 Los oe The Journal is issued on the second W ednesday of ~ February, April, June, August, October, and December. YS Ser. II. To Non-Fellows, Vol. 111.Part4,;| AUGUST, 18s. | Price 5s. JOURNAL OF THE ROYAL MICROSCOPICAL SOCIETY; CONTAINING ITS TRANSACTIONS AND PROCEEDINGS, AND A SUMMARY OF CURRENT RESEARCHES RELATING TO ZOOLoGY AND BOTANY _ (principally Invertebrata and Cryptogamia), MICROSCOPY, Sc. Lidited by oe PES. FRANK CRISP, LL.B., B.A., One of the Secretaries of the ‘Society and a Vice-President and Treasurer of the Linnean Society of London ; WITH THE ASSISTANCE OF THE PUBLICATION COMMITTEE AND A. W. BENNETT, M.A., B.Sc., __F. JEFFREY BELL, M.A,, Lecturer on Botany at St. Thomas's Hospital, | Professor of Comparative Anatomy. an King’s College, & 90. RIDLEY, M.A,, of the British Museum, and JOHN MAYALL, Jun., FELLOWS OF THE SOCIETY, WILLIAMS & NORGATE, _ LONDON AND EDINBURGH. PRINTED BY WM, CLOWES AND SONS, LIMITED,] SERS Sn pe Ff “. [STAMFORD STREET AND CHARING CROSS, 9 es: ; AE ( i ee La JOURNAL OF THE ROYAL MICROSCOPICAL SOCIRTY. Ser. 2.—VoL.. III. PART 4. (AUGUST, 1883.) CONTENTS. ———.0>9, 00 TRANSACTIONS OF THE SoOOlETY— PAGE VII.—On tHe Rep Moutp or Bantry. By Charles George Matthews, F.C.S., F.1.C. (Plates V. and VL) 4.005. 4 ues BSE X.—On rue Sprovtes or CucumaRIA HYNDMANNI, ©. OALCIGERA, AND TWO ALLIED Forms. By Professor F. J effrey Bell, M. A., Sec. R.M.S. (Plate VIIL) . oG Nee ck me OE See ee ee -XI.—Own a Meruop or Preservine THE Fresu-water Mepusa. By Peter Squire, F.L.S.. (Fig. 90) 9.2 se ls a en AOD Summary or Current RESEARCHES RELATING TO ZooLoGy AND Botany (PRINCIPALLY INVERTEBRATA AND Cryprocamia), Mioro- soory, &c., INCLUDING OriIGINaAL CoMMUNICATIONS FROM FELLOWS Anh’ orm 05 62 A ae ee ZooLoey. Early Stages of the Guinea-pig Ovwm 45 ae ee we te we see we ABT Activity of the Yolk during Impregnation .. «1 se ee ae oe ws 488 Germ-layers and Gastrula of the Mouse .. «s+ 8 oe «2 as oe 488 Embryology of Mice ., w« «. BEA Toe ware oer Wes. Sle) train gta oe ate Embryology of Rodents _.. Set eben tele OE Wah che ntspe hb eae Origin of the Vertebrate Mosdderti. (jo (6 at ae a ae Histology of the Ovary of Mammals... «+ «5 +» 00 es oF e 490 Histogenesis of Nerve-fibres Pe ige. os Olfactory Lobes in Vertebrates and Higher Arthropoda 3s See heen, Heke ee Colouring Matter of Egg-shells .. «. fe. abo ee owe eet ae Presence of Glycogen in Embryos of ‘Squalide oo iatean Gee tall @ eee Biological Stidiea:- > vs 20 36 ae ae bats sed ies eos 28a bh tad), eee Structure of the Nucleus. .< 6.) ve ioe) pe» on ih jue fee ee es itea Om Chromatophores of Cephalopoda’ 4. ss on oe as te we ee we AOE Development of Chromatophores of Poniala Se eet ee me ere Organization of Chitons .. du ee tape EAS One tee ee Characters of Marionia. ~~ ..° 2. on) ee eee 00s dos oe ng os CAO Ova of Ascidians.. .«. os dass) Be rlewes Spe: ker op co ce OT a Oxycorynia, a new Synascidian Genus 3s.) ois hos tee. ey ee ' Histology and Development of Insects .. 1s so» ss ee oe oe 49D Markings on Podura Scales ©... 00.00! in ale Soba. sei, eae oe 4 Dermal Appendages of Polymenus .. 11 ss oe ne te ee ee we ON Ee of Tegenaria guyonii—Organs in the Male Abdominal Sexual — : ee gion . oe ee ee oe oe. 8 oe oe ie / Anatomy of Pentastomum oxycephalum ge) ge et eee eds, Raph cult a teaat a aie Demodex phylloides - oe. ef oe oo ee 503 / Larval Development of Phonichilidium Plumulariz 1. is ss ee ao BOS Leiria of the Malacostrace, |: 16° ne ve * sa. oe 0'.6e kapha caer, Oe a Circulatory nae Stomatopoda .. oe oe of ee oe oe oe. ae 506) Copepoda living in Molluscs and Asoidians ), © 0. hea A ae (507. American Parasitic Oogepada ae. epee. “w6 abe WORSEN ARDC Bie Rhee aoe (7s. ) Summary or CURRENT te Je &¢e.—continued. Development opAnneins va, ge ae, ee AE be ee oe ae ea DOT Nervous System of Hir Es Cnt Via’ Dig Ror Dis ee eR OE Terres ede Pree ae we) |S) Bite of the Leech.. ERR 9 Ne ape pg trek oy OM SO oe Development of PUD ee tae Sv es eo SS BOD Development of Sipunculus PME a See nie ene OS eee EaYp Sternaspis scutata —. Bee ye See eR re ea Monograph of the Chetognatha.. Pea one eiols tee: jf tee ate Ava tp deeey YES Direct Reproduction of Tenid o.- we a0 so we oe oe we we ve DID Democrinus parfaiti .. Poet cuit eaeh TV aim Ny 512 Structure of Hydroid Polyps Rape ae cnt Re. eet age eee ae wy ace OLE Development of Hydra... Beek Migs ik tet ry eco nah A ONE Alternation of Generations in Hydro- iene er a ep es SBS Hydro-medusxe without Digestive Organs... 6+ +1 oe we ee oe O16 Phylogeny of the Siphonophore v.11 ee ose eae te te ne 16 Blue Colouring Matter of Rhizostoma.. Beet Gen Ak NO Limbryonic Tentacular Knobs of certain Phy Physophores aioe te Bray Bt sir EO Australian Aplysinide .. LULA AEP 519 Characters of Infusoria :. Beta Rb ied gh pe eH OON Development and Classtfication of Polytona, E Hie ae Ophryocystis Bitschlit _., So ogo et rae More ihe a OEE Social Heliozoan . : Be eNOS i Rink eta Gee vate toeices See Oo Living Organisms ie BEROWIBOHL SP See eo litaes GP BIE Borany. Continuity of Protoplasm throug gh the-Walls of Cells 4: 42 0. ne we ODA Pollination of Rulingia «. tae cen ae P20 Development of Chlorophyll-gr ains and Pigment- bodies... 925 Effect of Tension of the Burk on the Formation of the Annual Ringe of Wood, and on the Direction of the Medullary Rays .. 527 Formation and Properties of Duramen .. RED be. Polarization-phenomena of Lea and Artificial Colloid- celle « Eee eRe OLD Origin of “ Cell-passages’ Fae AGT Pome” Ss Roney Saye, Collenchyma...”- Seco apes ered GEN GN ca ie Te OOO, Structure of the Pericarp of Orchidece Dn Pewee hanes fo ea ate hue oo ial oe da E OO Chamisity of Woody Tissues’ 2.5 .0c: Sak. cain rete apes Be ov OOO SHATSLSPYOOMCES Of ABSCUVILGLLON. LM <5 3850 aa Vacaps ors Gee at os Fe OOO Selective Power of Absorption-of Roots .. 2. 1. ss ee ne we ws 80 MOopemeNaS-OfF Vater Un PUONUS S025 06s win ek ale Se poh Oe ae ag COOL Movement-0f Water. in the: Vessels sa) 2555 fates aes ae se hee pas COOL Heudahion of Water, from Leaues < oe 2 Mad ee ep cn, D8 eee se edt oes. OU PLY POLAT Ae POLLO Wiss ane nay tiga Soak Gee ee Fae eye OOK Pujiction of Tannin im Metastasis vs oe bine OOK Laas which regulate the Production of Male and Female Flowers... 532 Selenotropism of Plants —.. ine heneaae BS Ge = Pricer eee 3 « Withering of Flowers and Leafy Shoots... .. Cy See ORR T epee BBY Ron DOK Fatty Acids in Plants... .. Ba eus Wa ee PA ee eK OE OOO: Influence of Mineral Substances ¢ on Germination Ip IOS Is URS Seay ane ee ree eR 33 A) Occurrence of Iron in Plants... ~.. Bee ee Geta e Bel oe ods OOO Palzontological Development of Cryptogams peeennd hes tos ee, Sees ae OAD Organic Unicellular Bodies in Coal .. bento Cady Mens stale Seat cos OC & Fibrovascular Bundles of Vascular Cryptogams Eee aa igts oT tg) Saeag ke ON 2: Anatomical Structure. of Mosses..... bess Grete athe ie See oan ee a OOO _ Hybrid Moss -.. Sp gst aye eas Nee to OOS ¢ ‘ Localization of the Hymenium of Fungi . Pe NG a i ease ae US ol se ust hig ey IO S; ee Chemistry of Fairy-Rings”~ .. See es ate MEA ae ot, eo oe 1 OD. | Fungus- Parasites of the Aurantiacear Saba prise glist Awe Sheen: bat ee ay DD “ Ozonium”? pink ors fat lpia gage pe Atop algN SERGE et dee haw Oe ~ Harknessia ie oP : nis pe oe oe as on oe oe oe ee ONE og 540 _Lophiostoma carspitosum ak Sak aR eae Bs ota area ee: tere Roa a ORO .Oidium albicans .. ++ ect hi PME cap ee ae Save a OO ~~ Investigation and Culture of Pathogenous ‘Bacteria aienigestnas y EU dipr vee _- Earthworms in. Propagation.of Charbon seis. se ook ve ew oe nw OAL | Lransmission of Bacteria from the Soil into Hie Ag eins ais, Sige sow OEE ~ Fresh Method of: Vaccination for symptomatic Anthrax Deh ies whe eee ieee fae Particles in the Air of MG AMR Fe ans ee ly io ges, one RE & 55 ce i 22) Summary oF Current Researoues, &c.—continued. PAGE New Myxomycete.. 543 Structure, Development, and Liferhistory of a Tropical Epiph lous Lichen 544 Vegetation of Street Gutters... ws 545 Formation of Tetraspores.. 2 1 ee be te ue ee we gs eee ae, ORG. Reproduction of Porphyra. ia Shale ee ee Ree ete eee Cryptogamic Flora of Arctic Ice and Bide = oa ee eee Vaucheria-Galls .. .. >. Be pec ise che tab age pier ene Motion of Diatoms .. SoS Sid saa ae ee Fossil Diatoms of faze ia-H Hungary os. Naat} ae, ap hk var ge a a Diatom Types... EES LE BEES ONS See Microscopy. Bausch and Lomb Optical Co.’s New Binocular .«. Soci Sains Segue eee Fase’s Portable Dissecting Microscope (Figs. 91 and $2) arr sgor way OY Holman Lantern Microscope (Fig. 93)... 2, + 6 aE ta ete: Beast Ned 2 aE Nelson’e Studént’s Microscope (Fig. 94)... «. 04 Watson’s Portable Swinging Mirror and Substage Microscope Cig. 98) » Dot. Walmsley’s Photomicrographic Apparatus (Fig. 96) .. ne) Dae Hauer’s Photomicrographic Apparatus (Fig. 97) .. 1. se we ae we DOD Seibert and Kraf't’s Small Camera Lucida (Fig. 98). sie ae teat wegteOU Winkel’s Small Camera Lucida (Fig. 99) © .. 560 Correction of the Distortions produced by the Camera Lucida (Figs. 300-102) 560 Measurement of Microscopical Magnitudes (Fig. 103) 1. 1s) oe 567 Simple and Cheap Eye-piece Micrometer .. 4.0 ee ee ee ne we we 0 lelson’s New Nose-piece Adapter (Fig. 104) 50 aie Oy. tate ag ean eee Curties’ Nose-piece Adapter (Fig. 105) 2. ss - 62 ee ee ee we ee OTD Zeiss’s Stage-Micrometer (Fig. 106).. WEE RON Be ye Ts Queen’s Holder for Vieodet ss Prism n (Big. 107).. os eb ea” ies 3 ease ae Impromptu. Condenser oe RAN aie Fike ois) Illumination by Sunlight .. er awe i ee Blue-tinted Lamp Chimneys, Light Moderators, bie ay se ge ee Lhompson’s Polarizing Prism (Wigs. 108-112) = 6. ne we ee ne ie 575 Depth of Vision in Photomicrography . tc Piss ke Value of Photography in Microscopical Investigations ic Rede ee eT ee Abbe’s Refractometer (Figs. 113-116) «. Meir icy dis || Refractive Indices and Disper stve Powers dies Solids and Fluids .. ws 587 “ The Genus Microscopista” 5a ODM Sin os a ee Water Collecting-apparatus Cig 117). soi ape sos de ee ae ee Preparations of Coal... Rey ae aa age aoe es Cathcart’s Ether Microtome ig ig. 118) SF po twh blew haem eeance cet pte ee Glycerine Mounting Benne Bee no, eae 4 tae Ge ae <a ea ee Mounting Sections in Berks! Hox A i ai eyo tet, gon ee Sealing wp Preparations. so% ste nicest os ee) ag, eee pe Oe Opaque. Dry Mounts. scsi re fee aa eb se AP eh aR ane Examining Live Aphides .. -. pee Teer ee a YS Microscopical Examinations of Articles of “Commerce Pika Sew ee Ft. Microscopical Separation of Wheat- and Rye-meal i = dale hg ae Hunting for Lost Glaciers with a Microscope .. oe) Sant en See ee Microscopical Analysis of the Structure of Iron and Steel Fa. oo Se ae ae Microchemical Reaction Methods .. Mn haho vertts ne aoe eee Microscopical Examination of Dyed Bille pe on ie 607. ‘ Apparent Motions of Objects 2. se ed Sa ae aa ee de ee ee OB: ae Phenoinena of Motion (Fig: 119) > s.) ewe ees. Wa Nal ae ge Brownian or Pedetio Motion 0a. a Oe a Se a 8 Ra, oe ee, - o* - «, ad rd A * i 615 as - PROCEEDINGS OF THE Society a ROYAL MICROSCOPICAL SOCIETY. COUNCI TL. ELECTED 14th FEBRUARY, i883. PRESIDENT. Pror. P. Martin Duncan, M.B., F.B.S. VICE-PRESIDENTS. Ropert Brarrawarre, Hsq., M.D., M.B.C. S., F.LS. _. James Guatsuer, Hsq., F.RS., FRAS. _ CHARLES SrmwaRT, Esq, ILR.GS., E.LS. _. TREASURER. Lionen §. Braue, Esq., MB, F.R.C.P., EBS. SECRETARIES. Frank Crisp, Esq., LL.B, B.A. V.P. & Treas. LS. Prov. F. Jerrrzy Baru, M.A., F.ZS. Twelve other MEMBERS of COUNCIL. Joun Antuony, Esq., M.D., F.R.C.P.L. Atrrep Wii1AM BENNETT, "Esq, M.A., BSc, F.LS. Wauiiam Joan Gray, Esq., M.D. — Jd. Witt1am Groves, Esq. ‘A. ve Souza Guimarazns, Esq. Joun H, Inepen, Esq. JOHN Marranws, Hsq., M.D. Joun Mayan, Esq., Jun. Apert D. Micnarn, Esq., F.L.S. JoHN Mitiar, Esq., L.R.C.P.Edin., FLAS. ‘Witiiam Tuomas Sorrour, Esq. Freperick H. Warp, Esq., M.R.C.S. ROYAL MICROSCOPICAL SOCIETY. MEETINGS FOR 1883, at 8 p.m. Netiety JANUARY .. -.. 10 | Wednesday, May es - FEBRUARY .. 14 zs PUNE oe ok ee AD ” (Annual Meeting for Election of ie OCTOBER 52. 10 “Sater and Council.) @ NovemMBErR 14 oe ARCH : URS: 2 es “Avrin . ts : ‘ ri i DECEMBER .. Sa 37 THE ss ‘SOCIETY ” ry? STANDARD SCREW. “The Council have made ‘arrangements for a further supply of Gauges _ and Screw-tools for the “ Soomry” Stanparp Screw for Ozseorives. __.. The price of the set (consisting of Gauge and pair of Screw-tools) is ‘1s. 6d. (post free 12s. 10d.). Applications for sets should be made to the _ Assistant-Secretary. - For an explanation of the intended use of the gauge, see Jounal of the 3 bees I. ~- pp. 548- 9. : a I. Numerical Aperture Table. (26). The“ APERTURE” of an optical instrument indicates its greater or less capacity for receiving rays from the object and transmitting them fo the image, and the aperture of a Microscope objective is therefore determined by the ratio between its focal length and the diameter of the emergent pencil at the plane of its emergence—that is, the utilized diameter of a single-lens objective or of the back lens of acompound objective. This ratio is expressed for all media and in all cases by n sin wu, 2 being the refractive index of the medium Set u the semi-angle of aperture. The value of 2 sin wu for any particular case is the ‘numerical aperture” of the, objective. Diameters of the Back Lenses of various Dry and Immersion Objectives of the same Power ( in.) from 0°50 to 1°52 N. A. POSDSSSS SSS OSS COC OO OPER HERA Earth enim Be es i © 0°56 _ Examprr.—The apertures of four objectives, two of which are dry, one water-immersion, and one ole mm KA ~~ would be compared on the angular aperture view as follows eee (air), “ae (air), ne Hee 38 Sao actual apertures are; however, as pmmaneeint hohe Numerical | Aperture. (n sin U= a.) Dry Water- | Tomogeneous- Qbjactives: Immersion) Immersion abies | Objectives.! ‘Objectives. =) (m= 1-83), (w= 1°82.) + 180°. 0" | : 161° 23" | 153°.°39!" / 147° 42’ . 142° 40’ | ir 1389=12" aA 134° 10° | S 130° 267 | 126° 57” | : 123° 40’ ; T8080 28s GI 1165° 56’; 120° 33. | E55 B85) 1172 Bt! 148° 28’, 114° 44’ 1 7 eas 1 asp BS Bogie ts Yi, 137° 36"). 109° 20" 133°. 4’) 106° 45! 128°°55¢1.104° "15" | | Wa eaters oe praca A cae} Ds : 121° 26’| 99° 29’ 118°-.00' 9711" 114° 44’; 94° 56’ , 114° 365 | 2929343" 108° 36’; 90° 33’ 105° 42’) 88° 26' 1020.53! = 860-21 ae 100°. 10’; 84° 18’ 180%: 0 972 BLS. 82o Vit DOO OPO BOL FEL? 147°°-29'| 92° 24 1° *'78° -20" 140° 67 |. 89° 56’) 76°24") T8805! te OP Sz TAS SO }28°. 19!" |. 85°10"). 72° 36" $2389 07/21 82° 51) 70° 44 118° 38’ | 80° 34’! ..68° 54’ 114° TE |? 789-220 A= S672 =< 6 41092:10". 1-762 1 84. 65°: 18! 106°. 16’ | 73°58"). 63° 31" 102° 31"}..71° 49’|~ <61° on 98° 56’ | 69° 42"; 60° 0 95° 28": +672 BEH=* 58°. 16" 92° GF Ge a2 56° 32’ 88° 51’ | 63° 81’! 54° 50! 85° 41" |. 612-30"). 532: 99" 82° . 36’ | 59° 30’). “51° 28/4; 79°. 35") “57° Bl 49° 48%). 76° 38'-| 55° 84") 48° 9! 73° 44! | 538° 38’) ~46°°30’ 70°. 54’ | 51° 42’! 44° 51’ 68° 6 } 49° 48"| 43°14" | 65° 22' | 47° 54" 41° 37° 62° 40’ | 46° 2!) 40°°-0" 0’ | 44° 10’ 24' Angle of Aperture (= 2 w). 60° | @2) Preheat peel et el et et he et bed bel bed et Pet et DO DO DO DO HOD Cy Fs a4 Iilumi- nating | | Power, | bo ie) eH o 250 7250) Theoretical ~ Resolving Power, in Lines to an Inch. (A=0°5269 Me =line E. a 146,528 - 144,600 142,672 140,744 138,816 136, 888 134,960 133, 032 131,104 129,176 128,212 127,248 125,320 123,392 121,464 119,536 117,608 115,680 — 113,752 111, $24 109,896 107,968 106,040 — 104,112 102,184 100,256 98,328 96,400 94,472 Pene- -| trating Power. ” |@ EONae II. Conversion of British and Metric Measures. C1.) Linea. oe ieee ah gee Ree : Inches, &¢., int “Seale showing 3 Micronultimetres, §c., into Pe, &e, fi re ae the relation of Fs fas: te ins, | mm, ins. SC. : -Millimetres, | pe 039370 51 2°007892 ins. ee 8 “000079 | 2 “078741 | 52 2-047262 | 32, 1-015991 iam. oe ‘118111 | 53 2°086633 | "2 4.969989 m 3 000118 3 -126003 ZODEO oe se, 2h 4 -000157| 4 "157482 | 54 2 126003.) sb09 | 1° 698818 cm, ins. 5 000197 5 - 196852 a Bees sotoa «2°539977 ee: : 236223 |. 5 “2047 gona 2°8Y2197 ga : Sie ; -275593| 5'7 2244115) 2" 3.774979 : Feat) 8 -000315| 8 *314963 | 58 2°283489 | 72 3-698539 = A “00035 “3543 59 2°322855 | 1 -4-933995 | Be | -9 +000354}. 9 354334 | 5 360906 | 8090 * 23329 | | 10 -000894 | 10 (icm.) -393704; 60 Gem.) 2:3 ae bs Ee Veen a= -493075 |. 61 2°401 goog 8°3499 ee ee Se iE F| 13 000512 | 18 Lee eet le as soe er Sie 4 +000551| 2 ; teas : m. ere is -000591; 15 ~—--590556 | 65 STE oa 2 noesas lz zl | 16 -000630| 16 “629997 | 66 Bee er soon perero ER 17 -000669| 17 "669297 | 67 HIS eae fo allz =| 18 --000709 | 18 -T08668| 68 BRETT SOS gaeeas | Fa 1 748 : 2°716560 | soo ee =m | 19 000748 | 19 748038 | 69 z sic *050800 So ‘ ‘787409 | 7O(7em.) 2°755930 | so0 _ — [ee H 20 -000787 | 20 2 em:) *787 . heel aw ee = a : ‘ 826779 | 71 “7908 = “063499 - [Ee a ae ODOR eee -$66150| 72 2°834671 | 789 .072571 : Ls) z S93 000866 | 22 8 350 [ge | 93 -000906| 23 4905520 | 73 2874042 | 335084666 aed =n = 84 -000945 | 24 “944990 | 74 2°915412 — *101599 eld 25 -000984, 25 ~ —_--984962| 75 Bpoaiee | san. 5 126900 : = | 96 «001024 36 1:023631 | ‘76 2°992153 stp * 169332 feat] | a i ae item] S| a (OTR - -001102 | 28 1-102372 3°07 so - *007 Ee a -001142 | 89 1°141748} 79 3°110264 | 3 1-015991 |) ee Pa lke 001181 | 80 (8 em.) 1:181113 | 80 (8 em.) 3:149635 = 1-269989 = he E220 ee) 2 1587486 eal &| = 81 -001220) 81 1220483! 81 ORIN a aa c Ize jl 82° + 001960} 32 1.259854 | 82 3*228375 13 2°116648 : =F sae eo *001299| 3s 1299224 83- 3°267746 a= 2°539977 [Ee 34 -001339| 3 1338595 | 84 aca Seo Sxeaeee Si ‘IE « | 35 001378 | 35 1:°377965 | ~85 3° 346487 5 4933995 P| || 86 -001417| 36 1417886 fo SB esoe 86 qu qpodag ao)= Fi 87 001457. 37. +4567 Beers ae “07995 : lE z| i} 88 °-001496) 88 1-496076| 88 SS ES Bee es mia = L489: 1°535447 |, 89 8503968 Bie Oe = 001535 | 39 si | 89 4 2. 7:937429 a E z| | 40 -001575| 40 (4em.)1-574817 | 90 em.) 3°43339 | a5 9+524915 = ee AT -001614| 41 1‘614188 91 ~-3:582709 S em. 3 E z| -42 +001654| 49° 1°653558 92 3°622080 qe 1.111240 . | TSEH | | 483. -o01693| 43 1-692929 | 98 BOBTIO | oy 5 11269989 IBALL | 44 coisa | aa 1°732299,| 94 3°700820 | 9 1-498737 Ag a8 | 45. -001772) 45 1:771669 ; 95 - 3°740191 e 1°587486 2Oe % rE —] | 46 --001811- 4e 1:811040 $6 : = 48°71 9001 32 1°746234 3 | 47 ~-001850! 47 1°850410 | 97 BD 818092 fet So oT 904 9RS an lee 48 -001890| 48 1:889781| 98 pe 808302) 38 -2- 063782. fe rE ‘| || \ 49 -901929| 49 1-929151| 99 8°897673| 7 -9-999480 [TERI] 82 002802) 20 Gems 268022 10040 em—1 deem) 3 Eset pee 60002868 se 2 5079954 _ if lee S70 + :002756) deci. ins 3 7:619932 * fF =H 1 80 -003150|. - - 4 3-937043 wae 1B4 ~ {90 +003543 2 _7°874086 4 1-015991 - JET | | 100. 603937) 3 11-S11130 | 5 1°269989 gles 200 -007874 | rs 5 hota BITS 6 1°523986 | SB COO 2 OUI SEE eas ot iy eye AS GSD 216 Tia EST TOS Be || 400° -015748 | “6 23 622259: 8 . 2031982 ee 600 -023622) 8 31° 496346 Uisirey See(iped Ssccn ae 1000 p m. || 700. -027559 | 9 35°433389 | 1 2:798975 (10mm=tem. | 800 -031496; - ——_- 10 metre) 39-370432 1 ft. 3047973 = 10cm, =1dm. |} 900 035433 | ae : = 3°280869 ft. oe ‘i 10 dm, =1metre.| L000 C—inm). i cogebe ass: else *sommmvaZory VO Be eee eh ee eed, E6GECch. = ‘ ; ey 4 LEGGE -F (qi D 000L 3 ? i “saurUITAS0}00q 029F0Z-% Cas0qry 1) ~— ss ON00T : ; 2 gd oe Os aieene coin om 760/708 (-asoyo0y 1) 000T | j “SsouLLUBavOOp *“TIOAG 5 : i j ‘ D3 GO8G6LP-9 00L 6ELZGE: (-a3voap 1) 001 "SOIT FSCSES-F = CUPS 1) FLZ-LL2 ‘sqT83 T600GZ- = *SOULTBIS "MOAR 'Z0 299889-T OOL ‘squid $ZL09L-L = : S686LF-9 Or 6FSEEP- ST (18 T) OT OGLELE +L > 06 ots iS 906188-¢ 6 FII688- ST 6 OS601$+1 08 JAN STSSE0. = 9T6E8T-g 8 6LSGFE: ZL 8 PIOLFL-L OL L8E¢0- 19 (oxntT iu 000T LO6SES-F L F908 - OL die tae ‘OTL 848626 - FS 006 LE6L88..¢ 9 60T6S6-6 9 FLOTES +6 09 60028: SF 008 8h66ES- ¢ FLIOTL- L ¢ TIS&6I-8 0S TLLLIL-+GP : 00L SOGT6S-3 - 686ZLT-9 ¥ 6PIFSS-9 OF |: BESST9-9E : 009 6968F6-T g C0L629 -F € LS6G16-F 0g E69GTS-0E 00¢ 6L6962-T va OLF980-E G GCELLE-S 0% CCLOLF:+ 4% . OOF “somuel3 {0p CEGEFS- 1 » 1 699889 -T OL 919L08-8T 00S CES6LE-9 I “ Soe aia 9GLELE 6 LLOGOG-ZI 008 —~ 900T88-¢ 6: (‘1s100p 1) O0T OSGOTE-T 8 6620-9 Cep 1) OOr 916E81-¢ wi Qs LI688&-T 06 POOLFEL-T L C86C6P-G 06 CO LZ6Ge¢-F L- S8Cbes- 1 08 *so.yoop IE0Z88-F 08 LE6L88-§ 9. $92080-T OL FLOTES +6 9 LLLILZ'F OL —“- SF66ES-8 ¢. LP6S66- Of LISe6L-8 ¢ €ZG199-¢ 09 SS616E-% F- LIOTLL- 0S 6PIPLS-9 F 69Z1C0-S 0g 696E46- €- F6GLIO- OF L86S16-% g CLOLFE-S OF 6L6964: G: OLGGIF- 0&€ CCSLLE +E a ZILOES-T 0g 5 “‘seuTMBLd}IUBO L¥9808- 0Z Z99889:T if 8060Z2- 1 02 C68G6LP-9 I: SZEhSL- (-151)090 [) Or OGLELE-T 6 FOGOL9- CHMOD T) OL 9U6TE8-S 60+ T688é1- 6 OS60LS- T 8 SZZ6FE- 6 : 9T6E8T-S , 80+ 6CFSZL- 8 POOLFL-T L E0Z88F- 8 LG6GES-F LO- 9Z080L- L *so.1}{[1U00 SLILGF- : L LE6L88-§ 90- $69660- 9 PLOTES-6 9- ZEL99- 9 8h66ES-S co. G9ITLLO- ¢ LI€S61-8 Gg. LOLS0s ¢ SC6I6S-% F0- 66L190+ F 6F9FSS -9 F- GOLPEZ- t 6968F6-T &0- L6Z9FO- € L86S16-% § 9LOG8I- S$. 6L6666-T G0- C98080+ oS CCSLLG-S Ge TS0Z6L- 3 686LF9- 10. ZEFSLO- I 299889 -T I: 5 - €Z0T90- 5 WK : *SOULUIVT] | [TOL ‘survIg *SULCAD *SOMMUUIRAD TUL *sougtTT| [var + ‘sur ‘qno “sup "quo “SOIPIT I [Lat ‘of ‘soummpubyyipr o7ur “of ‘sway "of ‘summiy ojue “of ‘somumibyppe ‘of Ssoummupyg opur “op ‘soyour ongn9 ‘of ‘savour ongn9 on “op MENTE. i “LHD AA (*g) - *KBIOVAVO (") By Rie Wem ere ‘ponuipuoo—SOINSBOTT OTIION PUB YSTIIIG JO MOTs1eATIOD C3) III. Corresponding Degrees in the IV. Refractive Indices, Dispersive Fahrenheit and Centigrade Powers, and Polarizing Scales. Angles. Fabr. Cane Fahr. (1.) Rerractive INDICES. 500 100 2120 FoR 98 208°4 Diamond 400 96 204°8 350 94 eee ecm sates 800 92 197-6 || Bisulphide of carbon ea ae 194°0 || Flint glass 190°4 210 86 ieee. || CAOwn glass se 84 183+2 || Rock salt 200 82 179°6 1 195 80 Hee 190 73 172-4 || Linseed oil (sp. gr. +932) 185 76 1688 || Oil of turpentine (sp. gr. 885 180 74 105935 ue ey reas 12 72 161°6 im 2 on 1 70 158-0- ea water &D 165 68 154°4 A 160 66 Dee ee 4 155 64. 147-2 || Air (at 0° C. 760 mm.) a 150 62 143°6 B en et ee (2.) Dispersive Powers. = 135 56 prdsa-8 a 130 54. 129-9, || Diamond g 125 52 125-6- || Phosphorus Ps 120 50 122-0 tae : 2 115 48 119-4 JI of carbon 3 110 46 114°8 Flint glass @ 05 44 111-2 Crown glass S 100 42 107°6 Rock a 95 40 104 0 rae 3 90 38 100°4 Canada balsam = ep og 86°8 || Linseed oil (gp. gr. 932) $ w5 : 39 89°6 Oil of turpentine (sp. gr. *885) 2 0 ; . oO oe) Be BE ate : "06 26 78°8 Si 32 es : O44, 75:2 || Pure water : s 50 22 TG W Rape eee @5 +22 - 20 68°0 B24 40 Bie ae = 18 64°4 (3.) Pouarizina ANGLES; eS, oo "67 | = ' 60'S f ; 1 57°2 4 ~ Diamond ° 30 pEt 12 53°6 eS 25 - ‘ 10 - 50-0 |} Phosphorus | OO + i Pe re 46°4 || Bisulphide of carbon 15 ; 6 42°8 eA 10 ; . AG 39-9 || Flint glass. 5 — 15° 2 35°6 || Crown glass i Eel} ; (8) 32:0 : a BS . BIE eS 98-4 Bock salt —~ 10 . axe ye 6 24-3 || Canada balsam Ee BR OU Se, PLR | Limseod oll. Gp gr, *282) 2 — 25 : Seo. 44-9 || Ou of turpentine (sp. gr. *$86) - — 80 : — 12 10:4 || Alcohol as oy aa i —- 14 68 || Sea water — — 40° * -— 16 a Ry Ge —~45 —42:781 — 18 “_ 9:4 || Pure water —-50 —45°56| —-20 = =4:0 || Air ( 10 ) V. Table of Magnifying Powers. ME OBJEC- TIVES. | | Beck's 2, Beck's 1, | Powell’s 2, Powell's 1, and | Ross's A Ress’s B, f nearly* | =) Set 5.8 a : > z 1 2in, i; in =} i wo} Bf xR ot oF ee S ‘= i = | Lal Ld alm rts) Ol if b teat a om ge ah ot ho te soe 4 rs iE i ti Be SR: FD | fi io + ele e+ oh th. She EYE-PIECES. , ae 2 Beck's 4, Beck’s 5, = ae Powell's 3.} Ross’s C..| Beck’s.3, eth Ross's E. | Powell’s 5. Ross’s F. sss D. i | Focat LENGTH = < a. = = I<; | lin Zin. | gin. | din. | om | bin | Fin s | 1 | 10 | 1 Macniryixnc Power. 15 20 | 25 | 30 | 20 2-10 15 22 123 183 Si 162 25 5 25 373 6s]. 82 50 10} 50 75 123} 622 933 18:] 662} 100 15 1 75 11223 20 | - 100 150 25 125 1873 30} 150 225 33:] 1662 | 250 40} 200 300 50 4 © 250 75 60 4 300 450 70-4 350 525 80 } 400 600 80 i 450 73 100 500 75 110 | 550 $25 120 }- 600 900 180 }. 650 975 140°} 700 |} 1030 150} 750. | 1125. 160 | 800 | 1200 170 | 850 | 1275 180 4 900 4} 1350 190 | 950 -}- 1425 200 } 1000 | 1500 250-4 1250 | 1875 300 | 1500 } 2250 400 | 2000 {> 3000 500 | 2500 | 3750. 600 } 3000 | 4500 6000 COMBINED. 25 | 30 40 312 Siz 5 412]. 50 663 623 75 100 832 4 100 1332 125 | 150 200 1562 | 1873-4 - 250 1663 | 200 2662 1873 | 225 300 250 300 400 3123.|° 375 500 375 450 600 4162 |. 500 6662 500 600 800 625 750 J. 1000 750 900 -} 1200 875 | 1050 } 1400 1000. | 1200° | 1600 1125 | 1350 4 1800 1250. | 1500 § 2600- 1375 | 1650 | 2200 1500 | 1800 | 2400 1625. | 1950] 2600 1750 | 2100 | 2800 1875 | 2250 | 3000 2000 | 2400 } 3200 2125 | 2550 | 3400 2250 | 2700 | 3600 2375 | 2850 | 3800 2500 | 3000 | 4000 3125 | 3750°4 5000 3750 | 4500 | 6000 5000. | 6000. | S000 6250. | +7500 | 10000 ~ 7500 | 9000 } 12000 . in 16000 * Powell and Lealand’s No, 2 = 4, and Beck's No. 2 and Ross's B=8 x PERS Vy EM SE aS a ate eee ee AMPLIFICATION OF OBJECTIVES AND EYE-PIECES | “ 60 80 75 100 100 1332 150 200 200 2662 300 |. 400 375 500° * 400 5332 450 600° 600 800 750 $ 1000 — 900 | 1200 ~ 1000.-| 13333 - 1200. | 1600. 1500 2000 - 1800 “}- 2400" — 2100 | 2800 — 2300 | 3200 2700 | 3600 . 3000} 4000 — 3900 | 5200 4200 | 5600 ~ 5100} 6800". _5700 | 7600 ~~ 6000 | 8000 - 7500 | 10000 (H) W. EMIL BOECKER, MANU FACTURBING OPTICIAN, WETZLAR, GERMANY, SENDS GRATIS His CATALOGTE OF MICROSCOPES, CEJECTIVES, MISEOCTOMES, AND APPALATUS FOR SCIENTIFIC RESEARCH. Heinr. Boecker’s Microscopical ss ai Weizlar, Germany, MICROSCOPICAL | PREPARATIONS Se aff branches: of Natural History. * Loree Seleetion of Tnjesionm, Stained Preyerstions. Dnsex. Sane, Entezoa, and Lower Animals; Wezetabiec nation, Wands, Sriudes of Pai. Sie, Wosses:, Foot. Dietoms: and Sections: oi Rueks and Possiis. fnsiruments andi Spniienees for Wennting, & inion, wits aii fiom for using micrescapit: aijectives. Glass: Piotagrams: Ceteloeuc Wa. ES, Gratis end Post-fee, FRED. ENOCK, -. Prerasee oF Inseers, ann Pxeds oF Issecrs, Foe THE ‘Mics ceOScoS=, Wire ann Wireoot Peessuce, THE LATTER RETAINING MATURSL FORM 2ND COLOURS FERNDALE, WOKING STATION. JAMES HOW & CO. SUCCESSORS FO CEQ. MONET & SOs, ‘73, FARRINGDON ST. ( ie of 2, Foster Lene, ami 5, St. Heide St), BOWS MICROSCOPE LAW THE WINDATUSE WCROSUPS Liaw BOWS STUDENTS WICROSCUPE, 35 3a. THE POPULAR BEMOCULLE MEROSPE, 222 Eee. Reex Skemers ana erm Nircrosenen: Gasmem. THE BRITISH MOSS FLORA. By BR. BRAITHWAITE, MD. Parr VIL is now ready, price Gx Subscripts (ide Gd) may be sent to the The previous Parts may be had fom the Suthor, at 30%, Chgiem Rand, Lando -- HOW TO WORK WITH THE MICROSCOPE. goal BY -EfONEL S BEALE, ERS. pate a we TAR FEFVTE BWHIFICE = ~ Strongiy Bound and enierse:i te Sa paces: with Dow Pintes:, some of whith: are Chior. ADVERTISEMENTS FOR THE JOURNAL. ae Mr. Ozszuxs Brascows, of 75, Chancery Lane, WC. et ( 12 ) CHARLES COPPOCK (LATE PARTNER WITH R. & J. BECK), 100, NEW BOND STREET, LONDON, W. OPTICIAN AND Manufacturer of Scientific Instruments INCLUDING MICROSCOPES. | 7 ASTRONOMICAL AND. OTHER TELESCOPES. STANDARD AND OTHER METEOROLOGICAL INSTRUMENTS. CLINICAL THERMOMETERS. OPERA AND FIELD GLASSES. SURVEYING, NAUTICAL, and DRAWING INSTRUMENTS, including ARTISTS’ MATERIALS. CPHTHALMIC. INSTRUMENTS. SPECTACLES AND EYE-GLASSES. READING GLASSES. HAND MAGNIFIERS. STEREOSCOPES. POCKET AND CHARM COMPASSES, &c. N.B.—AGENT FoR R. B. Totes, oF Boston, Mass., U.S.A. 3 W. H. BuLLocu, oF CHicaGo, ILLs.; U.S.A. EA H.-R. Spencer & Co., N.Y., U.S.A. 7 JAMes L. PEASE, MAss., U.S.A. 35 M. PRAZMOWSKI (Late HarTNack & PRazmowski), PARIS. af M. A. NACHET, Paris. OGULISTS’ PRESCRIPTIONS RECEIVE PERSONAL ATTENTION, 100, NEW BOND STREET, LONDON, w. ae JOURN.R.MICR. SOC. SER.I.VOL.IM.PL. VI. 6 7s Edwin Wilson, del ev licr. " Spicules of Cueumana hyndmann, | C.caleigera & two alhed forms ‘ -PEAILN ew AUvVM\ HOWE AT: nope OF THE UVARDEN ROYAL MICROSCOPICAL SOCIETY. AUGUST 1883. TRANSACTIONS OF THE SOCIETY. X.—On the Spicules of Cucumaria hyndmannt, C. caleigera, and two allied forms. By Professor F. Jerrrey Betz, M.A., Sec. R.MLS. (Read 13th June, 1883.) Puate VIII. Tue descriptions given by earlier naturalists of the characters of species of Holothurians lack the precision and exactness which has been possible since the year 1844, when Diiben and Koren in their classical essay laid a solid foundation for systematic discussions, by giving an account of the characters of the microscopic spicules which are found in the body-wall and the suckers of this group of Kchinodermata. No competent zoologist has since then failed to make use of the weapon which the great Scandinavian naturalists put into our hands; the only possible difficulty, indeed, that presents itself to the mind is as to whether we are not here committing the same kind of error as that which has been seen in many other depart- ments where too much stress has been laid on a single character or set of characters. As a matter of fact, however, we still require a very large amount of definite information with regard to a number of forms, and that even with regard to some of the best-known of the species of the Northern Seas. Among those treated of by Diiben and EXPLANATION OF PLATE VII Fic. 1, 1a. Spicules from body-wall and suckers of Cucumaria hyndmanni. bb 2, 2a. ° 4 35 C. calcigera. » 93, 3a. x pe x Cucumaria sp. » 4, 4a. 3 C. montagui. CAM x 220.) ” Ser. 2.—Vot. III. Fa 482 Transactions of the Society. Koren was Cueumaria hyndmanni, and those authors may well have thought that, with Forbes’ figure of the external appearance, and their representations of the spicules, the characters and limits of that species, at least, would be placed beyond doubt.* This, however, was not to be; in 1857 Dr. Liitken described a “ new species ” which he dignified by an association with the name of Koren, and of which he said that its apparent resemblance to C. hyndmanni was opposed by the great differences in the characters of the spicules. In 1868 Professor Semper, in his great and classical work on the class, expressed the opinion that the differences in the spicules are very slight, and he proposed to unite the two species, with one of which—C. koreni—the earlier C. calcigera of the American naturalists is, in Litken’s own opinion, identical. This view has never been accepted by such investigators as have independently discussed the question since; Marenzeller, for example, enters into it at some length, and comes to the conclusion that C. hyndmanni and C. koreni are to be distinguished from one another. Our President and Mr. Sladen have some brief notes on the point in their work on Arctic Echinodermata, and though they give and are, so far as I know, the first to give figures of the spicules of C. calcigera, they do not in them direct attention to the characters which have most attracted my notice. Nor do Diiben and Koren give a representation of so well developed a spicular plate from the integument of C. hyndmanni as is to be found in the accompanying drawing (plate VIII. fig. 1). I wish to direct attention to the drawings of the spicules from the integument and from the suckers, first of all in a general way, as illustrating the characters and kind of the differences that there may be between two forms of whose specific distinctness there has been some doubt. In the next place, we may observe that the external thickness of the skin would appear to have some direct relation to the thickness of the spicules within it, the skin of C. hyndmanni being quite opaque; but this must not be assumed to be a truth that is to be stated without some kind of qualification ; an inspection of the figures of the corresponding spicular plates of C. caleigera shows that the tenuity of these latter is, as in some other species, in part made up for by their being to some extent laid over one another. While figs. 1 and 2 are representations of the plates that are found in great abundance in the general integument of the body, la and 2a show the supporting rods from the suckers, and bring to the mind the observation of Liitken that the rods of C. korent differ more among themselves than do those of C.hyndmanni. Itis * It is, however, to be noted that while Diiben and Koren say that Forbes’ figure of C. hyndmanni is “bad,” the specimen from which the spicules here described were taken exactly correspond to Forbes’ representation. Spicules of Cucumaria hyndmanni, &e. By Prof. Bell. 483 impossible to forbear from some attempt to find an answer to a ques- tion which arises out of this remark, and which, being put generally, may be thus expressed. How is it that in two allied species a . characteristic exhibits in one case constancy, and in the other variability? A closer examination of the one now in question seems to me to show us (a) that there is more variation in C. hynd- manni than we should have been led to expect, and (@) that C. calcigera (C. korent) has greater opportunities for variation, thanks to the greater elaborateness of the spicules now being dealt with. So far, I have endeavoured to direct attention to the specific differences between, and to draw such inferences as are most obvious from the plates of these two northern species. This is neither the suitable time nor place for entering upon the detailed examination or recapitulation of such other points in the external or internal anatomy, or in the “synonymy,” which are important to the systematic zoologist, but have no bearing cn any sort of problem that is presented to the microscopist. Yet another form of defensive spicule is to be found in a specimen in the British Museum, which is registered as having come from the coast of Jutland; presenting several points of resemblance to the Cueumaria tergestina of Sars,* it is, strange as it may seem, distinguished from it by the smaller size of the plates in the integument ;f while I cannot feel that we should be at present justified in uniting it with C. elongata; at least if it belong to that species the spicules of that “type” must vary con- siderably in different individuals. The last set of spicules which I shall have to mention are those here grouped as parts of fig. 4 a—€; they are taken, as are the two which are marked 4a, from one of the specimens collected by Colonel Montagu, which was in Leach’s collection, and was mentioned by Dr. Gray in the catalogue of British Radiata, under the title of Holothurra decollata. 1 had hoped by an examina- tion of the spicules of this example to be able to set at rest the very difficult questions that surround the determination of the name of this form, which may conveniently be still called C. montaguz; it will be seen, however, by the series of figures given, that during the seventy years or more that this specimen has been preserved it has been undergoing some slow kind of maceration, in consequence of which its spicules have become gradually broken down, and a curious “dumb-bell” shaped form becomes the most prominent, and apparently the most characteristic ; a similar kind of change seems to have affected the rod-shaped spicules in the suckers (fig. 4a), It is difficult to understand how this very gradual * Middelh. Fauna, p. 127. + The largest of those here figured is nearly a quarter of a pase long. I 484 Transactions of the Society. change has been brought about, but it is important to notice it, for the appearances are sufficiently well marked to be very decep- tive ; and it is the more difficult to explain when it is known that a specimen, also from Montagu, still exhibits quite clearly and well the spiculation of C. doléolum, while yet another which has not been in spirit for thirty-five years has the spicules broken down beyond recognition. Too much trust must not, therefore, be placed on the Micro- scope as a means of determining the specific relationship of some of the forms described by naturalists who did not themselves make use of this weapon of research ; unless the greatest care is per- sistently taken in the preservation of specimens, the dermal and hypodermal layers with the concretions therein developed may become broken down or altered. Indeed, at present, no time could be more usefully spent by a microscopist than that which should be devoted to the careful study and description of even the spicules of the British species of Holothurians ; for the worker of to-day the descriptions of Edward Forbes are found to be in- complete and unsatisfactory, in consequence of the total lack of information concerning these important structures. ( 485 ) XI.—On a Method of Preserving the Fresh-water Medusa. By Peter Squire, F.L.S. (Received 9th July, 1883.) Tue freshwater Medusa (Lemnocodium Sowerliz) found in the Victoria Regia tank at the Botanic Gardens, Regent’s Park, is a singularly beautiful object (see fig. 90). As I learnt from Mr. Sowerby that all attempts to preserve it for future observation had failed, 1 was induced to make some experiments in this direction. Various antiseptic media, such as Goadby’s solution, and solutions of glycerine, kreosote, and many other things were tried, but in no case was the result wholly satisfactory. Before giving the matter Fig. 90. up, I thought well over the structure of the animal, and its prob- able chemical constitution, and it occurred to me that, if albumen was chiefly concerned, bichloride of mercury would render it opalescent and less liable to change. Accordingly I plunged the creatures into very dilute solutions of this reagent (2 grains only in a pint of 20 oz. of distilled water). The result fully answered my expectations, and the animals were completely preserved, and in a form which makes them more easy of examination than when living. Their bodies being rendered opalescent, the minutest details become apparent, while during life the animals are so transparent as to be scarcely visible. In order to guard against failure I have since increased the strength of the solution to 4 grains in the pint. To obtain good results several precautions are necessary. As the animals live in water at a temperature of 85°F. it will not do to plunge them into a cold solution of bichloride, nor into a strong solution evenif warm. In either case the animals appear to sustain a shock. They shrivel up at once, and the specimens thus preserved have little resemblance to the living creatures. The solution must be previously raised to the temperature of 85° F., and its strength must not exceed 4 grains to the pint. The animals are best conveyed into it by means of a glass tube acting as a pipette. Under these 486 Transactions of the Society. circumstances the animals continue to live for some ten or fifteen seconds in the preservative medium, making their characteristic movements, and retaining after death their normal figure. To perform the operation described, I have used in my experi- ments test-tubes about 4 in. in length by } in. in diameter, each fitted with a new cork. Great care should be taken to use new tubes and new corks. These are filled with distilled water, and allowed to remain for a few days in a horizontal position. In all those cases in which the distilled water appeared to become coloured by caries of the cork, the corks were rejected and fresh ones substi- tuted. One of these tubes thus prepared is a little more than half filled with the bichloride solution, and the animal is conveyed into it with the pipette. After the death of the animal, the tube is allowed to lie horizontally so that the creature may be fully exposed to the action of the whole of the solution present; in the vertical position, the specimen would remain at the bottom of the tube in contact with only a small quantity of the medium. [Mr. Squire has sent us some test-tubes containing Meduse treated by his method. They fully bear out the claim he makes to have discovered a process by which the animals are preserved in a most effective manner.—Eb. | G 487} SUMMARY OF CURRENT RESEARCHES RELATING TO ZOOLOGY AND BOTANY (principally Invertebruta and Cryptogamia), MICROSCOPY, &c., INCLUDING ORIGINAL COMMUNICATIONS FROM FELLOWS AND OTHERS* ZOOLOGY. A. GENERAL, including Embryology and Histology of the Vertebrata. Early Stages of the Guinea-pig Ovum.j—Graf F. Spee has published the results of his observations on this subject. Up to the beginning or middle of the fourth day, the ova remain in the oviduct, whence they ntust be carefully extracted. Eges of two days have four segmentation spheres, around and between which a coagulated mass soon appears post mortem. On the third day the limits of the cells are unrecognizable; but they may be more or less isolated by bursting the ovum. After the fifth day, the coagulum no longer appears around the segmentation-spheres. In all the early stages post mortem changes are very great and rapid. While still free, after the fourth day, the ova lie in the tip of the uterus, whence they may be driven by forcing with a syringe a current of warm 0°5 per cent. salt solution into the vagina, and out of the tip of the uterus (after cutting off the oviduct). By employing this method, Spee has obtained germ-vesicles agreeing essentially with corresponding stages as found in other mammalia, the principal difference being that the cells are relatively larger, segmentation not having progressed so far. There is an outer wall close against the zona pellucida, and composed of a single layer of cells, spindle-shaped when seen in section, polygonal when viewed from the surface. At one pole is an accumulation of cells, the Keimhiigel, while at the opposite pole the cells at the outer layer are thickened. In a later stage the cells of the latter pole are found to have thrown out branching processes which penetrate the zona pellucida. Apparently these processes increise in size; and it is * The Society are not to be considered responsible for the views of the authors of the papers referred to, nor for the manner in which those views may be expressed, the main object of this part of the Journal being to present a summary of the papers as actually published, so as to provide the Fellows with a guide to the additions made from time to time to the Library. Objections and corrections should therefore, for the most part, be addressed to tue authors, (The Society are not intended to be denoted by the editorial ‘‘ we.” + Arch. f. Anat. u. Physiol, Anat. Abth., 1883, pp. 44-60 (1 pl.). Cf. Science, i. (1883) pp. 406-7. 488 SUMMARY OF CURRENT RESEARCHES RELATING TO probable that they make a hole through the zona by which the egg makes its exit. Spee has actually found, in one case, an empty ruptured zona. This is an important and interesting observation, because the fate of the zona pellucida has not been hitherto determined. Spee adds the suggestion that possibly the same protoplasmic processes which serve to free the egg, also act to fasten it to the wall of the uterus. As a continuation of Spee’s paper, V. Hensen* describes an ovum, soon after attachment to the uterine wall, found six days and twenty- three hours after copulation. The egg (0°13 x 0:08 mm. in diameter) lay in an open pit of the mucosa. It consists of a vesicle, with a mass of cells on one side, therefore agreeing in structure with the latest stage of the free ovum seen by Spee. Formerly Hensen considered the mass of cells to represent the ovum, and the wall of the vesicle to be an outgrowth of the epithelium of the uterus; but he now with- draws that interpretation, and accepts Schafer’s view that the whole is ovic. “The vesicle is therefore the single-layered primary chorion, which is derived from the ectoderm, and is separated very early from the embryo proper. In other mammals this separation does not occur until after the formation of the amnion.” The ectodermal cells of the germ-mass of the embryo come to form a hollow, and this hollow Hensen homologizes with the amniotic cavity of other mammals. Of course, therefore, it is bounded by the ectoderm, and, beyond that, by the endoderm. The apparent reversal of the layers is therefore due to the early development and peculiar position of the amniotic cavity, inside the ovum. In conclusion, Hensen insists upon the importance of showing that the histological value of the germ-layers is really preserved, even in so unusual a form of develop- ment as that of the guinea-pig. Activity of the Yoik during Impregnation.t—C. Kupffer recalls the active movement of a protoplasmatic prominence on the surface of the ovum of Petromyzon, observed by A. Miiller, Calberla, and him- self, immediately after the spermatozoon entered the yolk. He now reports a similar observation on Bufo. In this animal. several spermatozoa enter the ovum; but those that reach the egg a few minutes after spawning are not able to pierce the egg-membrane. One then sees little protuberances arise on the surface of ti:e yolk, and stretch up the membrane. Opposite each protuberance are one or two spermatozoa, their heads towards the yolk. It appears as if the yolk were actively striving to reach the spermatozoa. In a few minutes the protuberances sink back. In both Bufo and Petromyzon there appears this secondary act of impregnation after the male elements (or element) have penetrated the yolk. Germ-layers and Gastrula of the Mouse.t—In some rodents the germ-layers have apparently a position the reverse of that in other animals. This fact has led E. Selenka to investigate the early stages of * Arch, f. Anat. u. Physiol., Anat. Abth., 1883, pp. 61-70 (1 pl.). ~ SB. Akad. Wiss. Miinchen, 1882, pp. 608-18 (1 fig.). f Biol. Centralbl., ii, (1883) pp. 559-8 (9 figs.). Cf, Science, i. (1883) p. 407. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 489 white mice in the search for the explanation of the reversal. He has published a preliminary notice of his results. There is a special envelope of covering cells within which the cells of the embryo proper undergo their development. (This is perhaps the stage described by Spee—supra—in the guinea-pig, as a vesicle with a clump of cells at one end.) The embryo-cells lie at one end, separate into the two primitive layers, and become united with a support formed by a knob of cells attached to the uterine wall. This knob is not used in the construction of the embryo. ‘The mass of ecto- derm-cells becomes hollow, and the cavity increases in size. In the ectodermal cells limiting it, the ectodermal organs of the embryo are developed according to the typical processes in other mammalia. Embryology of Mice.*—The observations of Selenka and Kupffer on the development of mice have been critically reviewed by V. Hensen. He does not accept their views as to the gastrulation, or that the formation of the cavity bounded by the ectoderm is the gastrula development. Selenka attributes the reversal of the germ-layers to the proliferation of the ectoderm-cells ; but Hensen maintains it to be due to the invagination of the mass of cells forming the embryo- germ. The ectodermal cavity in Arvicola does not correspond, as would seem natural, to the amniotic cavity of the guinea-pig; for an amnion is subsequently developed in its interior. (Does not this rather indicate that Hensen’s homologizing the ectodermal cavity in the guinea-pig with the amniotic cavity is erroneous, and that it is really the same as the ectodermal cavity described by Selenka and Kupffer?) Finally Hensen discusses briefly the position of the germinal disk in guinea-pigs, and compares it with that of rabbits. Embryology of Rodents.}—J. Paladino gives the following résumé of his results, and, as they have a slight priority of publication over recent German papers they deserve especial attention. The whole cylinder formed during the first developmental stages of certain rodents is the embryo, and it is implanted on the decidual new formation by the caudal extremity. This is proved especially by the fact that it is this part from which the allantois arises. The cylinder, and the vascular portion of the decidual new formation, are continuous, and so remain throughout gestation by means of the vessels falsely called omphaloid. The decidua forms not only the placenta, but also the first envelope around the embryo,—the chorion, falsely so called. (This is in direct contradiction to the latest opinions of Hensen.) Between the embryo and the decidua is a large space, filled at first with blood, which Paladino thinks is probably pro- ducéd by the metamorphosis of the granulosa cells discharged from the Graafian follicle along with the ovum (!). Origin of the Vertebrate Mesoderm.{—G. Romiti discusses His’s view that the mesoderm has a double origin, in part from the primitive streak, and in part from independent cells, which His calls para- * Arch. f. Anat, u. Physiol., Anat. Abth., 1883, pp. 71-5. Cf. Science, i. (1883) p. 407. + Arch. Ital. Biol., ii. (1882) pp. 363-7. Cf. Science, i. (1883) p. 525. } Ibid., pp. 277-9. 490 SUMMARY OF CURRENT RESEARCHES RELATING TO blastic, and thinks derived from the yolk, and destined to form the connective and vascular tissues. Romiti admits the double origin, but maintains that the independent cells are derived from the germinal portion. The cells in the periphery of the mesoderm are derived “from the proliferation of some large cells which have emigrated from the segmented germ, and lie between the primitive layers.” Histology of the Ovary of Mammals.*—W. Harz finds in the ovary of mammals structures of an epithelial nature, which have the form of massive cords, of canals, or of groups of cells, which are all distinct from the structures of the germinal epithelium. These epi- thelial structures in the ovary can, however, only be derived from one of two sources; they must either be developed from the germinal epithelium or from the segmental system. It would appear to be certain that the canals and epithelial cords arise from the mesovarium and only pass at a relatively late period into the stroma of the ovary. In some cases, indeed (man, pig) remnants of the structures persist in the mesovarium or in the region of the hilus of the ovary (sheep) ; and this is a conclusive proof that they are not derived from the germinal epithelium. This view is supported by the statement of M. Braun, who has directly observed the passage of epithelial cords and canals from the wall of the glomeruli of the primitive kidneys into the rudiment of the genital organ. In some mammals the structures in question are not always rudimentary, but become exceed- ingly well developed (hare, horse, &c.); and between the two condi- tions, presented by the pig and the horse respectively, we have an intermediate arrangement, such as that seen in the cat or the sheep, where cords or cell-groups of epithelial nature are found extending some way into the ovary. The author is led to doubt the accuracy of the view which ascribes to these epithelial cords any share in the formation of the membrana granulosa, and he does not believe that the segmental cells have any part in forming the corpora lutea. With regard to the mechanism of the migration of the ova Harz believes that some attention must be given to the fact that a primor- dial ovum, before it sinks below the surface of the germinal epithelium, becomes overgrown by epithelial cells; this epithelial investment may perhaps exercise a pressure on the egg-cell, which is an agent in the movement. The albuginea appears to have a regulative action in this function of the germinal epithelium, for so long as primordial ova are being actively produced, it is non-existent; in connection with this we must remember that the albuginea is very poorly supplied with blood-vessels. The segmental tubes of the calf and of the cat call to mind the ovarian tubes figured by Pfliiger, and lead to the idea that this author’s ovarian tube is in part a development from the segmental system. Where genital rudiments are feebly developed primordial ova may be observed in those segmental tubes which are closely con- nected with the germinal epithelium. * Arch, f. Mikr. Anat., xxii. (1883) pp. 374-407 (1 pl.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 491 Histogenesis of Nerve-fibres.*—W. His has studied this subject on human embryos. In one only, 2°15 mm. long, it was found that the nucleated bodies of the cells of the medullary plate were already more crowded towards the central canal, early marking the central position of the ganglion-cells. The cells send out processes, most of which extend radially ; hence the majority of the cells, but not all, are bipolar. Perhaps the irregular outrunners are amceboid processes. There is at this stage nothing which can properly be called nerve- fibres. In an embryo of 5 mm. in length, the number of cells in the spinal cord is greatly increased. ‘They lie closer together, thickest centrally, and their nuclei, except in the peripheral portion, have for the most part their long axes running radially. Throughout the cord there is a system of radial fibres, many of which may be seen to be prolongations of the cells. ‘The fibres form a more or less well- marked external layer around the cord ; their external ends generally present a trumpet-like enlargement. The roots of the nerves are formed by the outgrowth of these fibres. The motor roots are first developed. They appear as processes of the ventral cells of the cord, penetrate the limiting membranes, and so enter the body-wall. The posterior roots arise later. His believes that the cells which Balfour, Sedgwick, and others have described as forming the beginning of the roots are merely those which grow out to become the ganglion cells distributed in the course of the nerves. Olfactory Lobes in Vertebrates and Higher Arthropoda.j— Professor G. Bellonci’s results are stated briefly as follows:—The olfactory lobes have the same essential characters in the above two groups of animals. The so-called olfactory glomeruli are character- istic of this region of the brain, and consist chiefly of a close nervous reticulum formed by the olfactory nerve-fibrils and the processes of the olfactory cells. The external relations of the olfactory lobes now discovered include a constant and most important connection with the optic region, as already described by the author in the higher Crustacea and with cerebral regions possessing high psychical functions, as is known to occur in Mammals also. These relations show an essential agreement to exist between the structure of the brain of Vertebrata on the one hand, and Arthropoda on the other ; and this agreement depends on physiological requirements common to the two groups. Professor Bellonci concludes with some theo- retical considerations having reference to the complete similarity in structure and connections which function is able to produce in the same organs of different types of animals. The animals studied were Squilla, Gryllotalpa, Anguilla, and Rana. Cclouring Matter of Fgg-shells.{—This subject has already been dealt with by Wicke, Sorby, and Liebermann. C. F. W. Krukenberg * Arch. f. Anat. u. Physiol., Anat, Abth., 1883, pp. 163-70 (1 pl.). Cf. Science, (1883) pp. 467-8. + Atti R. Accad. Lincei, Trans., vi. (1882) pp. 302-3. } Verhandl. Phys. Med. Gesell. Wiirzburg, xvii. (1882) p. 109. Cf. Natur- forscher, xvi. (1883) pp. 144-5. 492 SUMMARY OF CURRENT RESEARCHES RELATING TO has recently had the opportunity of examining a rich material of various coloured egg-shells and of enlarging our knowledge on the colouring matter yielded by them. He distinguishes the following colours differing chemically and spectroscopically from one another :—1. Oorhodein, already described by Sorby and Lieber- mann; 2. Biliverdin = Sorby’s oocyan, also found by Liebermann ; 8. Oochlorin and Ooxanthin, described by Sorby as yellow and red ooxanthin. The other colouring substances found by Sorby Krukenberg could not recognize. As regards the dissemination of the different colouring substances amongst the birds, and their distribution in the egg-shells, careful examination led to the conclusion that all flesh-, olive-, or leather- coloured shells, all those which are spotted, sprinkled, or marbled with red, brown, or black, and all spotted or scribbled over with ashy-grey, contain oorhodein, but seldom unmixed with oocyan. _ It is doubtless universally present. Even in most pale yellowish-brown eggs the oorhodein is not absent. In all green and blue egg-shells there is oocyan. In the shells of many closely related species, and even of one and the same species, startling examples are found of the opposing presence of both these colouring substances. In many species of birds colour is quite absent in the eggs, and a pure white egg charac- terizes the large family of the Psittacide. Of the two generally wide- spread colouring substances only one, oorhodein, is entirely absent in the families of the Cursores and Crypturide, whereas no similar case of absence has been observed with oocyan. The representatives of a few families have colouring matters entirely specific to their shells; thus the Cursores have oochlorin and the Crypturide ooxanthin. The opinion that the colouring substances in all eggs lie on the outer surface is, according to Krukenberg, incorrect. The shells of numerous species of birds are blue throughout, whilst those of some species are perfectly white outside or only coloured brown with oorhodein, but beneath the surface are coloured blue with oocyan. In those coloured with oorhodein the colour never penetrates very deep. A slight wetting of the shell with weak hydrochloric acid removes the colouring matter in many cases, and to remove very dark spots it is only necessary to wet the egg repeatedly with the acid. That the oorhodein and oocyan originate from quite different sources, that they are separately fixed on the shell, apparently in different places, as the egg passes from the ovary to the cloaca, is verified by the fact that, besides the constant limitation of the red pig- ment to the upper surface, and of the blue generally to the inner substance of the shell, there is always a diffused distribution of oocyan and oochlorin in contradistinction to the oorhodein, which is, without exception, more or less circumscribed. As typical instances of the last assertion are the pencillings on the eggs of the Fringillide, the red or brownish-black rings on the wide end of many shrikes’, woodcocks’ and gulls’ eggs, and the black and red-brown spots on the eggs of the falcon and thrush. It is generally ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 493 the broad zone at the wide end of the egg, or the latter itself, which is chiefly affected by the colouring of oorhodein. Leuckhart in 1853 expressed the opinion that the colours which, according to the obser- vations of Carus, are deposited on the shell in the oviduct, appear to be of two kinds. The one which gives a uniform appearance to the whole surface of the shell, originates apparently in certain specific pig- ments which combine with the separated lime; the other, which commonly appears in spots or in ramifying lines, originates from a more or less changed colouring matter of blood, which makes its way through the swollen vessels of the oviduct, and imprints itself on the egg. In the first case it is the green colour, in the others the red, with its manifold shades, which predominate over all others. It appears, from the chemical and physical properties of the pig- ments, that there is a closer chemical relation between oorhodein and hemoglobin than between the latter and oocyan. Presence of Glycogen in Embryos of Squalide.*—R. Blanchard has found that in embryos of Mustelus vulgaris, 84 cm. long, the yolk-sac is covered by a number of blood-vessels. On its internal surface there is a flattened epithelium, the cells of which, provided with a large nucleus, contain a certain number of large refractive granulations which are blackened by osmic acid. Some of these cells distinctly give the glycogen-reaction, but the same reaction is not to be obtained at any other point of the yolk-sac, nor in the umbilical cord. The author points out that, in mammals, the placenta is the seat of the formation of glycogen during the earlier stages of foetal exist- ence, and that, inasmuch as the membrane of the yolk-sac of vivi- parous Squalide plays the same part as the placenta, we may extend the statement as to the existence of glycogen from mammals to these fishes. Biologicai Studies.;,—H. EHisig placed in a basin of water an Octopus, a Gobius, and a Pagurus with an Actinian on its shell; the Octopus attacked the crab, which immediately withdrew into its shell, while the attacker instantly retreated, for the stinging organs of the Actinia had been too much for it. The same thing happened with the goby. A Pagurus without a shell was afterwards placed near the Octopus, and the latter examined it very carefully before it dared to seize it. At the same.time it is to be observed that the Actinian gets much assistance from its commensal, thanks to the locomotive and olfactory powers of the latter. Observations on thermal conditions showed that many fishes and other marine forms were but little affected by alterations in temperature ; while a study of the modes of resting of marine forms shows that much depends on what region of the sea the subjects naturally inhabit, and considerable differences are to be observed be- tween pelagic and more deeply dwelling fishes and cephalopods. * Bull. Soc. Zool. France, vii. (1882) p. 405. + Biol. Centralbl., iii. (1883) pp. 142-4. 494 SUMMARY OF CURRENT RESEARCHES RELATING TO B. INVERTEBRATA. Structure of the Nucleus.*—J. Chatin has selected as objects of his study the marginal cells of the Malpighian tubules of insects and myriopods. After describing the methods of investigation, and recommending the larve of Diptera and Lepidoptera, he points out that, at first, one rarely discovers all the details of the structure of the nucleus; as a rule, one only sees an enormous nucleus with from two to five nucleoli and a fine filiform plexus. The different characters presented by this last under different conditions are then described and discussed, and the nucleoli are described. The study seems to show that in the cells examined, as in certain others, the nucleus is formed of a chief mass in which are found the nucleoli and the plexus; these one is at first inclined to regard as secondary portions, but it is possible that the converse proposition is the more exact and that the “somatic mass of the nucleus” is simply a dependent of the reticulo-nucleolar apparatus. The nucleolus, whether simple or multiple, appears to the author to be with difficulty separated from the plexus, or reticulum, and indeed the latter often exists without the former. Chatin refers to the views of Klein in which the “ autonomy ” of the nucleus is contested, but looks to further observations for more satisfactory conclusions. Mollusca. Chromatophores of Cephalopoda.j—R. Blanchard was led to study these structures from the general consideration that there was some mistake in the view which attributed colour changes in reptiles and fishes to amceboid action, and to muscular influence in the Cephalo- poda. As to the general structure of these parts in the Cephalopoda, he finds no essential difference between them and the same bodies in Vertebrates. The chromatophore is, in fact, a simple connective cell, filled with pigment and possessing to a high degree the power of amceboid action; the surrounding tissues do not aid it in its activity. Those bodies are under the influence of the nervous system, but the radiating fibres supposed to be connected with it are not, as Harting has thought, nerve-fibres, but merely simple fibres of connective tissue which have a special arrangement in the region of the chroma- tophore, but have no connection with it. The author thinks that the anatomical and physiological “anomaly ” relating to these bodies in the Cephalopoda must now be regarded as definitely denied. Development of Chromatophores of Sepiola.t—P. Girod, who has already described the structure of the adult, now deals with develop- ing chromatophores in Sepiola rondeletii. The embryonic cells below the epidermis become differentiated into chromatophores and iridocysts. The former arise from initial cells, which, growing and becoming rounded, are the pigment-cells of the chromatophores. Each is surrounded by four peripheral cells, and forms with them a chromato- * Ann. Sci. Nat. (Zool.) xiv. (1883) art. 3, 7 pp. (1 pl.). + Bull. Soc. Zool. France, vii. (1883) pp. 492-6. { Comptes Rendus, xevi. (1883) pp. 1375-7. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 495 phoric group. Kach group touches four neighbouring ones, and every peripheral cell is in contact with one of its like. Where the four eroups meet there is a separate intermediate cell, which serves as the centre for fresh formations. The initial cell grows rapidly, its protoplasm becomes distinguish- able from that of the neighbouring cells, and the nucleus gets a well- marked contour. A little later indications of its pigmented character are to be seen, and then become more and more abundant. The peri- pheral cells meanwhile divide and give rise to the 16 to 22 cells which are the basal cells of the adult. Hach intermediate cell divides actively and gives rise to an intermediate group, which grows with the general growth of the integumentary surface, and so separates the chromatophoric groups. Some of the cells give rise to fresh chroma- tophoric groups, while others form the connective tissue of the layer in which the chromatophores are placed, while others, lastly, become fresh intermediate cells. The second set form linear series and give rise to reticula of various forms; the nuclei separate one from another, and the course of formation of the fibres may be well seen in embryos treated with Kleinenberg’s solution. The history of the development of the new intermediate cells explains how it is that, in the adult, we find chromatophores in different stages of development; and, on the whole, the intermediate cells may be regarded as constituting the fundamental connective tissue of the layer, and the radial fibres which converge towards the chromatophoric groups; while, moreover, they allow of the increase in extent of the layer, by giving rise to areas in which the same phenomena are observed as in the initial em- bryonic formations. Organization of Chitons.*—B. Haller has continued his investi- gations, and here commences with an account of the structure of the buccal muscles, to which interest has attached since Boll’s discovery of larger cells lying on the muscles; these latter themselves may be regarded as consisting of an internal contractile substance, arranged in longitudinal fibres, which, however, cannot be isolated or separated from one another; their surfaces are really fused so that the longi- _ tudinal fibrillation only is apparent. This internal contractile sub- stance is surrounded by a layer of protoplasm which contains a number of nuclei and has obviously a nutrient function; the larger cells would seem to be portions of this outer layer, which becomes compressed whenever a wave of contraction passes along the muscle. __ The buccal cavity seems to be the chief seat of the sensory organs of the Chitons, otocysts and eyes being absent; among the epithelial cells of the lips there may be found the brush-cells of Flemming, of essentially the same form as in the Pulmonata, where they were first discovered, An unpaired elevation on the floor of the cavity seems to be gustatory in function, and consists of sensory and supporting cells ; the goblet-cells which are so common in the buccal cavity of the Prosobranchiate Gastropoda are here completely wanting. There is a pair of feebly developed buccal glands, which are mere diverticula * Arbeit. Zool. Inst. Wien, v. (1883) pp. 29-60 (3 pls.). 496 SUMMARY OF CURRENT RESEARCHES RELATING TO of the wall of the cavity, and their epithelial cells are exactly like those of the side-walls; they provide a mucous secretion which is very intensely tinged by carmine, but this reagent has no influence on the cells themselves. Ganglion-cells may be found scattered in the musculature of this region. The so-called subradular organ ap- pears to be sensory; lying somewhat obliquely below the radula, its hinder portion is circular and is covered by a single layer of very high epithelial cells. More anteriorly the circle is incomplete, the groove dividing the organ into two bilaterally symmetrical halves. In the hinder and upper half of the organ we find spindle-shaped ganglia connected with one another by short commissures. After referring to the scantiness of our present information with regard to the gills of the Placophora, the author proceeds to point out that they present a bilateral symmetry, and that the longitudinal fold lying above the so-called branchial groove is not formed by a thickening of the epithelium, but by that of the deeper lying tissue ; anteriorly the longitudinal folds of either side unite above the head ; they also unite posteriorly. In Chiton levis there is a special epi- thelial layer below the gills, the cells of which are of considerable height ; these, which have as yet only been observed in the females, appear to be glandular in nature, and it seems to be probable that their secretion stands in some relation to the genital products. Two types may be distinguished in the gills themselves, presenting differ- ences of some importance in the number of the gills, and their relative size. The author is of opinion that the “ gills of either side” are not the homologues of the gills of other Gastropods, but that the separate parts are each really distinct gills. A gill, when carefully examined, does not here exhibit the saccular form but is seen to consist of separate transversely disposed plates, connected together superiorly by a longitudinal ridge. The conclusion arrived at is that the Placophora are Polybranchiate Gastropods. No answer can as yet be given to the question whether C. levis and Chitonellus with a smaller number of gills are, phylogenetically, older than C. siculus and others with a larger number of gills; there is no real difference in their structure, there are no signs of any rudimentary gills in C. levis, and there does not appear to be any concentration of nervous elements. The key to some of the problems of the structure of the Placophora is doubtless to be found in an examination of Chitonellus. Characters of Marionia.*—R. Bergh commences by pointing out that the Tritoniadse form a group which are intermediate between those Nudibranchs with a branched liver (kladohepatic), and those in which it is not branched (holohepatic). The family contains but few forms, all of which are elongated and quadrangular; in the anterior region of the back there is a delicate semilunar growth, the edges of which are provided with simple or compound digitate pro- cesses. After noting the other special structures of the family, and the characters of its three generic groups, the author comes to the special subject of his paper. * MT. Zool. Stat. Neap., iv. (1883) pp. 303-26 (1 pl.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 497 The genus Marionia was instituted by Vayssiére in 1877, and we know of ten species. The account of the nervous system of M. quad- rilatera shows that the central system is as small and flattened as in Tritonia ; the cerebropleural ganglia are, especially on their lower surface, very distinctly separated. In most of its characters it agrees with what is found in the better known genus, and the same is true of many of its other parts. M. affinis is a new species founded on a specimen found at Naples, and apparently closely allied to M. tetraquetra; its peculiarities are pointed out, and there are some notes on WM. tethydea and M. blain- villea, but the author does not seem to have arrived at any general conclusions. Molluscoida. Ova of Ascidians.*—A. Sabatier finds that, in Ascidians, the ovary is first made up of an agglomeration of nuclei, derived from the mesoderm, and united together by a small quantity of clear inter- mediate substance. 'The ovary has the constitution and characters of an embryonic connective tissue, in which “the protoplasmic atmo- spheres” are not sharply distinguished ; and this structure is to -be found in such portions of the adult ovary in which there is a fresh formation of ova. The egg arises from a corpuscle of this tissue, which developes within itself one or more granules, which become nucleolar, and which is itself the nucleus of the egg. Around the nucleus there becomes arranged a layer of transparent colourless protoplasm ; there then appears a very delicate amorphous capsular egg-envelope, and below this there appear on the surface of the yolk the follicular elements which become the follicular cells; they are small masses formed in the vitellus itself, and by it brought to its surface. As they increase they form a continuous layer around the egg. Below them and at their expense there is developed a second. membrane which lies on the yolk; this subcapsular membrane may become more or less thick. In certain cases the follicular cells remain flattened, harden, and give rise to a thick and structureless egg-envelope. The cells which, in the author’s opinion, are impro- perly called those of the testa arise from the yolk, of which they represent an eliminated element; they are imperfect cells and may be spoken of as celluloid globules. The intra-vitelline corpuscles are neither elements which have come in from without, nor capsular cells which have made their way into the yolk, but are masses of clear and finely granular protoplasm which are formed, by a process of concentration, within the yolk itself; finally making their way to the surface, they are at first “capsular” and afterwards “ granular ” cells. The author has investigated a large number of forms and he points out the necessity of studying and comparing a number of species if one would seriously attempt to come to any certain con- clusions as to the history of ova which seem to be in any points distinguished from those of other forms, and which exhibit many * Rev. Sci. Nat., xi. (1883) pp. 348-405 (4 pls.). Ser. 2,—Vot. III. 2k 498 SUMMARY OF CURRENT RESEARCHES RELATING TO remarkable and as yet unknown characters in their structure and development. Oxycorynia, a new Synascidian Genus.*—Dr. R. von Drasche describes a remarkable form of compound Ascidian (Oxycorynia fascicularis) obtained from Hogolen, an island in the Caroline Archi- pelago. The animals are arranged in heads presenting a general resemblance to a fir-cone, and supported upon cylindrical stalks, which, in the specimen described, are about 24 in. long and rather more than 1 in. thick. The oval spikes, which are sometimes pointed at the apex, attain a length of about 1} in. and a breadth of # in. The colour of the badly preserved specimen is a dingy yellowish green. The branchial aperture is surrounded by a stellate marking ; and on each side of the endostyle two or three dark lines run down from the branchial aperture; dark pigment also appears round the cloacal aperture. The individual animals are 10 mm. long, of which about 6 mm. belong to the branchial sac. The latter is of an elongated form, narrowed before and behind; and its hinder part covers a good deal of the intestine. At the foremost part of the animal is the simple round cloacal orifice. The branchial aperture is placed in the anterior third of the branchial sac; it is comparatively large, and is surrounded by a very delicate cylindrical membrane, often cleft into four parts. Examined from within, the branchial aperture is seen to be surrounded by a frill-like ring, which appears strongly coloured by pigment- granules. Outside this there are eight tentacles, alternately large and small. The short cesophagus leads into a small smooth stomach, the intestine proceeding from which forms a loop to the left of the cesophagus, and bends forward, passing into the rectum, which is filled with feecal masses, and may be traced nearly to the cloacal aperture. Within the loop of the intestine are placed the ovaries and the racemose testes, which consist of about six follicles, each of which opens by a small duct into the common vas deferens, which is traceable along the rectum. Posteriorly each individual animal has a filiform appendage, which passes into the common peduncle, in which it may be traced to a long distance by transverse sections. This appendage is divided by a septum into two parts. The pe- duncle itself consists of a dense tunic mass, in which the well known large vesicular cells with parietal nuclei are present in great quantity. The individual animals are united by an extremely delicate colour- less tunic. The individuals seated upon the margin of the peduncle are short-stalked, and their stalks gradually increase in length towards the middle, thus producing the spike-like form of the colony. The caudate larve lie partly in the branchial cavity itself, partly in diverticula of the body-wall. The embryo is characterized by a peculiarly formed appendage, which bears five adhesive glands. All the embryos observed showed indications of branchial hoops. At the summit of the common peduncle, where the appendages of * Verhandl. Zool. Bot. Gesell. Wien, xxxii. (1882) pp. 175-7 (1 pl.). See Ann. and Mag. Nat. Hist., xi. (1883) pp. 455-7. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 499 the individual animals enter it, there are numerous much-branched diverticula of the ectodermal processes. These bud-foundations form a conical elevation in the middle of the head; and the development of the buds seems to take place as described by Kowalevsky in Didemnum styliferum and Amouromium. Arthropoda. a. Insecta. Histology and Development of Insects.*—H. Viallanes finds that, in the larva, the visual apparatus consists of three principal parts: the imaginal disk of the eye, the nervous tract, and the optic ganglion. The first of these has the same structure as all other disks of the same kind, or, in other words, consists of a provisional, an ectodermal, and a mesodermal layer. Some time before the meta- morphosis the most superficial cells of the ectoderm increase in size and become elongated, while at the same time they acquire the property of being coloured in a particularly intense manner under the influence of certain staining reagents; and it is at this time that they become “optogenous cells.” The mesoderm of the optic disk has not the structure of the same layer in other disks. Jt is not formed by a fundamental homogeneous substance connecting the cells, but rather by fine nervous fibrils, with which nuclei are inter- mixed, and which appear to end in the basal membrane of the ectoderm, but really pass through it to become continuous with the extremity of an optogenous cell. The nervous tract is formed by fine nervous fibrils continuous with those of the mesoderm; so that, in other words, the mesoderm of the disk is only an enlargement of the nerve-tract; and thus, when differentiation is complete, we find that each optogenous cell is connected with the nervous centre. The optic ganglion is formed by the outermost portion of the cerebral ganglion, and is invested by a neurilemma. On the lateral parts of the optic ganglion and in the grey cortex there is a very complex organ, which may well be called the rudiment of the ganglionic layer, for in this we may see all the chief parts which enter into the constitution of the definite ganglionic layer; externally there is the layer of ganglionic cells, which, as in the adult, are formed of bipolar cells united to form short rows. Just within this there is an indication of the layer of palisade-like fibres, then a layer of fibres and nuclei, the last being the rudiment of the layer of nucleated fibres. The fibres of the nervous tract arise from the surface of the layer of ganglionic cells, just as the post-retinal fibres do in the adult. The only important difference between the chief parts of the optic apparatus in the larva and in the adult would appear to be in the more compact condition which obtains in the former. When metamorphosis occurs the provisional layer of the imaginal disk of the eye disappears, the ectoderm increases in size, and developes a membrane, while its edges become united with those of the neigh- * Ann. Sci. Nat. (Zool.) xiv. (1882) pp, 1-348 (18 pls.). 2K 2 500 SUMMARY OF CURRENT RESEARCHES RELATING TO bouring disks; its cuticle becomes the facetted cornea, and its basal membrane the posterior limiting membrane of the eye. While the neurilemma of the optic ganglion disappears, the ganglion itself grows, gets spherical in form, and becomes separated by a circular groove from the rest of the cerebroid ganglion. The ganglionic layer passes outside the optic ganglion, grows, and extends as a screen between it and the compound eye, while at the same time it becomes differentiated into its two primary layers. As the optic disk and the ganglionic layer increase in extent the fibrils of the nervous tract become separated from one another. As the former approach one another the fibres shorten, and each becomes one of the post-retinal fibres. As the ganglionic layer leaves the peripheral portion of the optic ganglion it carries with it a set of fibres; these are the pre- ganglionic fibres, and they continue to serve as a means of connection between the separated parts; they do not arise from cells placed on the surface of the grey cortical portion, but from others more deeply situated. Before this elaborate examination of the history of the eye M. Viallanes deals with the skin, where he notes the presence of a delicate structureless layer lying beneath the hypodermis of the larva, which he looks upon as the homologue of the basal membrane found by Haeckel in the cray-fish and by Graber in adult insects. In the larve studied by him there were observed between the skin and the muscles peripheral nervous ganglia, belonging neither to the ventral chain nor to the stomatogastric system ; in the larva of Tipula they are very remarkable for their regular and symmetrical distribu- tion, a pair being found in each segment. In Musca, however, they are arranged irregularly, while in Hristalis they are placed in the nerve-plexuses from which arise the nerves which go to special sensory organs in the anterior region of the body. The sensory nerves in the larve may terminate either by putting themselves into relation with sensory hairs, or by coming into the presence of a subhypodermic plexus, whence the prolongations appear to terminate freely. The dorsal vessel is, from a histological point of view, comparable to a capillary of a Vertebrate, but physiologically it is distinguishable from it by being contractile. This contractility is due to the develop- ment of muscular fibres in the protoplasm of its cells. The author’s studies on the involuntary muscles lead him to re-enunciate the doc- trine of Ranvier that organic muscles, whether striated or not, are supplied by nerves which, just before they pass into the muscles, form a ganglionic plexus. The author believes that the fibril of the wing of an insect is the homologue of the fibril of the muscle of a Vertebrate ; in Dytiscus the primitive fibre has no sarcolemma, and its contractile mass is reduced to a single column; in Musca the same fibre has no sarcolemma, but its contractile mass is made up of several columns; in the Vertebrate there is a sarcolemma. Each primitive fibre has on its surface a certain number of projec- tions (cones of Doyére), and each of these is provided with a nerve- ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 501 fibre ; the cylinder axis of this having penetrated into the cone, divides into two chief branches, which give off the secondary ones, and these divide dichotomously a number of times; there is therefore a terminal ramification analogous to what obtains in Vertebrates; nothing like this has ever yet been suspected of Arthropods, and it has been found that just as there are differences in Vertebrates so similar differences are to be seen in insects. M. Viallanes then treats of the phenomena of histolysis, and concludes with an account of histogenesis, discussing the integument and the muscular system as elaborately as we have reported him to deal with the eye. Markings on Podura Scales.*—Dr. A. Y. Moore agrees that the markings on Podura scales are caused by spines. These are attached to the scales, not at the small end only, but by nearly the whole of their under surface. If they were attached at the end, it is highly probable, he thinks, that they would become broken or bent from their normal position by a slight rub, whereas scales are found which have been scratched and the spines still remain, but in an injured condition. A woodcut is given of spines x 7600 by a Spencer im- mersion 1-6th in. objective. Mr. R. Hitchcock also refers + to some photographs by Dr. J. W.S. Arnold, made by sunlight with a 1-26th in. Wales objective, the magni- fication in two instances being 2470 and 2740 diameters respectively. A woodcut shows not only the appearance of the test Podura scale but also a portion of a scale of Degeeria domestica “so closely allied to Podura that it may be fairly assumed the structure of its scales is the same.” Several detached spines of the latter are shown, separated by a fortunate accident, enabling us to see the separate spines, “thus proving that they have an existence, and disproving some views that have been advanced in the past concerning the structure of the scale.” It will be remembered that the spines of Podura have been separated from the scales by an electric spark, so that they could be seen in a similar manner. 8. Myriopoda. Dermal Appendages of Polyxenus.t— The different forms of hairs in P. fascicularis are described and , figured by Scudder; those upon the body-joints varying from club-shaped spines, furnished with several rows of flattened teeth, to sabre-shaped spines, serrate on the convex side. The posterior extremity of the body is provided with a pair of cylindrical fascicles, resembling those of the larva of Anthrenus, but composed of very curiously formed bristles, shaped like an elon- gated fish-hook, the shaft gently curved, and the tip recurved and apically barbed. The shaft is armed with delicate spinules, and the crook furnished on the concave side with a few spatulate, drooping appendages. * «The Microscope,’ ii. (1883) pp. 186-8 (3 figs.). + Amer. Mon. Micr. Journ., iv. (1883) pp. 101-2 (1 fig.). { Proc. Bost. Soc. Nat. Hist., xxii. p. 67. Cf. Science, i. (1883) p. 371. 502 SUMMARY OF CURRENT RESEARCHES RELATING TO y- Arachnida. Pairing of Tegenaria guyonii—Organs in the Male Abdominal Sexual Region.*—Mr. F. M. Campbell describes some observations which he made on the deposition of semen by T. guyonii. He also gives an account, which may be taken as typical of the species, of the pairing of thirteen couples in confinement. Two cases are de- scribed in which during confinement the males killed the females after union, and an instance is also given of an attempt to impregnate an immature female, which was also destroyed by the male. In these cases hunger could not have been the cause of the attack. The author explains these occurrences, and also the accounts of females destroying males after union, by the suggestion that those instincts which are habitually practised throughout the far greater portion of the life of the species, and on which it is dependent, would scarcely be suspended for a longer period than is necessary for sexual union. Spiders fre- quently eat one another, and such an occurrence after pairing is only curious if considered apart from their habits. When the sexual desire is satiated their actions would be again directed by the dominant instinct of destruction which would be stronger if a general excitement be supposed to follow the union. The external abdominal sexual region is marked by a slight con- vexity, in front of which is placed transversely a row of transparent spines. Two papilla-like processes are situated just above the opening of the genital sinus. Neither of these organs have hitherto been noticed. The spines are tubular, point backwards, and project just beyond the convexity. They are generally twenty-four in number, and are placed singly or in groups of two, three, or four. <A tube runs from each spine, and, after making many and sudden convolutions, ends in a gland of a pear-shaped form. The contents of the glands have a high refractive power. The papille are erectile, and consist of pointed scales surrounding a fascicule of fibres which internally diverge, and are lost in the connective tissue lining the inferior side of the genital sinus. The points of the scales rest on one another, thus giving to the processes a conical form. The question arises as to the function of these glands and papille. They are not found in the females, nor has the author yet met with them in immature males, while their position denotes some share in the primary sexual process. As to the papille, he would suggest that their fibres when protruded are used for arranging or supporting the triangular sheet, or for assisting the collection of semen by the palpi. It is more easy to limit the conjectures as to the purpose of the glands to two alternatives:—(1) To pour their secretion on the semen when deposited ; or (2) to spin threads which would guide the semen to the silken sheet of which they might form a part. * Journ. Linn. Soc. Lond. (Zool.) xvii. (1883) pp. 162-74 (2 pls.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 503 Anatomy of Pentastomum oxycephalum.*—J. Chatin describes a form found in Alligator luctus. In treating of the integument he animadverts on the views of those who have assimilated the hypoder- mis of Arthropods to an epithelial membrane, and points out that, in Pentastomum at any rate, the hypodermis is merely formed by a mass of protoplasm, in which a number of nuclei are scattered. The pro- toplasmic areas grouped around the nuclei are not arranged along one and the same horizontal line. Regularly arranged pores are to be found in the integument, each segment of the body having a row of them; they are not, as some think, to be regarded as stigmata, but are rather the orifices of canals from glandular organs. These last may be uni- or multi-cellular ; in the former case they form an elongated flask-shaped sac with a large nucleus, and in the latter with small nuclei. The several portions of the intestine are not so distinctly separated as in most Arthropods; the anterior is, however, distin- guished from the median portion by its smaller calibre, and, in the living example, one may see that the median region is generally dis- tended by contents of a yellowish colour. The terminal is again narrower than the median portion of the intestine. In discussing the characters of the layers of which this part of the body is made up, Chatin refers to the views of those who would regard the epithelial zone as a layer of hepatic tissue, and directs attention to the uncer- tainty of the results of histochemic investigations, and the possibility, - from a histological point of view, of their cells being glandular elements. The author can find nothing in the structure of the nervous system of Pentastomum which would justify us in saying that it presents any aberrant arrangement. General sensibility appears to be better developed than in most parasites submitted to similar conditions of life, Linguatulide responding rapidly and vigorously to ordinary chemical or electrical stimuli. Unlike flat or round worms, these parasitic Arthropods appear to seek rather than avoid the light. Locomotion would seem to be effected either by the aid of the spines, and in the fashion of a mole, or by the creeping leech-like motion. Dealing with the zoological affinities of the specimens which he has had under examination, the author refers to the work of Jeffrey Bell, who, in order to determine two individuals found in a Boa con- strictor, thought it right to examine all the species mentioned as being found in Ophidians, and he not only approves of this mode of pro- cedure, but says that he has himself here followed it. Demodex phylloides.j—Professor R. Ramsay Wright having had submitted to him pieces of pork-skin largely occupied by this mite, and having found no other notice of it than that in a paper by Dr. J. Csokor of Vienna,{ gives an abstract of that naturalist’s researches. Three forms seem to be well recognized; that of man, of the dog, and of the cat; and Csokor would also speak of Demodex phyllosto- * Ann. Sci. Nat. (Zool.) xiv. (1888) art. 2, 30 pp. (1 pl.). - + Proc. Canad. Inst., i. (1883) pp. 275-81 (1 pl.). t The reference is not given by Prof. Ramsay. 504 SUMMARY OF CURRENT RESEARCHES RELATING TO matis Leydig and D. phylloides Csokor; the latter or pig parasite is then compared with those found in man and in the dog, and its three ecdyses—(1) between the egg and the six-footed larva; (2) between the six- and eight-footed larva; (8) between the latter and the adult—are established. In the smallest tubercles in the skin 50-60 mites may be found, and in the larger 500-1000. The cast-off cuti- cles are found towards the centre of the tubercle, the younger stages towards the duct of the gland, and the adults towards the base and periphery of the gland. Observation convinces the student that these mites are air-breathers. From his specimens of pigs, Csokor is in- clined to think that the transference of the parasite from pig to pig is more easily effected than is the case with D. canis. 3, Crustacea. Larval Development of Phoxichilidium Plumulariea.*— R. v. Lendenfeld gives some account of the early development of this new species of Pantopoda. Among other points he notes the characters of the pores on some of the appendages, which do not, as ordinarily, each communicate with a group of glandular cells, but from each pore there is a fine canal which leads into a well-developed primary duct, at the centripetal end of which we find the gland. These glands are large, saccular, or of an elongated pyriform shape; each is solid, and the protoplasm appears to be gradually converted into a secretion. There are two of these glands, and, centripetally to them there is a large stellate ganglion with a well-developed centripetally directed nerve, as well as nerves for the glands. As maturity is reached the hairs connected with these parts and the ganglia and nerves disappear, but the glands remain, in rudiment, as a bilobed organ. The author compares this form with others already known, and points out the diffi- culty of imagining how two species, both parasitic, could have arisen from one and the same non-parasitic species, and how it is that the larvee differ so much in their mode of development, while the mature forms are almost completely unaltered. Relationships of the Malacostraca.j —In this important and closely-argued paper J. E. V. Boas discusses the relationships one to another of the great divisions of the Malacostraca, and directs atten- tion to the characters of the appendages. The chief result of his studies would appear to be that the Malacostraca are derived from the Phyllopoda, of which Nebalia is their nearest ally. The group of Malacostraca which stands nearest to the Phyllopoda is that of the Euphauside, and especially the genus Thysanopus. From a form allied to this last the group of the Decapoda has been evolved; but they, as represented by their most primitive form (Pencide), have become go altered that it is not possible to follow those who have placed the Euphausidw and the Decapoda in one and the same order. The Mysidacow are also derived from a Thysanopus-like form, and their differences from the Schizopoda are so marked that it is hence- * Zeitschy. f. Wiss. Zool., xxxvili. (1883) pp. 3823-9. + Morph. Jahrb., viii. (1883) pp. 485-079 (4 pls,). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 505 forward impossible to place them in the same order. Of the two sub- divisions of the Mysidaceze—Myside and Lophogastride—the latter stand nearest the starting-point. The Cumacez have been derived from a form which was closely allied to the Myside. The Hedrioph- thalmata would appear to have arisen from forms intermediate between the Myside and Cumaceex ; they are, therefore, not to be regarded as lowly forms, or as having only distant relations to the Podophthal- mata, with which they are partly closely allied. But the Isopoda and Amphipoda differ so much from one another that it is impossible to include them in the same order. The Squillacee occupy a very isolated position; they are most nearly—though still distantly— allied to the Euphauside, but in some points they exhibit more primitive characters than any other group of the Malacostraca. The author illustrates his view by a phylogenetic table, which it is worth while to reproduce :— Amphipoda Isopoda ~ Cumacea Mysidee Ne Lophogastridz Squillidee Decapoda Euphausides Phyllopoda And he gives also the following systematic table :— Sub-class ManacostRaca. Order i. Euphausiacea. RD ieeer a 2 ee » ii. Cumacea. » lv. Isopoda. a v. Amphipoda. : Sub-order i. Natantia. a ae ceabede a ii. Reptantia. » vil. Squillacea. In his remarks on the appendages Boas points out that the same pair has often different names in different orders, while the same name 506 SUMMARY OF CURRENT RESEARCHES RELATING TO is often used for quite different pairs; thus, the third maxilliped of a Decapod corresponds to the second thoracic foot of an Amphipod, while the first thoracic foot of an Isopod is something altogether different to the first thoracic foot of a Decapod. Certain modifications in the received nomenclature are therefore proposed. All the appen- dages hitherto called maxillipeds and thoracic feet are grouped together under the name of trunk-feet or cormopods, and of these there are in all Malacostraca, with but very rare exceptions, eight pairs. This view is based on the considerations that in the genus Nebalia the body is easily divisible into head, trunk, and tail; the first, in which there are no signs of segmentation, carries the eyes, antenne, mandibles, and maxille, and is distinctly separated from the trunk, which consists of eight short segments: these all carry appen- dages which resemble one another, and differ from those in front of or behind them ; further, they correspond to what, in the Malacostraca, are spoken of as maxillipeds and thoracic feet. With the exception of the antennz, we always find in the appendages of the Malacostraca an endopodite and an exopodite ; but it is only in the cormopods that we find an epipodite developed. The author points out the differences between the antennular and the succeeding appendages, and comes to the conclusion that they are not equivalents of those that follow them, and that it would be well not to regard them as appendages atall. He is inclined to think that, like the eyestalks, they are appendage-like sensory organs. The suc- ceeding parts are then discussed; Boas states that the cormopods consist of a seven-jointed endopodite, an epipodite arising from the outer side of the first joint, and an exopodite from the second joint of the endopodite. One or both of these latter are frequently absent ; some of the joints of the endopodite may be fused, and the basal joint is often more or less closely connected with the trunk-skeleton. After a detailed account of what is seen in the different orders, we come to the caudal feet; of these the Malacostraca have typically six pairs, and behind them there is a footless segment. The different orders are next discussed in detail, and the whole concludes with a general review of the groups, which must be of the highest value to the scientific. carcinologist. Circulatory Organs of Stomatopoda.*—Prof. C. Claus has been making some observations on the larval stages of Alima and Erichthus, the structure of whose hearts he describes in detail. Dealing also with the circulatory vessels, he comes to the conclusion that the whole system of cerebral vessels with its numerous coils, many of which are mere capillaries, may be regarded as a large vascular loop connected with the aorta, just as the much simpler vascular loops in the ganglia of the ventral chain may be looked upon as appendages of the sternal artery. He regards as certain the homology of the anterior widened portion of the heart and its connected pair of arteries in the Stomatopoda with the heart of the Decapoda, and describes the ventral artery which has been overlooked or denied to exist as being a median * Arbeit. Zool.-Zoot. Inst. Wiirzburg, v. (1883) pp. 1-12 (3 pls.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 507 vessel of considerable size. He finds, at the origin of all the arteries which arise from the heart or the dorsal vessel, a pair of pocket-valves, which agree in structure with those found in the Phyllopoda and the Hedriophthalmata. A sympathetic nerve accompanies the dorsal vessel, and seems to correspond to the sympathetic of the heart of the Hyperida. The absence of antennary glands would appear to be compensated for by the presence of glands connected with the rectum. Copepoda living in Molluscs and Ascidians.*—C. W. S. Auri- villius has investigated the Copepoda inhabiting molluscs and Ascidians on the Swedish coast, and publishes the results in two papers illustrated with seven double plates. Only two species, both belong- ing to the Sapphirinide, were found inhabiting molluscs, a species of Lichomolgus on species of Doris, and a new genus and species (Modiolicola insignis) upon the branchie of Modiola and Mytilus. Twenty-one species, representing seven genera and five families, were found in the branchial sacs of Ascidians, two new species being added to those already described by Thorell and others. Nearly all the old species are redescribed, and a large part of them figured, and ana- lytical tables of the genera and species given, American Parasitic Copepoda.t—Prof. R. Ramsay Wright gives an account of some Copepods parasitic on fresh-water fishes; the first of these is Hrgasilus centrarchidarum un. sp., which was found on the gills of various Centrarchide ; in giving the details of this form an opportunity is taken for expressing the opinion that, when a revision of the species of Ergasilus is undertaken, it will probably be found that the form of the appendages offers valuable specific characters. In dealing with Achtheres micropteri n. sp., there are some notes on the spermatophores. Vermes. Development of Annelids.{—W. Salensky describes in detail the development of Nereis cultrifera, the eggs of which are laid in large lobate gelatinous masses, and each has in addition to the gelatinous covering a delicate vitelline membrane, which, as in all other Annelids, is finally converted into the cuticular membrane of the larva. The author does not agree with Goette in giving to the micromeres the name of ectodermic, or to the macromeres that of endodermic cells ; for the ectoderm is not only formed by the micromeres, but also at the expense of the larger cells. The cells do not definitely acquire their laminar significance until after the completion of the epiboly and the development of the ectoderm. The share in the macromeres is taken not only by the marginal, but also by the median portion of the ectoderm. Forty-eight hours after deposition epiboly has advanced so far that the macromeres, which are always four in number, are com- pletely enveloped by the ectodermal cells ; these last are not equally * Ofvers. K. Svenska Vet. Akad. Forh., 1882, Nos. 3 and &. + Proc. Canad. Inst., i. (1883) pp. 243-54 (2 pls.). { Arch. Biol., iii, (1882) pp. 561-604 (3 pls.). 508 SUMMARY OF CURRENT RESEARCHES RELATING TO thick throughout, being more delicate where epiboly commenced and in the region which, in time, will be the dorsal surface of the embryo, than on that which is opposite to it. On the former there are two prostomial pads which bound a prostomial invagination. The author cannot agree with Goette in thinking that the mesodermal elements are derived from the endoderm; he regards the mesoblasts as forming a continuous layer with the ectoderm, from the cells of which they cannot be distinguished either by their origin or their position. Other statements of the same author with regard to this layer are then canvassed, and Salensky says that, a few hours later, the pro- stomial buds disappear and the prostomium or blastopore becomes a small pentagonal orifice; the embryo is still spherical in form. This portion of the paper concludes by insisting on the analogy which exists between the formation of the mesoderm in N. cultrifera and the genesis of the same layer as described by Kleinenberg for Lumbricus trapezoides. On the fourth day we note a marked advance in the organization of the embryo. The ectoderm still continues to be differenti- ated and the groove which forms the rudiment of the ventral ganglionic chain becomes apparent; as yet, however, the medullary plates merely consist of a single layer of cells, not yet sharply marked off from the sides of the ectoderm. The two bands of mesodermal cells now diverge much more than in the preceding stage, while they still unite towards the hinder end of the embryo. Yet again, the relation of the mesoderm to the ectoderm is still very close, and it is difficult to determine whether it grows at the expense of the ectoderm or not. In the fifth day we see various organs appear, such as the setigerous sacs and the lateral and muscular plates; the embryo now becomes a little flattened on its dorsal side, and the ectoderm under- goes delamination in the more anterior regions. The mesoderm, as may be supposed, becomes considerably modified, but the endoderm only consists of five large spheres. The sixth day is marked by the appearance of the first rudiments of the feet, in the form of two pairs of tubercles, and herein hardly any share is taken by the ectoderm; the mesodermal segments become indicated, and each is seen to consist of the rudiments of the seti- gerous sacs, of the muscular, and of the lateral plates. On the next day the dorsal cavity becomes very apparent and contains amceboid cells, which are most probably of ectodermal origin. On and after the eighth day development proceeds very rapidly; the embryo becomes much larger, the cephalic region becomes separated by a crown of cilia, and the eyes appear on its margins. A post-oral circlet of cilia is developed, and the two become united on the back of the embryo. Between the cephalic ganglia and their commissure we see a cellular mass of triangular form, which is called the ocular plate, and it is this which is, in all probability, converted into the hypodermis which invests the eye. The conversion of the lateral plates into somato- pleure and splanchnopleure is, as in Huaxes and Scorpio, carried on independently in each segment. The other details of development are given in full; on the ninth day the embryo escapes. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 509 In giving an account of the post-embryonic development the author deals particularly with the digestive tract, and points out the differences between his account and that given by Goette, of Nereis dumerilii, in the history of which there would seem to be very considerable lacune, all the intermediate processes which would furnish the genetic con- nection between the part which that author considers as the rudi- ment of the digestive tube, and the tube itself, being neither described nor figured. Any conclusions based on a comparison of the mode of formation in these two species would be premature, and must be left for future observers. Nervous System of Hirudinea.*—M. Saint-Loup finds that the arrangements of the nervous system which were thought to be peculiar to Clepsine are very common among the Hirudinea. Commencing with Nephelis, where the transparency of the tissues assists in the investigation, he saw that the ganglia of the ventral chain had on their ventral surface six capsules quite distinct and easily isolated from the rest of the nervous mass. In Aulastomum similar capsules are to be observed ; and the same is true of the medicinal leech. The author has also been able to detect in all Hirudinea examined the intermedi- ate or unpaired nerve which was found by Brandt in Hirudo, but not detected by Baudelot in Clepsine. Similarities in structure are also to be seen in the supra- and sub-cesophageal ganglia, and in the sub- caudal mass. M. Saint-Loup hopes to be able to give a general morphological account of the nervous system of the Leeches. Bite of the Leech.t—G. Carlet, in continuation of his previous paper,{ states that, as soon as the leech is fixed, its anterior portion becomes sharply withdrawn, owing to the contraction of the longi- tudinal muscular fibres; this serves as a fixed point for the jaws. These work quite regularly backwards and forwards, and the move- ments may be registered as two per second. A preliminary phase in the bite is an uprising of the skin into a small mammillated process ; next we find three linear incisions, which are equidistant and do not meet. Gradually they do so, and we get a triangular wound, the three planes of which correspond to the three jaws. The denticles of the jaws are not strong enough to produce at one blow a wound which gives rise to a flow of blood. Continuing his observations,§ Carlet finds that the jaws of the leech are the essential agents in suction and deglutition; to effect the former the jaws separate from one another and allow of the entrance of the cesophagus; in deglutition the jaws approach one another, and by a kind of piston-action drive the blood in the direction of the stomach. Development of Phoronis.||—-A. Foettinger found in the morula- stage of Phoronis that the cavity contained a few spherical or oval * Comptes Rendus, xevi. (1883) pp. 1321-2. + Ibid., pp. 1244-6. } See this Journal, ante, p. 212. § Tom. cit., pp. 1439-40. || Arch. Biol., iii. (1882) pp. 679-86 (1 pl.). 510 SUMMARY OF CURRENT RESEARCHES RELATING TO corpuscles, sometimes surrounded by a fine granular substance filling the whole of the segmentation cavity ; the important question is, are these elements, which are clearly the first rudiments of the mesoderm, derived from the endo- or the ectoderm? Kowaleysky is in favour of the latter view, while Metschnikoff holds to their endodermal origin. If the larve are treated with acetic acid and immediately examined evidence will be afforded as to the presence of the first mesodermic elements at a time when the ovum is still segmenting; and, indeed, indications of them were in two cases seen, where the developing ova consisted of only eight blastomeres, for there is in them a central corpuscle which appears to have a mesodermal significance. The author has no distinct opinion as to the origin of this cell, but inclines to doubt the explanation given by Metschnikoff. As to the still earlier stages it is stated that the fecundated ova are developed outside the body of the parent, but that they remain attached to the branchize for a certain time. After the appearance of four blastomeres two divide, and so give rise to a six-stage of two large, and four smaller cells. Development of Sipunculus nudus.*—B. Hatschek here gives us another of his interesting and suggestive papers; in the earlier portion he deals with his observations of the phenomena of the development of S. nudus at different periods, and then proceeds to some theoretical considerations. Comparing the development of Sipunculus with that of Phas- colosoma, he finds a striking resemblance between the two, this point, however, being excepted, that in Phascolosoma there appear to be no embryonic investments. If the observations of those who have studied this form are correct, it follows that we have presented to us the problem of whether the investments in question have been com- paratively rapidly acquired by Stpunculus, or whether they have been lost by Phascolosoma ; the latter form must be re-examined with especial attention to this question. Hatschek believes that the Echiuride completely agree with the Annelida in their development, and, in discussing the relation of Sipunculus to the Annelids, he brings this point into prominence. We must ask ourselves how far the differences between Sipunculus and the Annelids are of fundamental importance. If we take the mode of formation of the germinal layer and of the closure of the blasto- pore, we find a considerable agreement; in the formation of the gastrula, the development of the mesoderm from two marginal cells of the primary endoderm, the cleavage of the mesodermal bands into a visceral and a parietal layer, and further, the mode of closure of the blastopore and of the development of the cesophagus at the point at which is placed the most anterior remnant of that orifice, the two “types” present the same processes. Differences between the two are to be found in the remarkable development of embryonic investments in Sipunculus, but, at the same time, these seem to have appeared only after it separated from the Annelid-stock. Compared with the * Arbeit. Zool. Inst. Wien, v. (1883) pp. 61-140 (6 pls.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. d11 developmental history of most Annelids, that of the Gephyrean under discussion appears to be very short ; examples of shortened develop- ment are, however, among Annelids to be observed in numerous Oligocheta and in the Hirudinea, though it is not of the same character as in these. At the same time it may be supposed to be a lately acquired arrangement. Compared with the well-known trochophore-larva, that of Sipun- culus corresponds to a stage much further developed ; while there are numerous points of resemblance, we find that, in the latter, the post- oral circlet of cilia is not feebly but well developed; further, the trunk and the secondary ccelom are well developed ; provisional organs appear to be absent, and the permanent retractors of the fore-body and the renal organs of the trunk are in full activity. In fact, it would seem that the trochophore stage is, in Sipunculus, passed through during the much shortened embryonic life, and that the pro- visional organs which characterize the head in that stage are com- pletely suppressed. 'To what stage in the development of an Annelid does, then, the young Sipunculus-larva correspond ? It can only be compared to some much more developed condition from which, how- ever, it will be found to differ in important particulars, and notably in the absence of any indications of metamerism. Points of interest are also to be observed in the history of the development of the muscular and nervous systems: compared with the Annelid we find that the layer of circular muscles is developed much earlier than that of the longitudinal, and that the latter never form a continuous layer. The very early development of the two pairs of retractors is also an important point, and may perhaps be regarded as an instance of precocious differentiation, such as is often observed with those organs which play a specially important part in the organization of any class of animals. The rudiment of the ventral medulla is median and completely unpaired, instead of, as in the Annelids, presenting two lateral cords; to this character, however, Hatschek does not attach much importance, nor does he think that it affects the homology of the structure in the two groups. A special comparison is next made between the Sipunculida and the Echiurida, but his later observations have done nothing to shake Hatschek’s view that there isa gulf between the two groups, which are so commonly united together; the latter, indeed, form a sub- class of the Annelida, while the “Sipunculacea”’ are to be regarded as occupying the position lately held by the “ Gephyrea.” In a note on the head-cavities the author states that in Poly- gordius the coelom of the head appears to be formed by a secondary outgrowth of processes from the coelomic sacs; in other words, it is not, as some have thought, a direct continuation of the celom. In another note attention is directed to the late development of the cesophageal commissure, which Hatschek, contrary to the opinion of Kleinenberg and Balfour, believes to be a cenogenetic phenomenon. The author has made some speculations on the relation of the axis of the trochophore to that of the gastrula, and finds that the aboral end of the gastrula is directly converted into the apical area of 512 SUMMARY OF CURRENT RESEARCHES RELATING TO the trochophore; in other words, the anterior portion in front of the pre-oral circlet of cilia retains its primitive relation to the axis of the gastrula; this result, though arrived at by a different path, is the same as that reached by Kleinenberg from his speculations on the characters of the nervous system. Sternaspis scutata.*—F. Vejdovsky has some observations on the work of other naturalists on this form, and takes the opportunity of again expressing his conviction as to the intermediate position of Sternaspis (between Gephyrea and Cheetopoda). Monograph of the Chetognatha.t—Dr. B. Grassi, in one of the quarto publications of the Zoological Station at Naples, gives a general account of the Chetognatha. The first part consists of three chapters, the first of which contains a definition of the group, and an account of its genera, Spadella and Sagitta, and its 20 real or nominal species. The geographical distribution is next treated of ; while the third chapter deals with the anatomy and_histo- logy. A bibliographical list of 65 papers precedes the second part, which is devoted to “ considerazioni.” The Chetognatha seem to form a very distinct group of forms, with various resemblances to, but with no less important differences from others, which have been supposed to be their allies; the fibrils of the muscular tissue present vari- cosities which correspond with their dark strie; the giant fibres appear to be homogeneous; the study of the peripheral nerve-plexuses may throw some light on the physiological value of these plexuses in other animals, while the changes undergone by the intestinal epithelium during the process of digestion seem to support the view that the secretion is the result of the action of the gland-cells. Direct Reproduction of Tenia.{— P. Mégnin has examined a young dog, in the intestines of which he found 3 large examples of Tenia serrata, and 12 small specimens. These last, only a few milli- metres in length, must, the author thinks, have been derived by direct reproduction from ova set free from the larger specimens; they cannot have been more than a few days old, and for a month the dog had been under close observation, and had been fed on perfectly pure food. Mégnin has examples of similarly young forms taken from a human subject, and he looks upon these cases of direct reproduction as afford- ing an explanation of those pathological cases in which Tenia-infection has persisted for several years. Echinodermata. Democrinus parfaiti.s—Mr. P. Herbert Carpenter points out that this supposed new generic type || has been founded by Prof. Perrier, owing to the erroneous descriptions of the basals of Rhizocrinus lofotensis, which have been given by Sars and Ludwig, and his want of * SB. Bohm. Gesell., 1882, pp. 439-50 (1 pl.). + ‘Fauna u. Flora des Golfes von Neapel. V. Die Chetognathen.’ 1883, 118 pp. (13 pls.). ¢ Comptes Rendus, xevi. (1883) pp. 1378-9. § Ann. and Mag. Nat. Hist., xi, (1883) pp. 334-6. || See this Journal, ante, p. 216. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 513 acquaintance with the observations of Pourtalés. Mr. Carpenter is convinced that D. parfaiti is the same as Rhizocrinus rawsoni. The fragmentary condition of the arms is nothing unusual, as these arms often break off at one of the syzygies; their absence, therefore, must not be taken as a proof of the feeble development of the arms. In another note * Mr. Carpenter discusses the statements made by some observers as to the absence of the basals in certain Neocrinoidsg, and gives reasons, based on morphological considerations, for believing that they are really present; their absence would lead us into many grave difficulties. Coelenterata. Structure of Hydroid Polyps.j—In this, his second, essay C. F. Jickeli deals with the histological structure of Tubularia, Cordylophora, and other Hydroids; commencing with an account of 7. mesembry- anthemum, attention is directed to the existence of two whorls of arms on the hydranths, but, as the author is as yet unable to come to any decision as to their morphological value, he speaks of the one nearest the mouth as the first, and the other as the second whorl. The number of arms presents marked individual variations. Among the ectodermal cells are those which are ganglionic; not numerous, they are generally, though not always, poorly provided with protoplasm ; most of them are bipolar, and their processes are generally set parallel to the muscular fibres. A detailed account of this form is followed by some observations on Cordylophora lacustris, Cladonema radiatum, Coryne greefii n. sp., which was found in an aquarium of the Zoolo- gical Station at Trieste; Gemmaria implena, Perigommius steinachi n. sp., Podocoryne carnea, Campanopsis sp., Lafoéa parasitica, Campa- nularia coliculata, Obelia plicata, Anisocola halecioides, A. setacea, Isocola frutescens, and Kirchenbauria sp. Sixteen genera have now been examined by the author. In Hydra he finds an ectoderm separated by a supporting lamella from the endo- derm, while the gastric cavity is directly continued into the arms, This simple condition is not,as Allman has shown, to be found in any other polyp, for in all others there is a greater development of the intermediate tissues ; these last may, in the Tubulariide at any rate, be spoken of as a third body-layer, though one cannot definitely call it a mesoderm; with regard to the development of this layer, we unfortunately know nothing certain. In the ectoderm there are to be found investing cells which often become epithelio-muscular, and rarely supporting, glandular cells, various kinds of stinging cells, cells which go to form the capsules of the urticating cells, flagellate elements, ganglionic and sensory cells. The first of these vary considerably in size, and when they diminish in height it is often found that the boundaries between the cells dis- appear, and the whole fuse to form a lamella, on the lower surface of which a layer of fibrils becomes differentiated. The musculature is always best developed on the arms; the supporting cells are best * Tom. cit., pp. 327-34. + Morph. Jahrb., viii. (1883) pp. 580-680 (4 pls.). Ser. 2.—Vot. III. 2 L 514 SUMMARY OF CURRENT RESEARCHES RELATING TO developed in the parts where the ectoderm is deepest. Various forms of capsules for the urticating cells may be developed, and these may be elongated, oviform, pyriform, bean-shaped, or curved, and all kinds of intermediate conditions are to be observed; connected with these there are various forms of muscular processes. Closely allied to the urticating-capsule-cells are those which the author distinguishes as flagellate-capsule-cells, which would seem to correspond to that stage of the outer rudiment of the urticating filament (the palpocil- cells) in which the filament has become converted into a flexible con- tinuation of the capsules. Not only can ganglionic cells be always observed, but in some cases (Hudendrium, Tubularia) localized aggre- gations of them are to be found at the base of the hydranth, or, as in Campanopsis, beneath that umbrella-like fold of the ectoderm which is found in the region of the metastome ; and it is important to note that in all these three cases there was a collection of glandular cells just below the ganglionic. No connection between the two could be detected, though there were indications of it in Campanopsis. The author holds to his original view that the ganglionic are derived from those embryonic cells which form a part of Kleinenberg’s inter- stitial tissue, and also give rise to the cells of the urticating capsules. Indeed, the author is convinced of the nervous nature of the last- mentioned bodies, and brings forward various facts and considerations to support his view; in particular we may note his observation that he has repeatedly found an absence of nervous elements in those parts of the ectoderm in which the urticating cells are highly developed ; and we may well believe in the existence of a muscular plexus. In the endoderm we find the ordinary nutrient cells, which are frequently provided with muscular processes. Glandular cells are found most regularly arranged in the region of the hypostome, and are, as a rule, all of one form; this layer is capable of the most marked changes in form. The elements of the “mesoderm” are to be found in all stages of development. The axial cells of the sarcostyle seem to be the least differentiated from those of the endoderm; in other cases we observe indications of a localization of the whole tissue, and this is especially seen in the arms. In all the polyps examined it was noted that, when the arms became compressed into one whorl, there was a tendency at the base to the formation of a continuous tissue. These layers can be made out in the supporting lamella, where this is best developed, and of them the median may be regarded as embryonic, the outer as ecto- dermal, and the inner as endodermal. The author enters into some considerations as to the homologies of the arm-like structures, into which our space forbids us following him. Development of Hydra.*—A. Korotneff has been chiefly studying Hydra aurantiaca, though he has also made some observations on H. fusca. The maturity of the eggs is spoken to by the appearance of two directive corpuscles, which do not seem to owe their origin to the division of a single vesicle, but to be independent formations. * Zeitschr. f. Wiss. Zool., xxxvii. (1883) pp. 314-22 (1 pl.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 515 After an account of the mode of cleavage, we find that when the internal cavity of the embryo is completely filled up the earlier blastomeres take on the appearance of true cells, and divide most actively in the outer layer of the epiblast. In H. fusca the egg is closely attached to the parent, while in H. aurantiaca the ectodermal cells of the parent which are in relation to the egg, gradually become glandular in character, and give rise to a special organ which produces a kind of mucous substance, by means of which the egg is attached, and from which a special layer is developed around it. The epiblast and hypoblast become separated, and the surface of the former becomes warty, while its cells develope pseudopodioid lobate pro- cesses; and there are indications of a chitinous egg-shell. Each epithelial cell then forms a cylindrical body, at the base of which are some yolk-spheres. The egg now separates from the body of the parent, and becomes attached to various objects. The glandular cells of the disk, now developed, excrete a glairy mucous substance, after the secretion of which the special cells lose their peculiar characters. About this period there is a histolysis of the hypoblast, the cells of which lose their distinctness, the plasma becoming concentrated around the nucleus ; the epiblast and hypoblast are not nowso sharply distinguished. The cells of the former undergo a retrograde meta- morphosis; and we find that the primary epiblast goes to form the egg-shell, while the yolk-membrane and the mucous layers are com- pletely used up, and take no part in the formation of the secondary epiblast. The author points out that the doctrine that if the epiblast is cast off the nervous layer ought to be most external (and in fact the ordinary ectoderm of Hydra consists of an uninterrupted layer of nerve-cells), is supported by his observations. He regards the histolysis (meta- morphosis) of Hydra as a direct result of external influences, which act in quite a special way. In the lower animals, and especially in the Coelenterata, we cannot say that the germinal layers play so definite a part as in the higher forms. These exceptions and varia- tions from what are regarded as general laws, which we see in the lower forms, are due to adaptations, the capacity for which in these organisms is much more considerable than in the higher animals; and thus we may understand how it is that the outer layer of the morula forms a shell. Alternation of Generations in Hydro-meduse.*—Mr. W. K. Brooks thinks it is hardly possible that the form of development which we now find in most of the Hydro-medusz can bear any close resemblance to their primitive life-history; and there are many reasons for believing that alternation of generations has gradually arisen through the modification of “ metamorphosis.” In Cunina we seem to have the ancestral form of development, a direct metamorphosis without alternation. The interesting and remarkable life-history of Cunina was first described by Professor M‘Crady, who found inside the bell of a hydro-medusa, Turritopsis, a * Jolins Hopkins University Circulars, ii. (1883) p. 73. 2L 2 516 SUMMARY OF CURRENT RESEARCHES RELATING TO number of hydra-like larve attached by short tentacles to the sub- umbrella, and furnished with a very long and flexible proboscis, with the oral opening in its tip. These are the larve of Cunina and are parasitic ; and they obtain their food by inserting the proboscis into the mouth of the Turritopsis, and thus sucking from its stomach the food which it contains. During the past summer both Turritopsis and Cunina were extremely abundant, and the author was fortunately able to trace the life-history of each of them. The larva of Cunina is a hydra, with the power of asexual multi- plication ; but instead of giving rise to medusa-buds like an ordinary hydroid, it becomes directly converted into a medusa by a process of metamorphosis ; it is a true larva and not an asexual generation, although the occurrence of asexual production renders the gap between this form of development and true alternation very slight indeed. In Cunina we have a series of this kind :— ais Larva—Larva—Larva, | | | Adult—Adult—Adult. If the larva which is produced from the egg were to remain per- manently in the hydra-stage, we should have a series like this :— ce Hydra—Hydra—Hydra, | Medusa—Medusa ; and such a history would be a true alternation. Hydro-meduse without Digestive Organs.* — Dr. Lendenfeld describes a new sub-family of hydroids, Hucopelline, in which the medusa has no digestive organs, and lives only a short time after its escape from the gonophore. Only one species, Hucopella campanularia, is known, and this is foundin Australia. The larva is a campanularian whose hydranths are carried upon short, unbranched stems, which spring from a creeping root. The medusa has a veil, well-developed marginal sense-organs, radial and circular chymiferous tubes, and large reproductive organs, but it has no mouth, stomach, or tentacles. It discharges its reproductive elements within twenty-four hours after its liberation, and it lives only about thirty-six hours. Phylogeny of the Siphonophora.t—Professor C. Claus treats of the relation of Monophyes to the Diphyide, and of the phylogenetic development of the Siphonophora. Nine years ago he pointed out that Monophyes might be compared to that larval stage of the Diphyide in which there is only one nectocalyx developed, at the * Zool. Anzeig., vi. (1883) pp. 186-9. t Arbeit. Zool. Inst. Wien, v. (1883) pp. 15-28. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. Fy side of which a gastric tube with filaments and a group of gemme is formed. After some notes of and criticisms on later studies and especially on those of Chun, the author comes to the conclusion that the Siphonophora arise from a stage in the development of the Hydroidea not unlike that represented by the Hydractinide; this form did not, however, become fixed, but continued to lead a free-swimming pelagic life, and so became capable of further development. It is probable that the cell-material collected at the aboral pole of the growing polypoid body formed a zone of gemmation from which, without stem or stolons being formed, polyps and medusoid buds could be given off. If the oral circlet of tentacles remained arrested in development one or another polyp-bud might, if it elongated and did not become provided with a mouth, become converted into a tentacular appendage which would take on the function of a “ fishing-line” (Fangfaden); a medusoid bud would become converted into and be gradually set free as a sexual form, while its place as the nectocalyx would be taken by a fresh medusa formed by gemmation. It is almost certain that this sexual animal had at first the marginal filaments and eye-spots, which were only completely lost during the later processes of adaptation, in just the same way as the Mnestra which is attached to Phyllirhoe has lost the marginal organs of the medusoid body. In the course of further changes we must suppose that the first developed medusoid bodies would lose the power of developing generative elements and would persistently retain the function of the nectocalyces or of the hydrophyllia. The sterile meduse would either become ° bell-shaped or have a deeply excavated swimming-sac, or cartilaginous covering pieces with atrophied subumbrella, and subumbrellar vascular apparatus. The oldest Siphonophora must have gone through a number of changes before they became converted into the present Calycophora, while the development of a pneumatophore was necessary for forms like the Physophoride ; it is almost certain that this divergence did not commence at a simple, but at a very advanced, stage. The appear- ance of the first-mentioned hydrostatic apparatus must be taken as a character of great importance, and we may group together those forms —Physophoride, Physalide, and Discoidea—which possess it under the name of the Pneumatophora. The organ would seem to have been developed, phylogenetically, at a stage much later than ontological evidence alone would lead us to expect; there are many points of affinity between Hippopodius, which is a Calycophore with a number of cells, and the physophorid Apolemia. The problem of whether the pneumatophora was a “neomorph” or a metamorphosed bud cannot yet be exactly determined, though the latter view is the more probable. The fact that this pneumatophore has an opening to the exterior explains its great importance as a hydrostatic organ, and the correlated suppression of the nectocalyces. We may pass through the simpler stage of Rhizophysa with an elongated stolon, to the more metamorphosed Physalidz, which are bladder-shaped ; and from them to the Velellide, the form of which is discoid; these are the most aberrant of the whole group. 518 SUMMARY OF CURRENT RESEARCHES RELATING TO Embryonic Tentacular Knobs of certain Physophores,*— While investigating the anatomy of the tentacular knobs of several genera of Calycophores, Mr. J. W. Fewkes was struck by their close resemblance to the “embryonic knobs” of Agalma. Tf the terminal filament of the Calycophore knob be reduced to nothing, we have left a tentacular appendage homologous with the embryonic knob of Agalma, Physophora, Agalmopsis and other Physo- phores. This resemblance seems to the author to have a genetic significance, and to indicate a relationship between two great groups of Siphonophora, called the Physophore and Calycophoree. In order to strengthen this supposition he was led to search out other re- semblances in the larve in which these structures are found. The result was that an interesting likeness between the single (“em- bryonic”) nectocalyx of Monophyes and the “primitive scale” of Agalma was found. The following reasons led him to regard these last-mentioned organs as homologous. Both are formed in the same way, both are embryonic and are lost in subsequent development. Woe have in the “primitive scale” of Agalma an indication of the oint in the development of the Siphonophora, where the separation of the Physophore from the Calycophore, or where the separation of both groups, from a “stem-form,” took place. The embryonic bell of Monophyes is an organ of motion; the primitive scale of the young Agalma, although homologous to a bell, has lost the function of motion, and is an organ of flotation; while in Agalmopsis (Halistemma) the embryonic bell is not even represented. The only structure in the larva of Agalmopsis (Halistemma), which shows the relation of this genus to the Calycophore is an embryonic tentacular knob, like that of the larva of Agalma, which is thought to be homologous to the tentacular appendage of the Calycophores. This statement of a possible genetic relationship between these two groups is not held to apply to the Pneumatophore (“ Pneumatophoride ” Chun), nor to the Discoiden. Blue Colouring Matter of Rhizostoma.j—R. Blanchard has a note on his own investigations into the blue colouring matter of Rhizostoma cuvieri, in which he points out the differences between his results and those lately obtained by Kleinenberg on the same body ; one which the latter author distinguishes as cyanein. The French observer finds that the tissues give up the colour after death, and that the blue colour of the aqueous solution disappears when heat of from 40° to 45° is applied, and gives place to a well marked rosy hue, which, again, disappears on cooling. Spectroscopic examination reveals the presence of three absorption-bands, one in the red, one in the yellow, and one in the green region; the second of these corre- sponds almost exactly in position to the sodium-band. If the aqueous solution is treated with ammonia the blue colour is immediately pre- cipitated under the form of small blue flakes which may be ¢éollected on the filter-paper and analyzed. The author hopes that further investigations will reveal the cause of the differences which obtain between his results and those of Krukenberg. * Amer. Natural., xvii. (1883) pp. 667-8. + Bull. Soc. Zool. France, vii, (1883) pp. 402-4. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 519 Porifera. Australian Aplysinide.*—Under the title of Ccelenterates of the Southern Seas II., R. von Lendenfeld gives an account of some new sponges. Of these the first is Aplysilla violacea, the general appearance of which is first described ; an examination of the skeletal structures shows that there are some striking differences between the Adriatic and the Australian species as to their modes of branching. The pores of this species are never closed, though there is a sphincter- like arrangement of contractile fibres by means of which the size of their aperture can be diminished. The histological structure is then carefully described, and in an account of the mode of digestion it is stated that if these sponges are placed for some days in water in which fine particles of carmine are suspended, it will be found that the epithelial cells not only of the afferent canals, but also of the ciliated chambers, take up these particles, and that they are also found, although in less quantity, in the epithelium of the efferent canal system of the oscular tube and of the outer surface. In other words, all the free surfaces are able to take up foreign bodies; and the same is true also of the migratory amceboid cells. If we remove the sponge from the carmine-containing water, and place it in fresh sea-water, we may follow out the fate of the carmine granules. After about six hours the epithelial flat-cells of the upper wall of the sub- dermal space, and the collar cells of the ciliated chambers are free from carmine, and particles of this substance will be found in the water; on the other hand, the amceboid cells underlying the epithelium of the subdermal space will be now seen to contain carmine, although before they had none at all. These observations lead to the con- clusion that, in A. violacea, small organic bodies are taken up from the ectodermal flattened cells of the subdermal epithelium, and make their way into the subjacent amceboid cells. Here the injected matter is digested, while the amceboid cells migrate, carry the undigested remains to the ciliated chambers, and then pass them on to the collared cells, whence they are extruded. Infusoria may frequently be observed in the subdermal spaces and in the afferent canals, while diatom-valves may sorhetimes be seen in the migratory cells. The presence of glandular cells is also noted, and they are said to closely agree in structure with the spongoblasts. Although this sponge is hermaphrodite, self-fertilization is guarded against by the earlier (by about fourteen days) maturity of the male elements. After an account of the characters of the generative products and of the horny fibres, Lendenfeld passes to Dendrilla, a new geuus, distinguished by the facts that the mesodermal connective tissue contains no granules and is hyaline, as in Aplysilla; the ciliated chambers are large, saccular, and arranged radially; the sexes are united, and the genital products are arranged in irregularly-shaped groups ; large subdermal spaces are not only developed under the * Zeitschr. f. Wiss. Zool., xxxviii. (1883) pp. 234-313 (4 pls.). 520 SUMMARY OF CURRENT RESEARCHES RELATING TO outer integument, but also at times beneath the walls of the oscular tube ; the species are not incrusting, and have a delicate stalk, while the horny fibres are tubes of spongiolin, arranged in dendritic fashion. D. rosea is found at Port Philip, as is also D. aerophoba. An elaborated and careful account is given of the external and histological characters of these forms. The paper concludes with a tabular review of the most important characters of the Aplysilline, which with the Aplysinine, are the two sub-families of the Aplysinide; the former contains the two genera Aplysilla, with three species, and Dendrilla, with the two described for the first time in this paper. Protozoa. Characters of Infusoria.*—G. Entz commences with an account of Actinobolus radians of Stein, which was placed by its discoverer in the family Encheline ; the investigations of the present author lead him to the discussion of the question of the genetic relationships between that family and the Acinetine, and as to which are the earlier. If we regard Actinobolus as an Encheline, the tentacles of which are lately acquired structures which, as more highly differen- tiated organs, form the sucking-tubes of the Acinetine, and if we regard this change as going hand-in-hand with the loss of mouth and arms and the greater loss of the cilia, we may consider that the Encheline are the older forms, and Actinobolus intermediate between the two. It would seem, however, that any discussion of this point will be more or less barren till we can come to some more definite idea as to the genealogy of the Ciliata; we find, that is, that R. Hertwig confidently regards the primitive Ciliate as having been a unicellular organism, which was provided with a continuous invest- ment of cilia, while Bergh looks upon the Peritricha as being the oldest Ciliata, which have been derived from the Cilioflagellata by the reduction of the flagellum and the differentiation of a cystostome and cystopyge. Mesodinium acarus and Didinium nasutum are closely compared with Urocentrum turbo, with the object of showing that the two former differ so much from the third in all essential points that it is not possible to place all three in the same category. The author is of opinion that there are several characters which are as, if not more, important than the ciliation; such are the absence or presence of a mouth, and in the latter case the characters of the peristome, the structure of the pharynx, the position of the anus and of the contractile vacuole. A study of the ciliation alone will certainly lead to many Infusoria being placed in wrong families. The author finds himself compelled to separate the Cyclodines from the Peritricha, and to regard them as nothing more than Encheline in which the ciliation has become confined to two circlets of cilia. It is suggested, but by no means asserted, that the “ proboscis” of D. nasutum is a colossal suctorial tentacle. Some points in favour of the phylogenetic views of Bergh are noted, but no definite opinion * Zeitschr. f. Wiss. Zool., xxxviii (1883) pp. 167-89 (1 pl.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 521 on the genetic relationship of the Cilioflagellata and the Peritricha is at present offered. Development and Classification of Polytoma, Ehr.*—J. Krassil- stschik describes Polytoma spicatum which he found in the same in- fusion { as P. wvella, It is distinguished from the latter by having a body pointed behind, and it is somewhat more slender, being when full-grown 20-25 pw by 10-12 p as against 19-23 » by 11-13 p. The development of both species of Polytoma is as follows :—The young passing from the resting stage divide into eight parts. This division is at first into two, then into four, and finally into eight. It extends throughout the whole body-substance within the envelope of the mother organism. The latter, as well as its two flagella, remains uninjured during the fission and their motion is not in the least dis- turbed. The eight cells assume at first a round form, then elongate, and take the shape of a Polytoma. After the bursting of the parent envelope the eight young ones escape, and begin to grow until they attain the size of a full-grown Polytoma. Then they also divide in the same way as tle earlier ones, but this time into four, and never into eight parts. The division into eight is not again met with, since each succeeding generation divides into four and only four, pro- vided that there is no considerable alteration in the temperature, nourishment, or life-conditions of the Polytoma. In from four to six days most of the individuals commence to conjugate in pairs, form zygotes, assume a spherical form, and after the secretion of a tolerably thick membrane pass again into the resting condition. During the fusion of the two zoospores, the nuclei also blend together. The conjugating Polytoma vary very little, if at all, from the non-conju- gating. The last generation are mostly distinguished by the size and bright colour of their starch-containing granules. This, how- ever, is not always to be relied on, as with rich nourishment all have somewhat large, bluish-green corpuscles, and in unfavourable circumstances even the conjugating individuals have only small pale granules, The size also to which the latter attain is not always the same. For the most part the young do not begin to pair immediately after their exit from the parent envelope, but grow somewhat first. Moreover, when they have not the opportunity to pair whilst still small, they continue growing to the size of a full-grown Polytoma, and still retain their capacity for conjugating. These can pair either with each other or with quite young Polytoma. It is easy to under- stand that where a full-grown conjugates with a young one, it seems as if it was the conjugation of a macro- with a micro-zoospore, or a male with a female. Exact observations on the development of isolated examples of Polytoma have however shown that there are neither macro- nor micro-, male nor female zoospores to be distin- guished ; further, that there is no distinction between the Polytoma of the last and the first generation, and that in certain circumstances the * Zool. Anzeig., v. (1882) pp. 426-9. + The infusion was made by moistening with water the muddy sediment from a fountain basin. To this infusion rotting leaves were added and the vessel set in a warm place. 522 SUMMARY OF CURRENT RESEARCHES RELATING TO Polytoma of the last generation not only divide into eight and then into four several times, but can also produce progeny with the capacity for conjugating. Besides conjugation, the Polytoma have another way of reaching the resting stage. In P. spicatum was observed a similar condition to that which exists in Chlamydococcus. After the loss of the cilia, the body-substance began to detach itself from the envelope, took the spherical form and secreted a clear membrane on its surface. After this no division of the cells took place, the membrane became some- what thicker, but how the little ball escaped from the parent envelope, and what became of it afterwards, could not be observed. Whether the Polytoma reach the resting state in one way or the other, in both cases we have globular cells. To further the trans- formation of the cells to the Polytoma, the cells, after remaining long in water, should either be dried and afterwards soaked in fresh water, or removed direct into a rich solution of organic matter (for example a 2-8 per cent. solution of gelatine in an infusion of hay). In both cases the young will during the night slip out of the cells. In the large cells a division into four first takes place, and in the small ones into two, and then the young ones appear. A palmella or pleuro- coccus condition was not observed. The cycle of development of a Polytoma lasts 3-14 days. If we compare the development of Polytoma with that of the chlamydomonads, we find at once that P. uvella cannot be called, with Cohn, Chlamydomonas hyalina, and that the Polytoma are not to be classed with the Chlamydomonads, although, like the latter, they belong to the Volvocinex. Further particulars as to the structure, the variety of division, and the development of both species of Polytoma, as well as their devia- tions from normal development, will shortly appear in the memoirs of the Odessa ‘ Neurussische Naturforscher-Gesellschaft.’ Ophryocystis Bitschlii.* — A. Schneider has discovered in the Malpighian vessels of Blaps a most curious new sporozoarium. It bas the form and external appearance of an Ameba; its body is often covered with simple or divided digitiform processes, which may equal or exceed the central mass in length. The latter, which is charged with granules, contains from one to ten spherical nuclei 3 » in diameter, with one or two punctiform nucleoli. The multiplication of the species is effected principally by cysts. Encystment takes place only between individuals with a single nucleus and of spherical form. The two conjugated organisms secrete around them successively several envelopes, each marked with an equatorial line of dehiscence. The phenomena which succeed one another in the cyst are very peculiar. Each of the two nuclei divides so as to produce three nuclei in the corresponding half of the cyst. Of the six nuclei thus produced, only two take part in the constitution of the reproductive elements, represented exceptionally by two small spores, and normally by a * Comptes Rendus, xevi. (1883) p. 1378. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 523 single large spore. A portion of the plasma of the cyst is implicated with the nuclei in this spore-formation. The four other nuclei and the rest of the granular mass of the cyst remain unused and become liquefied. The spore, resembling a Navicula, produces in its interior, besides a residuary nucleus, a certain number of falciform corpuscles, each provided with a nucleus. Social Heliozoan.*—Prof. J. Leidy describes a singular Heliozoan from Lake Hopatcong, N.J. The animal occurred mostly in groups composed of numerous individuals ; one, of irregular cylindroid shape, 0-84 mm. by 0°36 mm., contained upwards of a hundred individuals. They reminded one ofa mass of tangled burs. They remained nearly stationary even for twenty-four hours, and exhibited so little activity that, without careful scrutiny, they might readily be taken for some inanimate structure. The individuals composing the groups appeared to be connected only by mutual attachment of their innumerable rays, and none were observed to be associated by cords of protoplasm ex- tending between the bodies of the animals, as seen in Raphidiophrys elegans. They were of two kinds—some active and a smaller propor- tion which were in an encysted, quiescent condition. The active individuals resembled the common sun-animalcule. The body measured from 0:024 to 0:036 mm. in diameter—in the encysted individuals usually about 0°02 mm. The active individuals were observed to feed on two species of minute monads, which were swallowed in the same manner as in Actinophrys. After some hours a few individuals appeared to have separated from the surface of one of the groups, but they were as stationary and sluggish as when in association with the others. : The species is apparently distinct from others previously noticed and may be named Raphidiophrys socialis. Living Organisms in Brickwork.}—“‘ Wherever Science looks with “ close and careful eyes life appears to be found. The deepest sea- “ soundings reveal the existence of cephalopods, brittle-stars, or lower ** genera; the upper waters are full of invisible creatures; the dust of “ the air is laden with germs and infisoria; and there is no part of “ any living bodies but seems to be peopled with countless parasitical “dwellers. It is a little surprising, however, to be told that the “ decaying bricks of all our buildings in London and elsewhere are “ densely inhabited by special animalcula. This, however, is posi- “tively announced by M. Parize, who declares himself to have seen “ with the Microscope, in every portion of crumbling, weather-worn “ brickwork, minute living organisms, which are the real destroyers “ of the surface and even the walls of buildings. The harder the “brick the fewer these tiny burrowing things would be; but “ wherever the walls are seen to be ‘weathered’ there they are “ declared to exist, making their invisible lodgings in the material “ which would seem so impervious. We do not answer for the “ accuracy of these observations, but they cannot be called ridiculous * Proc. Acad. Nat. Sci. Philad., 1883, pp. 95-6. } Daily Telegraph, 3rd April, 1883. 524 SUMMARY OF CURRENT RESEARCHES RELATING TO “ when it is remembered that the sea-worm eats through stone and “ shells, and that even tobacco-leaves are bored by creatures which “ feed on them and dwell in them. That these odd beings can get “ nourishment from a bath-brick or a cornice cannot be imagined ; but ‘if they really inhabit our walls, as is said, one more proof is given “¢ of the ubiquity and wonderful variety of life.” BOTANY. A. GENERAL, including Embryology and Histology of the Phanerogainia. Continuity of Protoplasm through the Walls of Cells.*—The existence of an open communication between certain cells of the higher plants, viz. between the different elements which make up the sieve-tubes, has been shown by the recent investigations of Wilhelm, Janezewski, Russow, Tangl, Frommann, Strasburger, and others, and most emphatically by the observations of Gardiner { on the pulvinus of Mimosa. W. Hillhouse adds a fresh series of observations to the same effect carried on in Prof. Strasburger’s laboratory at Bonn. The preparations were made from the cortical tissue of the young stem of the laburnum, and from the cortex and base of the leaf of a number of other trees and shrubs, the best results being obtained in January. The method pursued with the most successful results was as follows. Radial and tangential sections as thin as possible were pre- pared, either from fresh material with a razor covered with a layer of absolute alcohol, or from material which had lain some days in abso- lute aleohol. The sections were then treated with dilute, and, after some minutes, with concentrated sulphuric acid, which had been pro- tected from the air for from 20 to 48 hours. The acid was then care- fully removed by a pipette, and the preparation washed several times with distilled water ; it was then inclosed in glycerin without having been once removed from the glass slide. By this means the whole of the cell-wall is removed ; the intercellular substance often completely disappearing also. The author describes in detail the preparation obtained in this way from a radial section through the base of the leaf of Prunus laurocerasus, where the parenchyma consists almost entirely of collen- chymatous cells abundantly pitted. The connection of the proto- plasmic strings of adjacent cells was here distinctly seen after the removal of the cell-wall. Similar results were obtained with a number of other plants, a very good example being furnished by the winter- buds of the sycamore. The protoplasmic threads which penetrate the cell-walls are, however, so delicate, so refringent, and appear to be so * Bot. Centralbl., xiv. (1883) pp. 89-94, 121-4 (1 pl.). + See this Journal, i. (1881) p. 70. } Ibid., ante, p. 225. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 525 slightly tinged by reagents, that no means at present exists of detecting them in situ. These facts are of the greatest importance in connection with Strasburger’s view of the unity of the entire plant. The author sug- gests that the continuity of the protoplasm from cell to cell may be an important factor in accounting for the contractility of the motile organs. Pollination of Rulingia.* —According to J. Urban, several species of this Australian genus of Buttneriacee possess curious adaptations to crossing by insect aid. The flowers are small (1 cm. or less in diameter) and whitish. The pistil secretes nectar, which collects about it or in the hollowed petals. At first the stigma is closely covered by five dilated staminodia, closely inflexed over it for a time, but later separate. In R. pannosa there is well-marked proterandry, the staminodia not separating, nor the stigma maturing, until the stamens are all dehiscent. RR. corylifolia, on the other hand, is synacmic, the expansion of the sepals and the dehiscence of the stamens occurring in regular succession, and being closely followed by the successive removal of the staminodia from the mature stigma. BR. parviflora is intermediate between the two species already men- tioned. Its flowers assume a rosy colour with age, like those of Trillium grandiflorum, Weigelia, &e. Development of Chlorophyll-grains and Pigment-bodies, t — Further investigation of these bodies by A. F. W. Schimper leads him to the conclusion that the growing point always contains differ- entiated chlorophyll-bodies or their colourless matrix, and confirms the view that these are not formed by rejuvenescence out of the cell- protoplasm, but always by division from those previously existing, and that they are the source of all the chlorophyll-bodies and starch- generators of the tissue which developes from the apical meristem. A very favourable instance of a green growing point is afforded by the roots of Azolla, which contain bright green chlorophyll-grains in their apical cells. They occur also in the growing points of the aerial roots of epiphytal orchids, especially in Dendrobrium spectabile, and in the roots of Lemna and the slenderer roots of Hydrocharis morsus- rane. Inthe majority of cases, however, the growing point and the merismatic parts of plants contain no chlorophyll, from the absence of sufficient light; and even when exposed to the light they frequently contain only the colourless protoplasmic matrix of chlorophyll-grains, i.e. starch-generators, as in the roots of seedlings of Zea Mays and Phaseolus, and the aerial roots of Impatiens parviflora. Colourless growing points contain colourless starch-generators, resulting from division, and not from rejuvenescence; these are always found in the growing point of the stem of seedlings, and give rise, by division, to all the chlorophyll-grains, starch-generators, and pigment-bodies of the entire organism, except those of the roots, which * Ber. Deutsch. Bot. Gesell., i. (1883) pp. 53-6. + Bot. Ztg., xli. (1883) pp. 105-11, 121-31, 137-46, 153-62 (1 pl.). Cf. this Journal, ante, p. 238. 526 SUMMARY OF CURRENT RESEARCHES RELATING TO are in the same way the products of the starch-generators occurring in the growing point of the radicle. A very good example of spherical leucoplastids is afforded by the transparent cells of the growing point of Impatiens parviflora ; also by those of Tropeolum majus and Dahlia variabilis. The plastids in the growing points of monocotyledons appear as a rule to be very small; they can readily be made out in the aerial roots of Hariwegia comosa and in Tradescantia. An exceedingly interesting point is that the plastids of seedlings are not formed during germination, but are already present in the seed, and that those found in the growing points of the radicle and plumule are the direct product of similar bodies contained in the ovum-cell, and therefore are directly derived from the parent plant. The cell- contents of the embryo are, however, far too dense for the plastids to be detected in them. One and the same plastid may undergo many metamorphoses; the leucoplastids may become chlorophyll-grains, and subsequently again lose their colouring matter; chloroplastids and leucoplastids may become chromoplastids. It is clear that the chloroplastid must be regarded as the original form of plastid, from which the others have subsequently developed. The lowest organized plants known to con- tain leucoplastids or chromoplastids are the Characez, the former in their apical cells, the latter in their antheridia. Leucoplastids owe their origin either to previously existing leuco- plastids or to chloroplastids ; this latter is the case with those flowers and fruits which change colour from green to white, as the berries of the “snowberry tree.” They do not appear here to have any special function. In other cases they are the generators of starch. On the other hand, in many flowers leucoplastids become transformed into chromoplastids. Chloroplastids (those which contain chlorophyll) are also derived either from other chloroplastids or from leucoplastids. To this class the author refers with hesitation the red and brown assimilating struc- tures of the Floride and Pheospores, as well as the brown pigment- bodies of Neottia nidus-avis. Chromoplastids exhibit every variety of shade between pure carmine-red and greenish yellow; other colours, as blue, do not appear to occur, though vacuoles and other bodies have been mistaken for them. They are sometimes more or less regularly spherical, more often of a crystalline form, but most often fusiform, acicular, or rod-shaped. As long as they are uninjured they never contain vacuoles. They are invariably derived from leucoplastids or chloro- plastids, even the form of these being sometimes not changed. Some- times they assume regular crystalline forms. They may be classified, according to their forms, under three types:—(1) nearly or quite spherical, (2) with two or more pointed ends, and (3) rod-shaped with rounded ends. The first type occurs in the aril of the yew, the berries of Solanum dulcamara, and the petals of Nuphar luteum. Those of the second type vary greatly in form, and are found in the perianth of Hemerocallis fulva and Asphodelus luteus, the fruit of Sorbus aucuparia and Euonymus europeus, the petals of Tropeolum majus, &c. We find ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 527 a combination of these two types in the hip of the rose, the fruit of - Lonicera xylosteum, the perianth of Iris pseudacorus, and the petals of Cucurbita pepo. The third type occurs in the perianth of Tulipa Gesneriana, the root of the carrot, and the perianth of Mawillaria triangularis. Chromoplastids are always developed from round leuco- plastids or chloroplastids. The angular form is the result of changes in shape of the entire plastid, not of any disruption. No connection can be traced between the form of chromoplastids and the systematic position of the plant in which they occur. The albumen of a number of plastids belonging to these three types passes over, in the living cell, partially or entirely, temporarily or permanently, from the living into the crystalline condition. In leuccplastids the albumen is comparatively rarely in the crystalline condition ; the forms observed may he classified under three types : — the fusiform, rod-shaped, and spherical. The two first types are very unstable. Their chemical composition is always very nearly that of living protoplasm; they may pass over directly into it without, at least at first, losing their crystalline form. The living portion of the plastid is renewed by the direct transformation of crystallized into living protoplasm. The albumen of chloroplastids is also compara- tively seldom crystalline. That of chromoplastids crystallizes more often. Except in Cucurbita, this takes place, in all the cases ex- amined, before the opening of the flower or ripening of the fruit, often in the very young organ. In the act of crystallization the colouring substance is either mechanically inclosed or is less often thrown out. These crystals agree altogether in form with those of leucoplastids; they are most commonly fusiform, less often rod- shaped. Effect of Tension of the Bark on the Formation of the Annual Rings of Wood, and on the Direction of the Medullary Rays.*— A careful series of observations on this subject by G. Krabbe leads him to the conclusion that as long as the structure of the bark has under- gone no substantial change either from wounds or from other processes, its tangential tension increases with the increase in thickness of the wood. In opposition to the view of Kny, he considers that the medullary rays are diverted from their original position in conse- quence of the greater contraction of the bark on the side towards which they tend. Formation and Properties of Duramen.{—J. Gannersdorfer ap- plies the term duramen (Kernholz) not only to the harder wood towards the centre of stems, but also to the layer of more or less dark- coloured wood often found in the neighbourhood of wounds or adjoining dead tissue. The vessels of this duramen frequently furnish thylle. For the dark-coloured contents of the vessels the author adopts Hartig’s term xylochrome. The following are among the more important results of his observations. - ee Akad. Wiss. Berlin, 1882, p. 1093. See Dabarorenee Xvi. (1883) p. 5 i ‘SB. Akad. Wiss. Wien, Ixxxv. (1882) pp. 9-41. 528 SUMMARY OF CURRENT RESEARCHES RELATING TO These formations of duramen are commonly produced in the first place by derivatives from the solid contents, especially starch, filling up all the elements of the wood. These products are formed in the affected part, as well as being conveyed from the adjoining normal parts. These products cause an increase in the mass of the duramen, so that its weight exceeds that of the alburnum. These substances must be in a fluid or half-solid state when deposited in the tracheal elements, since they reproduce perfectly the inner structure of the walls of the cells and vessels. As long as these substances are con- tained in the parenchymatous elements they are rich in tannin, so that they seem to constitute a link between the contents of the duramen and starch. In addition there also occur products of decomposition of a different kind, which, at least after they have been deposited for some time, considerably increase the power of resistance of the duramen. Nitric acid, or Schulze’s solution, and potash or soda-lye, used in succession, remove nearly completely the contents of the duramen, except in the case of Diospyros; and the uninjured cell-wails are then exposed with their thickening-layers, and distinctly exhibit the cellulose-reaction. If the deposition has lasted for a very long period, the cell-walls are themselves partially destroyed, and the pro- ducts of their decomposition mingle with the cell-contents. The contents of the duramen vary in their composition according to the species ; in Prunus, for example, and the Amygdalez generally, they consist chiefly of gum; in the Conifere of resin; in Syringa of resinous substances. Their mode of origin is the same in all cases. The function of the duramen, especially in stumps, is the protection of the subjacent tissue from injurious external influences. The same effect is produced by the thylle which occur in many plants, and by deposits of calcium carbonate. Polarization-phenomena of Vegetable and Artificial Colloid- cells.*—N. J. C. Miiller gives the following as the results of a series of observations on the polarization of vegetable colloids and of gelatine :— Hollow spheres in vegetable colloids and in gelatine have a nega- tive tension in the marginal layer; that is, they behave as if their marginal layer were made rigid by expansion of the cavity. Solid spheres, on the other hand, such as the natural spheroids of starch and inulin, have a positive tension—that is, they exhibit a rigidity due to compression. All cell-walls in the interior of the plant behave as if they were made rigid under negative tension. Polyhedral and spherical cells are optically uniaxial; cylinders and prisms optically biaxial. Transverse sections of all correspond to the optical section of the marginal layer of a hollow sphere. The cuticular layer and cork-membrane behave in the reverse way; they correspond to a colloid mass made rigid under compression, so that a calotte cut out of an extine-intine mass of the epidermis behaves precisely like a circular section of a glass tube. All vegetable colloids adapt them- selves to cylindrical cells, which correspond, in their optical properties, * Ber. Deutsch. Bot. Gesell., i. (1883) pp. 77-83. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 529 to the natural cylindrical or prismatic cells in the interior of the plant. The only instance of a different behaviour is in an artificial cylinder of gum-tragacanth, which resembles the stem-cell of Caulerpa. All the more delicate points of structure, such as pitting of the membranes, dots, or pores on the one hand, or projecting masses, ridges, or spiral bands on the other hand, can be imitated artificially in colloids rendered rigid. The former can be referred to the phenomena of hollow spheres, the latter to local compression or dilatation of the rigid mass. Origin of ‘“ Cell-passages.’’*—In the annual rings of many woody plants there are visible even to the naked eye long crescent-shaped spots, which are seen on tangential section to be passages, and which have been described under various names, “ Marktlecke,’ “ Zell- singe,” &c. These have been examined in a number of trees, willow, birch, alder, Pyrus, &c., by M. Kienitz, who has determined them to be always abnormal structures; and in fact to be passages produced by larvee, and filled up by new cells, the larve having devoured the cambium and other young cells at the time when the ring was being formed. The cells which break through the margin of the wound grow rapidly, and divide further by delicate septa; at the same time the cambial ring closes up completely; and from this time normal wood and normal cortex are again formed above the surface of the wound ; while, quite independently of the new cambium, the cavity is closed by the growth of the cells. Collenchyma.j—In a monograph on this subject, HE. Giltay treats chiefly of the mechanical importance and properties of collenchyma. Collenchyma occurs either at the periphery of organs, or less often in the centre; in the form either of collenchymatous bast, distinguished by the secondary sclerenchymatous elements not being lignified, as in Polemonium reptans, Lycium barbarum, Peperomia, Botrychium Lunarias and Ophiogiossum vulgatum, or as collenchymatously thickened medul- lary cells, as in Panicum imbecille and Erythrina marmorata. In the eollenchyma of the vascular bundles the author includes not only the ridges in Umbellifere, Labiate, &c., but also the stereome of Aroidex, inaccurately termed sclerenchyma by Schwendener. Although collenchyma occurs comparatively rarely in mono- cotyledons, it was found in all the climbing species examined, Aspa- ragus scandens, Lapageria rosea, Smilax, and Roxburghia viridiflora. With regard to the power of swelling of collenchyma, the author shows by numerous measurements on various plants, Feeniculum vulgare, Dipsacus ferox, Achillea filipendula, Pyrethrum multiflorum, and Rubia tinctorum, that the wall of collenchymatous cells may be 32 per cent. thicker in water than in alcohol of 95 per cent. As regards the history of its development, Giltay agrees with Haberlandt that the origin of mechanical tissue is as various as possible. 3 * Bot. Centraibl., xiv. (1883) pp. 21-6, 56-61 (2 pls.). + Giltay, E., ‘Het Collenchym,’ 186 pp. (5 pis.) Leyden, 1882. See Bot. Centralbl., xiii. (1883) p. 409. Cf. also this Journal, i. (1881) p. 768; ii. (1882) pp. 71, 812. Ser. 2.—Vou. III. 2 M 530 SUMMARY OF CURRENT RESEARCHES RELATING TO Structure of the Pericarp of Orchidew.*—J. A. Oecsterberg describes the structure of the pericarp in a number of plants belong- ing to the order Orchidew, with special reference to the course of the fibrovascular bundles in the flower. ‘The pericarp he states to consist of four distinct portions ; the protecting tissue, the mechanical tissue, the pneumatic and assimilating tissue, and the vascular bundles ; each of which is described in detail. Chemistry of Woody Tissues.j — N. Schuppe confirms the generally accepted chemical composition of cellulose, C; H,,O;. The gum which remains after treatment with water, alcohol, and dilute soda he finds to have, in the German and American walnut wood, the composition of cellulose; in the oak and mahogany the formula C,, Hx O11, (20; Hy, O; + C,H, O); in the poplar and alder, C; Hy O¢ (C; H,, O; + C, H, O). The wood-fibre, after extraction of this gum, yields an approximate average composition C 45:4 per cent., H 5-9, O 48-7. The pro- portion of lignin in various kinds of wood he finds to average about 17:62 per cent.; that of cellulose being about 40:7. For lignin he gives an approximate formula C,, H,, O,, which is also the composition of catechin ; the varying properties of lignin seem to have some rela- tion to the presence of tannic acid. The relative proportion of lignin and cellulose named above would give for the normal composition of wood a formula somewhat resembling 5C; H,, 0; + ©, H,; Os. First Products of Assimilation.t—In opposition to the state- ments of Loew and Bokorny, A. Mori still maintains his view as to the formation of an aldehyde as the first product of the mutual decom- position of water and carbon dioxide. He disputes their assertion that a red tint is produced in fuchsine sulphite simply by the evapora- tion of sulphurous anhydride without the application of heat. No trace of coloration was produced by placing two or three drops of the reagent on various substances, such as cotton thread, cotyledons of the lupin or scarlet runner, &c. Selective Power of Absorption of Roots.{ — Hervé Mangon records a remarkable instance of the power of plants to absorb different proportions of the constituents of the soil under different circumstances in the case of the ice-plant, Mesembryanthemum crystal- linum. The strongly refractive glands on the surface of the leaves contain a very large amount of saline ingredients. In these he found the percentage of chlorine in the ashes to vary between 5:4 and 12-1, of potassa between 11-1 and 18-7, and of soda between 4°4 and 10°3. . * Bot. Gesell. Stockholm, March 7, 1883. See Bot. Centralbl., xiv. (1883) . 125. é + Schuppe, N., ‘ Beitrage zur Chemie des Holzgewebes,’ 39 pp., Dorpat, 1882. See Bot. Centralbl., xiv. (1883) p. 105. + Nuov. Giorn. Bot. Ital., xv. (1883) pp. 203-5, Cf. this Journal, i. (1881) p. 906; ii. (1882) pp. 67, 361, 522; ante, p. 225. § Comptes Rendus, xevi. (1883) p, 80. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. deal Movements of Water in Plants.*—R. Hartig has carried on a series of experiments relating to the tissue through which the circula- tion of the fluids takes place in plants, and the causes which set them in motion. In the oak he finds the duramen, notwithstanding the large amount of water it contains, quite incapable of conduction ; while in the birch, on the other hand, the conduction takes place through the whole of the wood; and these may be taken as examples of two different types. The organs for the conduction of the sap are chiefly those provided with bordered pits, especially the tracheides ; and at times also the true vessels. The absorption of water by the roots is nearly altogether inde- pendent of the ascent of water through the wood. It is caused by the osmotic forces of the cells of the root, especially of the root-hairs ; often called the root-pressure. It is very largely dependent on the temperature of the soil, less so on the amount of water which it contains. Hence the beech, oak, larch, and pine contain the largest quantity of water in the height of summer, the birch on the other hand about April. The cause of the ascent of water in the wood is the difference in the density of the air in the conducting organs, by which the water is pressed upwards from cell to cell. The proportion of water and air in the conducting organs varies with the time of year; when the cell-walls are saturated the cell- sap may occupy from one-third to two-thirds of the cavity of the cell. It rises in them by the action of capillarity. While therefore the movements of water in trees are brought about mainly by the changes in the density of the air contained in them, the pressure of the atmospheric air exercises no or very little influence on the whole process. Movement of Water in the Vessels.,—J. Vesque thus summarizes the results of his researches on this subject :— 1. Water is conveyed through the vessels :—(a) when they are full of air; (b) when they inclose sufficiently long columns of water, inter- rupted here and there by bubbles of air, local transference ; but (c) no conveyance of water takes place when small portions of water are everywhere separated by bubbles of air. 2. When transpiration is active the vessels give up water to the surrounding elements, and become full of air. 3. When transpiration is sluggish, the air contained in the vessels diminishes in volume, and finally disappears altogether. The vessels are therefore always reservoirs of water; and, in special circumstances, are the agents for its conveyance. : Exudation of Water from Leaves.{—By an examination of plants in very early morning, Volkens has greatly extended the list of those * Unters. Forstbot. Inst. Miinchen, ii. (1882); iii. (1883) pp. 47, 94. See Bot. Ztg., xli. (1883) p. 250. + Ann. Sci. Nat. (Bot.), xv. (1883) pp. 5-15. See also this Journal, ii. (1882) p. 373. ¢ Ber. K. Bot. Gartens Berlin, 1883. See Science, i. (1883) pp. 491-2. 2m 2 5382 SUMMARY OF CURRENT RESEARCHES RELATING TO from which liquid water exudes. He describes the water-pores of 150 species, distributed through 91 genera and 36 families. He appears to have exercised great care to avoid errors from the possible presence of dew upon the leaves. In order to ascertain the amount of water in the stems of the plants exhibiting this phenomenon, he made use of double scissors, by which a piece about half an inch in length could be cut out at one stroke, thus diminishing the chances of affecting the relative amounts of air and water in the part at the moment of separation. By the use of this simple contrivance, he has shown that the amount of air and water in a vigorous plant varies considerably during the day, even when the specimen is kept under uniform external conditions. Most of his observations were made upon wild plants in open fields. Hypoxanthin in the Potato.*—E. Schulze finds that in the precipitate produced in the sap of the potato by phosphor-tungstic acid after removal of the albuminoids, together with peptones, other nitrogenous substances of the nature of xanthin are present. He succeeded in obtaining a substance which gave the reactions of hypoxanthin. Approximate quantitative determinations gave an average percentage of 0:00355 gr. of hypoxanthin in 100 cem. of the sap. Function of Tannin in Metastasis. ;—E. Kutscher thus sums up the results of a series of observations on this subject :— 1. Tannin may be an excretory product of metastasis, as in Ricinus, Phaseolus, the roots of many Cycadez, and in the leaf-glands of Hype- ricum perforatum. It is in this case not distributed through all the cells of the tissue, but occurs only in special excretory cells. In these it is often mixed with pigments, and disappears along with them ; it appears to have no other function. It usually causes a blue reaction with iron. 2. It may be of further use in metastasis ; as in Vicia Faba, and Helianthus annuus and tuberosus. It is then formed only during the construction of primary tissue and on its first differentiation, as in the growing point, the cambium, in young fruits, and in the formation of secondary roots. It is at first formed in all the cells of the tissue, permeating also the cell-walls and nucleus, and then passes into special tissues. A rapid consumption of tannin also takes place within the bud; this becomes afterwards slower but continuous, so that at the end of the period of growth only traces of it remain. It cannot, however, be stated with certainty that it serves directly as the formative material for primary meristem. Its chemical properties and life-history point to the conclusion that it serves as a medium for respiration ; i.e. that it undergoes oxidation. Laws which regulate the Production of Male and Female Flowers.t}—Comparing male with female maple trees, T. Meehan * Landw. Vers.-Stat., xxviii. (1882) pp. 111-5. See Bot. Centralbl., xii. (1882) p- 257. + Flora, lxvi. (1883) pp. 33-42, 49-64, 65-74 (2 pls.). t Proc. Acad. Nat. Sci. Philad., 1882, pp. 89-92. ZOOLOGY AND BOTANY, MICROSCOPY, ETO. Doe noted differences in their habits of growth. Taking a twig of the last season’s growth, in a flowering condition, one or two blossoms might appear alongside of the leaf-bud, in trees of either sex. So far there was no difference. But in the female tree the central or leaf-bud, when it pushed into growth in the spring, made a shoot of several or many inches in length, according to the vigour of the tree or parent branch. In the male tree, on the contrary, the central growth was not more than perhaps a quarter of an inch, forming a mere tuft of leaves on the top of what was a head of male flowers. The immense amount of pollen from the early flowers, forming the great bulk of all the polien produced by the tree, is scattered before the female flowers open, and is absolutely useless for any purpose of fertilization, or use- less for any purpose of individual benefit to the tree or to the race. These later opening flowers, formed on the wood of last year, are evidently the chief reliance, if not the only reliance, of the female flower for its reproductive energy. It may be stated in general terms that a highly vital condition is more closely allied with those attributes which characterize the female sex than with those characteristic of the male, and we may therefore reasonably look for some influence in the female direction on the male flower where these conditions exist. Therefore male flowers on a shoot characterized by a highly vitalized condition, would be likely to resist influences to which they would be otherwise subjected. In short, a male flower on a strong branch ought not to yield as readily to the excitement of heat as one growing on a weak branch. At any rate the fact that the whole of the weak spurs of the maple tree produce nothing but male flowers, and that these male flowers expand at a lower temperature than the females do, is conclusive as to the law, whatever answer the objection may receive. This law, thus demonstrated, will be of great practical value to culturists. As regards the influence which these facts must have on questions of dichogamy, there need not necessarily be any constant rule in the production of proterandrous or proterogynous flowers. We might expect to find proterandry prevailing to a greater extent in plants growing where there was a more constant succession of warm and cool days, than in the same species growing where the climate is not what is called changeable, that is to say, where the temperature is regularly low until the regular spring season has arrived, in which there would not be much difference in time between the advance of stamens or pistils. ; In conclusion, the author considers that if he may be allowed to generalize from this experience with the Eee tree, the following principles are proved :— Male flowers do not appear on female maple trees till some of its vital power has become exhausted. Branch-buds bearing female flowers have vital power sufficient to develope into branches. Branch-buds bearing male flowers have not vital power enough to develope into branches, but remain as spurs, which ever after produce male flowers only. 534 SUMMARY OF CURRENT RESEARCHES RELATING TO Buds producing male flowers only are more excited by heat than females, and expand at a low temperature, under which the females remain quiescent. A few warm days, succeeded by cooler ones, will therefore make a corresponding difference in time between the opening of the male and the female flowers, and possibly in the proportionate advancement of the stamens and pistils in hermaphrodite flowers. Selenotropism of Plants.*—Ch. Musset, struck by the heliotropic movements of plants, has made some experiments on the influence of the moon. He sowed seeds of plants known for their phototropic sen- sibilities, such as Lens esculenta, Ervum lens, and Vicia sativa. When they were some centimetres in length they were placed in the dark ; the branches became delicate, long, and white, while the leaves were tinted a slight yellow. On the 22nd, 23rd, and 24th of February, when the sky was exceptionally clear, they were exposed to the direct light of the moon from 9 p.m. to 3 a.m. Almost at once the branches became curved, presenting their concavity and terminal bud towards the moon. The bud seemed to follow the moon, and when the plants were placed at a window with a western aspect a fresh movement was seen, and this continued until the moon disappeared behind the hills. The author proposes to call these movements selenotropic. Withering of Flowers and Leafy Shoots.j — According to J. Wiesner the leaves of most plants transpire more strongly than the flowers; and in cut branches, or such as are insufficiently supplied with water from below, the leaves usually wither sooner than the flowers. Cut flowers wither less rapidly when there are no leaves attached to the shoots; and if transpiration is prevented from the leaves, the flowers remain quite fresh, showing that the transpiring leaves withdraw water from the flowers. The same is the case with plants growing in the ground when the supply of water is insufficient. The growing ends of branches and flower-stalks lose water and wither in the same way, not by direct transpiration, but by the water being withdrawn by the mature foliage. The surface of the floral leaves and of young leaves is greatly reduced by withering and desiccation, often as much as 50 per cent., resulting partly from the cessation of tension and turgidity, partly from the loss of the water of imbibition of the cell-wall. The open- ing of flowers is frequently the result of transpiration. Cut leaves which have been placed for a time under water wither more rapidly when exposed to the air than those that have not been moistened, the moistening favouring transpiration. Leaves absorb as a rule more water through the under than through the upper surface; rain and dew do not, therefore, usually supply much water directly to the plant; but both favour transpiration after the moistening has ceased. This is of advantage to the plant only when the supply of water to the plant from the soil is insufficient. * Comptes Rendus, xevi. (1883) p. 663. + Wiesner, ‘Studien uber das Welken von Bliithen u. Laubsprossen,’ Wien, 1882, ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 535 Hence in certain circumstances dew is injurious to the plant. When plants are withering, change in position of the leaves brings their under surface under the direct influence of rain, which is of advantage to them. Flowers which have been moistened do not usually wither more rapidly than those that have been kept dry; in consequence of secondary influences, they may even remain fresh longer. Fatty Acids in Plants.*—H. Schmidt and H. Romer find that the oil in the nucellus and testa of the seeds of Cocculus consists almost entirely of free stearic acid, with small quantities of other fatty acids rich in carbon. The menispermin of commerce, obtained also from the seeds of cocculus, is also nearly pure stearic acid. Nutmeg-butter contains also from 3 to 4 per cent. of free myristic acid, and a smaller quantity of other fatty acids. When dried bay-berries are digested in hot alcohol, distilled, and the oily residue washed with hot water, the presence of a considerable quantity of free fatty acid can be proved, consisting probably partly of palmitic acid. Influence of Mineral Substances on Germination.{—In a series of experiments on the influence of mineral substances on germin- ation, which influence is proved by the significant increase of the ash- contents of all seedlings, P. P. Dehérain and E. Bréal, and after- wards J. Boehm, have further examined the important part lime exercises on germination. Lentils, grains of corn, and beans were soaked in distilled water or in spring water, and then left to ger- minate or develope in distilled water or in several solutions of salt. The development of the separate portions of the plant and their ash contents were examined, and the results gained in separate experi- ments are as follows :— 1. In the first stages of their development the young plants absorb a considerable portion of mineral substances. 2. They even absorb, in considerable quantity, mineral substances that exercise no favourable influence on their development. 3. Of all the mineral substances applied lime exercises the most advantageous influence. Indeed seeds which develope very badly in distilled water, when allowed to germinate in spring water, develope normally at the ordinary temperature. The favourable influence of the lime-salts is especially remarkable in the development of the roots. 4. The form in which the lime is present is not by any means immaterial; it exercises a much more favourable influence when united with ulmic acid than with nitric acid, as if the ulmic acid tended directly to the nourishment of the young plants. 5. At the same time it cannot be asserted that the addition of foreign lime is necessary for the development of the young plant; for when seeds are placed in distilled water at a temperature from 30° * Arch. d. Pharm., xxi. (1883) pp. 34-8. See Bot. Centralbl., xiv. (1883) p. 8. + Ann. Agronomiques, ix. (1883) pp. 58-77. Cf. Naturforscher, xvi. (1883) p. 156. 536 SUMMARY OF CURRENT RESEARCHES RELATING TO to 35° they frequently develope normally without any lime being discoverable in the newly-formed organs. Occurrence of Iron in Plants.*— A. B. Griffiths finds that in plants (the Savoy cabbage) grown in soils without any artificial addi- tion of iron salts, the ash contains iron, the leaves yielding a very much larger percentage than the stalk. If ferrous sulphate is added to the soil, the proportion is greatly increased. Microscopical exami- nation showed that in the protoplasm of the chlorophyllaceous cells there were minute crystals (not crystalloids), sometimes solitary, sometimes arranged in groups round a common centre. ‘These were easily proved by chemical tests to be crystals of some salt of iron, probably ferrous sulphate ; they belonged to the monoclinic system, and their composition was probably FeSO,+7H,O. They occur in plants grown in natural soil, but are much more numerous in those grown in iron-manured soil. They were also found near to the chloro- phyll corpuscles, and the author suggests that they may act as reserves for the formation of the green colouring matter of chlorophyll. B. CRYPTOGAMIA. Paleontological Development of Cryptogams.t—Saporta and Marion trace the fossil remains of Siphonaceous Alge back to the Lower Silurian period. The higher alge, they consider, do not make their appearance till comparatively modern times, partly in the Jurassic; the Characez, Floridez, Pheeospores, and Fucaceze in the Tertiary. The flora of the dry land developed entirely from aquatic Proto- phyta. The Musci and Hepatic constitute a lateral branch, the main stem producing in succession the Filices, Rhizocarpexw, Lycopo- diacee, Gymnosperme, and Angiosperme. The primary and secondary strata furnish no remains of mosses, probably because they are entirely of marine or brackish origin. From a primary fern with undifferen- tiated sporangia, sprang the Filices, Lygodiacee, and Marattiacee. The latter have existed from the Carboniferous period; the Lygo- diacewe do not make their appearance till the end of the Cretaceous period. The Cyatheacez date from the commencement of the Carboni- ferous period, the true Polypodiacez only from the Rhetian. The Lycopodiacez with isosporous sporangia may be an independent branch from the Protophyta, and appear as early as the Devonian; the Hete- rospore are more highly differentiated Isospore, having their highest development in the Lepidodendra of the Carboniferous period, and then degenerating to the Selaginellez and Isoetew. The most highly developed Cryptogams are the Rhizocarpee, to which belong the Rhetian Sagenopteris and the Carboniferous Sphenophyllum. The Cryptogams form therefore, according to these authors, a main branch of the vegetable kingdom, which has sprung directly * Journ. Cl.em. Soc., xhii. (1883) pp. 195-7. + Saporta, G. de, and Marion, A. F., ‘Die palzontologische Entwicklung des Pflanzenreiches. Die Kryptogamen.’ 250 pp., Leipzig, 1883. See Bot. Centralbl., xiii, (1883) p. 411. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. Dave from the Protophyta. The Gymnosperms appear in the Carboniferous period, but only to a very subordinate extent. All the groups of Cryptogams had by that time been differentiated. The highest type of Cryptogams was defeated in the struggle for existence by the Gymnosperms and Angiosperms. Organic Unicellular Bodies in Coal.*—Further investigation of the peculiar organic bodies found in coal by P. F. Reinsch confirms him in the view that they are of two kinds totally different from one another. The smaller or T’riletes-form bears a remarkable resemblance to the spores of Sphagnum, and may probably be bodies of this de- scription. ‘They occur in such enormous quantities in some Russian coal as to constitute from 80 to 90 per cent. of its mass. A cubic centimetre may contain 5,827,000 of them, having an average diameter of 0°033 mm. The larger of these bodies are of a totally different nature, and are probably independent organisms forming a stage of development of some very simple plant-form. Cryptogamia Vascularia. Fibrovascular Bundles of Vascular Cryptogams. {— According to H. Potonié the terms xylem and phloém have neither a physiological nor a definite morphological meaning as applied to the vascular bundles of cryptogams. By phloém nothing further is to be under- stood than the part of the bundle which contains sieve-elements, and by xylem that part which contains the tracheids ; without associating with these ideas any definite limitation of these portions of tissue. As respects the fibrovascular bundles themselves, everything must be regarded as belonging to the bundle which stands in an unquestion- able physiological relationship to it as an anatomico-physiological unit of a high order. The mechanical adjuncts, therefore, which often inclose or accompany the bundle must be regarded as belonging to it. The stereome which commonly surrounds the bundle in the form of strings, is sometimes found within the mestome, as in Adiantum trapeziforma. The tracheome is, according to the most recent obser- vations, not the tracheal but the hydral system of the bundle, and may therefore be called the “hydrome.” The function of the “amy- lome,” or parenchymatous elements which usually contain starch, is to convey the carbohydrates. The starch-cells which often occur among the hydroids, but which are apparently not connected with one another by equivalent elements, form a continuous system. The hydrome and a portion of the amylome constitute together a system of a higher order, the “hadrome.” The osmotic force of the amylome either exhausts the hydroids of water or fills them with it. This physiological relationship explains the remarkable facts that where a number of hydroids lie close together the hydrome is regularly per- meated by threads of starch, and that all vascular cryptogams possess * Flora, Ixvi. (1883) pp. 187-9. Cf. this Journal, ante, p. 409. + Jahrb. K. Bot. Gartens Berlin, ii. (1883) pp. 233-78 (1 pl.). See Bot. Centralbl., xiv. (1883) p. 100. ; 5388 SUMMARY OF CURRENT RESEARCHES RELATING TO a hadrome. The “leptome” is the part of the bundle which contains albumen, and is composed therefore of sieve-tubes and cambiform, understanding by the latter term the elongated parenchymatous cells which accompany the sieve-tubes and contain nothing but albumen. The “protophloém” or “ protoleptome,” consisting, in Dicksoma antarctica, of sieve-tubes, must apparently be included here. The “ endodermis,” whose function appears to be purely mechanical, and the starchy layer adjoining it on the inside, proceed from a common histogen, the “coleogen.” In the young leaf-stalks of Dicksonia antarctica there is a gradual transition from fundamental parenchyma through the coleogen to the procambium. In many rhizome-bundles the coleogen is in immediate contact with the protohydrome. The rhizome-bundles of the Polypodiacew are stated to be not concentric, but bicollateral. The following is a table of synonymous terms. j Sieve-tubes a Phloem (Protoleptome) .. » Leptome.. | Cambiform ee Mestome. Hydrome .._ .: mylem.-.. .. = Ararlome ae a Hadrome Endodermis. Fundamental Tissue Stereome-sheath and adjuncts. Muscinee. Anatomical Structure of Mosses.*—G. Firtsch describes the mechanical contrivances in the anatomical structure of the following parts of the moss Polytrichum juniperinum :—the mechanical system of the stem and seta; the firmness of the stereids; the mechanism of the unrolling and erecting of the leaf; the contrivances for fixing the sporogonium in tle stem; and the hairy covering of the calyptra. Hybrid Moss.{—H. Philibert records a new instance of a hybrid moss, found wild, between Orthotrichum diaphanum and O. Sprucei. He considers it a true instance of a hybrid sporogonium, resulting from the fertilization of an archegonium of O. Sprucei by antherozoids of O. diaphanum. The hybrid was intermediate in its characters between the two parents, and also in the time of producing its repro- ductive organs. Fungi. Localization of the Hymenium of Fungi.t —N. Patouillard inquires why, if all the hyphe of a fungus are morphologically equi- valent, the hymenium is as a rule localized to the under side of the pileus, where it is not unfrequently renewed after having been once destroyed. He believes the reason to be that the under side of the pileus is the best protected part of the structure, and enumerates instances * Ber. Deutsch. Bot. Gesell., i. (1883) pp. 83-97 (1 pl.). + Rey. Bryol., x. (1883) pp. 8-13. t Rev. Mycol., v. (1883). See Bot. Centralbl., xiv. (1883) p. 130. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 539 where the ordinary rule is departed from. The “inverse” hymenium is not uncommon in the Agaricini. Hydnum compactum and species of Fistulina may have hymenophorous tubes or projections on the upper side. The upper part of the stipes of many species of Boletus has reticulate structures which are a true hymenium. [If the pileus does not afford sufficient protection for the development of the spores, it remains sterile, as in Polyporus annosus. P. alutaceus and Trametes suaveolens occasionally produce organs of fructification on the upper side. Although most Hymenomycetes require the protection of a pileus, the Clavariei do not. The Pezize seem to need the assistance of water, which the Agarici avoid; the Lycoperdacei surround their organs of fructification with a resisting envelope ; in the Sphzriacei this envelope is hard and carbonaceous. Chemistry of “ Fairy-Rings.”*—Sir J. B. Lawes, Dr. J. H. Gilbert, and R. Warington have continued their investigations as to the causes of the rings of luxuriant grass which are always more or less connected with the appearance of fungi. They consider that there is no doubt that the source of the nitrogen of the fairy-ring fungi is the organic nitrogen of the soil itself, which they assimilate, presumably, though not certainly as organic nitrogen, and eventually deposit as manure which becomes available to the associated herbage. Immedi- ately outside the ring the turf is generally found penetrated by a white cobweb-like mycelium extending to a depth of several inches, and sometimes even to a foot or more. . Fungus-Parasites of the Aurantiaceze.t—While previously only 34 species of fungus had been described as parasitic on the orange, lemon, citron, and allied trees, O. Penzig now brings the number up to 153, including exotic forms, 54 of which are new. Some of these, as Ehizoctonia violacea, Spherella Gibelliana, and Meliola Penzigi, entirely destroy the crop; while others appear only sporadically, but are always injurious. Hach species is described in detail, with Latin and Italian diagnosis, an account of its habitat, literature, synonymy, &c., with various biological and critical notices. Coloured nature-printed illustrations of 136 species are given. “Ozonium.” {—C. Roumeguére has investigated the connection between the old genus Ozonium and the filamentous mycelium of various hymenomycetous fungi. He finds that it may belong to no less than eleven species, viz. nine of Coprinus, one of Lenzites, L. trabea, and one of Craterellus, C. muscigenus. He is unable to confirm the statement that has been made, that “conidia” are formed on the ozonium. The white or fawn-coloured byssoid portion which forms a kind of puffiness of the base of the stipes of Coprinus on the surface of the ozonium is a form of sclerotium from which the Coprinus springs. The external layer of this sclerotium is composed of * Journ. Chem. Soc, xliii. (1883) pp. 208-23. + Penzig, O.,‘Funghi agrumicoli. Contrib. allo studio dei funghi parassiti degli agrumi,’ 124 pp. (136 pls.) Padua, 1882. t Réunion des délégues des Soc. say. a la Sorbonne, March 28, 1883. See Bot. Centralbl., xiv. (1883) p. 62. 540 SUMMARY OF CURRENT RESEARCHES RELATING TO filaments of the ozonium, cuticular filaments resembling those of ordinary sclerotia. The Coprinus, like the Lenzites and Craterellus, has an ozonium or not, according to its environment; just as other species of these genera have or have not sclerotia. Harknessia.*—The genus Harknessia was established by M. C. Cooke from the only known species, H. Eucalypti, parasitic on Hu- calyptus. G. Winter now describes a second species, H. Molleriana, also parasitic on Eucalyptus in Portugal, and which he regards as identical with Speggazini’s Melanconium uromycoide from the Argentine Republic. Winter now proposes the following amended diagnosis for the genus'::—Perithecia integra, pseudo-parenchymata, mollia; spore elliptic, unicellulares, colorate, pedicello articulato hyalino praedite, demum in cirrhis atris expulse. Lophiostoma czspitosum.t—S. Schulzer von Miiggenburg has found this rare pyrenomycetous fungus on dead branches of the haw- thorn. It occurred in two different forms; one had the typical form of Lophiostoma; the other, that of Melogramma, parasitic not on the wood, but on the inner bark. The fructification of the two forms is identical. It follows that the two kinds of stroma among the Pyre- nomycetes, those characteristic of Valsa and of Diatrype, cannot be taken as distinguishing characters of families or even of genera. Oidium albicans.{—According to F. A. Kehrer this fungus con- sists of two elements, filaments constituting a mycelium, and small toruloid structures, the conidia. The former consists of a variable number of cylindrical cells, with lateral or terminal buds or branches ; they are never composed of long unseptated tubes. The cylindrical cells are not unfrequently slightly swollen at the extremities, and somewhat constricted at the septa; they are of variable length, and about 0:025 mm. diameter. They are sharply defined, and when young the contents are quite clear; vacuoles and granules appear in them later. The buds or conidia are produced by budding either at the extremities of the filaments or near the septa, rarely at the middle of a cylindrical cell. They are globular or oval, and are formed in moniliform rows or in smaller or larger groups. At first simple, they may give rise to other buds by simple budding. They have a clearly defined outline, and the contents are slightly coloured. Instead of producing other buds, these conidia sometimes develope into cylindrical cells, giving rise to mycelia with lateral branches. The resting- spores are formed in the globular lateral buds of the mycelium, by the homogeneous strongly refractive protoplasm contracting into a central ball. The author gives lists of nutrient fluids which are more or less favourable, injurious, and destructive to the growth of the fungus, He believes it to be both saprophytic and parasitic in its nature.. * Hedwigia, xxii. (1883) pp. 19-21. + Oesterr. Bot. Zeitschr., xxxiii. (1883) pp. 113-5. + Kehrer, F. A., ‘Ueber den Soorpilz, 71 pp., Heidelberg, 1883. See Bot. Centralbl., xiv. (1883) p. 48. é ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 541 Investigation and Culture of Pathogenous Bacteria.*—Fehleisen gives a résumé of the methods pursued by Koch and others in the investigation of pathogenous bacteria. In the case of “ panaritium ” to which the fingers of servant-girls are especially lable, and which is frequently epidemic, he finds a very small micrococcus forming zoogloea colonies, which spreads over the surface as a yellow coating, which can be well cultivated on gelatin. This microccoccus appears to be almost exclusively confined to cases of panaritium. Earthworms in Propagation of Charbon.j—M. Feltz reports that, making a preparation of earth after the method of Koch, he placed in it fourteen earthworms ; some three weeks later he removed, one by one, six worms, which he washed carefully ; after as carefully cutting them up he injected them into guinea-pigs. These all died in less than three days; those inoculated by the first washings of the worms likewise died rapidly, while those treated by the last resisted the action of the poison. he author agrees, therefore, with Pasteur and disagrees with Koch as to the réle of earthworms. Some experiments on the attenuation of the poison were made by preparing slightly alkaline and sterilized infusions of chicken-broth, in which the charbon-poison was cultivated ; by placing fresh cultivations in stoves heated and kept to a temperature of 42° to 48° C., Feltz was able to convince himself that the poison loses its virus in direct pro- portion to the time of exposure, and that it may be completely lost. The morphological expression of this is to be seen in the tenuity of the bacterian filaments, and a certain shrinking of the germs. It would seem to be certain that nature may accomplish an analogous operation in the earth, and that we may thus explain the variations in the gravity of attacks by this poison. Examination of different victims leads to the belief that the “spontaneous ” cure of the poison is effected by the destruction and elimination of the bacteria by the digestive tract. The paper concludes with the account of some suc- cessful vaccination experiments. Transmission of Bacteria from the Soil into the Air.t—In the course of a research on the preseuce of bacteria in the effluvium and vapours of the fever districts, J. Brautlecht mixed baked sand, gritty earth, and tolerably loamy garden mould with liquid containing bacteria, and covered the mixture with a bell-glass according to the requisite rules of precaution. A few hours after there were, in the vapour condensed under the bell-glass, a great number of micro- organisms, of the same form invariably as those contained in the liquid used. The number of organisms raised by evaporation was great in proportion to the quality of the fluid soaking the earth; they were on the other hand fewer in number when cooled sand was sprinkled over the damp earth. * SB. phys.-med. Gesell. Wiirzburg, 1882, pp. 113-21. + Comptes Rendus, xev. (1882) pp. 859-62. { Tagebl. Deutsch. Naturf.-Vers. Hisenach, 1882. Cf. Naturforscher, xvi. (1883) p. 156. 542 SUMMARY OF CURRENT RESEARCHES RELATING TO Fresh Method of Vaccination for Symptomatic Anthrax.*— Messrs. Arloing, Cornevin, and Thomas call attention to subcutaneous injection of mitigated virus as a method of vaccination for this disease quite as efficient as venous and tracheo-bronchial injection. The serous matter from anthrax tumours is attenuated or mitigated by exposing it to heat. It is first dried at a temperature of 32° C. in a current of air; a certain quantity is then well mixed with twice its weight of water and kept on a stove heated to from 85° to 100°, for six hours. Only small quantities should be thus treated at a time, and the stove should be so regulated as to recover its initial temperature in less than two hours from the introduction of the mixture. In the use of the mixtures thus obtained, which are of different degrees of attenuation according to the heat employed, great care must be taken to adapt the proportions and strength of virus employed to the susceptibility of the animals exposed to its action. It is best to make two inoculations with an interval of six or eight hours between tl:em, the first with virus mitigated by a temperature of 100°, the second with virus which has been exposed to 85° A sheep requires ‘01 gramme of each kind of virus, an ox *02 or ‘03 gramme, according to its size; this is mixed in a mortar with 100 times its weight of water, and introduced by a syringe under the skin; the side of the neck or the inside of the thigh is the place selected. The result of experiments made on sheep, calves, and a heifer was a slight local swelling in the last-named animals; this gradually dis- appeared ; more considerable swellings were produced in the sheep. The temperature usually rises *2° to ‘7° after the first, -5 to 1° after the second inoculation, The resistance of inoculated subjects to the disease was proved by test-experiments. Besides its great power of resisting heat, the micro-organism of symptomatic anthrax, when dried as above directed, is able to resist the action of antiseptic agents. When obtained from serous fluids it usually occurs in the sporiferous condition. Organic Particles in the Air of Mountains.j —P. Giacosa has made a series of experiments on the nature of the organic particles found in the air at different heights on Monte Marzo, a mountain in Piedmont 2753 m. high; the observations were made in August by means of the pipette-bulbs recommended by Tyndall; and were controlled by similar observations in the plain at the foot of the mountain. He finds the air of the mountain always to contain germs, although in different proportion to that of the plain. The Schizomycetes were very much more rare; almost the whole of the particles found belonged to the class of micrococci. The observations appear to show that the currents of air are constantly giving a circular shape to the particles suspended in it, and that such particles can then be raised to great heights, although they occur there in smaller quantities than at lower * Comptes Rendus, xev. (1882) pp. 189-91. + Atti R. Accad. Sci. Torino, xviii. (1883) pp. 263-72 (1 pl.). ZOOLOGY AND BOTANY; MICROSCOPY, ETC. 543 elevations. Insects play a certain part in this circulation of organic germs. The essential composition of the air itself appears to be the same at all heights. New Myxomycete.*—V. Fayod describes a new myxomycete, growing on horse- or cow-dung, which may be a form of Ameba Limax Duj., and to which he gives the name Guttulina protea. It forms yellowish-white, shining, fusiform or horn-shaped eleva- tions from 1 to 3 mm. high, which, when immersed in water, break up into a great number of spores, which are hyaline, colourless, or slightly yellow, strongly refractive, more or less regularly elliptical, bean-shaped, or nearly triangular, with an average length of about 14 » and breadth of about 9 ». Their protoplasm is finely granular, and contains a comparatively large, usually central, nucleus. They do not germinate in water, but in a decoction of dung after about 20 hours. Shortly before germination a slowly pulsating vacuole makes its appearance, which disappears a few minutes before the protoplasm escapes as a myxamoeba or swarmspore through a lateral orifice in the membrane of the spore, only one being formed in each spore. i The free myxameeba, after moving about for a time, takes the form of a slug and contains a nucleus, the anterior end being occupied by the denser hyaloplasm, the posterior end by the less dense granular protoplasm, where there is also a large slowly pulsating vacuole. Like other amcebe, it has the power of taking up and digesting solid substances. No enveloping membrane can be clearly distinguished, though it probably possesses one. Their average length is from 16 to 22 4; they move about with considerable rapidity. These myxa- moebz possess a peculiar property of a sudden rapid propulsion, to from two to four times.their own length, accompanied by a temporary rounding off of their shape. Multiplication begins some time after germination, when the myxamceba has attained a considerable size. Its motion becomes gradually slower and at length ceases; it becomes round with short blunt projections, which are soon drawn in again, the nucleus at length disappearing. It now becomes more and more elongated, then hour- glass-shaped as the protoplasm collects at the two ends, and finally divides into two. Hach of the two new myxameebe rapidly assumes the slug-like form of the parent, and developes a nucleus. This process of division is repeated through several generations. It is well observed only in a dilute and pure nutrient fluid. They creep readily out of the nutrient fluid, and then assume indefinite, usually flattened disk-shaped forms. Although apt to collect together in great quantities, coalescence into a true plasmodium was never observed. Under favourable conditions they become transformed into spores, distinguished by their rounder form, greater refrangibility, and want of motility. It is only some time after this change that a membrane is distinctly visible. The spores germinate usually in four or five days. * Bot, Zig., xii. (1883) pp. 169-77 (1 pl.). 544 SUMMARY OF CURRENT RESEARCHES RELATING TO When the nutrient fluid is more concentrated or contaminated with bacteria, multiplication is greatly hindered; the myxamcebe are larger and put out lateral pseudopodia ; the proportion of hyaloplasm is smaller, and the movements slower, finally ceasing, the vacuole ceasing at the same time to pulsate. The myxamceba is then spherical, 12 to 15 » in diameter, with a yellow or brown membrane, and may be termed a microcyst. The application of reagents shows the membrane to be double. The microcysts may remain at least a month, and even dry up without losing their power of germination. The whole process of development resembles closely that of Guttulina rosea Cienk.; but the present species is distinguished by its size and absence of colour. Lichenes. Structure, Development, and Life-history of a Tropical Epi- phyllous Lichen.*—H. M. Ward’s observations led him to believe that the epiphyllous cryptogam examined by him supports the Schwendenerian theory that a lichen is a compound organism com- posed of an alga to which an ascomycetous fungus has become more or less intimately affixed. It is developed on the leaves of many plants, but it has been more closely watched on Michelia furcata. The lichen presents four types—orange-red, stellate patches, greyish- green blotches, clear grey spots, and white shining circles; but these pass imperceptibly into one another, and vary in size from a speck to 1-4th in. in diameter. The reddish spots of the earlier stages are algee, of which the radiating filaments are in part reproductive organs, and in part barren hairs. The alga subsequently passes into the grey and green stages, and by a modification of growth the invasion of a fungus-mycelium succeeds. The white matrix of the complete lichen consists of the same algal thallus invested by dense masses of the fungus hyphe, which produce shining black dots, viz. the fructi- fication. The author describes in detail the peculiarities of growth and reproduction of the alga and fungus, and the formation of the lichen. He alludes to and criticizes Dr. Cunningham’s account of Mycoidea parasitica, which plant is evidently closely related to that described by himself. Assuming that Mycoidea and Ward’s alga are generically the same, either Cunningham discovered a female organ of reproduc- tion which becomes fertilized and produces zoospores, or he confounded this with “ fertile hairs.” As regards the systematic position of the alga, a comparison with Ooleochete suggests that there is very little in common beyond the mode of growth of the disk-like thallus and the production of zoo- spores from certain cells. The genus Chroolepus, moreover, presents features which agree in several important points, viz. orange-red oily cell-contents, habitat, and production of zoospores in ovoid cells, de- veloped terminally and laterally. The structure of the thallus, and the relative positions of the main masses of fungal and algal portions * Trans. Linn. Soc. Lond. (Bot.) ii., 1883, pp. 87-119 (4 pls.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 545 agree with what occurs in heteromerous crustaceous lichens as Graphidea, but the perithecia indicate its angiocarpous alliance, bringing the form nearer such families as Pertusaria and Verrucaria, to the latter of which it may ultimately be referred. Alge. Vegetation of Street Gutters.*—The discovery that, among the causes of epidemic diseases, microscopical organisms play an im- portant part, is a great advance in the cause of science, which is capable of much further development. Dr. Hugo Winnacker communicates a number of observations which he made in the town of Gottingen, laying stress on the fact that scarcely any other water is subjected to greater change than that in running street gutters. Every hour produces deviations in the water-level, and from the dried edges every current of wind may carry germs which only need damp to regain active life in the habitations and breathing-places of men. The small vegetable organisms which are now found in the running gutters of Géttingen, vary much according to the season of the year and the particular locality, and, as often happens in nature, the rapid multiplication of one checking that of another, the one supplants the other. The author notes down, according to months and particular streets, the genera and species which he found in the gutters of Gottingen from October 1877 to August 1878. There occurred partly green or black filamentous alge (amongst which were Oscillaria, Vaucheria, Zygnema, and Cladophora), partly diatoms, and partly fungi, among which, besides Leptothrix and Fusisporium (of which a new species is described), are notably micrococcus, bacillus, spirillum, and bacterium ; the most suspicious found in the greatest quantity. With regular plentiful rinsing through clean water, the alge were predominant, and next to them the fungi. The vegetation is at its greatest activity from May to July. Fungi and alge struggle against one another for existence, each prevailing as the circumstances favour the one or the other. The drought of summer and the cold of winter chiefly destroy the alge and also a few fungi, but not micrococcus, bacillus, and bacterium, so that these thereby have the advantage. Alge are not injurious to men; but are, on the contrary, useful as regulators of vegetation. Green gutters are in no way detrimental. Among the fungi, moulds are harmless to the human organism. The only ones which are harmful as promoters of fermentation and spreaders of infection are the Schizomycetes, to which belong micro- coccus, bacterium, bacillus, &e. The following, in the words of the author, are the principal rules to observe for the preservation of public health :— 1. By constant and abundant flushing with clean water the strect * Winnacker, H., ‘Ueber die niedrigsten, in Rinnsteinen beobachteten pflanzlichen Organismen,’ 4to, Elberfeld, 1883, 19 pp. and figs. Cf. Natur- forscher, xvi. (1883) pp. 153-4. Ser. 2.—Vot. III. 2N 546 SUMMARY OF CURRENT RESEARCHES RELATING TO gutters will contain as little organic matter as possible, so that only alge and no fungi will be able to thrive in them. 2. But as this is only possible for a short space of time, all dam- ming up of the stream must be avoided so as to allow moulds the cpportunity of arresting the too great development of Schizomycetes. 3. As the Schizomycetes are most rapidly developed in the summer months that is the season requiring the greatest precautions. Formation of Tetraspores.*—In the general account of the Floridez in the first part of the second vol. of Rabenhorst’s ‘ Crypto- gamic Flora of Germany, &c., F. Hauck states that the dense and highly coloured protoplasmic contents of the tetrasporangia may divide into the four (rarely more or fewer) tetraspores in the six following ways, viz.:—(1) Tetrasporangium undivided, only one spore being formed from its contents. (2) Bipartite; the contents divided into two equal parts by a transverse wall. (3) Divided crosswise ; the contents dividing into quadrants by two successive bipartitions. (4) Tetrahedral division ; the contents dividing into tetrahedra by simul- taneous quadripartition. (5) Zonal division; the contents dividing into four parts by parallel walls. (6) Multipartite ; when the contents divide into more than four parts. Reproduction of Porphyra.t—The systematic position of the Porphyracee (Porphyra and Bangia) has long been a matter of doubt with algologists. In Rabenhorst’s new ‘ Cryptogamic Flora of Germany,’ &c., F. Hauck assigns them a definite place as the lowest family of Floridew, and describes the cystocarps (in Porphyra leucosticta) as produced by fecundation by means of a rudimentary trichogyne out of female cells similar in form to the tetraspores, the protoplasm of which divides mostly into four carpospores by division- walls both parallel and vertical:to the surface of the thallus. The antheridia and antherozoids are also described. Cryptogamic Flora of Arctic Ice and Snow.{—V. B. Wittrock describes the cryptogamic vegetation brought from a number of localities within the Arctic zone. The flora of the hard blue ice of the glaciers and of the Greenland inland ice is quite different from that of the eternal snow and of the snow-covered portions of the glaciers. The snow-flora comprises about 40 species and varieties, the ice-flora only about 10. The plant-forms of the snow-flora belong to mosses and alge; but the former exist only in the protonema form, and can therefore not be determined specifically. The alge belong to 8 families and the following 25 genera :—Chroococcus, Gleocapsa, Oscillaria, Scytonema, Stigonema, Navicula, Stauroneis(?), Penium, Cylindrocystis, Chionophila n. gen., Docidium, Tetmemorus, Cosmarium, Huastrum, Staurastrum, * Rabenhorst’s ‘ Kryptogamen-Flora yon Deutschlaid,’ &c. 1882. 2er Band: Die Meeresalgen, von F. Hauck,’ p. 11. ¢ Ibid., p. 25. + “Om Snéns och Isens Flora, Sirskildt i de Arktiska Trakterna.” Af Veit Brecher Wittrock. Ur “A. E. Nordenskjold, Studier och forskningar foranledda af mina resor i héga Norden.” Stockholm, 1883 (2 figs. and 5 pls.). Bot. Gesell, Stockholm, Marcel 7, 1883. See Bot. Centralbl , xiv. (1883) p, 155. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 547 Bambusina, Spheerella, Chlamydomonas (?), Oocystis, Pleurococcus, Gleotila, Ulothriz, Hormiscia, Conferva, and Cladophora. Ten species and varieties are new. The mass of the snow-vegetation consists of Spheerella nivalis, S. nivalis B. lateritia n. var., Chlamydomonas flavo- virens(?), Pleurococcus vulgaris 8. coherens n. var., and Cylindrocystis Brebissonii. The ice-flora consists entirely of algze belonging to 6 families and the following 8 genera :—Gleocapsa, Scytonema, Nitzschia, Ancylonema, Cylindrocystis, Cosmarium, Zygnema, and Spherella. In both the ice and snow-flora Spherella nivalis was frequently met with gamospores, usually spherical, 20-27 » in diameter, and with blood-red contents, and unilamellar cell-wall. When the spores germinate, the contents first divide into two naked portions, each of which again divides into two, which contract into a spherical form, and clothe themselves with a thin cell-wall. The ice- and snow-plants are mostly brightly coloured, and perform an important function in causing a not inconsiderable melting of the snow by their strong absorption of the rays of heat. Vaucheria-Galls.*—G. Benké has made a close examination of the galls which infest various species of Vaucheria, and finds them in all cases to be caused by the same parasite, Notommata Werneckii. The species attacked are V. sessilis, geminata, geminata var. racemosa, and dichotoma ; but, in opposition to previous statements, he finds it not always identical in form on the same species. They have always a vertical position, and often stand very close together. Motion of Diatoms.t—J. M. Adams suggests that, inasmuch as all efforts to find some outside means of movement have failed, it is very probable, if not almost certain, that the movements of diatoms are produced within the frustule. “The front view of Navicule, and of all elongated forms having a central nodule, usually shows a division of the vegetable contents into two or four parts, having a main central alley between them running both lengthwise and crosswise. Currents seem to be produced by some means through these central alleys, and water is forced out of the porous frustule at the ends or sides as through a Sieve, inasmuch as the cross lines of diatoms are merely attached globules of silex with spaces between. These globules of silex, being so close together, prevent a clear vision of the interior part of the frustule, but it seems probable that vibratile cilia line the surface of the vegetable matter within, and these beating in unison cause the water to flow in one direction or another, as they more or less unite in their action.” Could a fresh frustule be broken open, he believes the surface of the vegetable matter within would show this presumed _ ciliated arrangement. To this the following editorial comment is made :—“Our corre- spondent, like many others, finding no satisfactory solution of this problem through observation, resorts to speculation concerning it. * Magyar Nov. Lapok, vi. (1882) pp. 146-52. See Bot. Centralbl., xiv. (1883) p. 1. + Amer, Mon. Micr, Journ., iv, (1883) p. 59. 2Nn 2 548 SUMMARY OF CURRENT RESEARCHES RELATING TO We must caution the reader that it is not yet known whether the frustules are perforated or not, as will be seen from an article soon to be published in these columns. As for the presence of cilia within the diatoms, we have no more reason to expect to find cilia there than in any other cells in which the movement of protoplasm has been observed—as in desmids, or in the cells of higher water-plants, for example. Moreover, diatoms are not the only plants which move without visible cause. The desmids, for instance, move with vigour, and they are not inclosed in a silicious shell which obstructs examina- tion of the interior. In young desmids especially the cyclosis can be examined with satisfaction by high powers. Looking over the alge, we find that the Oscillarie are quite as remarkable in their movements as the diatoms, and we cannot yet explain it; and in the animal kingdom the Gregarine also move without giving the least indication of how the motion is produced. It is a subject for still further in- vestigation, and we have no doubt that with good objectives, supple- mented by staining fluids properly applied, the cause of the movement will soon be discovered.” Fossil Diatoms of Austria-Hungary.*—A. Grunow describes the following fossil diatoms from Austria-Hungary :—(1) In the “Saug- schiefer ” of Dubravica, a large number of species. (2) The “ Polier- schiefer” of Tallya. The diatomic remains are here united together with extraordinary firmness by silicic acid, forming variously radiating microscopic masses of crystals, which renders the examination ex- tremely difficult. (3) The argillaceous neogenous basalt-tufa of Holaikluk. The most abundant form here is Melosira tenuis, also closely united by silica, and often containing petrified silica in the interior of the cells. (4) The diatom-stratum of Kis-ker, of unknown age, with ordinary still existing fresh-water forms. (5) “ Kieselguhre,” vivianite, and “ ocker” stratum of Eger and Franzensbad. Several new forms. All the new species are depicted in phototypic illustrations. Diatom Types.—Dr. H. van Heurck is preparing a series of pre- parations to illustrate his synopsis of Belgian diatoms, representing the principal types and elucidating the critical species. There will be about 350 slides, containing at least 400-500 forms, and 25 will be issued monthly. M. Grunow will examine the slides to check the determinations. a MICROSCOPY. a. Instruments, Accessories, &c. Bausch and Lomb Optical Co.’s New Binocular.t—The Bausch and Lomb Optical Company have completed a binocular of their “ Investigator ” pattern, which has some variations in the construction and adaptation of the prism, and in the nose-piece in which the prism is fixed. The notices which have so far appeared of its con- * Beitr. zur Palwont. Oesterr.-Ungarns u. d. Orients von Mojgsisovics u. Neumayr, ii. (1882). See Bot, Centralbl., xiv. (1883) p. 146. + ‘The Microscope,’ iii, (1883) p. 89, from the ‘ Odontographic Journal.’ ZOOLOGY AND BOTANY, MICROSCOPY, ETO. 549 struction and advantages are not a little perplexing both theoretically and practically, but we transcribe them as they are given :— “1. A very large prism, with perfectly plane surfaces, cemented upon a glass disk. 2. As this combined prism and disk is fixed by the maker, it remains in place regardless of the whim of or want of skill in the observer. 3. The mounting of this combination is a brass nose-piece, which slides into the tube and is fastened by a new form of bayonet-catch, a novel feature in itself. 4, The monocular nose-piece is separate and is fastened in the tube in the same manner. 5. The effect with the prism in place is quite as good in this instrument as it is in the old forms when the prism is withdrawn, as it permits the passage of [more] light [than is] possible in objectives with the Society screw. 6. While a little more time is consumed in changing from mono- cular to binocular and back again than is the case in the old form, the loss is fully compensated for by the absolute accuracy of the new, which cannot get out of place. 7. As low powers only are used in binocular instruments, a given objective may be kept in the binocular nose-piece and the higher power in the monocular, an arrangement almost as convenient as in the well-known double nose-piece. 8. The bayonet-catch above mentioned may be applied, and probably will be in the near future, to objectives as a substitute for the Society screw. The fit is as good, and the time saved in changing objectives great.” The binocular is also thus referred to in the ‘ Amer. Mon. Micr. Journ.,’ iv. (1883) p. 97 :— “Mr. Edward Bausch has devised a modified form of the Wenham binocular. . . Instead of mounting the prism in a metal frame which can be moved in and out, as in the ordinary form of binocular, the prism is cemented to a glass disk which is fixed in a special nose- piece. The nose-piece can be readily attached to the Microscope by a spring-catch. In this way the prism is always secured in exactly the right place, and when a plain nose-piece is substituted, as when high-power objec- tives are used, there is nothing in the tube to reduce the angular aperture of the lens. The arrangement is less convenient than the ordinary plan, but if the advantages claimed for it are found not to be of sufficient practical importance to lead to its final adoption, there is no reason why the prism should not be mounted in the old way. We do not yet appreciate the advantages of the separate nose-pieces, and we understand that the makers desire to have the verdict of microscopists concerning this matter, before they adopt the plan. The prism is a very large one, and as the face which receives the rays is fully exposed it will transmit a larger angle of aperture than the Wenham prism, which is much smaller. It is well known that the mounting of the Wenham prism cuts down the angular aperture 550 SUMMARY OF CURRENT RESEARCHES RELATING TO of some objectives.* A large prism, however, gives a correspondingly large pencil of rays, and in the instrument we examined there was a glare of light in the left ocular, which led some one who used it to think there was a defect in the fitting of the prism. On covering the right-hand half of the eye-lens of the left ocular, the glare was entirely stopped out, and the binocular effect was perfect.” Fig. 91. Fase’s Portable Dissecting Microscope.—We regret to have omitted to state in describing this instrument at p. 415 that it was * There is some confusion here between the mechanical cutting down of the opening of the objective caused by the setting of the prism and the optical cutting down of the aperture-angle, which with the Wenham prism is necessarily one-half, only half of the rays from the objective being directed into each tube.—[{Ep.] ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 551 made for the Rev. Mr. Fase by Messrs. Swift and Son. Mr. Swift, with characteristic modesty, wrote us, asking us to take care to refer to it as “ Fase’s Microscope ” and not as “ Swifts’, > inasmuch as the = Fie. 92. Oil iS a= = (om Tag ra a= a SY Ege N i fi ? Ee ce Hi Ny — Ae a | HU) i S\ UTA dll al wh yin wre || SS —_—— _———— Ly = = a D i LE Fie \ aii i, il i ae credit of the design was so largely due to Mr. Fase; in consequence we lost sight of the maker, to whom so much is always due, more than we should otherwise have done. Figs. 91 and 92 give a better idea of the instrument than that at p. 416. Holman Lantern Microscope.*—Mr. J. A. Ryder describes this instrument (fig. 93) as follows :— “The instrument illustrated was recently made by Mr. Joseph Zentmayer, of Philadelphia, and presented by subscription to the Franklin Institute. It is the invention of Mr. D. 8. Holman, Actuary of the Institute, and is not only adapted to show transparent photo- graphs, but may also be converted, in a few minutes, into a pro- * Journ. Franklin Institute, exvi. (1883) pp. 67-9 (1 fig.). 552 SUMMARY OF CURRENT RESEARCHES RELATING TO jecting Microscope, polariscope, megascope, vertical lantern, as well as into a table Microscope. The condensers of the lantern are five Fic. 93. inchcs in diameter, and the whole apparatus is constructed in the most substantial way, and every part and accessory is of the best I | 2@AqAAZ A \NK\\Y | | workmanship. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 553 The principal and most important feature of the apparatus consists in making the object to be projected when the apparatus is to be used as a Microscope, or as a megascope, the centre of all the projecting and illuminating apparatus. The lantern-upright which carries the projecting lens or Microscope, and the upright which carries the lens and mirror for the vertical lantern, and the lantern itself, swing around a common centre, which is placed exactly below the centre of the stage on which the object rests. This enables the operator to arrange, with the greatest facility, the relative positions of each of these parts in any desirable position in respect to the object. This feature, it is claimed, has never before been accomplished, and makes the lantern more complete, especially as a megascope. The lantern and jet are movable, independently of each other, by means of racks and pinions. By this arrangement the conjugate foci of the condenser may be changed to suit low and high powers and narrow and wide angle objectives, doing away with all secondary condensers and accomplishing these adjustments better and with much greater facility. The raising and lowering of the lantern is effected by a peculiarly constructed clutch, which rigidly holds the instrument in an inclined position. The instrument is packed in a truncated pyramidal box, containing also the accessories, and forming at the same time a firm stand for the lantern, on which it may be rotated when in use. In consideration of the fact that the instrument can be used for such a variety of purposes for lecture illustrations, it cannot be regarded as other than a marked improvement upon a similar class of instruments hitherto used for such purposes. In the illustrating and projecting of living forms alone, in conjunction with a number of ingenious devices serving as live cages, Mr. Holman has done a real service for the cause of education. While it is, perhaps, not possible to enter into an elaborate or detailed study of any organic forms of even a moderate degree of complexity, if projected only for a few moments upon a screen, it is, nevertheless, a fact that the correct. likeness of such creatures so shown gives the beholder a far truer appreciation of what the things are of which he reads in books than he might possibly obtain elsewhere, provided the lecturer is able to explain in a lucid manner, and unravel the complicated life-histories of the living beings of which he displays enlarged images. In these living animal or perhaps plant-pictures we have displayed two classes of facts, namely, those of type and those of function. To the trained biologist they call to mind the occult processes of growth and repro- duction by which the forms become what we see them to be, This implies that a wide range of data is to be considered: first, there is the development and evolution of the form, together with what this indicates as to its systematic relationship; second, the vital actions displayed involve the consideration of physiological pro- cesses, and these again those internal quasi-chemical and physical actions and interactions by means of which the creature is enabled to maintain its existence and individuality. If such problems are not worth elucidating, we may ask what others there are which are worthy of elucidation? The physiologist who solves the problem of the life- 554 SUMMARY OF CURRENT RESEARCHES RELATING TO actions of an amceba or a maggot has put us in a fair way of appre- ciating those of a man. If, therefore, better and clearer ideas of animal existence can be fostered in young minds by the aid of any optical appliance whatsoever, that appliance should be welcome as an aid in practical objective instruction. No less effective is this instru- ment in the illustration of many common facts in physical science. The range of its applicability seems indeed to be limited only by the resources, ingenuity, and ability of the lecturer.” Nelson’s Student’s Microscope.—Fig. 94 shows a medium-size Microscope, constructed by Messrs. Swift and Son, embodying some suggestions of Mr. EH. M. Nelson Fig. 94. with special reference to histo- logical research with high powers where only a moderate outlay is allowable. The principal point of novelty is that the front of the stage is cut away so that the position of the substage, with the dia- phragms, condenser, &c., may be readily seen from above the stage, and the diaphragms rapidly changed; also permitting the finger to be placed on the upper edge of the slide for safety in focussing with high powers. Amongst other additions it may be noted that finders are applied to the stage by which the posi- tion of an object may be recorded without the use of mechanical movements, the graduations for the vertical movement being on the stage plate, and those for the lateral movement on the sliding bar carrying the object. The optical body divides in two for portability. The eye-pieces are fitted with different lengths of tubing, so that the 10-inch length is maintained with each from the diaphragm to the nose-piece, as with Powell and Lealand’s Microscopes. Mr. Nelson’s centering substage with lateral swinging diaphragm-carrier is also applied (for description and fig. see Vol. i 1881, pp. 125-6). Watson’s Portable Swinging Mirror and Substage Microscope.— We have always considered Bulloch’s Biological Microscope (Vol. IIL., 1880, p. 1078) to be one of the handiest and most practical forms of ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 555 stand made, and equally useful for biological examinations and for the more special examinations of test objects. Hitherto the instrument could only be obtained in America, which was necessarily a drawback to its use in England. Messrs. Watson have now, however, undertaken its manufacture (with some modifications), their instrument being shown at fig. 95. The fig. shows sufficiently the general form of the instrument: its special feature is that the substage bar and mirror bar are fixed to separate collars, so that they swing separately below and above the stage, the movement of each being independent of the 556 SUMMARY OF CURRENT RESEARCHES RELATING TO other. The feet on which the instrument stands are made to close together for portability, so that it occupies a space of 12 x 7 x 44m. The slides of the coarse adjustment fit on knife-edges in V-shape grooves, reducing friction, with perfect steadiness and smoothness, and working without loss of time. The fine adjustment moves the whole of the body of the instru- ment (instead of the nose-piece only), so that there is no change of distance between the eye-piece and object-glass, and obviating the necessity of altering the collar-correction as the fine adjustment is used—-the correction being found once for any given object, no further alteration is required. The stage is glass and has universal motions, and by a screw- adjustment the friction can be increased or diminished ; it is arranged to take off and be replaced by one with mechanical movements if desired. Altogether the Microscope is likely to be one of the most useful forms for those who do not desire a stand of large size. Walmsley’s Photomicrographic Apparatus—This simple and inexpensive form of camera (fig. 96), the design of Mr. W. H. Walmsley,* is intended to produce, by the aid of gelatine dry plates and ordinary lamplight, photomicrographs of a high order of excel- lence, and of almost all transparent objects requiring microscopical examination. It will answer equally well for photographing opaque bodies, if the latter be illuminated by the light of the sun reflected from a silvered mirror. Any Microscope, monocular or binocular, having an axial joint whereby the body can be inclined to a horizontal position, may be employed. The Microscope is placed upon a base-board 4 feet in length and 9 inches in width, upon one end of which is constructed a platform for holding the camera, of such a height that the tube of the Microscope when inclined shall be precisely in the centre of the camera, which is firmly secured to the platform by a thumb-screw beneath. The camera box, which is square to allow a lateral turning of the plates, has a removable cone frent, and bellows sliding upon a frame, with an extension of three or four feet, which has been found sufficient for all ordinary work, though it could be increased to any desired extent. A simple form of clamp holds the focussing frame tightly at any point of extension. A second front-is provided to replace the one carrying the cone, to which any ordinary photographic lens may be fitted, thus providing an excellent camera for copying or other studio or laboratory purposes. The focussing screen is of glass, with an exceedingly fine ground surface, mounted in a hinged frame, which is turned aside when the plate-holder is inserted. This screen is only used, how- ever, in adjusting and centering the object, the final and delicate focussing being done on a sheet of plate glass, as presently to be described. * Description kindly supplied by Mr. Walmsley. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 557 The plate-holder (single) is square, opening at the back to admit the plates, which can be placed either vertically or horizontally. The usual size of plate employed is 41 by 5} inches, but there is a “kit” furnished also, which permits the use of plates 8t by 4t—the proper size for lantern positives—which can be very readily made by contact printing from the finished negatives. Any coal oil or petroleum lamp of good illuminating power, and which can be placed at any desired height above the table, may be used. The Fiddian [luminator (originally intended for microscopic Fic. 96. nme purposes) has been found admirably adapted to use with the camera, and is the one figured in the illustration. It gives a strong white light through the lens composing its front, all the other rays being cut off by the metallic chamber and chimney containing the flame. It ean be raised to any required height, and is recommended as being the best lamp for the purpose. Although any microscope-stand with axial inclination may be used, Mr. Walmsley finds that those of the size and general form of Beck’s National and ‘‘ Ideal” stands are the best adapted to this class of work. The shortness of tube of the “Ideal” renders it specially valuable, whilst the revolving stage adds greatly to the proper adjustment of the object in the centre of the focussing screen, and the substage carrying an achromatic condenser is almost indispensable. A mechanical stage will also be found to greatly facilitate the necessary manipulations, though the very simplest form of stage, with clips, will, with a little care and patience, answer every requirement. In using this apparatus, the base-board is to be placed upon a 558 SUMMARY OF CURRENT RESEARCHES RELATING TO solid table and the camera firmly secured to the platform, as shown in the illustration. The Microscope (from which the eye-piece has been removed, and the tube, lined with a roll of dead black paper) is to be inclined to a horizontal position and firmly secured to the board by turn-buttons, with the end of the body inserted in the cone front of the camera, about the joining of which a piece of black cloth or velvet is to be wrapped to exclude all extraneous light. The lamp is now to be lighted and raised to such a height as will bring the flame exactly even with the centre of the stage, the direct light being used without the mirror, which must be removed. It is presumed that the proper object-glass has already been attached to the microscope-body, and that an achromatic condenser has likewise been inserted in the sub- stage. A Kellner eye-piece answers admirably for this purpose. A secondary condenser is sometimes necessary between the lamp and stage, as shown in the woodcut, to secure a bright and even illumi- nation all over the focussing screen. This accomplished, the object to be photographed is placed upon the stage, secured in position by the clips or slides, and focussed, which is readily done with the coarse adjustment, for the bellows of the camera being still closed, one can observe the image on the screen and manipulate the milled head of the adjustment at the same time. The image having been accurately centered on the screen, the bellows is to be extended until the desired magnification is reached, when it will be found that its sharpness is considerably reduced, whilst the screen has been removed so far from the object that it is impossible to readjust the focus and observe the image at the same time without some special appliance, controllable from the screen end of the camera. A very simple contrivance has been adopted in this case, which works with the utmost smoothness and delicacy. <A groove is turned in the periphery of the fine adjustment screw, around which a small cord is passed, and carried through a succession of screw-eyes on either side of the base-board to the rear, where a couple of small leaden weights are attached to its ends, thus keeping the cord taut. A very slight pull on either side, whilst the eye is fixed upon the image on the screen, suffices to adjust the focus with the utmost exactness. A glance at the illustration will show the arrangement of this focussing cord, which is applicable alike to stands having the fine adjustment screw on the nose-piece or at the rear of the compound body. Since no ground-glass has a sufficiently fine surface to admit of really sharp focussing of the image, with even moderately high powers, the final adjustment is made as follows :—The front and back of the plate-holder having been removed, a sheet of plate glass the size of the gelatine plate to be used is inserted, and the holder adjusted to the camera, when, by means of a focussing glass placed against the outer surface of the plate, a sharp and accurate adjustment can be made in a moment, after which nothing remains to be done toward securing the negative but to substitute (in the dark room) a sensitive plate for the plain glass, attach the holder to the camera, and make the exposure. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 559 Gelatine plates, possessing the two qualities of extreme sensitive- ness and great density after development, are essential for the pro- duction of the finest negatives by the foregoing process. The brands known (in America) as “ Beebe,” “‘ Hastman Rapid,” and “ Carbutt’s Special” combine these qualities in an eminent degree, and are recommended accordingly. Hither ferrous-oxalate or pyro-developer may be used with equal success, but they should be strong and active, as a rapid development is necessary to the best results. If ferrous- oxalate be employed, it should be made quite acid with citric or oxalic acid. It having been found by actual work that the chemical and visual foci of the rays from a lamp are almost exactly coincident, there is no need of employing specially corrected objectives with this apparatus. And the following table of exposures with Beck’s objectives may be depended upon as an accurate basis for work with the average of objects to be photographed :-— 13 inch, 2 to 3 minutes. 2-3 29 3 ” 4 ” 4-10 ” 7 ” 10 ” For opaque objects, illuminated by sunlight, exposures of six to twenty seconds, depending upon the power employed and reflecting qualities of the specimen itself, will generally be found sufficient. 1-5 inch, 8 to 12 minutes. f-10' = ES. .- 20 33 Fic. 97. Hauer’s Photomicrographic Apparatus.*—This (fig. 97) is a very simple method, devised by Max Hauer, of combining a camera with the Microscope. The standard which carries the cross-bar D slides vertically in the hollow pillar, and can thus be set (by A) at any * Dippel’s ‘ Das Mikroskop,’ 1882, pp. 576-7 (1 fig ). 560 SUMMARY OF CURRENT RESEARCHES RELATING TO desired point in a vertical direction. The cross-bar also slides through B, so that it can be set (by E) at any point in a horizontal direction. The camera is fixed to one end of the bar. It has an opening on its lower side, to which is attached a piece of tube, into which the eye- piece end of the Microscope passes. To keep out the light, a broad indiarubber band can be passed over the point of junction. Seibert and Krafft’s Small Camera Lucida.—This (fig. 98) is but an unimportant variation of the apparatus of Nachet and others, though somewhat cheaper. Two reflecting plates at a and b are inclosed in a small box, open below, and with an aperture atc. A portion of the reflecting surface is removed at a point d concentric with the optic axis, so that the direct rays, h, from the object are seen through the apertures at d and ¢ at the same time as those, g, from the paper. The camera is supported on the pillar e, and is attached by the ring f to the body-tube. Fic. 98. Winkel’s Small Camera Lucida. — This again (fig. 99) is not distinguishable in principle from Oberhauser’s apparatus.* A small right-angled prism P is protected by a ring and attached to a No. 2 eye-piece. The prism fastening can be turned on s, and centered by the spring f. It is inclined on its horizontal axis by means of s,. The prism projects the image of the object upon the drawing-paper inclined at an angle of 45°, the pencil being viewed direct. Correction of the Distortions produced by the Camera Lucida.t —The following is a translation, somewhat abridged, of Professor L. Malassez’s paper on this subject. It was directed specially to the * Of. this Journal, ii. (1882) p. 680. + ‘Laboratoire d’Histologie du College de France, Travaux de 1l’Année 1877-8, publiés sous la direction de L. Ranvier, Professeur d’Anatomie générale’ (8vo, Paris, 1879), p. 188. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 561 camera lucida of Milne-Edwards and that of Nachet, but so far at any rate as the latter is concerned, the supposed distortion does not exist, at least it cannot be detected by the micrometer. The paper may, however, be of interest from a theoretical point of view. “1. Nature of the Distortions—These camere lucidz which are so convenient and so generally employed have the grave inconvenience of giving drawings which do not exactly reproduce the form of the objects drawn, assuming, that is, that the Microscope and the paper are in their usual position—the Microscope vertical and the paper placed on the table or on any other horizontal plane. To be assured of this fact draw, for instance, a series of parallel and equidistant lines like the divisions of an object micrometer. Then if the micrometer is placed transversely on the stage of the Microscope, so that the divisions are directed from front to back in the drawing, we shall see that the lines drawn will no longer be equidistant; they Fie. 100. will be the wider apart according as they have been drawn at a greater distance from the foot of the Microscope. If the micro- meter is placed so that the divi- sions are transverse in the draw- ing, the lines will no longer be parallel; they will diverge from the foot of the Microscope (fig. 100). If we draw a square, we shall obtain a trapezium, a quadri- lateral figure of some kind more or less irregular according to the position of the square on the stage of the Microscope, but never a perfect square. A circle will never give a circle, but always an ovoid, &c. These distortions are little noticeable so long as the parts drawn occupy only a small portion of the field of view, and so they may be disregarded if absolute exactness is not required. But if the micro- scopic field is large, the distortions are considerable. A square, for instance, has given me a trapezium, the small base of which was 114 mm., and the sides 1386. There were therefore differences in the drawings of equal lines (the sides of a square) amounting to 22 in 114, exceeding 19 per cent. We see therefore to what errors we may be exposed if we use such drawings for exact measurements—measurements of the histological elements, of magnifying power, &c. 2. Cause of these Distortions.—The distortions are due to the fact that in these camere lucide the two surfaces at which the total reflec- tions take place are very close to one another, so that the reflection upon the table is not made along a vertical axis. In fact, if it were so, a part of the image would be seen on the stage and foot of the Microscope, and could not be received on the paper: such an obliquity Ser. 2.—Vou. IIL. 20 562 SUMMARY OF CURRENT RESEARCHES RELATING TO must therefore be given to the axis of reflection, as that the micro- scopic image shall be brought completely outside the foot of the Microscope. But the axis of reflection not being vertical—not being conse- quently perpendicular to the surface of the table, the microscopic image is formed on a plane which is obliquely inclined to the optic axis; whilst the object itself being on the stage of the Microscope, is on a plane perpendicular to the object axis. The result of this is that the relative distances which exist between the eye and the various points of the drawing are different to those which exist between the eye and the corresponding points of the object. Consider, for instance, two points of the object equally distant from the axis. These two points will necessarily be at equal dis- tances from the eye, whilst in the drawing the corresponding points will be at unequal distances, that on the right being further from the eye than that on the left. These differences will be produced so long as the plane of the drawing is not, like that of the object, perpen- dicular to the optic axis. By comparing the position of the table with that of a plane which is perpendicular to the axis, and meeting the table near the foot of the Microscope, we can exactly determine the differences which the relative distances introduce. The table is the further from the plane according as it is further from the Microscope, and the result of this is as if the different parts of the drawing had been made on planes perpendicular to the axis, but more and more distant from the eye. But as the amplifications of the drawings obtained by the camera lucida are larger according as they are received at greater distances from the eye, it follows that in a drawing made on the table the amplification would increase without limit in proportion as the drawing is distant from the foot of the Microscope. This explains the results of the experiments above mentioned. If with the camere lucide of Milne-Edwards and Nachet the divisions of a micrometer are the wider apart, according as they are drawn in positions further from the Microscope ; if a square gives a trapezium, a circle an ovoid, the large base of the trapezium and the large extremity of the ovoid being on the right, it is because from the con- struction of these camere lucide the amplification of the drawing increases from left to right in proportion as it is further off from the foot of the Microscope. 3. Means of Correcting these Distortions—I assume that it is not desired to change the construction of the camere lucide. It is plain from what has been said, that to obtain a drawing like the object it is necessary that the microscopic image should be collected not on a plane oblique to the optic axis, but on one perpendicular to it. It is easy to fulfil this condition. Two methods may be employed —(1) Either incline the Microscope so that the axis of reflection becomes vertical, or (2) leaving the Microscope in its ordinary posi- tion, draw not on the table but on an inclined plane, the inclination being such that this plane may be perpendicular to the axis of reflection. . _— SS —— ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 563 I have tried both these methods. The first has certain advantages, in that it allows the drawing to be made on the table or other hori- zontal plane, and also that the eye looks in the direction of the pencil. But the inclination of the Microscope is not without practical difficul- ties. It requires a special arrangement in order that in this position the instrument may preserve a sufficient stability (I except, of course, Microscopes made to be inclined, which can be readily adapted to this purpose). This process, moreover, cannot be employed when it is desired to draw preparations which contain moving parts, or other- wise require to be kept horizontal. With the second method it is necessary, it is true, to draw on a Fic. 101. SL, pg wo Hh OAT plane which is not horizontal, and the hand is therefore outside the direction of sight, which is less convenient; but by way of compensa- tion the process may be applied to any Microscope whatever, without its being necessary to modify its position or construction. All that is required is an inclined plane whose inclination may be varied at 2 One 564 SUMMARY OF CURRENT RESEARCHES RELATING TO pleasure, all the camer lucid not sending the image in the same direction according to the same angle. It is necessary also that this plane should be able to maintain a fixed position relatively to the Microscope, so that the agreement between the drawing and the micro- scopic image may be preserved during the whole process. Such a plane may be made in many different ways. The following is the one which I prefer :— Inclined Drawing-board.—This board (fig. 101) is composed (1) of a horizontal part on which the Microscope is placed, (2) of an inclined part on which the drawing is made, and (8) of a bracket, which serves to maintain the inclination of (2). The bracket is not fixed to the inclined part, but is carried by a slide, which, guided by grooves, may be pushed more or less under the inclined part, and so raise it. In these movements the bracket passes before a graduated scale at the margin of the board, which indi- cates the degree of inclination obtained. The slide may be completely drawn out of the grooves so as to allow a drawing, the outline of which has been made at the proper degree of inclination, to be com- pleted in a horizontal and more convenient position. Moreover, if it is necessary to refer again to the camere lucida, the slide and the bracket may be replaced exactly in the same position by means of the scale. The horizontal part of the board is fixed to the inclined part by hinges, which enables the inclination of the latter to be varied as desired, whilst at the same time keeping it in a constant relation with the Microscope so that the coincidence is maintained between the drawing and the microscopic image. The position in which the draw- ing was made may be easily found again by means of marks. The different pieces of this board may be folded upon each other to make it more portable, and when folded it forms a square with sides of about 18 to 20 cm. and 3 em. in thickness. Modified Table of M. Kiinckel d@ Herculais.—Where it is necessary to make the drawing at given heights above the table (for the measure- ment of the magnifying power, for instance), I modify slightly the excellent drawing table of M. Kiinckel d’Herculais (fig. 102). This is composed of a board resting on a base formed of a double box. The box on which the board is fixed may be raised more or less from the other. Two screws keep it firmly in any given position. The board may thus be more or less elevated as desired. In order to incline the board, all that is necessary is to fix it, by hinges on one of its sides, to the box on which it rests, and then to raise more or less the opposite side by means of a movable bracket or other means. 4, Determination of the Degree of Inclinationn—Whatever may .be the apparatus employed, the important point is to give the appropriate inclination to the plane on which the drawing is made, and to deter- mine this inclination I have employed two processes. i” The first, entirely empirical, consists in laying down on the draw- ing-paper a given length, a micrometric division, for example; then to modify little by little the inclination of the inclined plane until the division being shifted about in the different points of the field of view ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 565 always gives a drawing of the same length. It is necessary in this process to use objectives thoroughly aplanatic. In the second process we simply determine the direction of the optic axis in its path from the camera lucida to the table. This direc- tion being known, we shall evidently know the inclination which it is necessary to give to the board so that it may be perpendicular to the optic axis. How is the direction of the optic axis to be determined? Being a _ straight line, it is sufficient to know two points of its path, and this _may be obtained in the following manner :—Selecting a very limited point of the field of view and as central as possible, the crossing of two lines of a micrometer in squares, for example, this point is trans- Fie. 102. Oe 24) | ITNT —— mail ATTN = T o : Zt ATTA _ ferred to the drawing-paper. The latter is placed successively at two . different heights—on the table, for instance, and then on a box. . When the paper is placed on the table, the point by virtue of the . obliquity of the axis naturally falls further from the foot of the Micro- scope than when it is higher, on the box. We ascertain then very _ exactly (1) the distance between the verticals passing through the two - points, and (2) the distance between the horizontals passing through these same points (the height of the box). Then we construct a . right-angled triangle having for height the distance between the hori- . zontals, and for base the distance between the verticals. The hypo- thenuse of this triangle will evidently give the direction of the optic axis. _ To find that of the inclined plane, it is sufficient to take any given _ perpendicular to this hypothenuse, or, what is still simpler, to reverse the triangle, making the base the height, the inclination of the _hypothenuse being then that which the board ought to have. This may be readily understood, since the angle which the inclined plane makes with the horizontal is evidently equal to that which the optic 566 SUMMARY OF CURRENT RESEARCHES RELATING TO axis makes with the vertical, for this angle is no other than that which the apex of the triangle formed before it was reversed. The first of these methods is very easy to execute, but it requires much time and patience on account of the numerous trials which it necessitates. The second is very easy also, and much quicker, since it gives at once the result sought. I therefore prefer it, but in order to be quite syre that no error has been committed, it may be checked by the first. When the plane of the drawing is very exactly perpendicular to the optic axis, all the distortions will disappear. Equidistant lines will remain so, squares will remain squares—in a word, the drawings will be faithful copies of the objects. This correction is very striking when we employ the drawing-board above described. If the board is horizontal, all the distortions are produced; when it is suitably inclined, they immediately disappear. We may therefore, without changing in any respect the camer lucidee of Milne-Edwards and Nachet, obtain with these instruments drawings as exact as possible. Are these facts known? I believe so, and in a previous article* I have been content to allude to them; but having seen that they were not noticed in our classical authors, I have thought it well to direct the attention of microscopists to them.” Mr. R. Hitchcock, in a discussion on the relative merits of the Zeiss (double prism) and Grunow camere lucide, adds some remarks { concerning the distortion produced by the two forms. A stage-micrometer ruled in hundredths of an inch, and a 2-8rds in. objective were used. The Grunow instrument was first used, the inclination of the stand being, in two different experiments, 30° and 40° from the vertical. 1. Inclination 30°, lines of the micrometer running vertically across the field. The diameter of the field projected upon the paper was, approxi- mately, 7 in. The distance between the lines, near the margin ‘of the field nearest the Microscope on the paper was 1°03 in.; at the margin furthest from the stand it was 1:15 in. Hence the difference in magnification at the two extremes of the field was 12 diameters. 2. Inclination 40°. Repeating the same experiment under this inclination, the results were respectively 95 and 100 diameters ; difference, 5. - Zeiss’ camera lucida, inclination about 13°. As only half the field was projected on the paper, the lines had to be extended across to 7 in. to make the results comparable with those of the Grunow. 8. Lines vertical. Magnification at the extremes of a field of 7 in. diameter, respectively 104 and 113; difference, 9. This is greater than with the Grunow, but the actual distortion of vertical lines produced by this camera is only 4°5 at the greatest. 4, Lines horizontal. Owing to the small field visible, only two * Infra, p. 567. + Amer. Mon. Mier. Journ., iy. (1883) pp. 43-5 (2 figs.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 567 contiguous spaces were measured, showing an increase from the centre outward of 3 diameters. The above figures should not be considered as absolutely accurate, but approximately correct—sufiiciently so to illustrate the subject. The Grunow instrument shows the entire field of view on the paper. Measuring from the middle of the surface of the prism to the margin of the field on the paper, we find the angle of view to be 16°5°, the margin nearest the Microscope being only 3° from the vertical, the centre being 17° from that margin, and 14° from the opposite side. Hence, the distortion produced diminishes slightly toward the centre from either side; but the real difference from side to side is shown by the above results. The Zeiss instrument only gives half the field; but the centre is almost directly beneath the centre of the face of the prism, 3°5° from the vertical, hence the distortion is about equal on either side of the centre, and does not increase from one side to the other as in Grunow’s instrument. Such being the facts, a camera lucida should, the author thinks, be used with great discretion in making drawings for purposes of measurement—as, for example, in drawing blood- corpuscles for microscopical expert testimony. He does not think, however, the distortion produced is of very great consequence in most cases. It is only when large objects are to be drawn or measurements to be made that it deserves serious attention. Measurement of Microscopical Magnitudes—The article which Professor Melassez refers to above is contained in an earlier portion of the same volume,* in which he states his view that the different processes for measuring the linear magnification of objects seen under the Microscope give only approximative and inexact results, and after describing briefly the two methods generally employed, viz. the micrometer eye-piece and the camera lucida, he proceeds to consider the causes of the want of exactness proper to the latter, and explains how, by modifying it slightly, its errors may be corrected. In the following diagram (fig. 103) A B is the object ¢ of unknown dimensions on the stage of the Microscope, C D the camera lucida, O the optic centre of the eye. Unite by lines the point O to each of the extremities of the object A B, and draw the visual rays which, starting from the point O, follow at first the direction of the rays O A and O B, but which, instead of going through the camera, are reflected at C and at D, and then pass out of it. We know that by interposing a sheet of paper in the path of these rays we are able to see and to draw on the paper the image of the object AB. ab is the drawing obtained at a distance from the eye equal to that of the eye from the object ; a’ b’ that obtained at the distance of distinct vision ; a’’ b” that obtained on the table on which the Microscope stands. As is shown in the figure, the drawings will be the larger as the paper is further from the eye, although the image in all these positions always appears of the same size to the person drawing, which is due to the fact that * Ranvier’s Travaux, p. 114. + Strictly speaking, A B is the image of the object. 568 SUMMARY OF CURRENT RESEARCHES RELATING TO it is always seen under the same angle, and corresponds to a retinal image of the same size. Let us now suppose the image to be received at the distance of distinct vision, and let us see what, in these conditions, are the rela- tions which exist between the Fic. 103. dimensions of the object A B and those of the drawing ab’. Observe in the first place that A B and a'b’ form the base of two similar isosceles triangles, OA B and Oa'd’'; but in order that the bases may be equal, it 1s necessary that the altitudes should be so also, that is, that the dis- tance of the drawing from the eye should be equal to that of the eye from the object. Is this so in practice? Cer- tainly not, or at least very exceptionally. Indeed, if the distance of the drawing from the eye is constant (the dis- tance of distinct vision), that of the eye from the object is very variable. It varies ac- cording as the tube of the Microscope is more or less raised above the stage, and thus varying it may be either greater or less than that of distinct vision. If the distance of the drawing from the eye is greater than that of the eye from the object, which is the usual case with our ordinary Micro- scopes with short tubes, the drawing a’b' will be necessarily larger than the object AB. If it is less, on the contrary, the drawing will be smaller. A calculation may serve to give an idea of the extent of these variations. Let us suppose an object of 10 mm. in diameter at a dis- tance of 20 cm. from the eye. Take for the distance of distinct vision 10 Paris inches, say, 27 cm., and calculate what will be the diameter of the drawing. In the similar triangles OA B and Oa’D’ the bases being proportional to the altitude, we shall have Suppose, on the contrary, that the distance of the eye from the ZOOLOGY. AND BOTANY, MICROSCOPY, ETO. 569 object is 30 cm., we shall have for the same object of 10 mm. in dia- meter a drawing having the diameter a’, = SS 2 0, HY =D mii Thus an object of 10 mm. may, according to the arrangement of the instrument, give at the distance of distinct vision either a drawing of only 9 mm., or one of 134 mm. These are not exaggerated cases selected for the express purpose of making the variations greater, but are such as are habitually met with, and we may even observe still greater ones. The following is one mode of remedying these errors. Remove the eye-piece and objective (having taken the measure of the amplification), and replace the camera lucida exactly in its original position, that is to say, at the same distance from the stage of the Microscope; then ascertain experimentally the increase or diminution produced by the image being referred to the paper, and thus by a very simple calcula- tion we can correct the result previously obtained. Suppose, for example, that we had found by the old method a magnification of 270 times for a given optical system, and that having applied the above method we find that 10 mm. referred to the paper gives an image of 135mm. The magnifying power of the optical system having been increased 1°35 times, it is therefore in reality 1°35 times smaller than that which we obtained, i.e. ay or 200. This correction may be applied whatever is the distance at which the drawing is made, and it therefore becomes entirely useless to make it at the distance of distinct vision. The paper should be placed on the table which carries the Microscope, the magnification measured as usual, and then corrected in the mode above mentioned. This method has the inconvenience of requiring two very delicate experimental operations, which have to be undertaken at each exami- nation; but by modifying in another way the old method, we may avoid this and obtain directly the magnification produced by any given optical system. It is obvious, in the first place, that if the eye-piece and objective are removed, and the paper is placed on the table at a’’ b’’, the draw- ing will be much larger than the object. Since the triangle Oa b” is of greater altitude than the triangle O A B, its base a!’ b’’ will neces- sarily be greater than the base AB. But if we raise the paper little by little, the drawing will diminish proportionately, and finally a point will be reached where the drawing will be exactly the same size ag the object. It is the point where the two triangles Oab and OAB become equal, where their altitudes being equal their bases are equal also. The position being found in which the drawing and the object are equal in diameter, this equality continues whatever the changes in the tube of the Microscope. In raising or lowering the tube we increase or diminish by equal quantities the altitude of the triangles O AB 570 SUMMARY OF CURRENT RESEARCHES RELATING TO and Oab, and being equal, their bases enlarge by equal quantities. It would not be the same if the paper was in any other position. If we now replace the eye-piece and objective, the enlargement which the drawing will have will be produced entirely by the optical system formed by the eye-piece and objective, and that will be true whatever is the length given to the tube of the Microscope. As we see, this process consists in referring the microscopic image to paper which is no longer placed at the distance of distinct vision as in the old method, nor on the table which carries the Microscope, as in the process above indicated—positions which all require corrections —but at a distance from the eye equal to the distance of the eye from the object. How is this position to be determined ? The surest way is to find it experimentally by varying the position of the paper until the drawing and the object are of equal size (the eye-piece and objective being removed). If to refer the image to the paper we utilize the phenomenon of double sight (double vue), the paper must evidently be placed at the height of the stage, assuming that the sight is exactly similar in the two eyes, which is not always the case. If we employ the camera lucida, the paper must necessarily be placed higher than the stage, because the double reflection and the refraction which the visual rays undergo in the camera produce a diminution in the direct distance between the eye and the paper. With the new camera lucida of Nachet, for instance, the loss being about 3 cm., the paper must be placed 3 cm. above the stage of the Microscope. For greater exact- ness the paper must, of course, be raised on one side, as previously described. Simple and Cheap Eye-piece Micrometer.*—Mr. W. M. Bale points out how a simple but efficient eye-piece micrometer for ordinary work may be constructed without any expense, except of a little time and patience. The material is fine silk, a single fibre of which is not perceptibly thicker than a cobweb, and is far less difficult to manipulate. It may be ravelled out of a ribbon; a corded ribbon, in which the transverse threads are straight, and woven over by two series of longitudinal threads, is better than an ordi- nary one, in which the threads of the warp and woof have acquired a series of “kinks” which are difficult to get rid of. The best eye-piece for the purpose is a C or D. The method of procedure is as follows :— Unscrew the field-lens, and at two opposite points on the under side of the diaphragm (not close to the edge) apply minute spots of rather stiff balsam. Cut a piece of the silk fibre about as long as the diameter of the eye-piece, and with the forceps place one end of it in contact with one of the spots of balsam, to which it will adhere, after which the other end is similarly attached to the opposite spot of balsam. With a pointed but blunt penknife the two ends are pressed well into the balsam and drawn apart till the line is “ taut,” * Southern Science Record, iii. (1883) pp. 13-16. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 571 the balsam being at the same time spread out and made drier and stiffer. The field-lens is now screwed in, and the eye-piece held to the light and examined, to see if the thread is straight; and if it be found to have in it a number of small flexures due to the weaving, it is best to replace it by another. So far there is no particular difficulty, but the next step, which is to attach another fibre parallel with the first and very close to it, is rather a delicate operation, as it must be done without disturbing the first, and the distance apart of the two must be regulated with the utmost nicety. This distance will of course depend on the space to be measured; assuming that it is desired to measure 1-1000th in. with a C eye-piece and a 1-4th in. objective, it will be about 1-30th in. The field-lens having been replaced, the eye-piece is inserted in its proper position, and a stage- micrometer laid on the stage, with the thousandth divisions in the field (under the 1-4th in.) ; the eye-piece being now placed so that the silk lines are parallel with the ruled lines on the stage-micro- meter, it can at once be seen whether the fibres are too close or too distant. If either is the case the field-lens must be removed and one of the fibres shifted, which may be done without much difficulty with the blunt-pointed penknife, pressing down the ends in the balsam and at the same time gently rolling them almost imperceptibly to one side. The field-lens is again replaced and the eye-piece placed in position and examined, and if necessary the operation repeated till the two fibres are exactly coincident with two of the lines on the stage-micrometer, when the space between them, as seen on the magnified image, will represent 1-1000th in. I have fixed a third line at the same distance as the second from the central one, or 1-100th in. from each other. These last two threads are near the opposite sides of the diaphragm, their actual distance apart being about 7-16ths in. Finding the balsam scarcely sufficient to keep the fibres tight I cut very small narrow slips of postage-stamp paper, moistened them, and fastened down the ends of the fibres with them, at the same time pulling them “taut,” with a slight pressure, but taking care not to move them laterally ; there is a good deal of risk, however, of the latter, and as the mucilage dries immediately, it will be necessary, should the fibres prove on examination to be displaced, to remove the paper forcibly, most likely breaking the fibre, and necessitating its renewal. ‘The dots of balsam being placed well back from the margin of the diaphragm, there is room for the attachment of the slips of paper between them and the edge. If a transverse line is desired crossing the others, it is best to fix two fragments of the paper on the opposite sides of the diaphragm, and mount the ends of the thread upon them (fastening them down with other pieces), so that the fibre is clear of the others, and there is no risk of dragging them out of place in attaching it. The eye-piece, as described, gives direct measurements of 1, 2, 4, 5,6, and 10 thousandths ofaninch. The lines on an ordinary stage- micrometer appear with the 1-4th in. fully six or eight times as thick 572 SUMMARY OF CURRENT RESEARCHES RELATING TO ‘as the silk fibres, and the latter should therefore be made to coincide with the centres or corresponding edges of the ruled lines ; it is, however, impossible to attain perfect accuracy unless the stage-micrometer be much more truly divided than those in ordinary use. Nelson’s New Nose-piece Adapter—Mr. E. M. Nelson has devised a new form of adapter (fig. 104), for rapidly changing objec- tives, founded on the principle of the Fic. 104. bayonet-joint. A collar is screwed upon the objective furnished with three radially disposed projecting pins placed at equal distances apart. The adapter, which screws into the nose-piece, is provided with three internal annular slightly sloping grooves and three vertical notches. The pins are slipped up the notches and a partial turn given to the objective secures it firmly in place. iN Curties’ Nose-piece Adapter.—Fig. 105 lI ~—sshows the first rough model of this device = AM : : ’ oe which is designed as an improvement on Pease’s “Facility” nose-piece (ante, pp. 425-6). s The nose-piece screws on the Microscope by the usual “Society ” screw shown at the top, and may remain there permanently. A is a box, or cap, fitting over three equal seg- Fic. 105, ments B of a ring having the “Society” | screw on the inner surface. Hach segment has on its upper edge a grooved tooth work- ing against a flat spiral, and on its lower edge a guide-piece C passing through a a slot on the edge of A. The rotation of A MK ii / acting on the guide-pieces forces the seg- ———— ments to travel in the spiral, in one direc- tion moving them towards the periphery, consequently expanding their circle, so that the objective may be slid in, and in the other direction causing them to move towards the centre when they grip on the threads of the objective. E is a fixed pin to limit the rotary motion of A. With this device no alteration is required to the usual brass-work of the objectives. Any objective having the “Society” screw can be slid into the nose-piece at once, when one-sixth of a turn of A to the left will cause the segments to grip it in place, whilst the reverse movement will release it. The objections to the nose-piece appear to us to be, Ist, the diffi- culty of centering,—the segments have to be made x0 loose, that there can be no good centering ; and, 2ndly, the liability to injure ‘the thread of the objective through there being no provision to insure ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 573 the position of exact correspondence of the outer and inner threads. This is apart from the objection common to all these forms of adapter, that they are liable to let the objective drop off when the adjustment- collar is turned, especially if it moves somewhat tightly. Zeiss’s Stage-Micrometer.—This micrometer (fig. 106) is intended more particularly for the measurement of objects, the whole of which cannot be seen in one field of view. The upper plate is graduated, and rotates on the middle plate. Fic. 106. MUTT LAL haa all The latter is moved laterally on the lower fixed plate by the screw shown on the right. The number of whole turns of the screw is regis- tered on the small dial with index, by means of an endless thread on the periphery of the drum, working on a toothed wheel on the same axis as the index, while parts of turns are shown by the graduations on the drum of the screw. Queen’s Holder for Woodward’s Prism.—Fig. 107 shows an arrangement issued by J. W. Queen and Co., of Philadelphia, for readily applying the Woodward prism. The prism is mounted between jaws 574 SUMMARY OF CURRENT RESEARCHES RELATING TO attached to a sliding and rotating rod carried at one end of a bent arm. The other end of the arm has a slot 1} in. long fitting on a clamping arrangement, which can be attached to the stage. The clamp consists of a bar with a notch cut in its upper end, and with a short piece of tube fitting over it. The bar is pushed up by a spiral spring, but when the milled head beneath is turned, it is drawn down within the tube, thus shortening the length of the notch cor- respondingly with the thickness of the stage. The slot enables the arm to be moved so that the prism may be ad- justed in the optic axis with varying : diameters of stage. The hemispherical lens might be substituted for the prism, which, indeed, we think, would be found more generally useful. Fig. 107. Impromptu Condenser.*—Prof. Rindfleisch suggests that the absence of a condenser may, on emergency, be supplied by a drop of distilled water placed on the lower surface of the slide, where it will act as a convex lens. Illumination by Sunlight.t—Dr. J. Edwards Smith says that “in the study of very minute and delicate structures requiring the utmost separating or resolving power of the objective, remarkable effects are to be secured by condensing sunlight on the top of the object by means of the concave mirror, the object being mounted with a cover in the usual way. The objective used should, of course, have wide aperture. The mirror being posed slightly above the level of the stage, the sun- light is thrown on the surface of the cover, and making a very acute angle therewith. Although not absolutely necessary for this purpose, those stands furnished with swinging substages, allowing the mirror to rise above the level of the stage, are extremely handy and con- venient. By the employment of this illumination in conjunction with object-glasses of wide apertures, the most difficult diatoms, such as Amphipleura pellucida, Frustulia saxonica, &c., are easily and forcibly displayed.” Monochromatic sunlight is procured most easily as follows: cut with a diamond, or a point of a file, a small piece of blue glass roughly to fit the cap of the eye-piece, so that when the cap is restored to its place the blue glass shall be between the eye and the eye-lens of the eye-piece, and the light is thus modified before it reaches the eye. This is the handiest method of obtaining monochromatic light he has ever tried, and the resolutions are quite as strong and effective as when the cupro-ammonia cell is used in the usual manner. In working with sunlight care should be taken to exclude the full strength of the solar beam ; that is, if the sun be clear and bright. * ¢ Berliner Klinische Wochenschrift,’ 1883, p. 183, but the above noted from Bizzozero’s ‘Manuel de Microscopie Clinique,’ French transl. by Dr. C. Firket, 1883, p. 333. t A How to See with the Microscope,’ 1880, pp. 186-7, 191-2, ZOOLOGY AND BOTANY, MIOROSOOPY, ETC. 575 Too much light, supposing the manipulations are tolerably well attended to, will be manifest by the appearance of a multitude of diffraction lines, and these, as a rule, may be recognized by their extending beyond the objects observed. Under very high amplifica- tions, involving the use of powerful eye-pieces, we can, of course, make use of a little more of the solar beam. Another method of sunlight illumination will be found useful at times—the “ reflex” illuminator with direct sunlight. In this case the solar beam can be received through the closed window and reflected from the plane mirror. “This illumination is only suitable for work with wide apertures, and over the most minute objects, and the mount must be free from surrounding objects of a coarse character, else, from the extremely oblique character of the illumination, these stronger and coarser objects will project their strong shadows across the field, causing nothing but confusion and chaos. With the genuine form of the Wenham ‘reflex’ an epithelial scale would hardly be recognized were there several in the field. The principal advantage in the use of , the ‘ reflex’ with sunlight is in arriving at a knowledge of surface markings, and for this purpose it is indeed very valuable.” .“ The mirror may be substituted for the hand-lamp when working in the evening, but the most favourable results are obtained with the light direct. This reflex and sunlight illumination is especially desirable when one wishes to trace out structure situated in one particular plane, to the exclusion of that lying in adjacent planes. In the general squabble to produce the so-called penetration, this very important item has been lost sight of.” Blue-tinted Lamp Chimneys, Light Moderators, &c.*—Dr. J. BE. Smith, referring to the attempts made to modify artificial illumina- tion by the introduction of blue-tinted chimneys, white-ground illuminators, &c., says that he has patiently tried the entire list and rejects them all, from the fact that there is no real advantage secured by their adoption, which cannot be obtained in a simpler way without them. The neutral tint “light moderator,” so-called, is a pleasant thing enough for use with moderate amplifications; yet there is nothing seen with it that cannot be as well shown without it. The blue-tinted chimney cuts down seriously the intensity of the lamp illumination to an extent which will defeat the resolution of any severe test, while, on the contrary, any and all work with the lower powers can be as well accomplished without its aid. Thompson’s Polarizing Prism.{—Neither the polarizing prism of Nicol nor that of Foucault can be regarded as perfect. The latter especially has so small an angular aperture available, as to be very inconvenient for any but narrow beams of parallel light. Prof. 8. P. Thompson has sought to improve upon the existing forms of polarizing prism ; and his investigations into the cause of their defects have led him to produce prisms having a considerably wider effective angular aperture. * <How to See with the Microscope,’ 1880, pp. 189-90. + Lond., Edin., and Dubl. Phil, Mag., xii. (1881) pp. 349-51. 576 SUMMARY OF OURRENT RESEARCHES RELATING TO In the text-books it is usual to tell students that in the Nicol prism the ordinary ray is suppressed by total reflection, because the ordinary index of refraction is greater than that of balsam, and that the extraordinary ray is transmitted because the extraordinary index of refraction is less than that of balsam. Neither of these statements is completely true. All that its inventor claimed for the Nicol prism, and all that it actually performs, is as follows :—The critical angle of total reflection being different for ordinary and extraordinary rays, the ordinary ray is totally reflected and thrown out of the field at an incidence at which the extraordinary ray is still transmitted, the available field of polarized light being the region between the points where the extraordinary ray itself vanishes by total reflection and the ordinary ray enters by lack of total reflection. The former limit is in all ordinary Nicol prisms marked by a broad blue iris or band of colour, the latter is delimited by a curved band at the opposite side of the field, in which, amidst a prevailing line of red and orange, a , system of interference-bands can be seen. The existence of these interference-fringes was examined by the author in 1877, in a paper which appeared in the ‘Proceedings of the Physical Society of London, vol. ii. p. 157. In the Foucault prism a similar limi- tation of the field occurs, interference-fringes being visible at both limits. The refractive index of balsam for light of mean refrangibility may be taken at 1°54, that of the ordinary ray in calc-spar as 1-66, that of the extraordinary ray as 1487. The reciprocals of these are very nearly in the respective proportions of 65, 67,60. The extra- ordinary index, however, is 1-487 only for rays at right angles to the crystallographic axis, having there a minimum, and increasing up to 1:66 for rays whose direction coincides with that of the axis. The ellipsoidal wave-surface of the sheet of extraordinary waves lies partly without and partly within the spherical wave-surface for Canada balsam, while the spherical wave-surface of the sheet of ordinary waves lies wholly within. Hence total reflection may occur for the extraordinary as well as the ordinary rays, but of the extraordinary rays only those can suffer total reflection which are situated in such a direction with respect to the optic axis that their corresponding portion of the ellipsoidal wave-surface lies within the spherical wave- surface for balsam. As the Nicol prism is usually constructed, this limit of possible extraordinary total reflection occurs for rays (in a principal plane of section) inclined at about 10° to the balsam film, giving rise to the limit of the polarized field marked off by the blue iris before mentioned. Prof. Thompson has succeeded in widening the available field of polarized light by constructing polarizing prisms in which this blue iris, and the total reflection of the extraordinary ray which produces it, are got rid of. This can be done by cutting the crystal so that (1) the balsam film lies in a principal plane of section, and (2) the crystallographic axis is at right angles to the axis of the prism. The result of this mode of orientation of the axis and film is to gain 9° of angular aperture at this side of the “ field,” supposing the ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 577 angles respectively made by the film and by the terminal planes with the axis of the prism to be the same as in the Nicol prism. It is possible to produce a further increase in width of available aperture at the other side of the field by reflecting back the ordinary ray more than in the Nicol prism by making the terminal faces more oblique ; but there is then more loss of light by reflection at the surfaces. Besides the advantage of a wider angular aperture, this new form of polarizing prism has the advantage of producing a field in which the rectilinear polarization approximates more uniformly and sym- metrically to a polarization in one plane than is the case in the ordinary Nicol. There is, however, more waste in cutting the spar, with proportionate increase in cost. Prof. Thompson has been good enough to supplement his original paper by the following additional remarks and diagrams. Fig. 108 is the ordinary Nicol prism, as cut from a symmetrical rhomb of spar. (Such a rhomb might be split so as to give four ordinary Nicols. Fig. 109 is the Hartnack prism, so cut that the film lies at right angles to the optic axis. Fig. 110 is the Thompson wide-angled prism, cut so that the film of balsam is in a principal plane of section, and the longitudinal axis at right angles to the optic axis of the crystal. Fic, 108. Fic. 109. Fie. 110. a x Y ah Film inclined about 23° to long axis of prism. End faces mostly make 68° with the long axis. Optic axis inclined at about 43° to planes of end faces. (X Y optical axis). Film perpendicular to optic axis. Longi- tudinal axis of prism does not lie at right angles to the optic axis of the crystal. Film runs from front edge a b to the back edge behind cd, and therefore it is in a principal plane of section and contains the optic axis, and the optic axis is at right angles to the longitudinal axis of the prism. The reason why the new method of cutting secures a wider angle to the field of the extraordinary ray may be further elucidated by the diagrams figs. 111 and 112. Fig. 111 is to demonstrate the point that in the ordinary Nicol, although the maximum refractive index of extraordinary rays is less than the refractive index of Canada balsam, yet that at certain angles of incidence the extraordinary ray does not pass through the balsam film, but suffers total internal reflection. In this figure Ser. 2.—Vot. III. 2P 578 SUMMARY OF CURRENT RESEARCHES RELATING TO the dotted line X Y represents the optical or crystallographic axis of the spar, inclined obliquely to the plane of the film of balsam. Following out Ampére’s modification of Huygens’s construction for the wave-surfaces, the smaller circle represents the wave-surface of ordinary rays (with which we are not dealing here), and the ellipse the wave-surface (much exaggerated in ellipticity) of extraordinary rays. The wave-surface of the ray in the balsam film will be then represented by the dotted circle whose radius has a certain value Hie. 111. Fic. 112. intermediate between the major and minor semi-axes of the ellipse. Suppose a ray 1,1’, to strike through the spar obliquely upon the film, its path will be found by producing it till it cuts the further side of the ellipse; there drawing a tangent to the ellipse meeting the bounding surface at B', and thence drawing a tangent to the dotted circle, giving as a radius through the point of contact the direction marked 1’, which is the direction of this ray through the film. This may be taken as the typical case of all the rays in the useful polarized field of the Nicol. But now consider another ray 2, 2’, which traverses the spar in a direction making a greater angle of incidence with the film. A tangent drawn at its point of emergence from the ellipse meets the limiting surface at B*, which falls inside the dotted circle. In this case it is impossible to draw a tangent back to the dotted circle: signifying that total reflection takes place internally. Rays then whose directions through the spar are at very small angles with the balsam film, are in the ordinary Nicol cut off totally, and the limit of their transmission is in the ordinary Nicol marked by the well-known blue band. Fig. 112 shows the wave-surfaces in the new prism, the ellipsoid here appearing as a circle whose radius is equal to the semi-major axis of the ellipse of fig. 111, since the optical axis is in this case in the plane of the film and at right angles to the longitudinal axis of the prism. Take, as before, a ray of 1,1', draw a tangent at the point of emergence, meeting the plane of the balsam surface at B', the tangent drawn from Bb’ back to the dotted circle gives the direction 1", of the transmitted ray ; and since it is obvious that in no case can the point B’ at any incidence fall within the outer circle, much less within the dotted circle, it is clear that in all cases, and at every incidence, the extraordinary ray is transmitted. Hence the greater width of the field. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 579 Mr. R. T. Glazebrook also describes * a polarizing prism designed to obviate the lateral displacement in the image produced by the Nicol prisms and to give a field in which the plane polarization should be as nearly as possible complete. It was not, however, designed for microscopical work, Depth of Vision in Photomicrography.t;—Mr. G. E. Davis, in an article on “ Penetration in Objectives,” calls attention to the differ- ence that must necessarily exist between the appearance of a solid object seen by the eye through the Microscope and the same object in a photomicrograph. What is seen through the Microscope is the result of the combined effects of the accommodation of the eye and the focal depth of the objective, but when a picture is thrown upon a sensitive plate it is evident that the first element is nearly eliminated, and the only depth of vision attainable is that which the objective itself possesses. The following table shows the focal depth of the objective, the accommodation depth of the eye, and the total depth of vision for objectives from 4 in. to 1-20th in. (A eye-piece.) Anna Focal Depth | Accommodation Total Objective. N.A. of Objective, Depth of Eye. Dep peo ision in, v3 4 0°07 922 2080 2602 4 0:14 262 2080 2342 13 0:14 86 230 316 13 0°17 69 930 299 13 0-21 57 230 287 3 0:34 10°6 20 30°6 Z 0°57 6°3 20 26°3 $ 0°82 4°4 20 24°4 Z 0-60 1:99 2°3 4-29 2 0:76 1:57 2-3 3°87 + 1:20 0-99 2°3 3°29 pac 0°83 0°72 ~ 0°58 1°30 as 0:97 0°61 0°58 1°19 ay 1-10 0°54 0°58 1°12 os 0:98 0°37 0°21 0°58 ob 1:10 0°33 0°21 0°54 —_——_—— eee From this table it will be seen that large objects cannot possibly be penetrated even with objectives of low angle and medium power. The seeds of Betula alba measure 1100 » across, and require therefore 550 « of penetration to see the whole of one of them under one focussing.{ This cannot be obtained from a 14 in. objective of 0-14 N.A., even allowing the 230 » which the accommodation of the eye affords, and if we wish to photograph such an object, the 4 in. of 0:07 N.A. will not have sufficient focal depth. * Proc. Phys. Soc. Lond., v. (1883) pp. 204-16 (6 figs.). t. Micr. News, iii. (1883) pp. 172-6. } i.e. half the depth—diameter in the ease of a spherical object. 2P 2 580 SUMMARY OF CURRENT RESEARCHES RELATING TO The spherical Foraminifer Orbulina universa is 600 » in diameter, consequently a depth of vision of 300, is necessary to see the whole under one focussing. The 1} objective and A eye-piece magnifying together 30 diameters, will just suit this, provided it does not possess an aperture exceeding 0°17, but if we wish to photograph this spherical body a much lower objective than the 14 in. must be employed, as the focal depth of this objective is not higher than 86 p. O. universa affords a good proof of the accuracy of Prof. Abbe’s figures. Under the 1} in. objective of 0:14 N.A. the spheres are splendidly seen, and the same may be said of the 2 in. of 0°14 N.A. and B ocular, but when the picture is thrown upon a ground-glass screen the want of penetration is soon apparent, for it is only when the amplification of the picture has been reduced to rather less than 10 diameters that a satisfactory result is obtained. Similar illustrations may be offered of the higher power objectives. The larger species of Polycistina require a depth of 75 » to show them distinctly, whereas a 1-2 in. objective of 0°34 N.A. in air, when used with the A eye-piece, to produce 100 diameters of amplification, possesses but 10°6 micras. A 1-6th objective, magnifying 300 diameters, loses exactly 1, in depth between 0°60 N.A. and 1:2 N.A., so that while the spores of Penicillium glaucum (diameter of spores 3 ») could be photographed with the former, it would be impossible to obtain perfect sharpness with the latter. The figures in the table for the 1-12th in. and 1-20th in. objectives are equally confirmed by the results obtained in practice. The short diameter of Bacterium termo may be taken as 0°8 yp, requiring a penetration 0°4 » to yield a clear picture, and this is obtainable by using a homogeneous 1-12th in. of 1:10 N.A. to produce an amplifica- tion of 600 diameters. A 1-20th in. objective, magnifying 1000 diameters, although producing a fairly sharp picture to the observer’s eye, cannot produce an equally sharp image on a prepared plate, as the focal depth of such an objective will only approximate to 0-37 », and this statement is borne out by the photographs published by Dr. Sternberg, in his translation of Magnin’s ‘Treatise on the Bacteria, wherein those pictures taken with a Beck’s 1-5th in. are much clearer, though smaller, than the plate taken with Zeiss’ 1-18th. There is more detail in the latter, and here comes in the value of amplification and aperture. Reference is also made to the increase in the depth of vision in direct proportion with the refractive index of the mounting medium. The great gain in stereoscopic effect, on objects mounted in a medium of high refractive index, has led Mr. E. Ward, of Manchester, to mount opaque objects in balsam, with extremely good results. Value of Photography in Microscopical Investigations.*— R. Hitchcock discusses the question whether photography affords a means of illustration or demonstration in any wise equal or superior to drawing by hand. On the one side it may be said that a photo- * Amer, Mon. Mier. Journ., iy. (1883) pp. 33-4. ————s ZOOLOGY AND BOTANY, MICROSCOPY, ETO. 581 graph is necessarily a faithful and absolutely correct representation of the object. This may be true and it may not be true. Ordinarily it is so. But somewhat depends upon the nature of the object. A trans- parent object does not appear the same as an object shown by reflected light, and it will not be produced the same upon a photographic plate. The colour of the parts influences unequally the actinic power of the transmitted light. Thus, in an insect preparation, the yellow chitinous portions obstruct the most active rays of light. In order that the detail observed in these parts by the eye shall be impressed upon the sensitive plate, a rather longer exposure is neces- sary than for the other parts. The dry plates, however, are far more sensitive to rays of yellow light than the wet plates heretofore commonly used, and they will give better pictures than the latter. Still, there is a loss of detail in many preparations because of the absorption of actinic rays by certain portions of the objects. On the other hand, it may be said that the photograph only clearly represents what is in focus at one time, while the observer studies and gets the relation between different planes by moving the focussing serew backward and forward. Hence a pencil drawing more truth- fully represents an object as it appears to the mind of the observer. This is undoubtedly a fact; and for this reason there can be no doubt of the superior value of the drawing. Yet drawings require a much longer time for execution, and their excellence partly depends upon the skill of the artist, and partly upon his familiarity with the use of the Microscope. Both the photographic and free-hand methods have, in fact, advantages of their own, the photographic, however, furnishing evidence of the accuracy of the observations which it is relied upon to sustain. Abbe’s Refractometer.*—Since the introduction of homogeneous- immersion objectives it has become a matter of increasing importance to be able to readily determine the refractive index and dispersive power of a fluid, without having to resort to the old cumbrous methods by hollow prisms, &c. The refractometer devised by Pro- fessor Abbe enables this to be done with a facility and accuracy that leaves nothing to be desired. The leading principle of the apparatus depends upon the obstruc- tion of the rays by total reflection at the surface of the fluid under examination. Wollaston and others have previously adopted the method of observing the maximum intensity of the reflected ray, but a great advantage is gained by observing instead the minimum intensity, so to say, of the transmitted ray. In the former case there is a difficulty in ascertaining the precise point when the light reaches its maximum, whilst in the latter a very small amount of light is easily detected in the darkened field. The principle will be better understood by reference to fig. 118. Two similar prisms A and B of highly refracting flint glass, with * Abbe, E., ‘Neue Apparate zur Bestimmung des Brechungs und Zer- streuungs-vermogens fester und fliissiger Korper,’ 8vo, Jena, 1874, 79 pp. (1 pl. and 7 figs,). 582 SUMMARY OF CURRENT RESEARCHES RELATING TO their hypothenuse surfaces contiguous so as to form a parallel plate, are placed in front of a telescope having an object-glass at J, with crossed threads in its focus at F', and a second (eye-piece) lens at L. Suppose that any fluid, or semi-fluid, of less refractive index than the prisms, is spread in a thin layer between them, and they are rotated on an axis at right angles to the plane of the paper. When the telescope, with the prisms in front of its objective, is now directed to any bright object, a given point P of the latter will send a pencil of parallel rays through the prisms in a direction parallel to the axis of the telescope. These rays will therefore be collected by the objective J to the centre of the ocular-field, at F, and the eye behind the ocular will see that point of the field illuminated. This, however, will only be so as long as the angle y, under which the parallel rays reach the internal surface of the prisms, is less than the critical angle corresponding to the difference in the refractive indices of the flint and the fluid between the prisms. If, according to the position Fig. 113. of the prisms, this angle should exceed the critical angle for the rays which are directed to F, no ray can reach this point of the ocular field, nor any other point F’ of the lower half of the field (as the diagram is drawn). For the rays which could be collected by the objective J to such a point F’, must of necessity enter the objective as a parallel pencil inclined upwards in front of J, and (as will be readily seen by considering the refraction of the prisms) must meet the surface C under greater obliquity than the axial pencil just considered; consequently they will undergo total reflection if the axial pencils are totally reflected. Under the condition assumed above, the points of the upper half of the field only could possibly receive light through the prisms, because the parallel pencil which is directed to such a point (F’’) is inclined downwards, and is there- fore transmitted through the surface C under a smaller obliquity. If now, by rotating the prisms, the angle y for the rays directed to the central point F of the field, should just be equal to the critical angle, all points of the field above F will receive light through the prisms, whilst all points below F will remain dark, provided monochromatic light is used; the observer will therefore see through the ocular one half of the field bright and the other half dark, the intersect- ing line of both halves just coinciding with the crossed threads at F. By noting the angle a at which this occurs the refractive index of the fluid is readily obtained. For sin B = : sin a (v being the refractive index of the glass prisms) y = 6 + w and n = vsin y. a 7 ZOOLOGY AND BOTANY, MICROSCOPY, ETO. 583 With white light the boundary line between the dark and bright parts of the field of view is coloured on account of the difference between the refractive indices of the differently coloured rays, a fact which is made use of to determine the dispersive power of the fluid. For this purpose a “compensator” is added consisting of two direct vision (or Amici) prisms, R and § fig. 114, so constructed that rays of a given colour D will pass through each without deflection, whilst rays of a different colour will be deflected towards the former, and make with it an angle & in the direction of the principal section. By turning the screw head T of the pinion acting on a circular rack at P the prisms simultaneously revolve in opposite directions, and starting from the position shown in the figure (the “primitive plane ”) in which the two principal sections are parallel, and the refracting edges directed to the same side, they pass through equal angles in opposite directions, so that the two principal sections remain always Fic. 114. symmetrically inclined to the primitive plane. a The principal sections will again coincide after revolving 90°, 180°, &c., with this differ- F ence, however, that at 90° the refracting edges will lie in reversed directions, whilst at 180° both will be in the same direction, the opposite of that which they occupied in the original position. : It follows, therefore, that the rays cor- responding to the line D will pass through the prisms (provided they can pass at all, i.e. are not totally reflected) without deflection, whatever their relative position, and that all other colours will undergo deflection only in that plane in which the two prisms coincide, i.e. the principal plane. During the revolution the extent and direction of the dispersion within that plane varies for any two colours as the diagonal of a parallelogram whose sides are proportional to the dis- persion / of the single prisms, and correspond with the direction, whatever it may be, of the principal sections. Hence the “compensator” acts as a single direct-vision prism for the colour D, with a constant principal section, but variable dispersion within that section; and in every position of the prisms, by their revolution (either way) through an angle z, the amount of their dispersion for the assumed colour, and for all others proportion- ately, is k = 2k cos z. Consequently this amount may have all values from 2 k to + 2 k. If we look through such a combination of prisms at a luminous line perpendicular to the central plane of the principal section, it will be seen to extend into a spectrum constantly lengthening as the prisms revolve, becoming contracted again, as the revolution is con- tinued, to a colourless image, and again expanding into a spectrum with the colours in reversed order. By means of this device any desired amount of dispersion between the limits — 2% and + 2k may be introduced into the pencils 584 SUMMARY OF CURRENT RESEARCHES RELATING TO of rays transmitted through the film of fluid at C; and by properly regulating this amount, the relative dispersion of the fluid and the flint-glass of the prisms may be exactly compensated for, or balanced, and the dividing line of the ocular field made to appear colourless even with white light. At the same time the position of the com- pensating Amici prisms (the angle z with which the compensation is obtained) affords all necessary elements for computing the dispersion of the fluid under investigation, provided the refraction and the dispersion of the glass-prism A is exactly known from previous measurement. The author shows that the dispersion of the fluid (for any definite interval of the spectrum) may be obtained by means of the formula 6n=A+t Ba, where A and B are co-efficients which depend on the refractive index of the prism A and of the fluid, and the dispersive power of the prism A at the same time, whilst o depends on the angle z of the compensating prisms only. The co-efficients A and B may be easily computed for every instrument and arranged in a tabular form, a definite interval of the spec- . trum (e.g. from D to F) being ) assumed for én. Fig. 115 shows the instru- ment complete. FJ is the small telescope magnifying two or three times. In the focus F of the object-glass are the double cross threads. At the upper end the telescope is attached to a tube, in which the eye-piece O (consisting of a convex lens) slides. At its lower end the telescope is screwed to T DS, containing the two prisms of the compen- sator; D again is fixed to the sector A. The two prisms between which the fluid is placed are atC. One of these is fixed to an axis which passes through the support G, and has also attached to it at K an alhidade or movable index-arm B. The refracting edge of the prism is at right angles to the plane of the sector and the axis of the telescope. The second prism is simply ledged on the former, being held in place by a spring. The graduation on the sector is arranged so as to give the refractive index directly, and shows thousandths, so that with the naked eye the refractive index to three ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 585 places of decimals is readily obtained, and with a lens an approxima- tion to the fourth place is possible. The prisms of the compensator are revolved by a pinion acting on circular racks, the milled head of the pinion being shown at ¢ A drum e moving with the lower prism is graduated from 0 to 60, and back to 0, the graduations showing the angle z for every 3 degrees. The instrument is attached to a metal base, and has a concave mirror g. In its normal position for observation it is inclined as shown in fig. 115, but in order to insert the fluid between the prisms, the telescope, sector, &c., can be turned completely away from the observer so that the upper end ¢ of the sector nearly touches the table, the hypothenuse surface of the lower prism being then horizontal. This is accomplished by the sector not being fixed to the support G, but to an axis passing through it, the prisms with the alhidade being on another axis within the former. Thus the prisms and index can be moved together on the inner axis, or the whole sector, together with the telescope, can be moved on the inner axis, carrying with them the prisms and index. The following are the directions for use issued with the instrument by Dr. Zeiss, of Jena, by. whom it is made :— “On removing the instrument from its box (taking hold of it by the foot and support G only) it should be placed so that the sector with the telescope is turned away from the observer, the prisms C being towards him. After taking out the small wood, or cork, wedge (used for security in transit) the movable prism should be slipped off by slightly pressing down the spring and drawing it backwards ; the surfaces of the two prisms which come into contact are thus free. After the prisms have been thoroughly cleaned, and the hypo- thenuse surface of the fixed prism brought into a horizontal position by turning the alhidade, a drop of the fluid to be examined is to be placed in the centre of the prism by a glass rod, the movable prism being replaced by pressing the spring down with the finger. The sector with the telescope is now to be turned up so that the eye-piece is towards the observer, and the alhidade brought to the beginning of the scale. Looking through the telescope, the mirror is adjusted so that the whole field of view is uniformly illuminated, and the eye-piece drawn out till the cross threads are seen sharply defined. The alhidade is then moved forwards till the lower half of the field of view is obscured, and the screw turned until the boundary between light and dark becomes a line as colourless as possible. By again turning the alhidade this line is adjusted to lie along the two adjacent points of intersection of the double cross threads. The position of the alhidade-index on the graduated arc, and the position of the drum, are then to be read off on the respective scales, a lens being preferably used for the former. After further turning the screw till the boundary line a second time becomes colourless, it is again adjusted on the cross threads, and the sector and drum read off. 586 SUMMARY OF CURRENT RESEARCHES RELATING TO The mean of the two readings on the sector gives, direct, the refractive index of the fluid (to the third decimal place), for the then temperature of the instrument and for the Fraunhofer line D. By estimating the fraction of the intervals the fourth decimal may be obtained. The mean of the drum-readings gives the value of z from which the dispersion of the fluid for the colour interval between D and F may be obtained from the dispersion table which accompanies the instrument, and gives the value of the quantities A, B, and o of the formula at p. 584, for every reading of the sector and the drum. The elements on which the figures of the table have been computed are taken in such a way, that the formula bn=A+Bo gives the dispersion of the fluid for the interval from D to F of the spectrum, i.e. the difference of the refractive indices for the Fraunhofer lines F and D. The value of the factor o corresponding to z is to be taken with a negative sign when z exceeds 30. The index of the alhidade is properly corrected if pure water at about 18° C. gives as the mean of the two readings n = 1°3330. If the index should have been displaced it can be adjusted by loosening the two screws at the back of the alhidade, by which the index is attached to it, and shifting the latter until the proper reading with water is obtained.” It is also pointed out that it is imperatively necessary that in cleaning the prisms (with water or alcohol) only soft and very clean linen should be used, and that, as the prisms are made of heavy and therefore easily injured flint-glass, they should be cleaned immediately after use.* Two simplifications of this instrument are also described by Professor Abbe, enabling the refractive index only to be determined. They are both intended to be held in the hand. One has the sector and scale, with a direct vision prism over the eye-glass, and has the full range of scale. In the other the sector is replaced by an eye- piece scale, and is limited to fluids of refractive indices between 1°30 and 1:48. Itisa very handy instrument for use with aqueous or saline solutions. All the forms can be made use of for readily determining whether substances have been adulterated or are pure, or the degree of concentration of solutions such as sugar. As, however, these two forms are of more limited use, and in particular do not admit of the determination of the dispersive powers, it is unnecessary to give here any more detailed description. The paper contains very full descriptions of all the three instru- ments, with directions for use, and elaborate discussions on the principles and limits of exactness of the methods, and on the in- fluence of the errors of observation on the results. It also con- * Formerly strips of paper were placed between the prisms to keep them a little apart, but recently the movable prism has been ground slightly concave so that the paper is not necessary. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 587 tains a description of a new form of “spectrometer,” for the exact measurement of the refractive indices and dispersive powers of prisms, which, however, is mainly of interest to physicists. Professor Abbe subsequently suggested * an addition to the refractometer, in order to enable the refractive indices of solid bodies to be determined. For this purpose a small part of the metal back of the fixed prism is removed and a small prism is cemented on. A piece of the substance to be examined is then attached to one of the faces of the large prism by a fluid of high refractive index. In fig. 116, A is the prism of the refractometer, S the solid substance —a plate with one surface polished and cemented to the face C of the large prism by means of a drop of cassia-oil, or monobromide of naphthaline ; a, the small prism cemented to A, in order to admit rays from above to the face ©. If the angle y of the Bg IG. incident rays at C, on rotating the prism A, be- comes equal to the critical Ag angle for the substance 5 —relatively to the flint- Ds si \\\ \\s ‘\, glass of A—total reflection wie! AN Ce i) = Ne x begins, and the under half ‘_ — — 1/; of the ocular-field appears brightly illuminated, the upper half less so. The line of intersection being brought just upon the cross-wires and made colourless by means of the compensator, we have again the same conditions as in the case of transmitted light. In order that the total reflection shall be obtained from the solid substance S, and not from the fluid film by which it is cemented to A, the refractive index of this fluid must of course exceed that of the solid under investigation. Refractive Indices and Dispersive Powers of Solidsand Fluids.t —Professor L. Matthiessen of Rostock gives a table of refractive indices and dispersive powers, prefaced by the following observa- tions :— “Tt is well known that recently in practical optics the theory and technic of microscope objectives have attained special interest. In- portant advances in the perfecting of the Microscope are connected with the names of Helmholtz, Abbe, Amici, and Stephenson. The problem of eliminating spherical and chromatic aberration in objec- tives has through them (in different directions) been brought nearer a solution, although in the optical properties of transparent solid and fluid bodies there are still many obstacles to further perfection to be overcome. In the substances hitherto observed the dispersive power generally increases with the refractive index, and substances are wanted which combine small dispersion with a high refractive power or vice versa. Moreover the fluids hitherto observed all have a propor- TOO —| * “ Ueber die Bestimmung der Brechungs-Verhiltnisse fester Korper mittelst des Refractometers,” SB. Jenaisch. Gesell. f. Med. u. Naturwiss., 1879, pp. 35-44. + Centr. Ztg. f. Opt. u. Mech., iii. (1882) pp. 73-4. 588 SUMMARY OF CURRENT RESEARCHES RELATING TO tionately larger dispersion than solids of equal refractive index. For the homogeneous-immersion method, however, fluids are required which agree in refraction and dispersion with the glass of the objec- tives. Finally, it is found that with an increasing total dispersion Refracting Substances. Observer. nD, nH — “B. Fluor spar.. dec ig took = St. 1°43390 0°01004 Distilled water, 292°C. . Ve Wi 1°33292 0°01305 Sulphuric acid——(hydr. ) 4:5 per cent. . 5; 1°33862 0°01350 Sugar candy—sol, 10 percent. .. .. | v.O. 1°34756 0°01351 Alcohol, 38> A POLiCeN bs cen) toni Yaad = v. W. 1°35686 0°01368 86 rogep tem = 1:36343 | 0-01376 Calespar (e) Hofm’ TH. , ns 1°48639 0-01381 Chloride of sodium—sol. 8°6 per cent. - 1°34702 0:01428 Sugar candy—sol. 30 percent. .. v. O. 1°38080 0°01451 Chloride of ammonium—sol. 9° 7 per cent.) vy. W. 1°35098 0:°01466 Arragonite (y) Pr Ae One R. 1:53013 0°01477 Glycerine, 49°7 per cent. eae re v. W. 1°39242 0:01493 Acetic acid, 97°6 per cent. ~ 1°37455 0°01501 Chloride of zine—sol. 18 per cent, | 5. 1°36719 0°01559 Chloride of caleium—sol, 16°7 per cent. Ss 1°37392 0:01599 Topaz (8) .. Se ac Ce ge R. 1°61375 0°01691 Quartz (0) Hofm. i. ate SOR ee Te Wk 1°54417 0:01711 Glycerine, 100 per cent.. $3 1:46196 0:01712 Chloride of sodium—sol. 26-6 per cent. a3 1°37963 0°01715 Topaz (a) .. R. 1°62109 | 0-01715 Chloride ofammonium—sol. 24° 8 percent. yv. W. 1°37947 0-01720 Chloride of zinc—sol. 31°0 per cent. 5 1°39169 0°01757 Quartz (¢) Hofm., III. R. ae 2 - 1°55323 0°01777 Wrownerlassee ck te.) Get ee ae 2 Lo. 1+50867 001867 Heavy spar (y) H. 1°63630 0:02043 Ghloride, of calcium—sol. 40°6 per ‘cent. v. W. 1°44313 002106 Heavy spar (a) a Oe ic ; 1°64797 0:02145 Crown glass (Merz IV. v.) 50 60 he Ta Me 1°53032 0°02194 Turpentine cigs Bamadictae fore 6 1°47212 0:02311 LPG Geo) kell © Se ee me St. 1:54400 | 0:°02904 Arragonite (Cer omcoe. Ae R. 1°68589 0°02950 Calespar (0) Hofin. III. saphges a eee v. W. 1°65844 0°03032 Flint glass 50 eg wht Aaya hed Lo. 1°56945 0:03086 Naphthaline in Benzol dot son. BoA ho Ve. 1°49513 0:03815 Benzine, A. -.. femme dae meas AK soi v. W. 1:49721 003853 MAEHZOVON PUIG 6 56 xd os, oa. nv Ve. 1°49947 0°03893 SP 05, 1) 70 een Layee 1°53215 0°04360 Oil of anise appl Sse are Card ee . 1°55725 0°05977 ISP nd Be Ve. 1°75303 0°06709 Flint glass (Merz TE)). %: Bay, bflee v. W. 1°75139 007008 Monobromide of naphthaline .. ay oo Ve. 1°65815 0°08369 Bisulphide of carbon .. .. .. «. v. W. 1°62403 0:08411 + 55 IG 47 (are 5 1°63307 0: 08576 MOUMNACARIA ag 3s cscs v. W. 1°61883 011270 there is generally a larger partial dispersion in the blue. It is to this point, as it seems to me, that the opticians will in future have to direct their attention in the correction of the chromatic aberration. A comparison of the above three conditions can, however, only be made by means of a tabular statement of the measurements hitherto ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 589 carried out. ‘These measurements, which were extended to the whole spectrum, are scattered here and there in books, and moreover are not all of equal value, being affected partly by personal and partly by instrumental errors. For the purpose of forming a normal table for the partial dispersions, I have collected about 200 of the best and most authentic series of refractive indices, which embrace the Fraun- hofer lines A, a, B, C, D, E, 6, F, G, H, or at least the seven lines B, C, D, EH, F,G,H,. From this series the accompanying table has been compiled for optical purposes, in which the substances with the index D or “D are arranged according to the total dispersions H, — B or "H — "B.” [| We have not thought it necessary to print the whole table of 173 data but have selected 44.) The observers were Fraunhofer (F.), van der Willigen (v. W.), Baden-Powell (B. P.), Rudberg (R.), Mascart (Ma.), Dutiron (Du.), Heusser (H.), Ditscheiner (D.), Stefan (St.), Verdet (V.), Veress (Ve.), von Obermayr (v. O.), Swan (Sw.), Lohse (Lo.).” “The Genus Microscopista.’’"*—The Annual Address for 1882 to the Microscopical Society of Victoria was delivered in November last by the Vice-President, the Rev. J. J. Halley. After referring to the small number of members and the still smaller number who contributed papers, the address continued as follows :—* In such circumstances, perhaps, this Annual Address may properly take the form of what would in theology be called apologetic. We must defend our position, and show the raison d’étre of our exist- ence. Looking, then, at our Society as we are accustomed to look at the various divisions of sentient life as they come under our investi- gation, we will proceed to examine the various species of what we may call the genus Microscopista, the generic characteristics of which are, that they examine minute objects with artificial aid more or less elaborate and that they do this with a more or less useful end in view. Of this great genus, whose habitat is the civilized world, the first species is the M. delectata (sic), or the playing microscopist. This is the lowest species in the scale of development, and some observers con- sider that the other species are all derived from this one, while a few who have no love for the genus affirm that this is the one and only species, the others so-called being only transient varieties. But M. delectata, though often despised, is by no means to be set aside. We will grant that in his hands the instrument is a plaything and nothing more,—that he looks at the wondrous beauties revealed merely to please the eye,—that he peers into quaint and curious forms merely to satisfy curiosity,—that the valve of a diatom is interesting to him merely as it is strange, and that the organs of an insect or the home of a Bryozoon only allure as they are novel. In this there is nothing to be despised. The great order of the Bimana must be amused, and the more rational the amusement the better; and surely it is not less rational to find amusement in examining the wonders of * ‘Southern Science Record,’ ii. (1882) pp. 285-9. 590 SUMMARY OF CURRENT RESEARCHES RELATING TO Nature,—her painting of marvellous beauty,—her sculpturing of unrivalled forms,—than in turning over the prints of man, or spending time examining and collecting his effigies; surely as reasonable as counting the pips on a card, as cannoning ivory balls, or bouncing indiarubber ones over a net. We will not, then, push out of existence the playing microscopist, for my own part I have for him a very tender regard, being perhaps myself but little removed, if at all, from this species. In your name I will welcome all such to our gatherings, assuring them that they will find here much to amuse them if they do not care to learn; but we will hope that in consorting with higher forms they will imperceptibly, perhaps, yet surely, by the force of association, put on new features, lose obsolete and useless organs, and develop into higher and higher forms, and this not in descendants yet to be, but in a conscious life-history. Again I say we are delighted to find, and would gladly have more in our midst of, M. delectata. We advance next to M. evocationes(sic), or the collecting microscopist. This is only one of the somewhat despised forms :—‘ Only a collector,’ with an elevated head and a righteous shrug, is a phrase often heard. But in great economical systems ‘mere collectors’ play a most. im- portant part. This solid world, with its fertile plains, is just a vast collection gathered together by collectors, organic and inorganic. And collectors provide the material for others to work on and work up. The higher workers not infrequently have neither the time nor the opportunity to collect, and, so far as the preparation of micro- scopic mounts is concerned, have often not the manual skill and delicacy of touch to be successful. Such must depend for their mental pabulum in its raw state on others. And there is work of immense importance to be done by the ‘mere collector’ If such cannot add to our knowledge by their own investigations, if from their brains can come no world-shaking theories that shall make their name and our Society’s name familiar as household words, they can add to the treasures of our cabinet, their quick-seeing eye can pick out new forms, their diligent feet can take them to unexplored parts, and their delicate hands can mount their finds in such a way that the true investigator will be able to read with his glass, as in a glass, natural riddles, adding to the world’s store of knowledge. Our Society cannot afford to despise the collector. Far from it; we will thankfully receive from any quarter, and ardently welcome, genuine specimens of M. evocationes. M. tabernarius, or the tradesman microscopist. A large and growing species, every day producing novel varieties, and one that in these days must be treated with no little respect. Utilitarianism has invaded the old halls of science, and in these modern days not one but many a philosopher’s stone has been found in the crucible of the chemist and the jar of the electrician; and mean homes have turned palaces, and common delf silver-plated, at least, through fortunate discovery. Yes, gold in abundance has followed in the track of the scientists. All this is but vero verius, nothing more true. In saying the scientific plaything of yesterday is the mighty ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 591 machine of to-day—the toy of an enthusiast one day, the necessity of life to thousands the next—it would be but a work of supererogation to remind you of the giant strides made in the development of electric science and practice. In our own line we can perhaps look for no startling discoveries that shall revolutionize the world of daily life, but there is yet room for the Microscopista tabernarius. I do not mean the man who makes the instruments, for him there undoubtedly is ample room, and almost every month we have to hail improvements that make our work more easy. But the Microscope is a tool of trade for some. We have heard that the intricate and charming markings of diatoms and Foraminifera have been used by pattern designers, and in some trades the Microscope is daily used. About a year ago I was at the Italian National Exhibition at Milan. Among the most interesting of the exhibits was the process of silk producing and manufacture. At that exhibition the results were not merely shown, but all the details from the beginning to the end, and a row of microscopists with persistent care examined the silkworm eggs, picking out and rejecting every egg that showed any symptom of disease. But why go to Milan? Has not the greatest of your legislators declared that by the aid of a powerful Microscope he was enabled to determine on the spot the magnificent character and splendid suitability of the Stawell stone for our new halls of legis- lature? In this Society it would be of thrilling interest to hear what was the powerful instrument he used—how he used it in the trying circumstances of the Parliamentary picnic—what he learned—and how he learned it by looking at a lump of sandstone? But this is perhaps too much to expect; let us be content that the value of your instrument has been acknowledged in those halls of wit and wisdom. I think I must place this new-caught specimen in a unique sub- species of his own, and label him WM. ludificatio. I hardly dare trans- late this title, but its English synonym is not far off ‘humbug.’ Under M. tabernarius, as a sub-species, we will place M. detergi- tata (sic), or the detective microscopist. Here we come to a class directly useful to mankind. By the aid of the Microscope we discover largely what it is that we eat and drink, how sometimes very widely the real differs from the apparent, and how true it is that “things are not what they seem ”— a wide field, that has hitherto not been taken up to any ex- tent by our Society. Under this species I had intended to have ranged myself during the past year, and to have done something worthy of your attention for this meeting: but, alas, it has been but a good resolution, and gone, I fear, where many other good resolutions have gone before it. This I have done: prepared a series of test starches for com- parison, some eighteen or twenty slides of which I had the pleasure of placing in the Society’s cabinet. I have also made a preliminary examination of some of our ordinary articles of food, not sufficiently exact to go into detail, but enough to give to you a hint as to what may be done, and to indicate a useful line of work. For example, I have found arrowroot adulterated with sago, and arrowroot, tapioca, and sago all showing more or less of the well-known form of potato- starch. Cocoa has exhibited potato-starch, sago-starch, in one case 592 SUMMARY OF CURRENT RESEARCHES RELATING TO the beautiful grain of tous-les-mois, besides sugar crystals and inor- ganic matter, that may be colouring matter, or may be dirt—in one case, I suspect, plaster-of-paris. Mustard showed pea-flour, potato- starch, and wheat-flour, as well as inorganic matter, probably plaster- of-paris. Oatmeal showed wheat-flour, and maizena potato-starch. I give these just as examples of what is and of what may be done. It is not our province to do with legislative action, yet we have, I think, a right to know what it is that we eat and drink. Many of the adulterations are in themselves harmless to the public health, though not to the public morals. This species of microscopist is much needed, and I regret that, so far as our Society goes, we have no member that has given himself up to this work in a systematic and careful manner; but certain it is that such a work needs doing, and doing well. I can only bid you hope that our energetic Secretary will secure for us numerous specimens of M. detergitata, M. medicus is the medical microscopist. Our learned and much honoured President comes, of course, under this title. One would say that specimens of this species would be found in abundance about our rooms, making themselves heard above the more subdued voices of other species; for surely the Microscope must be a necessity for medical men, and one would certainly have predicated that our Society’s literature would have been enriched by their contributions many and learned ; but, with the one exception of our President, I do not think that for years a solitary specimen of the M. medicus has been heard in our gatherings. I cannot altogether account for this: I do not know if the class is an exceptionally shy one— shrinking from pub- licity—in no case courting profane gaze, and with a modest dislike to uttering opinions in gas-light, and never on any occasion advancing thoughts that are not well matured and tested. It may be the M. medicus has a difficulty in consorting with other species of the same genus, and prefers buzzing only where his more immediate kin are found. I do not know what bait must be prepared to catch this re- markable shy form: possibly our President may give our Secretary a few hints on the subject. My last species is the M. germanus, a true genuine microscopist. Of this species we have some admirable examples, men who patiently and perseveringly take up some section of the wide world of science, and work on and on till they have worked out some beautiful system, or worked up the whole life-history of a race. It is those men who add to the sum of the world’s knowledge, and so add to the sum of its happiness. The discovery of truth in any one line cannot but be beneficial, for every discovery of truth helps in the discovery of other truth, and sometimes in lines remote enough from ‘the first. The story of the world of science is full of instances of this. And every man who lays a stone may know that he is doing something for the completion of that grand temple of truth that shall fill the world with its radiance. Gentlemen, we exist that we may bring together these various classes, all interested, though in different ways, with microscopy. Men of kindred pursuits naturally desire to meet each other, or should do ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 593 so, that there may be mutual help and the interchange of ideas, and that by such help knowledge may ‘ grow from more to more.’ I think I have shown that we have a right to exist, that by our existence we may not only amuse and profit each other, but do good in the community in which we are placed, and perchance do something to help in the advance of knowledge in the mighty world of science. May I trust that next year will be far more prosperous than any preceding ones have been?” Avy, J. H.—The Methods of Microscopical Research. Part I. Introduction. Part II. On Instruments and their Uses. Chapter I. The Microscope, pp. i-vi. 8vo, London, 1883. AYLWARD’S (H. P.) Camera Lucida. [‘‘ Very cheap camera lucida which can be used with the eye-pieces of any maker without requiring an adapter. ‘The reflecting surface is a thin cover-glass, which is made adjustable in order that the instrument may be used with either deep or shallow eye-pieces.” | Micr, News, ILI. (1883) p. 208. Bavscu’s (B.) New Binocular. [Supra, p. 548.] Amer. Mon. Micr. Journ., TV. (1883) p. 97. The Microscope, IIL. (1883) p. 89 (from Odontographic Journal). BrEurens, W.—Bericht iiber einige, wahrend des Jahres 1882 publicirte Verbess- erungen ete. von Mikroskopen und mikroskopischen Apparaten. (Report on improvements, &c., in Microscopes and Microscopical Apparatus published during 1882.) [Abstracted from this Journal. ] [‘* Wir wenigstens glauben nicht, dass ein deutscher Mikroskopiker je zu ‘Wenham’s universal inclining and rotating Microscope’ greifen wird. (Sollten dieses und ahnliche englische Instrumente sich nicht noch dahin vervollkomnen lassen, dass der Beobachter auf dem Kopfe stehend lin- durch sehen kann ?) ” | Bot. Centralbl., XTV. (1883) pp. 253-5, 350-1 (5 figs.). Bizzozmro, G.—Manuel de Microscopie Clinique avec des instructions sur l’emploi du Microscope en Médecine légale, &e. (Manual of Clinical Microscopy with instructions for the employment of the Microscope in medical jurisprudence.) Translated from the 2nd Italian edition with notes and several additional chapters, by Dr. C. Firket (infra, p. 613). xii. and 359 pp., 45 figs. and 7 pls. 8vo, Bruxelles, 1883. [Chap. I. Description and Use of the Microscope, pp. 1-19 (8 figs.).] Buss, E. J— Germination of Fungus Spores under the Microscope. [Describes Dallinger’s Damp Chamber and the authov’s device. | : Sci.-Gossip, 1883, p. 137. Brappury, W.—The Achromatic Object Glass, XX., XXI., XXII, XXIII. XXIV., XXYV. Engl. Mech., XXX VII. (1883) pp. 305-6, 329-30, 356-7, 377-8, 405, 451. Couen, E., and J. Grimu.—Sammlung von Mikrophotographien zur Veranschau- lichung der mikroskopischen Structur von Mineralien und Gesteinen. (Collection of microphotographs for the demonstration of the microscopical structure of minerals and rocks.) Part VIII., 8 microphotographs. 4to, Stuttgart, 1883. Curtiss’ (T.) Nose-piece Adapter. [Supra, p. 572.] Engl. Mech., XXX VII. (1883) pp. 333, 365, 385. Curtis, R. J.—The Clinical Use of the Microscope. [Considers that “the following list will comprise a battery of objectives which will most satisfactorily cover the whole ground of microscopy :— 3 in. 10°, 1 in. 25°, 1-2 in. 45°, 1-8 in. 180°,” with a set of eye-pieces of 2in., 1 in., 1-2 in., 1-3 in., 1-5 in. The Microscope, 111. (1883) pp. 71-6, from Peoria Medical Monthly. Davis, G. E.-—Penetration in Objectives. [Supra, p. 579.] Micr. News, III. (1883) pp. 172-6. Ser: 2.—Vol. IIL. 2 Q 094 SUMMARY OF CURRENT RESEARCHES RELATING TO Davis, G. E.—* To our Subscribers.’ —*“‘ Our Free List.” Micr. News, ILI. (1883) p. 182. Guazesroor, R. T.—On Polarizing Prisms. [Supra, p. 579.) Proc. Phys. Soc. Lond., V. (1883), pp. 204-16 (6 figs.). Govr.—Intorno allo scopritore di una singolare illusione ottica. (On the disco- verer of a singular optical illusion.) [Post.] [With remarks by Sig. Respighi.] Atti R. Accad. Line. Trans., VII. (1883) pp. 183-8. GratTaroLa, G.—Su un possibile errore nelle misurazioni micropetrografiche. (On a possible error in micropetrographic measurements. ) {In measuring, by means of the fine adjustment screw, the vertical dimen- sions of an object inclosed in a transparent medium, such as a microlith in quartz or felspar, or the vertical distances between two points in such a medium—in short differences of level—the true difference is equal to that shown by the direct reading of the screw multiplied by the refractive index of the medium. ]} Atti Soc. Tose. Sci. Nat., Proc. Verb., III. (1883) pp. 244-6 (1 fig.). Grimm, J.—See Cohen, E. Haiues, H. F.—Adapters for Microscopes. [Note on letter of J. A. Ollard infra as to Nelson’s and Curties’ Adapters. ] Engl. Mech., XX XVII. (1883) p. 389. Harpy, J. D.—Gas lamp for microscopic use. [Exhibition — An adaptation of the albo-carbon burner to a table lamp- stand. | Journ. Quek. Micr. Club, I. (1883) p. 197. Hircucocr, R.—Instructions in Dry-plate Photography (in part). (‘The object of these articles is to enable the reader to make good photo- graphs with the Microscope, and to prepare lantern-tratisparencies for use in illustrating articles read before Societies or public lectures,” with “ full instructions for developing and finishing negatives, glass positives, and paper prints.”] Amer. Mon. Micr, Journ, TY. (1883) pp. 84-8, 106-9. Homogeneous-immersion Lenses, [The cement of Mdller’s slides shows no signs of deterioration from cedar oil. Hollis’ glue appears to be quite proof against the oil. Ward’s brown cement seems to be equally efficacious. ] Micr. News, III. (1883) p. 208. JapanzA, N.—Sopra alcuni sistemi diottrici composti di due lenti. (On some dioptric systems composed of two lenses.) Atti R. Accad, Sci. Torino, XVIII. (1883) pp. 601-18 (5 figs.). Jounson, G. C.—Photo-micrography. [Since the introduction of rapid gelatine dry plates he showed that good pictures might be obtained by the use of objectives of Ligh power, such as the 1-16th in., even with ordinary gaslight.”] Rep, and Proc. Manch. Sci. Stud, Assoc. for 1882, p. 17. June, H.—Neuer Zeichenapparat (Embryograph) fiir schwache Vergrésserungen. (New Drawing Apparatus—Embryograph—for low amplifications.) _ [ Post.] Zeitschr, f. Instrumentenk., III. (1883) pp. 165-7 (2 figs.). M‘Inrosu, D.—United States Patent for a Microscope, No. 273752, 18th June, 1882 (title only). Zeitschr. f. Instrumentenk., III. (1883) Mai, Wrapper. Manufacturers, Hints to. [Recommendation to “ make stands that are adapted to the wants of students rather than to attempt to reform or educate the Harvard Medical College professors ””—where Hartnack Microscopes are almost universally em- ployed—‘ up to an appreciation of the excellency of American stands and costly objectives.”’} Amer, Mon, Micr. Journ., TV. (1883) pp. 97-8. Monoyrer.—Formules générales des systemes dioptriques centrés. (General tormulz for centred dioptric systems.) [Intended to show that for the formule of analytical geometry employed by Gauss those of elementary algebra may be substituted without at all diminishing the exactness of the results. ] Comptes Rendus, XCVII, (1883) pp. 88-91, ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 595 Moort, A. Y.—Amphipleura pellucida by central light. [Considers the real explanation of the resolution when the mirror is central to be that the edge of the front cell of the objective radiates the light, and all light reaching the bottom of the slide at a greater incidence than the critical angle is reflected upwards, and enters the lens after having passed through the diatom.] The Microscope, 11. (1883) pp. 49-51 (1 fig.). Nexson, H. M.—On a quick-acting Adapter for Microscopical Objectives. [ Ante, p. 858. ] Journ. Quek. Micr, Club, 1. (1883) pp. 152-3. 5 % New Nose-piece Adapter. [Supra, p. 572.] Engl. Mech., XX XVII. (1883) pp. 333, 365, 385. OuLaRD, J. A.—Adapters for Microscopes. [Note on Nelson’s and Curties’, supra, p. 572.] Engl. Mech,, XX XVII. (1883) p. 365. Oitawa Microscopical Society. [Note on the formation of the Society and their offer of exchange of micro- scopic material. | Sci.-Gossip, 1883, p. 138. See also Amer. Mon. Wicr. Journ., TV. (1883) p. 99. [PEAsE’s] “‘ Facility ” Nose-piece. [Ante, p. 425.] Amer, Mon. Micr. Journ., TV. (1883) p. 103 (1 fig.). PERAGALLO, H.—Considérations élémentaires sur l’ouverture des objectifs micro- scopiques et les moyens de la mesurer. (Elementary considerations on the aperture of microscopic objectives and the methods of measuring it.) Journ, de Microgr., VII. (1883) pp. 326-36 (7 figs.), from Bull. Soc. d’ Hist. Nat. Toulouse. Pravo, P.— United States Patent for a Photo-micrographic Camera, No. 274515, 18th October, 1882, [Title only.] Zeitschr. f. Instrumentenk., II. (1883) Mai, Wrapper. “ Prismatique.”—Object-glass working, VI., VII. Engl. Mech., XX XVII. (1883) pp. 283 (1 fig.), 473-4. Prisms v. Mirrors. [“ It has long been an opinion among microscopists that the best and strongest light for the illumination of microscopic objects is obtained by substituting a prism for the ordinary mirror. The advantages offered by the prism are more theoretical than practical, while the quantity of light reflected by a silvered mirror is far greater than can be obtained from a prism of equal size. The only advantage of the prism is the reflection from the single plane surface, while the mirror gives a reflection from both the outer and inner surfaces of the glass. But practically this is of absolutely no consequence. A well-silvered mirror reflects 95 per cent. of the light incident upon it. We will soon give a process for silvering glass which yields perfect results and is readily applied by any person.”] Amer, Mon. Micr. Journ., 1V. (1888) p. 119. [QurENn & Co.’s] “ Acme” No. 3 Improved [Microscope]. Amer, Mon, Micr. Journ., 1V. (1883) pp. 110-1 (1 fig.). RespicHi.—sSee Govi. RinpFieiscu.—[Impromptu Condenser. Supra, p. 574.] Berliner Klinische Wochenschrift, 1883, p. 183. Ryprr, J. AA—The Holman Lantern Microscope. [Supra, p. 552.) Journ. Franklin Institute, CX VI. (1883) pp. 67-9 (1 fig.). Scurenck.—Exhibition (New York Microscopical Society) of a new form of Microscope-table. [“ The particular feature of the table was a revolving centre upon which the Microscope is intended to be placed.” ] Amer, Mon. Micr, Journ., TV. (1883) p. 100. Smiru, G.—Apparatus for Photomicrography. [Post.] Amer, Mon. Micr. Journ., TV. (1883) p. 118. from British Journal of Photography. SroweEu., C. H.—Projecting Lanterns. [Post.] The Microscope, III. (1883) pp. 51-3. 2Q2 Q 596 SUMMARY OF CURRENT RESEARCHES RELATING TO StTowE.i, C. H.—Microscopy in the University of Michigan. 7 [Description of the nature and extent of the microscopical work in the University. ] The Microscope, III. (1883) pp. 63-8. x , and L, R.—[Suggestions for early publication of the proceedings of the American Society of Microscopists.] _ Zhe Microscope, IIL. (1883) p. 69. Tuomas, C.—A new form of “ Life-slide ” (“* Thomas’s Vivarium’’). [See Vol. II. (1882) p. 688.] Trans. Essex Field Club, III., pp. xlix.—l. (2 figs.). Van Hevrcx, H.—La Lumitre électrique appliquée aux recherches de la Micro- graphie. (The electric light applied to microscopical researches.) [I. Production of Electricity (Méritens’ and Reynier’s Dynamos; Tommasi and Reynier’s Batteries.) II. Storage (Kabath’s and Tommasi’s Accu- mulators.) III. Lamps (Reynier, Swan, and Stearn.) IV. Illumination of the Microscope (Stearn’s method, ante, p. 29.) V. Photo-micrography. Additional Note (Reynier’s new Accumulators). | Journ. de Microgr., VII. (1883) pp. 244-60 (13 figs.). Warson’s New Microscope-stand. [Supra, p. 555.) Mier. News, III. (1883) p. 205. Waricut, L.—Optical Combinations of Crystalline Films. [Describes easily-made combinations of mica-films put together with canada balsam dissolved in benzol. Contains alsoa reference to an appa- ratus made by Swift and Son by which all the preparations and crystals requiring highly convergent light can be shown on the stage of any Microscope provided with a draw-tube.] Proc. Phys. Soc, Lond., V. (1883) pp. 186-95 (1 pl.). Zeriss, C.—On the method of using Abbe’s test-plate. [The directions issued by Dr. Zeiss with the test-plates and printed ante, p. 281. : Journ, Quek. Micr. Club, I. (1883) pp. 154-6. » 95 Dissecting Microscope. [Exhibition and discussion; also on Stephenson’s Binocular. ] Journ, Quek. Micr. Club, 1. (1883) pp. 200-1. Zencer, K. W.—Berechnung des Endomersions-Objectives fiir Fernrohr- und Mikroskopobjective. (Computation of the Endomersion Objective for Telescope and Microscope Objectives.) [Post.] SB. K. Béhm. Gesell. Wiss. Prag, 1881 (1882) pp. 467-79. “5 o Dioptrische Studien. (Dioptric Studies.) [On “ Endomersion objectives.” Post. SB. K. Bohm. Gesell. Wiss. Prag, pp. 479-92. B&. Collecting, Mounting and Examining Objects, &c. Water Collecting-Apparatus.*—Mr. C. F. George has used the following in searching for Hydrachnide, and has found no other piece of apparatus so efficient :— A piece of thick brass wire (fig. 117), is bent at about 6 in. from one end into a ring 4 or 5 in. in diameter. After connecting with some finer wire the two extremities of the ring, bend the stout wire at right angles to the ring, and continue it for about 4 in. Then make another ring about 15 in. in diameter, and there terminate the wire, leaving the small ring, however, not quite complete. The two rings will thus be parallel to each other. On the upper ring stitch a piece of tape, and to this sew a piece of muslin, made to the shape of a conical bag, and having its wider end affixed to the tape. Into the lower opening of this bag a small, wide-mouthed glass bottle, of about two ounces capacity, should be fastened by a piece of thread or fine string, and the lower ring is then sprung round the neck of the bottle. 'The other end of the brass wire, which was left * Journ. Post. Mier. Soc., i. (1882) pp. 158-9 (1 fig.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 597 projecting for about 6 in., is now to be firmly lashed to a light cane or stick, and the apparatus is complete. In order to use the apparatus, move it gently backwards and forwards on the surface of the water, under the surface, or just above the bottom of the pond, and among the weeds; the muslin will allow the water to pass through it, whilst any living organisms will be retained by the bottle. This can from time to time be examined with Fig. 117. a pocket lens, and when it is found to contain anything, the lower ring of wire can be slipped off, and the neck of the bottle pushed up through the upper ring, inverting the net. The contents may thus be poured off into another bottle, and after rearranging the apparatus, fishing may go on again. The object of the piece of wire connecting the two ends of the net is to keep all stiff, so that the bottle can be turned in any direction, and yet both the upper and lower mouths of the net will remain open. Preparations of Coal.*—P. F. Reinsch’s preparations of coal from the carboniferous strata, the Dyas and Trias (the material being very difficult to reduce to thin and sufficiently transparent sections), are made by using the finest emery employed in polishing mirrors. Powdered chalk obtained by levigation, and carbonate of lime preci- pitated from lime-water by soda, are alsoused. A small piece of cork serves as arubber. During the process the preparation is moistened with glycerine, Catheart’s Ether Microtome.t—C. W. Cathcart’s object in venturing to add another to the many forms of freezing microtome was :—(1) to obtain a simple ether spray-producer which would not allow any ether to escape unevaporated; (2) to have an efficient microtome for use with the ether spray, which would be so simple in its mechanism as to admit of manufacture and production at a comparatively low cost. The microtome can be sold at 17s. 6d., including the spray-producer, and it freezes 1-4th in. of tissue in 14 or 2 minutes, using in the process about 2 drachms of ether, which cost something less than a farthing. The instrument is thus described by the author :—“ The spray- producer works on the same’ principle as the scent sprays which have * Bull. Soc. Belg. Micr., ix. (1883) pp. 87-8. + Journ. Anat. and Physiol., xvii. (1883) pp. 401-3 (2 figs.). 598 SUMMARY OF CURRENT RESEARCHES RELATING TO been in use for a long time, where a jet of air playing across the top of a tube draws up the fluid from its interior by tending to make a vacuum in it. The bellows used are the ordinary hand ones sold for carbolic and other spray-producers, these being as cheap and efficient as any that can be got. In working at the spray points, I began by selecting the size of air-hole that these bellows could easily feed with a continuous blast of air, and then, experimenting with various sizes of vaccine tubes, I found at last, that with the smallest size I could produce a spray which, at about 1-2 in. distance from any object, contained just as much ether as the given blast of air could evaporate. There was then of course no running of the ether to waste, while at the same time an intense cold was very rapidly produced. The method of adapting the spray points to one another is a modification of the ordinary one, and is adopted from a German model, It is as Fie. 118. ij C. COPPOCK, 100,NewBond St. We London, W. follows :—Two fine brass tubes are taken—one is brought to the requisitely fine point for the ether, and the other, being closed at the end, has the air-hole bored at the side a little below the closure. The point of the ether tube is then placed over the middle of the air-hole, and the tubes, laid one over the other, are soldered together in this position ; the free ends of the tubes are then connected with the air bellows and the ether bottle respectively by means of indiarubber tubing, and this part of the apparatus is complete. The microtome (fig. 118) consists of the framework, and the mechanism for raising the section. The framework is of 1-2 in. mahogany, and is in the form of a base with two upright parallel pieces screwed on to it. The base A, which is about 2} by 4 in, is bored to allow the tubes for raising the section to pass up between the parallel pieces, and has a projecting part at one side to allow of ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 599 its being clamped to the table M’. The two parallel parts BB, which are of the same 1-2 in. mahogany, stand about 1} in. apart ; they are 4 in. long, and, rising to 1 in. high, each carries on the upper surface a piece of quarter-in. plate glass CC, of the same length and breadth as itself. This is to support and steady the knife as it is pushed across the tissue to be cut, while the fact of the tissue coming up between the plates allows that part of the knife which is to cut the specimen to be kept free of contact until it touches the tissue. The method of raising the section plate H is as follows:—About 2 in. of accurately fitting double brass tubing are taken, and into the outer one D the nut F ofa fine screw is firmly soldered at what is to be its lower end. The inner tube E has the section plate fixed to its upper end by two screws, with, however, two small pieces of vuleanite intervening between the plate and the tube, so as to dis- connect them as much as possible, and into the lower end of the inner tube a transverse bar is fitted, against which the screw coming through the outer tube presses when it is desired to raise the section plate to which the inner tube is attached. By means of a small screw-nail fixing the outer screw to the bar in question, the inner tube can be withdrawn, as well as pushed up whenever that movement is required. A milled head G has been substituted for the ordinary capstan arms, for turning the main screw round. The spray points are introduced at the requisite distance below the section plate by cutting a narrow slot through both tubes, and fixing to the inner one a piece of bent brass, into which the spray points can be pushed and held firmly, while a small shoulder on the latter prevents them from passing beyond the centre of the under surface of the plate. Finally, the ether bottle J (with the tubes K and L) is fastened to the side of one of the upright pieces of the framework by a simple hook and eye, the hook being fixed to a collar round the neck of the ether bottle, and the eye to the side of the framework in question. It will be seen, I think, from this description, that with the exception of the fine screw for raising the tissue, the details of the mechanism are very simple, hence the low price at which it can be sold; and in practice it has been found to work admirably.” The instrument is to be obtained from Mr. C. Coppock. Glycerine Mounting.*—For vegetable sections glycerine is one of the best preservatives, but the difficulty of confining it within the cell has been deemed insuperable. A method invented by Professor Hillhouse enables this end, it is said, to be perfectly attained. The mode of operation is as follows :— No cell is used, the object being merely placed in a drop of glyce- rine of sufficient size to reach the edge of the cover-glass when it is dropped in. Canada balsam, dissolved in turpentine, is then applied round the edge so as to close the cell, by means of a small glass rod drawn out to a point, but terminating in a little knob. If a litile of the glycerine should exude beyond the cover-glass, it need not be * Midl. Natural., vi. (1883) p. 166. 600 SUMMARY OF CURRENT RESEARCHES RELATING TO removed ; it can be covered with the Canada balsam as easily as if it were under the cover-glass, and without interfering with the security of the cell. The Canada balsam is, of course, best if of such a con- sistence as not easily to become hard and brittle. Professor Hill- house mentions as one of the advantages of this method, that if the section should slip from beneath the cover-glass on the application of pressure, as the thinnest and therefore best sections are apt to do, they would still be visible through the transparent balsam, if its upper surface were made parallel to the slide. It was jocularly suggested at the meeting at which the process was explained that the next step in advance would be to dispense with the covér-glass alto- gether, and encase the object in a layer of glycerine, protected by a horizontal film of balsam. Mounting Sections in Series.*—Referring to Dr. J. Frenzel’s method of mounting,t Mr. R. Threlfall says that it was pointed out to him by Mr. W. H. Caldwell that the use of hot absolute alcohol in the method has many practical disadvantages. He therefore made some experiments in order to find a better solvent, and after a little consideration came to the conclusion that paraffin of low boiling point would probably dissolve the paraffin in which the sections are imbedded more quickly than the guttapercha film to which they are attached. This proved to be the case to a certain extent; the gutta- percha was, however, appreciably soluble. He therefore tried a solution of raw caoutchouc in benzine, instead of guttapercha, with perfectly satisfactory results. A thin solution of caoutchouc in benzine or chloroform is prepared and poured over the slide so as to form a film in the same way that collodion is poured on a photographic plate. When the film is dry the sections are arranged on it, and the temperature of the slide raised to the melting point of the paraffin; the sections then fall on to the indiarubber film which has become sufficiently sticky to adhere to them perfectly. When the slide is cold it is treated with naphtha or any light paraffin oil, the solvent action being the more rapid the lower the boiling point of the oil used. Absolute alcohol is readily miscible with the naphtha or light paraffin, so that the solvent is readily removed. The slide can now be placed in successive alcohols, stained and returned to absolute alcohol. It is now to be cleared with kreasote or oil of cloves and mounted in the ordinary way. Apart from the great advantage of being able to stain on the slide, this indiarubber method seems to possess some points of superiority over the shellac method of Giesbrecht. This depends on the fact that sections can be mounted in balsam direct from the naphtha. The following are some of the advantages over Giesbrecht’s method :— 1. The indiarubber is more uniform and therefore safer for small objects. 2. The indiarubber is dry and thus allows a more minute arrange- ment of the sections on the slide. * Zool. Anzeig., vi. (1883) pp. 300-7. + See this Journal, ante, p. 307. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 601 3. The naphtha solves the solid paraffin quicker than turpentine does. 4, No traces of indiarubber are visible after mounting, since india- rubber becomes perfectly transparent in balsam. These methods have been put to a rigorous test by Mr. Caldwell and are now in use in the Morphological Laboratory of Cambridge University. Sealing up Preparations.*—Dr. C. Norner, of the Veterinary Institute of Vienna, describes a method adopted there by Prof. Csokor for the above purpose. : Take the ordinary commercial resinous turpentine, break it into small pieces, and dissolve them in a water-bath, then pour the liquid into another vessel and let it cool. A hard, dark-brown, brittle mass is thus formed upon which the pressure of the finger makes no impression. A little of the resinated oil of turpentine may be added to the liquid, but the whole must be heated for several hours in the water-bath in order to obtain the requisite degree of hardness on cooling. The turpentine thus prepared is placed on the cover-glass by means of a heated knitting-needle (fixed on a piece of wood), the other end being bent at right angles for about 15-18 mm. to corre- spond with the width of the cover-glass. The bent end being pressed into the turpentine and withdrawn, the turpentine adhering to it is spread out on the margin of the cover-glass, and this repeated until it is completely surrounded with turpentine, which is finally drawn a little over the edge. Care, however, must be taken not to overheat the needle so that the glass cracks. If the cover-glass should not be sufficiently firm, or if any glycerine still remains on the edge, a com- bination of gold size and turpentine may be used. The gold size has the advantage of agreeing well with the glycerine, so that it is not necessary to remove the latter completely. When the gold size is dry a second layer of turpentine may be put on. The author generally uses this combination to inclose worms, when the cover-glass cannot be completely closed on all sides in consequence of the thickness of the object. The ring of turpentine may be laid over the gold size without detriment. The method of sealing glycerine preparations by turpentine has, the author says, the great advantage of extraordinary durability. The object so prepared can also be cleaned at any time with a piece of wash-leather without the fear of injuring it by too much pressure. An additional layer of varnish, which is absolutely necessary for gold-size and other preparations, is dispensed with by this method of treating glycerine preparations with turpentine. It has the dis- advantage of being more tedious than in the case of gold size, but practice soon brings dexterity. Opaque Dry Mounts.;—Mr. J. E. Fawcett prepares opaque dry mounts by building up on the turntable a cell with hot wax partly on * Arch. f. Mikr. Anat., xxi. (1882) pp. 351-4, + Micr. News., iii. (1883) pp. 153-4. 602 SUMMARY OF CURRENT RESEARCHES RELATING TO the disk of black paper forming the background, and partly on the glass slide. There is thus no untidiness of the paper not fitting the bottom of the ordinary vulcanite cell, or if it is placed on the under side of it, being scratched off. Then again, if the background is put at the back of the glass slip, it is invariably bright, instead of dull. When the slide is dry and ready for sealing up, all that is necessary is to place the cover on it and put it once more on the turntable, when one turn, with the application of the wax-brush, is sufficient to make it a permanent mount. It can then be finished with the usual varnishes. The wax must be kept very hot, and the brush should be left in it when not in use. Mr. Fawcett also commends cells built up with wax for transparent dry mounts, and the use of wax to help to fill up the sides of balsam cell mounts, between the closing cement and the finishing varnish, though for the latter purpose shellac in spirit would be much more convenient. Wax is also a remedy, he considers, for the running in of the cement used for sealing, and for dampness in the case of “dry ” preparations, but as to this see the discussion on the subject in vols. iii. (1880) and i. (1881) of this Journal. Examining Live Aphides.*—Mr. H. J. Slack says that when we want live aphides to examine under the Microscope in a vigorous condition, we must handle them with extreme gentleness, or their soft and delicate bodies will be injured and the creature killed. Their slightness of structure is, however, accompanied with great endurance of conditions that would be quickly fatal to many stouter organisms. Most insects would be rapidly killed by immersion in paraffin oil; but young and vigorous aphides will often live for some time, and occasionally for hours in this fluid, such as is burnt in lamps. If two or three of the insects are very carefully placed in a little cork cell, f filled with paraffin oil, and covered with thin glass, they are in a handy condition for examination. The result of numerous experiments made with the best American petroleum oil, commonly called crystal oil in the lamp-shops, is that the survivals are very uncertain, but sufficiently frequent for the process to be well worth trying. They keep pretty quiet in the fluid, and it enables higher powers to be used with con- venience. A 1-2 inch objective, magnifying about 100 linear, with a full-sized instrument, is very handy. The illumination should be varied; but one of the best ways is to use both an achromatic con- denser and a lieberkuhn, or little silver reflector, at the end of the objective. The largest hole and central stop of the condenser will give a fine dark-ground illumination. When used in combination with the lieberkuhn, it lights up the inside of the object, while the less transparent parts receive reflected rays from the silver surface. The student will find a great many cases in which this mode of treating a refractive and reflective object produces the best results. The eyes of the Aphis seen in this way are like half mulberries, and the little eye * Knowledge, ili. (1883) p. 246. + A phial cork 5-8ths inch in diameter cut across so as to make a disk 1-16th inch thick with an oblong hole in the centre and gummed on a slide. The gum is not dissolved by paraffin oil. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 603 projecting from the corner of the larger group is well displayed. Where the view of the compound eyes is a full-face one, the darker pigment is seen so strongly that its true position is concealed. A profile view shows the little lenses to be clear, like glass, and the pigment to be behind them. Microscopical Examinations of Articles of Commerce.*—A. Tomaschek points out the value of microscopical examination in the determination of the purity of many articles of commerce, and gives the following illustrations :— Tea-leaves are readily recognized by their peculiar idioblasts. Barley-meal is very well characterized by the beautiful tabular cells with thick wavy margins belonging to the palez which are always found in the meal in consequence of the close adherence of the palez to the fruit. The following method is recommended for their detection :—A drop of concentrated hydrochloric acid is thrown on to the meal and rolled in it. A piece of the dough thus obtained is placed on the slide, and another drop of hydrochloric acid run on to it before covering with the cover-glass, and the cover-glass then pushed lightly backwards and forwards. The tabular cells are not only not attacked by the acid, but are coloured by it a bright sulphur- yellow colour. They may be detected even after the baking of the barley-meal. The microscopical appearance of wheat-meal is distinguished by the peculiar properties of the paste, which can be best demonstrated in the following way :—A thin layer of meal is placed on the slide, carefully covered with a cover-glass, and then moistened by a drop of water placed on its margin. The cover-glass is then lightly pressed, and pushed backwards and forwards, the gelatinous substance being thus separated from the starch-grains, and appearing in the form of dense clouds. If glycerin is used it solidifies into bluntly angular granules, averaging 0:08-0:01 mm. in length. In order to obtain the iodine reaction characteristic of a nitrogenous substance, a com- paratively large quantity of the reagent must be used, as the golden- yellow reaction of the proteinaceous substance does not appear until the starch-grains have absorbed what iodine they require. This gela- tinous substance is especially well recognized by its reaction with cochineal. If cochineal-powder is scattered over the wheat-meal, and moistened merely by breathing on it, the proteinaceous masses at once take a beautiful carmine-red colour, the starch-grains remaining quite colourless. Microscopical Separation of Wheat- and Rye-Meal.{—L. Witt- mack records the following observations on the microscopical distinc- tions between wheat-meal and rye-meal. The amount of starch gives no certain character, and the size of the starch-grains is not in itself sufficient ; the maximum size of the starch-grains of rye is 42-52 p ; * Verhandl. Naturf. Ver. Briinn, xix. (1881) p. 15. See Bot. Centralbl., xi. (1882) p. 318. + SB. Bot. Ver. Prov. Brandenburg, xxiv. (1882). See Bot. Centralbl., xiii. (1883) p. 91. 604 SUMMARY OF CURRENT RESEARCHES RELATING TO of wheat 28-35 ». Better characters are obtained from the grains themselves. The denseness of the pitting in the transverse cells of wheat gives them a chaplet-like appearance. difficult to meet with in the finer kinds of meal. The shell or pericarp is often Wheat. Rye. Ke K Skin, average thickness Sr Pg. aici \ a0 43-50 31-40 Epidermal cells of the skin or pericarp—length 116-160 136-400 _ 5 55 breadth 20-28 26-62 a re porous pitting very close less close Sub-epidermal transverse-cells—length .. .. 114-192 72-90 se i breadth.. .. 14-17 11-14 As ‘s thickness of walls 5°8-8°7 3°3-5°0 hae very dense less dense, ” ” pine 5 ama amen inconspicuous Starch-cells—average larger diameter 56-72 40-64 5 shorter diameter 32-40 24-40 Iso-diametrical starch-cells—diameter 40-48 32-36 Good characters are also obtained from the hairs. Before grind- ing, both ends are removed from the grain ; the embryo-end on account of the oil which it contains ; the opposite apex on account of its hairs ; but a few hairs are still to be found in the meal, which give the following characteristics :— Wheat. Rye. be KB Length ofhairs... .. .. «. 120-742 50-420 Diameter of the largest .... 15-21 9-17 ma at the bulbous base.. 28 23 Hs of the smallest.. .. 9-10 8 - at the bulbous base.. 14 11-14 Thickness of wall of the hair .. 7 3-4 Breadth of cell-cavity 1-4-2 (rarely 5) a Wheat has therefore thick-walled hairs with narrow cell-cavity ; rye thin-walled hairs with wide cell-cavity. V. Berthold * confirms in the main Wittmack’s statement. He finds the gum-cells of wheat to be decidedly larger than those of rye; the former measuring 3, the latter 1:5-2 ». The thickness of the wall of the hairs of wheat he states at 5-8, of rye 3-6 »; the diameter of the cavity of the former 1-5-4, of the latter 4-12 p, Hunting for Lost Glaciers with a Microscope.{—Considerable work has been done in this direction in Germany and elsewhere by various observers, work with which geologists are more or less * Zeitschr. f. Landwirthsch. Gew., &c., 1883, pp. 1-3. See Bot. Centralbl., xiv. (1883) p. 247. Z . } + Nova Acta Acad. Leop.-Carol., xlv. p. 35. See Science, i. (1883) p. 177. a ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 605 familiar, and Dr. H. Geinitz gives the results of an extended study of the plagioclase rocks and phonolites of the Mecklenburg drift. The method consists in examining thin sections of the rocks found in the drift, and comparing them with the descriptions given by the Scandinavian lithologists of rocks known in situ in that penin- sula. In this way various basalts, diabases, gabbros, diorites, and phonolites are referred to certain localities in Sweden, whence they are supposed to have been derived. Interesting results can be obtained by such methods; but they are often uncertain, since it cannot be predicated that rocks of the same character do not exist, or have not existed, in the intermediate drift or water-covered areas. Microscopical Analysis of the Structure of Iron and Steel.*— The first step, writes Mr. J. C. Bayles, to be taken in practical micro- scopy is the training of the eye to observe what may be seen without the aid of alens. This is accomplished by the patient examination of characteristic fractures, and noting similarities and differences. After the naked eye has become familiarized with all it can see, the student should continue his investigations assisted by a hand lens with a power of from two to three diameters, and absolutely achromatic. Specimens to be studied with a view to determining their internal structures should be surfaced in a planer, and smoothed by draw- filing in the direction of the fibre. The surface thus obtained is treated with slightly diluted nitric acid, which gives a rapid and wide development of the structure, which may be studied with advantage while it lasts, and will prepare the student for finer work. For fine development more care and time are needed. After planing, the surface of the metal is ground with fine emery or under a metallic mirror-grinder. It is then treated with acid. A thorough develop- ment with weak acid requires from twenty-four hours to six days, according to the composition of the metal. Small specimens are pre- pared by planing down from the back to a thickness of 1-32nd to 1-16in. The planed face is then ground and surfaced on a fine whetstone, developed with weak acid, and mounted between glasses with Canada balsam. In selecting a Microscope, cave should be taken that the lenses give a good definition, that there is no “shake” or lateral motion in the adjustments for focus, and then the table should admit of inclination at any angle found most convenient for observation. Concerning the results to be expected from the microscopical analysis of metals, Mr. Bayles expresses the belief that it opens a vast field of knowledge not yet reached by either chemical analysis or physical test. ‘There are many conditions, the result of changes produced by mechanical treatment, to which chemical analysis gives no clue and which are detected, but not explained, by the test of the physical laboratory. The Microscope will, no doubt, explain many of the mysterious changes which occur in metals of given chemical composition under different conditions, and will give the metallurgist an opportunity of studying the anatomy and physiology of iron and steel, which, in a most important sense, will supplement * Science, i. (1888) p..101. 606 SUMMARY OF CURRENT RESEARCHES RELATING TO analysis and mechanical test, which have thus far, to some extent, run in parallel lines. When, between the report of analysis and the fracture of the broken test-piece, we can place a polished longitudinal or cross-section of the material, its internal structure developed by acid and admitting of careful microscopical study, we are furnished with the missing link in the chain of evidence required for a correct conclusion as to the nature of the material under investigation. Microchemical Reaction Methods.*—A. Tschirch describes the great advantages of the Microscope in technical chemistry, especially in the examination of foods, and expresses regret that many chemists consider their laboratories complete without such an instrument: he enumerates many examples of its usefulness, such as starches, textile materials, &c.; even in the domain of pure chemistry, its application is necessary in the hematin reaction for the detection of blood- stains, the composition of urinary deposits, the search for strychnine, atropine, &e. These advantages led to its more extensive employment in pure chemistry, and the name of microchemistry was given to it by Doébereiner. The author thinks that microchemistry must always be distinguished by a series of colour reactions, that in the same manner as the changes of colour, &c., in experiments on the large scale are examined in the test-tube, so must they be similarly observed on the slide of the Microscope. The actual process is simple; the objects to be examined must be either in thin sections, fine powder, or as fibres; a drop of the reagent is placed on a slide and allowed to flow slowly towards the object, the operator observing through the instru- ment: many physical as well as chemical changes may be thus detected ; expansion or contraction, refractive changes, commencement of coloration, evolution of gas bubbles, solution, &c. The iodine starch reaction of Stromeyer was the first to be employed with the Microscope ; from it is learned the topography and division of starch in plants, the way it is stored up, and the process of its conversion ; this reaction has also taught the difference between pure cellulose and woody fibre, and the nature of intercellular substance. The reactions with zine chloride and iodine, and with sulphuric acid and iodine, are also striking instances of the value of microchemistry, affording an easy method of distinguishing vegetable from animal fibres, the first colouring pure cellulose violet, and the second dissolving it with an intensely blue colour, the lignin incrusting the fibres having been previously moved by maceration in nitric acid, alkalis, or Schultze’s maceration fluid. Thus sulphuric acid and iodine stain cork dark yellow, thereby affording a trustworthy test for all membranes or sections containing suberin. ‘The solubility of pure cellulose in *“ cuoxam,” discovered by Schweitzer, is also credited to micro- chemistry: the reagent may be prepared by digesting copper turnings in concentrated ammonia, or by decomposing a concentrated solution of copper sulphate with ammonia until the precipitated hydroxide is redissolved. * Arch. Pharm., xx. (1882) pp. 801-12. See Journ. Chem. Soc.—Abstr., xliii, (1882) pp. 376-8, ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 607 The maceration process of Schultze is a valuable aid to operations in microchemistry ; the substance is treated with nitric acid and potassium chlorate either in the cold, or in cases of obstinate samples, is boiled for a short time, when the cells are isolated by the solution of the intermediate lamelle. Amongst the instances given of its utility in food analysis is the separation of those peculiar cells of radiating branchial form which exist in the tea-leaf, and are not found in other leaves used for its adulteration (they are, however, found in some of the Camellia family). This treatment has also the advantage of dissolving the coloured incrustations of cinnamon, roasted coffee, &c., and leaving the sub- stances ready for further examination. Potash plays an important part in microchemistry, as it renders many objects transparent which are not made so by other reagents; it was by successive treatment with potash solution, acetic acid, and iodine that Bohm was able to perceive in chlorophyll the small particles of starch which had hitherto escaped observation. The most striking success in the science is that of Sachs with Trommer’s sugar-test, which, with slight modifications, enables the microscopist to identify, and even estimate quantitatively; cane- and grape-sugar, dextrin, gums, and albuminous substances in single cells. The author alludes to the tinctorial methods which are employed in the examination of microbes, but which do not come under the strict domain of chemistry; he urges more extensive use of the Microscope, together with the micropolariscope and spectroscope, and the study of botany and physics among chemists. Dr. T. Schuchardt, of Gorlitz (Silesia), has issued a special list of chemical reagents supplied by him for the use of botanical- physiological Institutes, arranged after Poulsen’s ‘ Botanische Micro- chemie.’ Microscopical Examination of Dyed Silks.*—In an article by M. Marius Moyret, it is pointed out that if the silk fibre is seen lengthwise, it appears uniformly dyed ; but in transverse sections it is found that the dye forms a concentric ring, the depth of which ordinarily diminishes gradually from the circumference towards the centre. The observations made by M. Lembert establish, also, that if we dye silk with a simple colour, such as cochineal, the colour penetrates in time more and more towards the centre of the silk, becoming at the same time deeper and deeper; so that, if we take successive ‘specimens from a lot of yarn during dyeing, they will exhibit under the Microscope rings of colour which become broader and broader, until they reach the centre. If a silk dyed a light shade of one colour is plunged into a bath of a second colour, and dyed to saturation, the section will show under the Microscope an outer ring, the colour of which is a result of the two dyes employed, and an inner part having the pure tone of the second dye. Or if we plunge a silk dyed to saturation with one * Chem. Review, xi. (1882) p. 203, fiom ‘ Teinturier Pratique.’ 608 SUMMARY OF CURRENT RESEARCHES RELATING TO colour into a second colour, but without saturating it, with the Micro- scope we sce an outer ring, which is the result of the two colours, and a central part of the primitive shades. Apparent Motions of Objects.*— Prof. F. C. Van Dyck considers that the familiar fact that objects viewed through the Microscope seem to move when the position of the mirror is slightly changed, has not been discussed in its optical bearings. “The phenomenon is easily observed by using nearly parallel rays to illuminate the object, and placing the mirror approximately central under the stage. If daylight is used, set the Microscope at a considerable distance from the window, and use the plane mirror. If lamplight is used, set the lamp at the focus of the concave mirror, or use a lens to make the rays parallel and reflect them from the plane mirror. If the object be so thin as to be sensibly in one plane, it will maintain its location in the field whatever change be made in the position of the mirror, so long as it is accurately focussed. But if the tube of the Microscope be raised or lowered, so as to throw the object slightly out of focus, a shifting of the mirror on its bearings will cause an apparent motion of the object to one side or the other. If an object of considerable thickness be used and the focus obtained for a central plane, rocking the mirror will cause the lower parts of the object to move to one side, while the upper parts move to the other side. I have an insect’s foot with claws, which, treated in this way, seems to work the claws like scissors. Minute details of an object may be made to disappear under spots on the cover-glass, and various similar effects can be produced. . Let us suppose that the illumination is received from the left of the observer, and that a micrometer is inserted in the eye-piece to facilitate observation. 'Take three points A, B, and C, in the optical axis, A beyond the focus of the objective, B at the focus, and Ca little above the focal plane. Suppose a pencil sent from the mirror along the axis, passing A, B, and C, and the centre of the objective. The images of A, B, and ©, will fall with their centres on the axis. If the edge of the mirror toward the observer’s right be tilted up, the point A, beyond the focus, will appear to be displaced toward the right of the field of view, the point B will remain stationary, and C which is above the plane focussed upon, will move toward the left. Now it can be shown that if the spherical aberration of an objective could be corrected for a series of points and their images, all the images must remain stationary. The necessity for correction consists essentially in the fact that the margins of lenses with spherical surfaces are too strong relatively to their centres. Hence, with an uncorrected lens, the image of the point B, made by the central portion of the lens, would fall on the axis; but an image of the same point, produced by rays entering the left-hand margin, would fall to the left of the axis, as well as nearer to the lens. ‘The essence of correction is to relatively weaken the * Amer. Mon. Mier. Journ., iii, (1882) pp. 72-3. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 609 action of the margin, so that the image shall fall on the axis and at the same distance from the lens as the image formed by its central portion. Suppose this correction to be made for the point B. Let the mirror be tilted as described, so that a pencil of rays passes through A to the left margin of the objective. This pencil makes a smaller angle with the front surface than a pencil coming from B and entering at the same place. Hence, the pencil from A will