**r <*>K«flr >** r* - >' '^. ^ 4 vy 'V ^ M v. W *-#% r~ v- • Vt% W Journal of tbe Ropal microscopical Society CONTAINING ITS TRANSACTIONS AND PROCEEDINGS AND A SUMMARY OF CURRENT RESEARCHES RELATING TO ZOOZL.OG-Y" .A-HSTID BOTANY (principally Invertebrata and Cryptogamia) MICROSCOPY, &cg- EDITED ,BY R. G. HEBB, M.A. M.D. F.R.C.P. Physician to Westminster Hospital WITH THE ASSISTANCE OF THE PUBLICATION COMMITTEE AND J. ARTHUE THOMSON, M.A. F.R.S.E. Regius Professor of Natural History in the University of Aberdeen A. N. DISNEY, M.A. B.Sc. CECIL PRICE-JONES, M.B. Lond. FELLOWS OF THE SOCIETY AND A. B. RENDLE, M.A. D.Sc. F.L.S. HAROLD MOORE, B.Sc. Assistant in Botany, British Museum Woolwich Arsenal Minimis partibus, per totum Naturae campum, certitudo omnis innititur quas qui fugit pariter Naturam fugit. — Linnceus. FOR THE TEAR 1905 TO BE OBTAINED AT THE SOCIETY'S ROOMS, 20 HANOVER SQUARE, LONDON, W. of Messrs. WILLIAMS & NORGATE, 14 Henrietta Street, London, W.C. and of Messrs. DULAU & CO., 37 Soho Square, London, W. X* $ THE JUpl < JJftiq as capital ^at^tg. Established in 1839. Incorporated by Royal Charter in 1866. The Society was established for the promotion of Microscopical and Biological Science by the communication, discussion, and publication of observa- tions and discoveries relating to (1) improvements in the construction and mode of application of the Microscope, or (2) Biological or other subjects of Microscopical Eesearch. It consists of Ordinary, Honorary, and Ex-officio Fellows of either sex. Ordinary Fellows are elected on a Certificate of Kecommendation signed by three Ordinary Fellows, setting forth the names, residence, and description of the Candidate, of whom the first proposer must have personal knowledge. The certificate is read at two General Meetings, and the Candidate balloted "for at the second Meeting. The Admission Fee is 21. 2s. ; and the Annual Subscription 21. 2s., pay- able on election, and subsequently in advance on 1st January annually. The Annual Subscriptions may be compounded for at any time for 31/. 10s. Fellows elected at a meeting subsequent to that in February are only called upon for a proportionate part of the first year's subscription. The annual Subscrip- tion of Fellows permanently residing abroad is 1/. lis. 6^. or a reduction of one-fourth. Honorary Fellows (limited to 50), consisting of persons eminent in Microscopical or Biological Science, are elected on the recommendation of five Ordinary Fellows and the approval of the Council. Ex-officio Fellows (limited to 100), consisting of the Presidents for the time being of any Societies having objects in whole or in part similar to those of the Society, are elected on the recommendation of ten Ordinary Fellows and the approval of the Council. The Council, in whom the management of the property and affairs of the Society is vested, is elected annually, and is composed of the President, four Vice-Presidents, Treasurer, two Secretaries, and twelve other Ordinary Fellows. The Meetings are held on the third Wednesday in each month, from October to June, at 20 Hanover Square, W. (commencing at 8 p.m.). Visitors are admitted by the introduction of Fellows. The Journal, containing the Transactions and Proceedings of the Society, and a Summary of Current Besearches relating to Zoology and Botany (principally Invertebrata and Cryptogamia), Microscopy, Silvestri, F. — Primitive Thysanuran 306 Sykes, Mark L. — Protective Resemblance in'Insecta 306 CONTENTS. XV HACK Hallek, B. — Structure of Tracheate Syncerebrum 306 Reitzenstein, W. v. — Structure of Ocelli in Periplaneta and Cloeon HOT Poulton, E. B. — Inheritance of Acquired Characters in Insecta 307 Riley, W. A. — Development of Head Skeleton in Blatta 307 Neniukofp, Dimitri — Digestion in Cockroach HOT Sellards, E. H. — Palaeozoic Cockroaches 307 Silyestri, F. — Oenogyna l>aeticum 308 Buonion, E. — Stalked Eggs of llhyosa persuasoria 308 Lea, Arthur M. — Ants' X est Beetles 308 Arrow, G. J. — Sound Production in Lamellicorn Beetles 308 Lass, M. — Structure of Female Flea 308 Enderlein, Gcnther — New Flightless Fly 309 Goeldi, Emilio A. — Mosquitoes of Para 309 Ducke, A. — Social Wasps of Para . . 309 Hormizaki, K. yon — Synopsis of Families of Palsearctic Lepidoptera 132 Kitchin, V. P. — Variation in Mel itasa aurinia 43'2 Phillips, E. F. — Structure and Development of the Compound Eye of the Honey Bee 433 Merlin, A. A. 0. Eliot— Foot of House-Fly 433 Grunberg, K. — New (Estrid Larva from Hippopotamus 433 Silvestri, F. — Metamorphosis of Lebia scapularis 433 Mollison, Th. — Function of the Follicular Epithelium in Melolontha vulgaris . . 434 Goding, F. W„ & W. W. Fkoggatt — Monograph of Australian Cicadidx .. .. 434 Bordas. L. — Salivary Glands in Nepa cinerea 434 „ „ Glands of Hemiptera 434 Vos8, F. — Tltorax of Gryllus domesticus 434 Jaoobi, A. — Species of Pceciloptera 435 Kellogg, V. L., & R. G. P>ell — Notes on Insect Bionomics 586 Handlirsch, Anton — Phytogeny of Insects 586 Balducci, E. — Notes on Larvx of Arpyia vinula 588 Pictet, Arnold — Influence of Nutrition and Humidity on Lepidoptera 588 Chapman, T. A. — Pupal Suspension of Thais 588 Byatt, Horace A. — Numerical Proportion of Mimic to Model 588 Kellogg, Vernon L. — Experiments on Bombyx mori 588 „ „ Regeneration in Larval Legs of Caterpillars 589 Semichon, L. — Urate Cells in Hymenoptera 589 Passerini, N. — Luminosity of Luciola italica 589 Annandale, Nelson — Aquatic Gloio -Worm .' .. 589 Gross, J. — Spermatogenesis of Sycromastes marginatus 589 McCracken, Isabel — Inheritance of Dichromatism in Una lapponica 590 Boutan, L. — Bamboo-Beetle and Coffee-Plant 590 Enderlein, Gunther — Sexual Dimorphism in Rat Louse 590 Carpenter, F. W. — Reactions of the Pomace Fly ■ 590 Carpenter, G. H. — Injurious Insects in Ireland 591 Briggs, Ella M. — Life-Hi story of Case Bearers 591 Enderlein, Gunther — New Genus of Diptera from Falkland Islands 591 Perez, Ch. — Histolysis of Muscles on Larval Muscidse 591 Aldrich, J. M. — Catalogue of North American Diptera 591 Roselle, F. du — Specific Peculiarities of External Genital Organs in Sarcopsylla 591 Enderlein, Gunther — New Flea from Armadillo 591 Lutz, Adolpho — Brazilian Tabanidm 592 Lauterborn, R. — Chironomid Larvae 592 Phisalix, C— Poison in Bees' Eggs 691 Kershaw, J. — Habits of Gerydus chinensis t591 „ Butterfly Destroyers in Southern China 692 Longstafp, G. B. — Notes 071 Butterflies from India and Ceylon 6^2 Zander, Enoch — Male Genital Apparatus in Bubalidx 692 Sharp, D., & F. G. Smith — Notes on Coleoptera 692 Boas, J. E. V. — Cockchafer- Years 693 Perazzo. Umberto — Variations in Hydrophilus piceus 693 Austen, E. E. — Diptera, etc., of Uganda 693 Needham, J. G., & others — May Flies and Midges of Neio York 693 Grassi, B. — Neio Chironomid 693 XVI ( ONTEXTS. PAGE Dell, J. A. — Structure and Life-History of Psychoda sexpunctata 693 Dotton, J. Everett, & others — Congo Floor-Maggot 694 Grunberg, K. — Culicidx of Cameroon and Togo 694 Baker, C. F. — Fleas and, Disease 694 Brunelli, G. — ( 'vary of Termite* 694 Annandale, N. — Note* on Larva of a Coreid Bug 694 Ris, F. — Peculiar Organ in Phryganids 694 Hancock, Joseph L. — Habits of Striped Meadow-Cricket 695 GiLiiANDERS, A. T. — Notes on Arboreal Insects 695 Carpenter, G. H. — Injurious Insects in Ireland 695 5. Arachnida. Lankester, E. Ray — Structure and Classification of Arachnida .">3 Ross, P. H., & A. D. Milne— Tick Fever in Uganda 53 Warburton, C, & N. 1). F. Pearce — Oribatid Mites from the Neighbourhood of Cambridge 53 Smith, Frank P.— Spiders of the Erigone Group 182 Baldwin, W., & W. H. Sutcliffe — Fossil Scorpion from Lancashire 182 Thon, Karel — Secretion in Female Gonads of Hydrachnids .. . 183 Soar, C. D.—Two New British Water-Mites 183 Nordenskiolb, Erik — Minute Structure of the Tick .. 183 Pritchett, Annie H. — Auditory and Olfactory Sense of Spiders 309 Richters, F. — Eggs of Tardigrada 310 Imms, A. D. — Marine Pseudoscorpion from the Isle of Man 310 Hodgson, T. V. — Pentanymphon Antarcticum .. .. 310 Cole, Leon J. — Ten-legged Pycnogoitids 310 Loman, J. C. C. — Decolopoda of Eights 311 Berlese, A. — Myrmeeophilous Acari 311 Laveran, A., & M. Vallee — Ticks as Transmitters of Bovine Diseases 435 Trouessart, E. — Fertilisation in Mites 435 Kclczynski, Vl. — Arachnological Notes 435 Thon, K. — New Breathing Organ in Mites 435 Rossikov, K. N. — Monograph on the Kara-Kurt 592 Hallez, Paul — Parasitism of Larval Phoxichilidium on Bougainvillia 592 Passerini, N. — Terrestrial Mile adapted to Marine Life 592 Jumbunathan, N. S. — Habits and 'Life- History of a Social Spider 592 Kraepelin, K. — Geographical Distribution of Scorpions 695 Bordas, L. — Poison-Glands of Latrodectus 696 Banks, Nathan — North American Spiders 696 Hansen, H. J., & W. Sorensen — Classification of the Tartar ides 696 Borner, C. — Structure of Pedipalpi 696 Loman, J. C. C. — New Pycnogonid 696 Carpenter, G. H. — Ceylonese Pantopoda 697 e Crustacea. Andrews, E. A. — Spermatozoa of Crayfish 54 Brcntz, L. — Phagocytic Cells in Amphipods 54 Kane, W. F. de Vismes — Distribution of Niphargus 54 Abric, P. — Development of Sacculina 54 Gurney, Robert — Fresh- and Brackish-water Crustacea of East Norfolk . . . . 54 Yerkes, R. M. — Reactions of Duphnia pulex to Light and Heat 55 Zograf, N. von — Unpaired Eye and Frontal Organ of Branch iopods 55 Hodgson, T. V. — New Pycnogonid from the South Polar Regions 55 Moseley, M. — Rudimentary Gill in Astacus Fluviatilis 183 Ariola, V. — Heteromorphism in Rock Lobster 183 Rodx, J. — Fresh- water Decapods of Celebes 183 Stenta, Mario — Mereicola ovata Keferstein 1 84 Cole, Leon J. — Pycnogonids of Bermuda . 1 84 Bocvier, E. L., & G. Seurat — Commensal Crab on a Sea- Urchin 311 McIntosh, D. C. — Variations in Number arid Arrangement of Male Genital Apertures in Nephrops norvegicus 312 CONTENTS. XV11 PACK MoIntosh, D. C. — Proportions of the Sexes in Nephrops norvegieus 312 Coutiere, H. — Scales of Pandalidas 312 Illig, G. — Luminosity of Gnathophausia 312 Cuenot, L. — Phagocytary Organ of Decapods 312 Gadzikiewicz, W. — Minute Structure of Heart in Decapoda 313 Smith, Geoffky — Life-History of Gnathia maxillaris 313 Genthe, K. W. — Notes on Alcippe lampas 313 Gruvel, A. — Chilian Cirripeds 314 Coutieke, H. — Notes on Crustacea 435 Gadzikiewicz, W. — Structure of Heart in Malacostraca 436 Hoffendahl, Kurt — Structure and Development of Poecilasma aurantium .. .. 436 Alcock, A. — Indian Ocean Paguroids 436 „ ,, New Species of Cymonomus 437 Smallwood, Mabel E. — Life of Salt- Marsh Amphipod 437 Brehm, V., & E. Zedekbauer — Frcxh- water Plankton Crustacea 437 Scourfield, D. J. — So-called " Olfactory Setas" of Cladocera 437 Baudouin, Marcel — Fixation of Lernxenicus Sardinse 437 Thompson, Millett T. — Metamorphoses of Hermit Crab 593 Illig, G. — New Mysid Genus 594 Bouvier, E. L. — Atlantic Penmidse and Stenopidse 594 Holt, E. W. L., & W. M. Tattersall — iVew Schizopods 594 Kacovitza, E. G. — New Cave Isopod 594 Ramsch, R. — Female Gonads of Cypridina 594 Ortmann, A. E. — Affinities and Distribution of Cambarus 697 Andrews, E. A. — Sperm-receptacle of Cambarus 697 Lenz, H. — East 'African Decapods and Stomatopods 698 Calman, W. T. — Neio Species of River-Crab from Yunnan 698 Coutiere, H. — Abyssal Crabs 698 „ „ Epipodites of Eucyphota 698 Calman, W. T. — Ceylonese Cumacea 698 Mayer, Paul — Ceylonese Caprellidx 698 Walker, A. O. — Ceylonese Amphipods 698 Artom, Cesabe — Artemia salina 698 Chilton, Charles — Distribution of Terrestrial Isopods Introduced into Australasia 699 Richardson, Harriet — New Genus of Isopods 699 Nowikofp, M. — Sense-Organs of Limnadia lenticularis 699 Annulata. Linville, H. R. — Tube-formation in Annelids 55 Johnston, H. P. — Fresh-water Nereids 56 Benham, W. B. — Genital Ducts in Oligochxta 56 , „ New Species of Genus Phreodrilus 56 Ladreyt, F. — Urns of Sipunculus nudus 56 Gerould, J. H. — Embryonic Envelope of Sipunculids 56 M'Intosh, W. C. — Notes on Polyrhxta 184 Allen, E. J. — New British Sabellarian 184 Fauvel, P. — Alleged Otocysts of Alciopidx 184 Bretscher K. — Xerophilous Enchytrxidx of Switzerland 185 Spiess, C. — Digestive Apparatus of Ardastoma 185 Liyanow, N. — Metamerism of Hirudinea 185 Wilson, E. B. — Mosaic Development in the Annelid Egg 314 Schroder, Ola y — Ventral Sen*ory Organs of Palolo Worm 314 Gravier, Ch. — Polynoid Commensal of lialanoglossus 314 Gungl, O. — Anatomy and Histology of Blood Vessels in Lumbricus 315 Pearl, Raymond, & W. N. Fuller — Variation and Correlation in the Earthworm 315 Ikeda, Iwaji — Gephyrea of Japan 315 Stevens, N. M. — Ovogenesis of Sagitta °.15 Foot, K., & E. C. Strobell — Maturation in Allolobophora faztida 438 Brasil, L. — Phagocytary Resorption in Seminal Vesicles of Lumbricus 438 Schepotieff, A. — Setal Pockets in Polychsets 438 Dec. 20th, 1905 b XVlii CONTENTS. PAGE Moore, J. Percy — Neto Species of Sea-Mouse 438 Lignau, N. — Regeneration in Protodrilus 438 Lefevre, George — Artificial Parthenogenesis in Tlialassema mellita 439 Gravier, Ch. — Sexual Forms in Fresh-icater Nereids .. 439 KoLMBR, W. — Crystals in Hirudo and Pontobdella 439 Michaelsex, W. — 01 igochaeta of Lake Baikal 594 Soulier, Albert — Annelids of Cette 594 Malaquin, A. — Phenomena of Asexual Reproduction in Salmacina and Filigrana 594 Hekubel, Marcel A. — Integumentary Structures of Sipunculids 595 Skorikow, A. — New Species of Echiurus 595 Arnesen, Emily — Blood-vessels of Rhijnchobdellids 595 Perez, Ch., & E. Gendre — Oogenesis of BrancheMion 595 Enders, H. E. — Commensals in Tubes of Chsetopterus 699 Gemellt, Agostino — Neurofibrils in Ganglion Cells of Annelids 699 Krawany, J. — Central Nervous System of Annelids 700 Lddwig, H. — Gail-forming Annelid on Ophiuroid 700 F 'age, Louis— Modifications of Segmental Organs in Epitokous Polychaets .. .. Tod Mingazzini, P. — Pelagic Sipunculid 700 Freudweiller, H. — Vascular System of Oligochaeta 700 Holmgren, E. — Epithelial and Connective Tissue Cells in Hirudo 701 Nematohelminth.es. Conte, A., & A. Bonnet — New Nematode from Helix 57 Linstow, Von — Descriptions of Nemotodes and Cestodes 57 Mauval, L. de — Acanthocephala of Birds 185 Schneider, P. — Oxyuris Vermicularis in Peritoneal Cavity 185 Loeb, L., & A. J. Smith — Blood-Coagulating Substance in Anchylostoma .. 185 Jammes, L., & H. Mandoul — Alleged Toxic Action of Intestinal Parasites .. .. 186 Linstow, Von — Notes on Nemotodes 186 Leidy, J., jun. — Researches in Helminthology and Parasitology 186 ■ Linstow, O. von — New Helminths from West Africa 186 Cobb, N. A. — Freshwater Nematodes of New Zealand 316 Man, J. G. de — New Free-living Nematode from Patagonia 316 Gemmill, James F. — Iehthyonema grayi 316 Jagerskiold, L. A. — New Genus of Terrestrial Nematode 440 Shipley, A. E. — Notes on Nematodes ,. 440 Rauther, Max — Structure and Relationships of Gordiidas 595 Marval, L. de — Monograph on Acanthocephala of Birds 596 Tretjakoff, D. — Chromosomes of Ascaris 701 Domaschko, Adalbert — Gonad Walls in Ascaris megalocephala 701 Linstow, O. v. — New Species of Strongyloides 702 Platyhelmiuthes. Kowalewski, M. — New Cestode Genus 57 Engler, Kurt — Abnormal Alimentary System in Opisthorchis felineus 57 Johnston, S. J. — Australian Entozoa 57 Pratt, Henry S. — New Distomes 58 Lichtenheld, G. — Echinococci of Domestic Animals 1S6 Patz, S. von — Dibothriocephalus latus in Dogs 187 Child, CM. — Amitosis in Cestoda 187 Bourquin, J. — Cestodes of Mammals 187 Rosseter, T. B. — Gonads of Taenia sinuosa . . - 187 Fuhrmann, O. — Neiv Trematodes 187 Stoipenbrink, F. — Degeneration of Gonads in Starved Planarians 187 Sablssow, H. — Nervous System of Tricladidas from Baikal 188 Wilhelmi, J. — Excretory System of Fresh-water Triclads 188 Sekera, E. — Viviparity in the Eumesottominae 188 CONTENTS. XIX PAGE Coe, W. R. — Sexual Phases in Geonemertes 317 Walton, L. B. — Land Planarian from Ohio • 317 Maclaren, Norman — Two Interesting Trematodes 317 Osbokn, H. L.— Habits and Structure of Cotylaspis insignis 317 Jammes, L., & H. Mandoul — Bactericidal Action of Cestodes 440 Shipley, A. E. — Notes on Cestodes 440 Szymanski, M. — Neio Bird Tapeworm 440 Zschokkl-, F. — Arctic Cestodes 440 Linstow, O. v. — New Helminths 441 Coe, W. R. — Anatomy, Development and Habits of Geonemertes agricola 441 „ „ North American Nemerteans 441 Janicki, C. v. — Copulation in Cestodes 596 Ijima, Isao — New Cestode Larva Parasitic in Man .,. .. 596 Goldschmidt, R. — Maturation, Fertilisation, and Development in Zooganus mirus 596 Schubmann, W. — Oogenesis and Development of Fasciola hepatica 597 Fredericq, L. — Planaria alpina in Belgium 597 Luther, Alex. — Eumesostominm 597 Mattiesen, E. — Development of Fresh-water Dendrocada 597 Bergendal, D. — Structure of Car inoma 598 Shipley, A. E., & James Hornell — Parasites of the Pearl Oyster 702 Minckert, W. — Histology of Cestodes 702 Tosh, J. R. — Internal Parasites of Salmon 702 Fuhrmann, O. — Bird Cestodes of Eastern Asia 702 Marshall, W. S., & N. C. Gilbert — New Trematodes 703 Maclaren, N. — Structure and Affinities of Trematodes 703 Laidlaw, F. F. — Ceylonese Polyclad Tur'bellaria 703 Coe, Wesley R. — North American Nemerteans 703 Incertae Sedis. Calllery, M., & F. Mesnil— New Enteropneustan Family 58 Spengel, J. W. — New Enteropneustan Species from Naples 58 Ritter, W. E., & B. M. Dawis — Young Stages of some Enteropneusta 58 Waters, A. W. — Bryozoa from Franz-Josef Land 58 Stiasny, G. — Excretory Apparatus in Eutoprocta 318 Schepotieff, A. — Position of Rhabdopleura 441 Ritter, W. E., & B. M. Davis — Notes on Young Enter opneuita 442 Dublin, L. I. — Germ-Cells in Pedicellina americana 442 Gravier, Ch. — Ptychodera erythrxa 598 Rotifera. Piovanelli, Sebastiano, and others — Three New Par asitic Rotifers 188 Murray, James — New Botifers from Scotland 318 Bryozoa. Cumings, E. R. — Development of Fenestella 703 Echinoderma. Hambach, G. — Revision of the Blastoids 58 Klem, Mary J. — Revision of Paleeo zoic Palasechinoidea 59 Martensen, Th. — Siamese Sea-Urchins 189 Pace, S. — Species of Cucumaria from Plymouth 189 Minckert, \V. — New Crinoid 189 Herbst, Curt — Artificial Production of Vitelline Membrane in Unfertilised Ova of Sea Urchin 318 b 2 X X CONTENTS. I'AGE Bather, F. A. — New Devonian Ophiurid 319 Monks, Sarah P. — Variability and Antotomy of Phataria 442 Doderlein, L. — Sea-urchins of German Deep-Sea Expedition 443 Meyer, K. — The Origin of the Water -Vaxcidar System of Eehinoderms 443 Bell, F. Jeffrey — South African Eehinoderms 443 Perrier, Remy — Antarctic. Holoihuroids .. 444 Kcehler, K., &. C. Vaney — Deep Sea llolothuroids of Indian Ocean 444 Kellogg, Vernon L. — Regeneration in Liwkia diplax 598 Krahelska, M. — Merogonic Development of Sea-Vrchin < >va 598 Russo, Ach., & G. Polara — Internal Secretion in Gonads of Phyllophorus urna 598 Kcehler, R., & C. Vaney — New Holothurian from French Coast 599 Ostergren, Hjalmar — Northern Synaptids 599 Edwards, 0. L. — Species of Hohthuria 704 Ostergren, Hjalmar — Korean Holothurians 704 Grave, Caswell— Tentacle Reflex in Holothurians 704 Norman, A. M. — Note on Cucumaria Montagui Fleming .. .. 704 Henderson, E. H. — Development of an Asterid with Large Yolked Eggs 704 Herdman, W. A., & Jane B. Herdman — Ceylonese Eehinoderms 705 Minckert, W. — Regeneration and Syzygy in Comatulidse 705 Chadwick, H. C. — Ceylonese Crinoids 705 Ccelentera. Davenport, Gertrude Crotty — Reproduction and Variation in Sargartia Incise 59 Heicke, A. — Anatomy of Madreporaria 59 Kinkelin, F. — Medusas from the Devonian 59 Jaderholm, Elof — Antarctic Hydroids 59 Goto, Seitaro — New Leptomedusan 60 Hargitt, C. — Early Development of Eudendrium 60 Billard, Ormand — Development of Hydranths of Campanularidse and Plumu- laridss 189 Wagner, G. — Movements and Reactions of Eydra 319 Torrey, H. B. — Biological Studies on Corymorpha 320 Motz-Kossowska, S. — Gymnoblastic Hydroids of the Western Mediterranean .. 320 Hargitt, Chas. W. — Notes on Hydromedusse from Naples 320 Torrey, R. B., & J. R. Mery — Regeneration and Non-Sexual Reproduction in Sagartia 321 McMurrich, J. Playfair — Chilian Actiniae 321 Carlgren, O. — The. Mesenteric Musculature of Actiniaria 321 Duerden, J. E. — Morphology of Coral Polyps 322 Stephens, Jane — List of Irish Ccelentera 444 Hallez, P. — Bougainvillia fruticosa Allm. — a Variety of B. ramosa, Van Ben .. 444 Maas, O. — Classification of Medusas 444 Simpson, J. J. — New Cavernu) 'arid from Ceylon 445 Thomson, J. Arthur — Deep-Sea Alcyonaria from Indian Ocean 445 Schneider, K. C. — Primitive Germ-Cells of Ctenophora 445 Bedot, M. — History of Investigation of Hydroids 599 Carlgren, Oscar — Polyparium ambulans Korotneff 599 Hartlaub, Cl. — Magellan and Chilian Hydroids 599 Thomson, J. Arthur — Southern Antipatharians 599 Downing, E. R. — Spermatogenesis of Hydra 705 Fenchel, A. — Synonymy of Tubularia larynx 705 Thornely, Laura R. — Ceylonese Hydroids 705 Simpson, J as. J. — New Type of Siphonogorgid Alcyonarian 706 Schneider, Alfred — Axis of Gorgonidas 706 Porifera. Minchin, E. A. — Phylogeny of Hexactinellid Sponges 189 Pick, F. K. — Genus Raspailia 190 Ijima, Isao — Studies on the Hexactinellida 190 Thielf, J. — Chilian Sponges 600 Topsent, E. — Studies on Dendroceratida 706 CONTENTS. XXI Protozoa. I'AGK Jennings, H. S. — Physical Imitations of the Activities of Amazbze 60 Cash, J. — British Fresh-water Rhizopods 01 Jennings, H. S. — Asymmetry and Spiral Swimming 01 Kofoid, C. A. — New Opalinid 61 Balfour, A. — Trypanosomes in Anglo-Egyptian Soudan .. ..' 61 Laveran, A. — Effect of Human and, Ape Serum on Trypanosoma 02 Soulie, H. — Hxmogregarine in Psammodromus algirus 02 Jennings, H. S. — Movement and Reactions of Amoebx 190 Penard, E. — Contractile Vacuole in Amoeba 191 Fowler, G. H. — Structure of Itadiolaria 191 Zacharias, Otto — Swarms of Volcox 191 Foa, Anna — Fission in Trichonympha 191 „ „ Two Flagellate Parasites 191 Lingard, A. — Giant Trypanosoma in Bovine Blood .. 191 Laveran, A. — Trypanosomes of French West Africa 192 Rogers, L. — Trypanosomes and Leishman-Donovan Bodies 192 Thiroux, M. — Trypanosomes in Paddas 192 Laveran, A. — Trypanosomes and Tsetse in French Guinea 192 Jennings, H. S. — Behaviour of Lower Organisms 322 Cash, James — New and little-known British Fre*h~water Rhizopods 323 Schouteden, H. — Longitudinal Division in Opalina ranarum 323 Brumpt, E. — Trypanosomes and Hxmogregarines of Teleosts 323 Billet, A. — Culture of a Frog's Try panosome in a Leech 323 Lebailly, C. — Htemotiagellates in Teleosteans 323 Brasil, L. — Anisogamy in Gregarines 323 Stebblns, J. H., jun. — Hxmosporidia of Rana 323 Lister, J. J. — Dimorphism in the Nummulites 445 „ „ Dimorphism in English Species of Nummulites 446 Henderson, W. D. — Notes on Infusorians 446 Keysselitz — Flagellata in Blood of Fresh-ivater Fishes 446 Crawley, Howard — Movements of Gregarines 446 Leger, L. — Meiameric Cytoplasm in Gregarine 446 Brasil, L. — Anisogamy in Monocystis 446 Nuttall, G. — Biology of Piroplasma canis 447 Jakimoff, W. L. — Trypanosomes of Nagana and Mai de Cader as 447 Bentley, C A. — Leucocytozoan of the Dog 447 Crawley, Howard — Coelosporidium Blatiellas 447 Fuhrmann, O. — Diseases of Fishes 447 Laveran, A. — Pseudo-Hxmatozoa 447 Penard, E. — Genus Amozba 000 Castellani, A. — Protozoa in Human Fxces 000 Hacker, V. — Radiolarian Skeleton GOO Vassal, J. J.- -New Hxmatozoon in a Squirrel 601 Perez, Ch. — Microsporidian in Crabs 601 Stebbing, James, Jun. — New Blood Parasite of Frog 601 Lingard, A. — Trypanosome of Dourine 001 Caullery, M., & F. Mesnil — Sexual Reproduction in Actinomyxidia 001 Thiroux, M. — Trypanosoma Paddx 601 Schaudinn, F., & E.Hoffman — Spirochxta pallida 002 Robinson, Thos. — Notes on Radiolaria 706 Conn, H. W. — Fresh-water Protozoa of Connecticut 707 Kofoid, C A. — Craspedotella an Example of Convergence 707 Nabarro, D., & E. D. W. Greig — Human and Animal Trypanosomiasis .. .. 707 Fantham, H. B. — Neio Species of Lankesterella 707 Hickson, S. J. — Micro-Organisms and Disease 708 Thiroux — Trypanosoma duttoni .. 708 xxil CONTENTS. BOTANY. GEN.EKAL, Including the Anatomy and Physiology of Seed Plants. Cytology, including' Cell-Contents. PAGE Kraemer, H. — Nature of Colour in Plants .. 63 Hus, H. T. A. — Spindle Formation in the Pollen-Mother-Cells of Cassia tomentosa . . 193 Denniston, R. H. — Structure of the Starch- Grain 193 Kohl, F. G., & others — Structure of the Cell of the Cyanophycese 325 Gerassimow, J. J. — On the Size of the Nucleus 326 Davis, B. M. — General Cytology 448 Gregoire, V., & J. Berghs — Heterotype Division 448 Fischer, Alfred — Cell-Structure of Vie Cyanophycese 448 King, C. A. — Cytology of Araiospora 448 Am an d, A.—" Bios" of Wildiers 449 Christman, A. H. — Sexual Reproduction in the Busts 449 Strasburger, E. — Cytological Studies and Heredity 709 Bernards, C. — Kinetic Centres in Plants 709 Sypeens, B. — Nuclear Divisions in Endosperm .. -. 709 Digby, L. — Cytology of Apospory 710 Structure and Development. Vegetative. Col, A. — Arrangement of the Vascular Bundles in the Stem and Leaves of some Dicotyledons . . 63 Chrysler, M. A. — Development of the Central Cylinder of Aracex and Liliacex .. 64 Hill, A. W. — Structure of the Sieve- Tubes of Angiosperms 64 Fritsch, K. — Seedlings of Gesneriacese 65 Jeffrey, E. C. — Fossil Sequoia 65 Coulter, J. M., & M. A. Chrysler — Regeneration in Zamia 193 Drabble, E. — Anatomy of Palm Roots 194 Holm, T. — Anatomy of Anemiopsis californica 195 Bessey, C. E. — Stomata of Holacantha 195 Mayes, Oscar — Course of Laticiferous Tubes in Leaves 326 Cooke, E., & Schiveley — Structure and Development of Epiphegus virginiana . . 326 Guerin, P. — Secretory Apparatus of the Dipterocarpex 326 Mahen, J., & X. Gillot — Pitcher-formation in Saxifrages 326 Hodard, C. — Anatomical Investigations on Stem-galls 327 Winkler, Hans — Regeneration in Passion-Flower 327 Schiller, J. — Stipular Formations 449 Penhallow, D. P. — Anatomy of Catalpa Hybrids 603 Petersen, H. E. — Leaf-Nervation in some Species of Bupleurum 603 Cannon, W. A. — Water-Conducting Systems of some Desert Plants 603 Harvey, R. J. — Axillary Scales of Aquatic Monocotyledons 710 Reproductive. Lyon, H. L. — Embryogeny of Ginkgo 65 Wieland, G. R. — Pro-embryo of the Bennettitese 195 Ferguson, Margaret C. — Life History of Pinus .. 196 Kirkwood, J. E. — Comparative Embryology of the Cucurbitacese 197 Coulter, J. M., & W. J. G. Land — Gametophyte and Embryo of Torreya taxifolia 328 CONTENTS, XX111 PAGE Winkler, Hans — Parthenogenesis in Wikstrcemia indicu 328 Bibliography 329 Gebber— Structure of the Flower in CruciJ 'era: 450 Muller, W. — Inflorescence of Boraginacex and Solan acex 450 Lotscber, P. K. — Structure and Function of the Antipodal Cells 450 Strasburger, E. — Apogamy in Alchemilla 451 Toumey, J. W. — Notes on the Fruits of Opuntia 451 Bibliography 452 Thomson, R. B. — Megaspore Membrane in Gymno*perms 604 Roncati, N. — Development in Ovule and Seed of Anona ,. 604 Frye, T. C, & E. B. Blodgett — Points in the Life-History of Apocynum .. .. 604 Riddle, L. C. — Development of the Embryo-sac and Embryo of Batrachium longi- rostris 605 Johnson, D. S. — Seed- Development in the Piperales 605 Shattdck, C. H. — Morphological Study of Ulmus americanus 710 Physiology. Nutrition and Growth. Moller, A., & F. W. Neger — Mycorhiza of Pines 65 Nikolski, M. — Nutrition of Fungi by Carbohydrates 66 Pierce, G. J. — Artificial Parasitism 66 Charabot, E., & G. Laloue — Distribution of Essential Oil in an Annual Plant .. 67 Haberlandt, G. — Sense-organs of Plants 67 Raunklaer, C. — Appreciation of Depth in Rhizomatous Plants 67 Kuster, E. — Formation of Moots and Shoots in Cuttings 67 Molliard, Marin — Animal Parasites and Floral Teratology 68 Milburn, T. — Colour Changes in Fungi and Bacteria 68 Dauphin, J. — Influence of Radium on the Growth of Fungi 69 Becquerel, P. — Germination of Moss-Spores and the Nutrition of their Protonemas in Artificial Media 69 Laurent, J. — Carbon Nutrition of Green Plants by Organic Substances 197 Bergen, J. Y. — Relative Transpiration of Old and New Leaves of the Myrtus Type 198 Kellicott, W. E. — Daily Periodicity of Cell-division and of Elongation in the Root of Allium 198 Ursprung. A. — Periodicity of Groioth in Thickness in the Tropics 198 Spalding. Effie S. — Mechanical Adjustment in Cereus giganteus to Varying Quan- tities of Stored Water 329 Gallaud, J. — Study of Endotropic Mycorhiza 329 Schellenberg, H. C. — Hemicellulose as a Reserve Substance in European Forest- Trees 330 Tschirch, A. — Heterorhizy in Dicotyledons 330 Moore, G. T. — Soil Inoculation for Leguminous Plants . . 452 Snow, L. M. — Development of Root-Hairs 606 Gins, L. — Arrangement of Starch in the Starch-Sheath of the Perianth of Clivia . . 607 Dixon, H. H. — Supply of Water to Leaves on a Dead Branch 711 Cannon, W. A. — Transpiration of Fouquieria splendens 711 Livingston, B. E. — Relation of transpiration to Growth in Wheat 712 Gallaud, I. — Endotropic Mycorhiza 712 Dauphin, J. — Groivth of Fungi in Artificial Media 713 Irritability. Haynes, Julia A. — Geotropic Response in Stems . . .. t 330 Tischler, G. — Distribution of Statoliths in Roots 331 Teodoresco, E. C. — The Effect of Low Temperature on Zoospores of Algm .. .. 331 Livingston, B. E. — Chemical Stimulation of a Green Alga 332 Neger, F. W. — Germination of Spores 332 Stracke, G. J. — Immunity of Plants to their oion Poison 453 Molisch, Hans — Heliotropism Induced by Radium 607 Kinzel, W. — Influence of Light on Sporogonium-formation in Liverworts .. . . 607 XXIV CONTENTS. I'AGE Pourievitch, M. K. — Influence of Temperature on Respiration 607 Burns, G. P. — Traumatic Curvature in Roots 607 Aderhold— Effect of Leaf- Fungi on the Productive Power of the Plant 608 Kurzwelly, Walther — Resistance of Dried Plants to Poisonous Substances .. 608 Schroter, Alfred — Circulation of Protoplasm in the Mucorini 713 Latham, Elizabeth — Stimulation of Sterigmatocystis 713 Adams, J. — Effect of Very Low Temperatures on Moist Seeds 714 Hensel. Esther P.— Movements of Petals 714 Chemical Chang-es. Emerson, J. T. — Blackening of Baptisia tinctoria 198 Ward. H. Marshall — Action of Wood on Photographic Plates 332 Caldwell, J. S. — Effects of Toxic Agents upon the Action of Bromelin 608 General. Arber, E. A. Newell — Fossil Flora of the Culm Measures of Devon 69 Rendle. A. B. — Patagonian Plants 69 Merrill, Elmer D. — Philippine Plants 70 Illustrations of German Orchids 70 Britten, J.. & G. S. Boulger — British and Irish Botanist* .. 70 Garry. F. N. A. — Notes on the Drawings for "English Botany" 70 Engler — Syllabus der Pflanzenfamilien . . . .' 71 Blbliography 71 Scott, D. H. — The President's Address : What were the Carboniferous Ferns ? (Plates I. to III. ; Figs. 32, 33) 137 Scholl, L. H., & others — Identification of Trees in Winter 199 Cushman, J. A. — Localised Stages in Common Roadside Plants 199 Copel and. E. B.— Variation of California Plants 199 Livingston, B. E. — Relation of Soils to Vegetation 200 Prain. D.— Asiatic Plants 200 Stirling, J. — Flora of the Australian Alps 200 Bibliography 201 Maiden, J. H. — Botany of Funafuti 333 Morrison, A. — West Australian Droseras 333 White, C. H. — Autophytography : A Process of Plant Fossilisation 333 Bibliography " 333 Wery, Josephine — Experiments on the Attraction of Bees by Flowers 453 Ule. E. — Relation between Ants and Plants 453 Perkins, G. H. — Fossil Fruits from the Tertiary Lignites 453 Harper, Roland — Explorations in Georgia 454 Engler, A. — Botanical Relationship between Tropical Africa and America .. .. 609 King & Gamble — Flora of the Malayan Peninsula 609 Merrill, Elmer D. — Blanco's Flora de Filipinos 609 Cockayne, L. — Botany of the Southern Islands of New Zealand 610 Berry, E. W. — Fossil Grasses and Sedges 610 Yokoyama, M. — Japanese Mesozoic Plants 610 Lotsy, J. P. — X-Generation and 2X- Generation 611 Bibliography 611 Baker, J. B. — Revised Classification of Hoses 714 Prain, D. — Mansoniex, a new Tribe of the Natural Order Sterculiacex .. ,. .. 715 C RYPTOGAMS. Pteridophyta. Hieronymus, G.— Ferns of Tropical America 71 Bibliography 72 Ford, S. O. — Anatomy of Psilotum triquetrum 201 CONTENTS. XXV PAGE Bruckmann. H. — Prothallium of Ophioglossum vulgatum 202 8omerville, A. — Polystichum 202 Bibliography 202 Bibliography 334 Christensen, C— Index Filicum 454 Campbell, D. H. — Affinities of Ophioglossacese and Marsiliacese 454 Calegari, M. — Asplenium Seelosii Leybold 455 Bibliography 455 Christ, H.— Chinese Ferns 611 Bibliography 612 Goebel, K. — Apospory in Asplenium Dimorphum 716 BRrcHMANN, H., & K. Goebel — The Rhizophores of Selaginella 716 Bibliography 717 Bryophyta. Camus, F. — Sphagna from the Environs of Paris 73 Grout. A. J. — Easy Identification of Hepaticse 73 Macvicar, B. M. — Bare Scottish Hepaticse 73 Douin, I. — Cincinnulus trichomanis 73 Bibliography 74 Roth, G. — European Mosses , 205 Bibliography 205 Bibliography 335 Lampa, E. — Researches on some Liverworts 458 Sablon, Leclerc i>u — Moss-Sporogonium Compared with Fern-Plant 458 Schiffner, V. — Nematode Galls in Mosses 459 Stirton, J. — New and Rare Scottish Mosses 459 Macyicar, S. M. — Scottish Hepaticse 459 Evans, A. W. — Hepaticse from Florida 460 Bibliography • 460 Braithwaite, R. — British Moss-flora 613 Eyans, A. W. — Ceratolejeunea ' 613 Bibliography 613 Bolleter, E. — Fegatella conica 718 Goebel, K. — On the Distribution and Mode of Life of Exormotheca 719 Meylan, C. — Mosses of the Jura 719 Bibliography 719 Thallophyta. Alg-se. Oltmanns, F. — Morphology and Biology of Algse 76 Techet, K. — Behaviour of Marine Algse in Belation to Salinity 76 Sauvageau, C. — Sphacelariacese 76 Wolfe, J. J. — Cytology of Nemalion multifidum 77 Adams, J. — Chantransia Alarise .. .. 77 Gepp, A. & E. S. — Rhipidosiphon and Callipsygma 77 Davis, B. M. — Oogenesis in Vaucheria 78 Fritsch, F. E. — GEdogonium 79 Wesenberg-Ltjnd — Mgagropila Sauteri 79 Wille, N. — Northern Plankton 79 Forti, A. — Phytoplanhton of Asia Minor 79 Scherffel, A. — Chrysomonadinese 80 Bibliography 80 Fritsch, F. E.— Plankton of Tliree English Rivers 209 Lemmermann, E. — Phytoplanhton of some Plan Lakes 209 Ostenfbld, C. H. — Studies on Phytoplanhton 210 Bessey, C. E.— Classification of Protophyta 210 West, G. T. — Remarks on Glaeocapsa 210 XXVI CONTENTS. PA"JE Fritsch, F. E. — Reproduction of Anabsena 211 Phillips, O. P. — Cyanophycese 211 Eeinhard, L. — Phytoplankton of Donjec 212 Murray, G. — Clement sia Markhamiana 212 Cushman, J. A. — Division in Desmids under Pathologic Conditions 212 Gepp, A. & E. S. — Penicillus and Rhipocephalus 212 Karsten, G. — Microspores of Diatoms 213 Cohere, J. — Diatoms of the Montagne Noire, Pyrenees 2i3 Mueller, Olga — Laminaria bullata 214 Berwick, T. — Demonstration of Masked Chlorophyll in Laminaria 214 Warner, F. M.—Endocladia muricata 214 Toni, G. B. de— Floridese 214 Lea vitt, Clara K. — Callymenia phyllophora 215 Foslie, M. — Lithothamnia of the Adriatic and Morocco 215 •Jonsson, H. — Marine Algse of East Greenland 215 „ „ Marine Algse, of Jan May en 215 Lemmermann, E. — Algal Flora of the Sandwich Islands 215 Bibliography 216 Chalon, J. — Marine Algse of North and West France 33S Dorogostaisky, V. — Algse of Lake Baikal 339 Gepp, A. & E. S. — Antarctic Algse 339 Bornet, Ed. — Acrochastium and Chantransia 339 Heydrich, F. — A New Genus of Squamariacese 340 Teodoresco, E. C. — Dunaliella, anew Genus of Polyblepharidese- 340 Brand, F. — Cladophoracese 340 Paulsen, O. — Plankton Investigation round Iceland 340 Fritsch, F. E. — Studies on Cyanophycese 341 Bibliography 341 Vickers, A. — Marine Algse. of Barbadoes 464 Setchell, W. A. — Parasitic Floridese of California 464 Gepp, A. & E. S. — Leptosarca 464 Howe, M. A. — New CMorophycese 465 Borgesen, F. — Siphonocladus 465 Collins, F. S. — Chlorochytrium 465 Janse, J. M. — Polarity and Organ- Formation in Caiderpa prolif era 465 Cushman, J. A. — Zygospores of Desmids 466 Morteo, E. — Diatoms of the Orba 466 Edwards, A. M. — Trochiscia moniliformis 466 Schr, J. — Algse of the Weser District 466 Larsen, E. — Fresh-water Algse of East Greenland 466 Lemmermann, E. — Fresh-water Algse of the East Indies 467 Serbinow, J. L. — Peromelia glaiophila 467 Trotter, A. — Plankton of Lake Laceno 467 Bachmann, H. — A New Chlamydomonas 467 Serbinow, J. L. — Clilamydomonas '468 Bibliography 46S Jackson, D. D. — The Movements of Diatoms and other Microscopic Plants .. .. 554 Mazza. A. — Marine Algology .. .. 615 Gepp, A., & others — South Orkney Marine Algse .. 615 Smith, H. M. — Seaweed Industries 616 Bosse, A. Weber van — Dictyosphseria 616 Edwards, A. M. — Diatoms of the Territories 616 Yatsu, N. — Cytology of the Forms of Stigeoclonium 616 Bibliography 617 Artani, A. — Cultivation of Green Algse 720 Pascher, A. — Sexual Reproduction in Stigeoclonium 721 Molisch, H. — Brown Colouring Matter in Algse 721 Bergon, P. — Spore Formation in Biddulphia mobiliensis 721 Borgesen, F., & H. Jonsson — Arctic and North Atlantic Marine Algse 722 Simmons, H. G. — Marine Flora of the North Atlantic, North Pacific, and Polar Sea 722 Laing, R. M. — Ceramiacese of New Zealand 722 CONTENTS. XXV11 Enwald, K. H., & K. M. Levander — Finland Algse 723 Hansgirg, A. — The Algse of Lower Austria 723 Migila, W. — The Algse of Germany 723 Suhr, J. — Algse of the Weser District 723 Hardy, A. D., & G. 8. West — Desmids from Victoria 724 Lemmermann. E. — Marine Phytoplankton 724 BlRLIOGEAPHY 725 Fungi. Trow. A. H. — Fertilisation' in the Saprolegniese 82 Ruhland, W. — Studies on the Fertilisation of Albugo Lepigoni and some Perono- sporese 82 Cuboni. G., & others — Vegetable Pathology 82 Saito, K., & C. Wehrner — Fungi Causing Fermentation 83 Eberhardt, Albert — Contribution to the Study of Cystopus candidus 8 5 Kuyper. H. P. — Perithecium of Monascus 84 Kuhland, W. — Disease of Oaks 84 Schellenberg, H. C. — New Sclerotinise 84 Rick, J. — Tropical Hypocreacese 84 „ ,. Laboulbeniacese from the Vorarlberg 85 Grijns, G. — Ascus form of Aspergillus fumigatus 85 Chapman, A. C. — Wild Yeast Infection 85 Klein, E., & Mervyn Gordon — Origin of a Rose-coloured Yeast 85 Henneberg, W. — Study of Yeast 85 Will, H., & others — Research on Yeast 86 Jordi, E., & others — Studies of Uredinese 86 Bubak, Fr., & C. M. Gibson — Infection Experiments with Uredinese 87 Dietel, P. — Distribution of Uredinese on their Host-Plants 87 Emerson, Julia I. — Relationship of Macrophoma and Diplodia 88 Osterwalder, A. — Rotting of Cherries by Glceosporium 88 Laueert, K. — Leaf-disease of Ribes alpinum 88 „ Morphology of a New Cytospora 88 Tubeuf, V., & Joh. J. Vanha — Disease of Potato 88 Sohorler, B. — Distribution of the Musk Fungus (Moschuspilz) 89 Jordi, Ernst — Uromyces on Leguminosse 89 Petri, L. — Diagnostic Value of the Capillitium of Tylostoma 89 Osterwalder, A. — Fruit Decay caused by Fungi 89 Sorauer, P. — Injury due to Frost followed, by Fungi 89 Bubak, Fr. — Diseases of Sugar Beet 90 Vanha, J. — Brown Discoloration of Potato Leaves 90 Lagerheim, G. von — Disease of Figs 90 Appel, Otto, & H. F. Stkunk — Diseases of Cacao 90 Lafar, F. — Handbook of Technical Mycology 90 Crossland, G, & J. Needham — Fung us Flora of Hearth-rug 90 Havsman, W. — The Detection of Arsenic by Growth of Penicillium 91 Bibliography 91 Istvanffi, J. von — The Wintering of Peronospora in the Vine 217 Vuillemin, P. — Membrane of Zygospore 218 „ „ Hyphoids and Bacteroids 218 Oddemans, C. A. J. A., & C. J. Koning— Tobacco Disease due to Sclerotinia .. .. 218 Salmon, E. S. — Two Supposed Species of Ovularia 218 Prunet, A. — Notes on the Occurrence of Black Rot 218 Magnus, P. — Mycological Notes 219 Salmon, E. S. — Further Cidtural Experiments with Biologic forms of the Erysi- phacex 219 Henneberg, W. — Vitality of Yeast in Varying Conditions 219 Bonnier, Gaston — Nuclear Fusion in Yeast Spores 219 Ippolito, G. D., & E. Lasnier — Diseases due to Cladosporium 220 Oudemans, C. A. J. A. — Disease of Larch 220 XXV111 CONTENTS. TAGF. VriLLEMiN, P. — Isaria forms of Penicillium 220 Stoll, O— Morphological and Bioloaical Characteristic* of PenciUium Species .. 221 Schellenberg, D. H. C. — Busts of Pines 221 Semadeni. O. — Puccini fe found on Umhelliferas 221 Dietel, P. — Notes on Uredospores of Uromyces brevities and U. punctatostriatus .. 221 Eriksson, Jakob — On tlie Vegetative Life of some Uredineas 221 Hennings. P., & others — Notes on Uredinese 222 Ward. Marshall — Becent Besearches on the Parasitism of Fungi 222 Lindroth. Ivar — Destruction of Birch and other Wood by Polyporus nigricans .. 223 Banker, Howard J. — Notes on the Variability of Eypothele repanda 223 Falck, Richard — Spore Dispersion in the Basidiomycetes, and the Biological Value of the Basidium 223 Istvanffi, Gv. de— Two New Pests of the Vine in Hungary 224 Guttman. A. — Practical Notes on the, Beet Disease 224 Goethe. Rudolf — Canker of Fruit Trees 224 Speschnew, N. N. — Fungal Parasites of the Tea Plant 224 Nechitsch, A. — Mould Ferments from India 225 Halstf.ad, B. D.. & J. A. Kelsey — Beport on Fungicides 225 Lutz, L. — Mycological Notes 225 Mafblanc. A. — Vegetable Pathology •• •• 225 Jungner. J. B. — Inter-relation of Pests of Cereals • • • • 225 Ternetz. Ch. — Assimilation of Atmospheric Nitrogen by a Turf Fungus.. .. ■■ 226 Hockauf. J., & H. Rtetnyorth — Poisoning by Fungi 226 Bubak, Franz — Diseases of Sugar Beet in Bohemia 226 Fischer. Ed. — Biological Species of Parasitic Fungi, and the Development of Nero Forms 226 Kindshoven, J.. & W. Frfckmann — Diseases of Plants, with Methods of Prevention or Cure 227 Bibliography 227 Bonnier, Gaston — Biology of Saprolegniem 343 Clausen. P. — Development of Ascnmycetes 343 Kuyper, H. G. — Development of Monascus 344 Pegi.ion, V. — Wliite Milrlew of Euonymus 345 Salmon, E. S. — Erysiphacex 345 Wehrner. 0. — Aspergillus .. .. 345 Clinton, G. P. — North American Ustilagineas 345 Dietel, P. — The Genus Phragmidium 346 Mentemarttni, Luigi. & others — Notes on Uredinese. 346 Fischer, Ed. — Swiss Uredinese, 347 Arthur. J. C. — Amphispores of Grass and Sedge Busts 347 Rolfs, F. M. — Potato Disease's 348 Appel. O., & others — Diseases of Trees .. 348 Butler, E. J. — Plant 'Diseases in India during 1903 348 Hollrfng. M. — Plant Diseases during the year 1903 349 Cooke, M. C. & others — Diseases of Cultivated Plants 349 Lt-stner, G., & others — Plant Diseases 349 Hiltner, L., & others — Diseases of Beet .. 350 Boudier, M.. & others — French Mycology .. .. 350 Borquflot. O., & H. Hertssey — Trehalose in Fungi 351 Gfeguen. F. — Effect of Turgescence in Fungi 351 Oudemans, C A. J. A. — New Parasitic Fungi 351 Atkinson, G. F. — Edible and Poisonous Fungi 351 Ferry, Rene — Immunity from the Poison of Fungi 352 Lutz, J. — Abnormalities in Fungi 352 Lafar, Franz, & others — Technical Mycology 352 BlBLTOGRAPHY 352 Loewenthal, W. — Chytridiacex .. .. .■ 471 Worontn. M. — Monoblepharidex 471 Molliard, Marin. & others — Culture Experiments with Morchella 471 Wehmer, C. — Fermentation with Mucor 472 Mangin, L., & P. Viala — Stearophora radicicola 472 CONTEXTS. XXIX PAGE Magnos, P. — Sclerotinia Crataegi 473 Maire, Rene — Cytological Researches* on some Ascomycetes 47:-! Mabsee, G. — Bi -nucleate Cell* in Ascomycetes 473 Johnson, T. — Willow Canker .. .. 474 Salmon, E. S. — Specialisation of Parasitism in the Erysiphacex 474 Henneberg, W. — Research on Yeast 474 Lindau, G. — Hyphomycetes .. .. 474 Arthaud-Berthet, J. — Agricultural Microbiology 475 Sydow, P., & others — Uredinese 475 Duchaussoy, H. — Dry-rot 475 Heinisch, W., & J. Zellner — Chemistry of Amanita muscarius 475 Lloyd, C. G. — Mycological Notes 476 Ruhland, W. — Effects of Copper on Fungi 476 Traverso, G. B. — Nomenclature of the Organs of Pyrenomycetes and Deuteromycetes 476 Saccardo, P. A. — Sylloge Fungorum 476 Guttenberg, H. Ritter von — Physiological Anatomy of Fungus Galls 476 Solereder, H. — Witches' Brooms of Quernus rubra and other Woody Plants .. .. 477 Nestlek, Anton — The Fungus of Lolium temulentum 477 Rae, Carleton, & others — British Mycology 477 Hohnel. Franz von — Mycology 477 Smith, Worthington G. — Sowerby's Drawings of Fungi 478 Wize, Casimir — Fungal Parasites of Insects 478 Zederbauer, E. — Myxobacterise 478 Lister, A. & G. — Notes on Mycetozoa 478 BlBL.OGRAPHY 479 Peglion, Vittorio — Vegetable Pathology 617 Gallaud, I. — Delacroixia coronata 617 Wehmer, C. — Mucor Species and Alcohol 618 Saito, K. — Rhizopus Oligosporus 618 Thaxter, Roland — A New Species of Wynnea 618 Muscatello, G. — Observations on Peziza ammophila 618 Aderhold, R., & \V. Ruhland — Sclerotinise of Fruit Trees 618 Fischer, Ed. — Sclerotium Disease of the Alder 619 Cuboni, G., & L. Petri — Disease of Olive Trees 619 Salmon, E. S. — Erysiphacex of Japan. II. 619 Aderhold, R. — Infection Experiments with Thielavia basicola 619 Saite, K. — On the Occurrence of Saccharomyces anomalus in the Brewing of Sake 619 Desoopfre, Andre — The Yeasts of Charente 620 Hansen, Emil (Jhr. — Development of Yeast in the Soil 620 Klebahn, H. — Research on Fungi imperfecti 620 Peglion, Vittorio — Disease caused by Pencillium glaucum 621 Frank — Phellomyces sclerotiophorus 621 Lindau, G. — Hyphomycetes 621 Uzel, J. — Cercospora beticola Parasitic on Sugar and Fodder Beet 622 Holway, E. W. D. — North American Uredinem 622 Arthur, J. C. — Mexican Rusts 622 Kauffman, Calvin H. — Genus Cortinarins 622 Lloyd, C. G. — Mycological Notes 622 Loewenthal, W. — Experiments with Parasitic Fungi 623 Sorauer, P. — Handbook of Plant Diseases 623 Funguid Diseases on the Cotton Phmt 623 Morgan, A. P., & others — American Mycology 623 Hollrung, M. — Disease of Sugar Beet 624 Lafar, F. — Technical Mycology 624 Carnoy & others — Fat Bodies in Plant Nuclei 624 BlB'.IOGRvPHY 624 Blakeslee, A. F. — Two Conidia-bearing Fungi 728 Petri, L. — Disease of Haricot Beans 728 Mdth, F. — Witches' Broom on Bear Trees 728 Klebahn, H. — Botrytis Disease of Tulips and Lily of the Valley 728 Mirande, Marcol — Biology of Entomophytes 728 XXX CONTENTS. PAGE Stager, R.— Biology of Ergot 729 Voglino, P. — Phyilaciinia Corylea.. 72'.i Guilliebmond, A. — Morphology and Cytology of Yeasts 729 Hest, J. J. van — Vacuoles in Yeast-Cells 729 Fedebley, Haery — Fusion of Ustilago Conidia 7: 10 1 1 i-x'KE, Ludwig — Infection of Cereals by Smut Spores 730 MessalongO, C. — Deformation caused by an JEcidlum 730 Fischeb, Ed., & othebs — Vredinese 730 MuBElLL, W. A. — Polyporaceze of North America. — XL A synopsis of the brovn pileate species 731 Lloyd, C. G. — Mycological Notes 731 Lindad, G. — Hyphomycetes 732 Hennings, P., & othees — Fungi of the Mark Brandenburg 732 Morgan, V., & others — American Mycology 7:52 Ivibchnee, Oskak — Diseases of Plants .. 732 Lawrence, W. L., & others — Diseases of Cultivated Plants 733 1>at r, E. — Studies in My xobacteria .. .- 733 Bibliography 734 Lichens. Elenkin, A. — Observations on Endosaprophytism in Heteromerous Lichens .. .. 95 Bibliography 95 Mc Andrew, James — Notes on Lichens 229 West, W.— Habitat of Lichens 230 Schulte, Fritz — Anatomy of the Genus Usnea 230 Bibliography 230 Elenkin, A. — Theory of Endosaprophytism in Lichens 356 Briosi, G.,& E. Farneti — New Lichen Type 357 Fink, Bruce — How to Collect and Study Lichens 357 Britzelmayer, Max — Notes on Lichens 357 Bibliography 357 Zopf, W., & others — Multi-nucleate Condition of Lichen Spores 481 Britzelmayer, Max — Lichenological Notes 4S1 Aecaxgeli, Alceste — Studies of Dsnea 481 Bibliography 481 Picquenard — Lichens of Finisterre 627 Schneider, Albert — Classification of Lichens 627 Lederer, Michael — Lichen Flora in the Neighbourhood of Amberg 627 Hue, L' Abbe — Lichen Cephalodia 628 Elenkin, A. — Polymorphism of Evernia furfur acea 628 Sargent, F. Le Boy — Lichenology for Beginners 628 BlBLIOGEAPHY 629 Schneidee, Albeet — Chroolepus Aureus a Lichen 735 Dabbishire, Otto V. — Lichens from the Antarctic 735 Sargent, J. Le Roy, & Bruce Fink — Lichenology for Beginners 736 Wolff, Gertb. P. — Development of Lichen Fruits 736 Bibliography 736 Mycetozoa. Bibliography 358 Schizophyta. Schizomycetes. Firth — Epidemic or Bacillary Dysentery 96 Selteb — Spore-production by Bacillus Anthracis and other Spore-bearing Bacteria 96 Delden, A. van — Bacteria of Flax" Betting" 96 Swellengeebel — Morphology and Biology of Bacillus Zopfii 97 CONTENTS. XXXI PAQB Itersek, Van, jun. — Decomposition of Cellulose by Aerobic Organisms 98 Beijekinck, M. W., & A. van Delden — Bacterium that obtains its Carbon Food from the Air 98 Milbtjrn, T. — Variations in the Colours of Moulds and Bacteria 98 T. Muto (Tokio) — Bacillus helixoides, a bacillus that forms Colonies with Snail- like Movements 98 Smith, R. Greig — Nutrition of Bacterium Acacise 99 Harrison, F. C. — Bacterial Disease of Cauliflower 99 Uyeda, Y.— Tobacco Wilt Disease 100 Bibliography 100 Bonhoff — Identity of Loeffler's Bacillus typhosus murium with the Bacillus para- typliosus " B." •• •• 221 Smith, R. Greig — Bed String of the Sugar Cane 231 Chester, F. D. — Bacillus subtilis Group of Bacteria 232 Ellermann, V. — Bacillus fusiformis 232 Riemer — Septicaemia affecting Geese < •• •• 233 Kothman, E. A. — Glischroba'cterium as the Cause of Mucous Fermentation of Urine in Man 234 Neumann, R. O. — Pathogenic Capsulated Streptococcus from the Naso-pharynx .. 234 Smith, R. Greig — Variable Galactan Bacterium 235 Betten court, A., & C. Franca — Epidemic Cerebrospinal Meningitis and its Specific Cause 235 Leonard, E. L. — Bacterium cyaneum: a new Chromogenic Organism 236 Bibliography 237 Scharz, C. — Bacillus hypothermos, a micro-organism pathogenic for cold-blooded animals 358 Tissier, H. — Distribution of the Microbes in the Intestines of Infants 359 Doerr, R. — Spirillum pyogenes Mezincescu 360 Mori, N. — Micro-organism causing an Epidemic Disease among Cats 360 Bruini, G. — Thermophilic Microflora of the Human Intestine 361 Wheury, W. B. — Biology of the Cholera Spirillum -161 Sanfelice, F. — Streptothrix pseudo-tuberadosis 362 Gorini, C. — Bacillus acidificans presamigenes casei 362 Klein, E. — Vibrio Cardii 362 Woolley, P. G. — Bacillus violaceus Manilx 362 Gaehtgens, W. — Bacillus jasmino-cyaneus and Bacillus flavo-aromaticus . . 362 Michelski, J. — Bacillus conjunct ivitidis subtiliformis 363 Adametz, L., & T. Chszaszek — Formation of Volatile alkaloids byWacillus nobilis 363 Bibliography 365 Nelson, E. M.—The Tubercle Bacillus (Figs. 79-81) 412 Smith, R. Greig — Bacterial Origin of Macrozamia Gum 482 Petri, L. — Besearches on the Bacteria found in the Intestine of the Larva of Mosca Olearia 483 Jones. Mabel — Micro-organism showing Bosette Formation 483 Lehman, K. B., & H. Curchod — Bacterial Niveau of Beijerinck 4S4 Harrison, F. C. — Comparative Study of Sixty-six Varieties of Gas-producing Bac- teria found in Milk 485 Waelsch, L. — Bacillus Involutus 485 Morgan, H. de R. — Micro-organisms of Meat Poisoning 486 Schreen, V. — New Microbe of Pulmonary Phthisis 487 Sanfelice, F. — Tuberculosis and Pseudo-tuberculosis 487 Hautefeuille — Benal Tuberculosis in a Carp 4S8 Panek, M. K— " Barszcz " 489 Delacroix, G. — Bacterial Infection of Cabbages 489 Grips, & others — Swine Septicaemia 490 G ruber, M. — Clostridium Polymyxa Prazmoicski 491 Bibliography .*. 491 Omelianski, W. — New Colourless Thiospirillum 629 Schardinger, F. — Bacillus macerus, an Acetone-forming Bacillus 630 Veley, L. J. — Bacterial Bods of Pelomrjxa palustris 630 Strong, R. P. — Virulence and Immunising Powers of Micro-organisms 631 XXX11 CONTENTS. I'AGE Lohnis, F. — Bacillus Freudenreichii :!"> Furhmann, F. — Two Varieties of Vibrio aquitalis fiuorescens 633 Smith, Th. — Differentiation of the Human and Bovine Tubercle bacillus 1,34 Smith, R. Greig — Origin of Natural Immunity towards the Putrefactive Bacteria 736 „ „ Bacteria and the Gum of Hahea Saligita 737 „ „ Bacteria and the Gum of Linseed Mucilage 737 Kraemer, H. — Oligodynamic Action of Copper Foil on Intestinal Bacteria .. .. I'M CONTENTS. XXX1U MICROSCOPY. A. Instruments, Accessories, &c. (1) Stands. PAGE Koristka, F. — Koristka1 s Large Model Microscope (Figs. 25, 26) 101 Fogan, W. — Differential Screw Fine Adjustment 102 Ladd's StwlenVs Microscope (Fig. 34) 238 Portable Microscope (Fig. 35) 239 Zeiss' New Laboratory Stand (Fig. 36) 240 Reichert's New Large Stand, A 1, with Extra Wide Tube and New Lateral Micrometer-screw (Figs. 37. 38) 241 „ Large Stand. No. 1 A, fitted with Tip-up Stage- Clips (Fig. 39) .. .. 243 „ New Mineralogical Stand (Fig. 40) 245 „ Large Mineralogical Stand (Fig. 41) 247 „ Microscope for Determining Hardness of Substances (Figs. 42, 43) .. 247 Stead, J. E — Engineer's Metallurgical Microscope (Fig. 57) 364 Swift's New Compound Metallurgical Microscope (Fig. 58) 366 Reichert's Medium Dissecting Microscope (Fig. 59) 366 „ New Microscope for Brain Sections {Fig. 60) 367 Tafner's New Preparation Stand (Fig. 61) 368 Imperial Standard Yard 368 Finlatson, D. — The Ashe-Finlayson Comparascope (Fig. 82) 414 Koristka's Large Model Mineralogical Microscope (Fig. 85) 492 Leitz' Mineralogical Stand No. I. [ Fig. 86) 492 „ Demonstration Microscope (Fig. 87) 495 „ Mineralogical Stand No. II. (Fig. 88) 495 „ Mechanical , Stage (Fig. 89) 497 Tuzson, J., & M. Herrmann — Object-Stage, with Sliding Measurement Adjustment (Figs. 90, 91) 497 Bibliography 499 Old Microscope by Shuttleworth (Fig. 138) .. 635 Old Microscope by W. & S. Jones .. .. 635 Pocket Botanical and Universal Microscope (Fig. 139) 636 Wilson Screio- Parrel Simple Microscope (Fig. 140) < 36 Horizontal Travelling Microscope (Fig. 141) 637 Pillischer's New Modd " Kosmos" (Fig. 142) 639 Sommerfeldt, E. — Microscope specially adapted for Mineralogical Investigations at High Temperatures 639 Hirschwald's New Microscope Model and Planimeter-Ocular (Figs. 144,145.. .. 640 Vollbehr, O. — Microphotoscope, or Military Staff Map Loup 642 Stcdnicka's Pancratic Preparation Microscope 643 Bibliography 644 Henrici, Jacob F. — Note on a Microscope Presented by Linnteusto Bernard Jussieu (Fig. 159) 738 Wilson's Screw- Barrel Simple Microscope (Fig. 160) 739 Watson's Praxis and. Bactil Microscopes (Figs. 161-4) 740 Beck's '■'Imperial" Metallurgical Microscope (Fig. 165) 743 „ Metallurgical Microscope. " London Model" (Fig. 166) 745 Ashe-Finlayson Comparascope (Figs. 167, 168) 745 Voli.behr's Microphotoscope (Fig. 169) 748 Reichert's New Microscope Stands with Handles (Figs. 170, 171) 748 (2) Eye-pieces and Objectives. Keeley, F. J. — Spencer Objective 103 Bibliography 103 Dec. 20th, 1905 c XXXIV CONTENTS. I'AUE Reichert's Objectives with Borguet'a Spring Safety Action (Figs. 44, 45) .. .. 249 Bibliography 249 Reichert's New Erect Image Preparation System for Preparation Microscopes (Fig. 62) 368 Meyer, P. — New Method of using the Plankton Searcher (Figs. 63, 64) 869 Waslem, G. C. van — Simple Form of Index Ocular 370 Leitz' New Formula Object-glass 499 „ New Objectives 500 Malassez, L. — The Notation of Microscopical Objectives 500 Chalmers, S. D. — Theory of Symmetrical Optical Objectives 501 " H." — Construction of Aplanatic Combinations of Lenses with or without Achro- matism 501 Leitz' Camera Ocular (Fig. 92) 502 Bibliography 502 Stddnicka, F. K. — Tlie Abbe Condenser used as an Objective 644 Strehl, K. — Discrepancy between Diffraction Theory and Geometrical Optics in Actual Instances of Telescope and Microscope Objectives 644 Drysdale, C. V. — Direct Determination of the Curvature of Small Lenses .. .. 751 (3) Illuminating1 and other Apparatus. Reichert's Swing-out Condenser and Iris Diaphragm (Figs. 46, 47) 249 Ross, H. C. — Electric Warm-Stage, for Use with the Microscope, combined with a Nernst Lamp to Illuminate the Microscope (Figs. 48, 49) 250 Improved Methods of Working with the Vertical Illuminator 251 C.Baker's Electric Lamp for the Microscope (Fig. 50) 252 Pfeifper's Hot-Air Chamber (Fig. 65) 371 Reichert's New Achromatic Condenser (Fig. 66) 371 Stead, J. E. — Hluminator for Opaque Objects (Fig. 67) 372 Bibliography 372 Lazarus-Barlow, W. S.— New Hot Stage (Plate VII. ; Fig. 84) .. 419 Leitz' Apparatus for Observation of Ultra-Microscopical Particles (Figs. 93 -95) . . 502 „ Universal Projection Apparatus (Figs. 96-98) 504 Beck, R. & J. — New Vertical Illuminator for Metallurgical Examinations (Fig. 99) 506 „ „ Monochromatic Trough (Fig. 100) 507 Leitz' Triple Revolver with Large Protection Diaphragm (Fig. 101) 507 „ Thermometry Stages (Fig. 102) 507 „ Drawing Board (Simple Form) (Figs. 103, 104) 508 Holmes, JZ.—Polariscope .. •• 509 Walsem, G. C. van — The Micro-pantograph as a Drawing Apparatus (Fig. 105) 509 Koristka's Illuminator for Opaque Objects (Fig. 106) 510 Bausch and Lomb's Improved Form of Camera Lucida (Fig. 107) 511 „ „ Adjustable Drawing Board (Fig. 108) 512 Bibliography 512 Fischer, A. — Locking Arrangement for Microscopical Demonstrations 645 Paul, R. W.— Optical Arc Lamps (Fig. 146) 646 Locke's High Power Jet (Fig. 147) _ •• 6^7 Leppin & Masche's Projection Apparatus with Optical Bench Extension (Figs. 148-50) 647 Eddjger's Projection and Drawing Apparatus (Fig. 151) .. .. 650 Tandler, J. — Simple Apparatus for Drawing and Photographing Microscopical Sections 651 Schott, O. — New Ultra- Violet Mercury Lamp {Uviol Lamp) 751 Beck's Eyeshade (Fig. 172) 752 Abbe Camera Lucida (Fig. 173) "52 Beck's Parabolic Illuminat or (Fig. 174) , 753 „ Parabolic Illuminator with Sorby's Reflector (Fig. 175) 753 Bibliography 753 CONTENTS. XXXV (4) Photomicrography. pagb Photomicrography with the Aid of Ultra-Violet Light 103 Jones, Chapman — Three- Colour Photography 104 Thompson, J. — Photomicrography and Photomicrometry 106 Bibliography •• 106 Kohler, A., & M. von Rohr — Photomicrography with Ultra-violet Light (Figs. 109-112) '.. .. 513 Leitz' "Universal" Microphotographic Apparatus (Figs. 113-115) 518 Bibliography 520 J. W. Gordon's Apparatus for Photomicrography (Figs. 152, 153) C51 Ries, J. — A Perfectly Steady Stand for Photomicrography 052 Bibliography 052 Beck's Vertical and Horizontal Photomicrographic Camera (Fig. 176) 753 Taylor & Co's. Focusing Magnifier (Fig. 177) 755 Bibliography 755 (5) Microscopical Optics and Manipulation. Gordon, J. W. — The Tlieory of Highly Magnified Images (Figs. 1-24) 1 Gifford — Aperture Table 106 Mostyn, C. — Resolution of Amphipleur a Pellucida 107 Biltz, W. — Pltramicroscopic Observations on the Decomposition of Sulphur from Thiosulphuric acid and of Selenium from Selenic acid 107 Garnett, J. C. Maxwell — Colours in Metal Glasses and in Metallic Films . . .. 107 Chabrie, M. C. — Construction-Principle of an Optical Apparatus for obtaining very Large Magnifications \The Diastoloscope~\ (Figs. 27-29) 108 Bibliography 109 Conrady, A. E. — An Experimental Proof of Phase-Reversal in Diffraction-Spectra 150 Rheinberg, J. — The Influence on Images of Gratings of Phase-Differences amongst their Spectra (Plate IV.) 152 Bibliography 253 Conrady, A. E. — On the Application of the Undidatory Theory to Optical Problems (Figs. 74-78) 401 Rayleigh, Lord — An Optical Paradox (Fig. 83) 417 Treoster, C. — Dark Field Illumination 520 Resolution of Grayson's Bands 521 Rheinberg, J. — Doubling of Lines in the Abbe Experiments not due to the Dia- phragms above the Objective 521 Strehl, K. — Limit of Visibility of Isolated Elements in the Microscope 521 Wood, R. W. — Achromatisation of Approximately Monochromatic Interference Fringes by a Highly Dispersive Medium, and the consequent Increase in the allowable Path-difference 521 Bibliography 522 Conrady, A. E. — Theories of Microscopical Vision — Second Paper (Figs. 123-8) 541 Stoney, G. J.— On" An Optical Paradox" (Fig. 129) 557 Ozapski's Elements of the Theory of Optical Instruments 653 Von Rohr's Image- Formation in Optical Instruments from the Standpoint of Geometrical Optics 654 Strehl, K. — Diffraction-Image and Absorption-Image 654 Bibliography .. 654 Braun's Methods of Identifying Sub-microscopic Structures ; Allied Investigations on Double Refraction 755 Prytz-Kopenhagen, K. — Microscopical Determination of the Position of a Reflecting Surface during Optical Contact 756 Bibliography ,, .. 756 (6) Miscellaneous. Bibliography 110 LiNN.a:us and the Use of the Microscope 253 Kingsfobd, T. G. — Method of Constructing small Glass Tanks (Figs. 51, 52).. .. 255 XXXVI CONTENTS. PAGE Cheshire, F. J. — Hock Crystal 255 Legros, V. — Photoqrammetric Focimetry 255 Rapeu, C. V.— A New Spherometer (Figs. 555-55) 255 BIBLIOGRAPHY 258 Gordon, J. W. — Uigh Power Microscopy 372 Wilson, C. E. A. — Elements of Applied Microscopy 374 Hyatt- Woolf, C. — optical Dictionary 374 Peiser, J. — MicroscopisV s Screen 374 " Paterfamilias" — Comparison of British and Foreign Students' Microscopes .. 523 Bibliography 524 The Optical Convention (Figs. 130-7) 559 Chance Brothers, Optical Properties of Glasses produced by 654 „ „ Cover-Glasses of thin Glass for Microscopic Preparations .. 656 Bausch, Edward — Manipulation of the Microscope 656 Scales, F. Shillington — Elementary Microscopy 656 B, Technique. (1) Collecting Objects, including- Culture Processes. Marpman, G. — Diagnostic Media for the Study of Bacteria 110 Hewlett, R. T. — Detection of Bacillus Enter iditis Sporogenes in Water .. . . 110 Bekxer, O. — Plate Culture of Anaerobic Bacteria 110 Fraenkel & Simmonds — Isolating Bacillus Typhosus from the Blood and Organs after Death Ill Otto & Neumann — Bacteriological Examination of Water in the Atlantic Ocean 111 (■reite — Isolating Tetanus Bacillus from the Spleen Ill Hintf.rberg & Reitman — Varieties in the Groivth of Bacillus Pyocyaneus on Nutrient Agar 112 Mdsgrave, VV. E., & M. T. Clegg — Cultivation and Staining of Amcebse .. .. 112 Bibliography 114 Dwouetzky, A. — Cultivation of Tubercle Bacilli from Bacterial Mixtures .. .. 259 Serkovvski, S. — New Levelling Apparatus 259 Hagemann — Simplification of the Drigalski Medium 259 Gord n, M. H. — Differentiation of Streptococci 259 Sellards, A. W. — Anaerobic Cultures with Phosphorus 259 Lesage, A. — Cultivation of the Amaibie of Tropical Dysentery 260 Rost, E. R. — Cultivating the Bacillus of Leprosy 261 Dibdin, W. J. — Flagella of Bacillus Typhosus 374 Gautie, A. — Quantitative Estimation of the Bacillus Collin Drinking Water . . 375 Heller, Otto — Rothberger's Neutral Bed Reaction 375 Perotti, R. — Methods for isolating the Micro-organisms of Putrefaction 376 Endo's Method for Detecting Typhoid Bacilli 376 Lipsuhutz, B. — Simple Medium for Cultivating Gonococcus 377 Wichmann, H., & H. Zickes— New Method for obtaining Pure Cultivation of Yeast 377 Kloumann, F. — Effect of Coffein on Typhoid and Coli Cultures 377 Petkowitsch, D. S. — Fuchsin-Agar as a Diagnostic Medium for Typhoid Bacteria 378 Statham, J. C. B. — Cultivation of the Leishman Body 378 Parkes, W. C. C, & F. H. Joseph — Use of Acid Media in Isolation of the Plague Bacillus 378 Watkins-Pitchford, H. — Bacteriology of Plague 378 Burke, J. B. — Spontaneous Action of Radio-active Bodies on Gelatin Media .. .. 524 Omelianski, W. — Formate Broth in the Differential Diagnosis of Micro-organisms 657 Bi erger, L. — Identification of Colonies of Pneumococcus 657 Blecher, C. — Apparatus for Dissolving and Filtering large Quantities of Gelatin and Agar, etc. . . . . 65S Rosenau, M. J. — Methods for Determining the Immunity Unit for Standardising Diphtheria Antitoxin 658 Tarozzi, G. — Method for Growing Anaerobic Organisms under Aerobic Conditions 659 CONTENTS. XXXV11 PAGE Marrassini, A., & R. Schiff-Giokgini — Difference of Behaviour of Bacillus typhosus and B. coli communis in Media containing Sulphate of Copper and Red Prussiate of Potash 660 Thiroux — Cultivating Trypanosomes 757 Lesage, A. — Cultivation of Amcebze 757 Kern, F.—New Bacteria Filter (Fig. 178) .. •• 758 Schouten, S. L. — Pure Culture from Celh Isolated under the Microscope (Fig. 179) 758 Cache, A. — Method for Collecting the Gas of Fermentation 761 (2) Preparing- Objects. Fuhrmann, F. — Preparing Suprarenal Bodies of Guinea-Pigs 262 Bibliography 262 Sanzo, L. — Apparatus for the Automatic Fixation of Embryos (Fig. 68) 379 Dublin, L. I. — Preparing Germ Cells of Pedicellina Americana 380 Andrews, E. A. — Removing Avian Blastoderms 380 Jones, C. Pbice — Examination of Bone Marrow 380 Myers, B. D. — Fixation of Tissues by Injection into the Arteries 380 Bibliography 381 Eosenau, M. J.— Blood Spreader (Figs. 116, 117) 525 Phillips, E. F. — Preparing and Staining Eye of Honey Bee 525 Osterhout, W. J. V. — Imbedding with Incomplete Dehydration 526 „ „ Fixat ion in Vacuo (Fig. 118) 527 Tellyesniczky, K. V. — Fixing and Staining Nuclei . . . . 660 Schlater, G. — Fixation and Staining Muscle Fibres 660 Marcus, H. — Demonstrating Blood Formation in Osseous Fishes 660 Scheben, L. — Examination of the Spermatozoa of Ascaris megalocephala .. . . 761 Nowikoff, M. — Methods of Examining the Eyes and Frontal Organs of Branchiopods 761 Stromson, F. A. — Investigating the Anatomy and Development of the Venous System of Chelonia 762 Charlier, A. — Demonstrating the Structure of Gutta-percha Plants . . .. .. .. 762 Fischer, G. — Demonstrating the Structure of the Respiratory Tract of Birds .. .. 762 Pavlow, W. — Creosote as a Dehydrating Medium for Imbedding in Paraffin .. . . 763 Konascko, P. — Injection of Fine Vessels 763 Downing, E. B. — Demonstrating the Spermatogenesis of Hydra 764 Jj6decker, C. F. — Decalcification of Dental Enamel 764 Marshall, W. S., & P. H. Dernehl — Demonstrating the Blastoderm of Polistes pallipes 765 Glaser, O. C. — Preparing Fasciolaria tulipa and its Larval Excretion Organs . . 765 Jaderholm, G. A. — Demonstrating Neurofibrils 765 Ruzicka, Vl. — Demonstrating the Structure of Red Corpuscles 7»5 Korff, K. von — Demonstrating Teeth of Mammalian Embryos 765 (3) ^Cutting, including: Imbedding- and Microtomes. New Imbedding Bath (Fig. 30) 114 Plowman, A. B. — Celloidin Method for Hard Plant Tissues 262 Small wood, A. M. — Preparing and Staining the Eggs of Haminea Solitaria.. .. 263 Reed, H. S. — Demonstrating Enzyme-secreting Cells , .. 264 Bibliography 264 Fihrmann, F. — Paraffin Imbedding Bath (Figs. 69, 70) 381 Reichert's Medium Microtome (Fig. 71) .. 382 Pi rone, R. — Use of Iodine after Fixation in Sublimate 383 York, H. H. — Agar-Agar and Paraffin Method for Imbedding Plant Tissues .. .. 527 Harman, N. B. — Accessory for Freezing Microtomes 528 Osterhout, W. J. V. — Simple Freezing Microtome ((ugs. 119, 120) 528 Leitz' New Microscope (Figs. 154-7) 661 Arndt's Double Saw 664 Reichert's Microtome with Handle (Fig. 18<>) 766 Flatter's Microtome (Fig. 181) 766 Siding, A. — Preventing Rolling of Paraffin Sections .. ., 769 XXXV111 CONTENTS. (4.) Staining and Injecting. paob Giemsa — New Method of Making Romanowski's Chromatin Stain 115 J. Q. T. — Staining and Preserving Algx 115 Marino, F. — Staining Protozoa 264 Bonhoff — Differential Staining of Bacillus Typhosus in Sections 265 Bibliography 265 Sdrinko, O. V. — Method of Differentiating the Cortical from the Medullary Portions of Adrenals 384 Joseph, F. H. — Fugent : a New Stain 384 Savill, T. D. — Staining Arteries 384 London, E. S. — Demonstrating the Finer Structure of the Nervous System .. . . 384 Bonhoff, H. — Differential Staining of Typhoid Bacilli in Sections 385 Thesing, E. — Spore Staining 385 Scagliosi — New Method of Spore Staining 385 Ruffini, A. — Method of Staining Sensory Nerve Sheaths 385 Fischer, A. — New Method for Staining Glycogen 385 Whitney — Pyronin Methyl-Green 386 Blumenthal, J. M. — Methods of Staining the Diphtheria Bacillus 386 Fasoli, G. — Staining Negri's Bodies in Hydrophobia .. .. 386 Peter, K.—New Yolk Stain .. .. 386 Foa, P. — Demonstrating Fatty Infiltration in Tissue 387 Bibliography 387 Mendoza, A. — Staining the Tubercle Bacillus with Eosin 529 McWeeney, E. J. — Staining the SpirochxtsB of Syphilis 529 Curtis, & P. Lemoult— Affinity of Artificial Colouring Matters for Connective Tissue 530 Halphen, G., & A. Riche — Tlieory of Histological Staining 530 Miller, E. F. — Multiplex Slide-holding Device for Staining Sections 530 Leszczynski, R. — Differential Stain for Gonococcus 664 Managetta, G. Beck von — Persio-acetic Acid as a Stain for Vegetable Tisstie . . 664 Nabias, B. de — New Method of Rapid Staining Nervous Tissue ivith Gold Chloride 664 Skrobansky — Method of Contrast Staining with Bleu-de-Lyon and Picric Acid . . 665 Mendoza, A. — Staining Tubercle Bacillus ( JG5 Buerger, L. — Neio Method of Capsule Staining 665 Deflandre, C. — Demonstrating Fat in the Animal Liver 665 Dogiel, A. S. — Staining Nerve Endings in Skin of Mammals 666 Pugh, W. T. G. — Examination of Cultures and Smears from Throat and Nose . . 666 Bethe, A. — Staining Nerve Fibrils 666 Sanzo, L. — Use of Electrolysis for the Metallic Impregnation and Staining of Tissues 666 Burton, J. — Easy Method of Staining and Mounting Algx and Fungi 769 Neumayer, L. — Apparatus for Staining simultaneously Numerous Sections (Fig. 182) 770 Gemelli, A. — Demonstrating the Neurofibrils in Ganglion Cells .. 771 Melissinos, K. — Apparatus for the Simultaneous Staining of Several Sections fixed to Cover-slips or Slides (Fig. 183) 771 Merton, H. — Examination of the Retina of the Nautilus and certain Dibranchiate Cephalopods 772 Ruzic'ka, Vl. — Theory of Vital Staining 773 (5) Mounting-, including- Slides, Preservative Fluids, etc. Shattock, S. G., & C. F. Selous — Two Methods for Comparing Normal with Abnormal Tissues under the Microscope 116 Collins, J. R. — Hanging-Drop Preparations 117 Horder, E. — All- Metal 'Cover-Glass Holder ("Fig. 31) 117 Bibliography 118 Powell. J. G. R. — Copal as a Mounting Medium 387 Walsem, G. C. van — Method for Removing Small Quantities of Centrifuged Deposit 387 Osterhout, W. J. V. — Imbedding Microscopic Algx 530 „ „ Rapid Method of Mounting in Aqueous Media (Fig. 121) .. 532 „ „ Simple Slide-holder 532 CONTENTS. XXXIX PAGE Merlin, A. A. C. E. — Modification of the Rousselet Live-box (Fig. 122) 532 Mair, \V. — Method for Freeing Paraffin from Cedar-wood Oil .. 533 Fowler, E. S. G. — Method for Preserving Bacterial Cultures for Class Purposes .. 533 Bibliography 533 Cristina, D. — Method for Mounting Celloidin Sections 774 Fiorentini, P., & M. .Signer— Method of Staining and Permanently Preserving Urinary Sediment 774 (6) Miscellaneous. Bohm & Oppel's Microscopical Technique ilS Bibliography 118 Schlapfer, V. — Modification of Cornet's Forceps (Fig. 72) 38S Marx, H., & E. Ehnkooth — Simple Method for Distinguishing between Human and Animal Blood 388 Fleischmann, A. — Apparatus for making Wax Plates for Reconstruction Models .. 389 Bies, J. — Needle for obtaining Blood for Examination (Fig. 73) 389 Breuil, P. — Examining Caoutchouc by the Aid of the Microscope 389 Bibliography 389 Lee, A. Bolles — Microtomists' Vade Mecum 667 Bibliography 667 Parker, F. St. John — Keeping Polyzoa 774 Metallography, etc. Turner — Hardness of Metals 118 Fremont, C. — Possible non-brittleness of Steel under certain conditions 119 Bose, T. K. — Certain Pro/ >erti*s of Alloys of Silver and Cadmium 119 Stead, J. E. — Sulphides and Silicates of Manganese in Steel 265 Bibliography 266 Stead, J. E. — Micro-Metallography with Practical Demonstration 273 „ „ Methods for Detecting the more Highly Phosphorised Portions in Iron and Steel (Plates V. and VI.) 284 Wedding, K. H. — The Defects in Ingot-Iron Castings 390 Smeaton, W. C. — Notes on the Etching of Steel Sections 390 Hopkinson, B. — The Effects of Momentary Stresses in Metals 391 Kosenhain, W. — Further Observations on Slip-Bands in Metallic Fractures. Pre- liminary Note 391 Crocker, E. G. — Iffects of Stress upon Metals 391 Kourbatoff, M. — Metallography of Quenched Steels 392 Lejeune, P. — The Cooling of Steel in Quenching 392 Guillet, L. — Aluminium Steels 392 Bibliography 392 Glazebrook, K. T., & H. le Chatelier — International Committee for Investi- gating the Constituents of Steel 534 Guillet, L. — Cobalt Steels 534 „ „ Classification of Ternary Steels 535 Sauveur, A. — Metallography Applied to Foundry Work 535 Osmund, F., & G. Cartaud — Scientific Development of the Art of Polishing .. .. .r>:{5 Breuil, P. — Special Constituent Obtained by Quenching Aluminium Bronze . . .. 536 Bibliography 536 Hall, E. H. — Thermal and Electrical Effects in Soft Iron 668 Braune, H. — Influence of Nitrogen on Iron and Steel 668 Lecarme, J., & H. le Chatelier — Brittleness of Cemented Mild Steels 669 Chatelier, H. le — Technique of Microscopic Metallography 669 Guillet, L. — Alloys of Copper and Aluminium 670 Heyn, E. — Constitution of Iron-Carbon Alloys 670 Sauveur, A. — Metallography applied to Foundry Work 671 xl CONTENTS. rxaz Honda, K., & S. Shimizo — On the Magnetisation and the Magnetic Change oj Length in Ferromagnetic Metals and Alloys at Temperatures ranging from -186° C. to +1200° C 671 Bibliography 672 Hanks, H. Or.— Notes on il Aragotite," a Rare California Mineral 673 Saniter, E. H. — Etching of High Carbon Steel 775 Hadfield, R. A. — Metallography of Iron and Steel 775 „ „ Experiments relating to the Effect on Mechanical and other Properties of Iron and its Alloys produced by Liquid Air Temperatures 775 Carpenter, H. C. H. — The Types of Structure and the Critical Ranges on Heating „ ,. and Cooling of High Speed Tool Steels under Varying Thermal Treatment 776 Rogers, F. — Heat Treatment and Fatigue of Steel 776 Hopkinson, B., & F. Rogers — The Elastic Properties of Steel at High Tempera- tures 776 Sauveur, A. — Metallography Applied to Foundry Practice 777 Gutllet, L. — Special Steels 777 Dejean — Induction Galvanometer for the Study of Freezing and Critical Points .. Ill Mellor, J. W. — The Crystallisation of Iron and Steel 777 Bibliography 778 PROCEEDINGS OF THE SOCIETY. Meeting, December 21, 1904 120 January 18, 1905 131 February 15, , 267 „ Marcti 15, „ 270 April 19, „ 394 „ May 17, , 397 „ June 21. „ 537 „ October 18, „ 779 „ November 15, „ , 781 General Index to Volume 785 JOURNAL OF THE ROYAL MICROSCOPICAL SOCIETY FEBRUARY, 1905. TRANSACTIONS OF THE SOCIETY. I. — TJie Tlieory of Highly Magnified Images. On the Diffraction of an Object-Glass with Circular Aperture. By Sir George B. Airy. Philosophical Transactions, vol. v. p. 283. The Theoretical Limits of the Besolving-Power of the Microscope. By Professor Helmholtz. Poggendorjfs Annalen, 1874, Jubelband, p. 569 ; Wissenschaftliche Abhancll ungen , vol. ii. p. 185. On the Theory of Optical linages, with special reference to the Microscope. By Lord Bayleigh. Philosophical Magazine, 5th scries, vol. xlii. p. 167 ; Journ. B.M.S., 1903, p. 447. On the Theory of Optical Linages, with special reference to the Microscope. Supplementary paper. By Loi'd Bayleigh. Journ. B.M.S., 1903, p. 474. By J. W. Gordon. (Read December 21st, 1904.) Synopsis. — For the convenience of readers who may like to have the theory of high magnification in a very compendious form, the following synopsis of this paper is submitted : I. The image formed by any aperture of a luminous point is an illuminated area, the shape and dimensions of which depend upon the form and size of the aperture (Airy, p. 5). II. The focussed image of such a point is an antipoint, the shape of which is derived from the shape of the aperture by a rule of inverse resemblance, so that the antipoint is narrow across any diameter across which the aperture is broad, and vice versa. Tins rule of inversion results, in the case of a symmetrical aperture, in an approximate reproduction by the disc of the antipoint of the form of the aperture turned through an angle of 90' (Airy, p. 5). III. In the case of a circular aperture, transmitting a beam in which the light arrives at the aperture in the form of plane wave- Feb. 15th, 1905 B 2 Transactions of the Society. fronts, the form of the antipoint is a circular disc surrounded by- rings, the disc having a radius estimated by Sir George Airy at 2^ (Ail'V' r' 5)' IV. In the case of a circular antipoint the light amplitudes vary in successive zones according to a numerical law illustrated by fig. 2, on p. 6 (Airy, p. 6). V. The law of diffraction from spherical wave-fronts is such that, if F be the radius of curvature of the wave-front where it passes the aperture, and 6 be the angle to the axis of collimation of the axis along which a beam of parallel light passing the same aperture would be diffracted, the diffracted cone will come to focus in the focal plane at a point distant by sin 0.F from the axis of collimation (Helmholtz, p. 10). VI. The dimensions of the antipoint depend only upon the divergence angle of the focussed beam, and are in no way deter- mined by the magnitude of the aperture causing diffraction (Helm- holtz, p. 11). VII. If any optical system yields a correct — that is to say, a flat and aplanatic — image of a plane object, the law of magnification in that system will be that the conjugate images will be propor- tioned to one another inversely in the ratio of the sines of the divergence angles of the beams by which they are severally formed. Thus the law of relative magnitudes is the same for conjugate images as for conjugate antipoints (Helmholtz, p. 12), and, therefore, VIII. The state of resolution of a correct image cannot be either improved or impaired by mere change of scale brought about by eye-piece magnification or otherwise, but depends only upon the angle under which incident light is received from the object (Helmholtz, p. 12). IX. If two beams of light, although originating in independent light sources, follow very closely adjacent and nearly parallel paths, so that they interpenetrate one another, they will modify one another where they interpenetrate, and may thereby become attuned to one another almost as if they had had a common origin, and so as to be capable of exhibiting all the phenomena of interference (Eayleigh, p. 16). X. The limit of resolving power is not simply a question of the propinquity of luminous objects, but depends in a material degree upon the phase relations of the light by which they are severally rendered visible (Eayleigh, p. 17). XI. A dark bar on a bright field may theoretically be visible as a boundary between adjacent luminous areas if it has a breadth of -^ X and, under favourable conditions of illumination, even if its breadth be less than this (Eayleigh, p. 18). XII. Is the antipoint itself polyphasal ? The black and white dot phenomena discussed in the light of this hypothesis (p. 19). Highly Magnified Images. By J. W. Gordon. 3 The theory of the formation of the image in a Microscope as at present developed is to be found, so far as I am aware, in the papers above enumerated. Having regard to the great interest and importance of the subject, one must consider this a singularly meagre list, and it is, no doubt, incomplete, since I have depended ex- clusively on my own reading, which is but fragmentary. I shall no doubt be asked why I have omitted to notice the many papers which have been written in recent years upon the so-called Abbe theory. The answer to that question is very simple, but I must preface it by protesting once more against the use in this connection of Professor Abbe's name. Something of discourtesy is involved in thus making a distinguished man responsible for an hypothesis which he never fully formulated, and has of late explicitly disavowed. Lord Eayleigh has proposed the name " spectrum theory " (Journ. E.M.S., 1903, p. 450) for one of its many forms, but this term has not in fact become current, and if it had it could hardly express the whole confused body of mutually in- compatible speculations winch go under the name of the Abbe theory. For tins is a case in which quot homines tot scntcntice. It seems impracticable therefore to break away from the accepted nomenclature, and I employ it under protest and with a sincere ■apology to Professor Abbe whose name is thus misused. Mention has just been made of the confused variety of theories which go by this generic name. But they all have one point in •common. That is to say, they all set out to explain the image of the object seen in the view plane of the instrument by the image of some- thing else seen in another plane, usually by the image of the source of light seen wherever its image may happen to fall in the tube of the instrument, or by the image of a theoretical source of light seen in the principal focal plane of the objective. JSTow quite apart from the obvious criticism that this image of the source of light itself stands in need of explanation and of the same explanation as that which the image in the view plane demands, there is another and even 'more fatal objection to any theory which proceeds upon these lines. For the calculations necessary to connect these two disconjugate images one with the other cannot be made, the reason being that the conditions of aplanatism in the one plane imply a want of aplanatism in the other plane. Thus, if we assume an objective to be so corrected as to yield a flat and aplanatic image in the view plane of a flat object on the stage, that assumption implies two things about the lengths of the optical paths : (1) that all paths from the aperture to a given point in the image are equal, the aperture being, for this purpose, taken to coincide with a plane wave-front, coming to focus in that point ; and (2) that all points in the object are equidistant optically from their conjugate points in the image. The first of these follows immediately from the well- known theorem concerning the equality of optical paths between b -1 4 Transactions of the Society. a point and its image. The second is a corollary, easily deducible from the first, which establishes the equality of all optical paths between a flat object and its flat image formed according to the sine law.* Both may be comprised in the one proposition, namely, that in a fully corrected system all paths between the aperture and the focal plane are equal. Now it is obvious that this proposition can- not lie true for two discon jugate focal planes. The following diagram will make this clear. Here let Sx S2 S3 be the aperture, and let Px P2 be central points in two disconjugate focal planes. Then if the system be aplanatic for the point P2, all optical dis- tances between the aperture Sx . . S3 and the point P2 will be equal to one another. In like manner, if we assume that the system is aplanatic also Fig. 1. for the point P1} we shall have all paths between the aperture Si . . S3 and the point Pi equal to one another, and therefore the path S3. .Pi is optically equal to the path S2. .Pi. Let S3..PX be extended to P3 and make Px . . P3 = Px . . P2. Wherefore the path S3 . . . P3 = the path S2 . . . P2, and therefore P3 is a point in the image formed by the aperture Sa . . S3 of a plane surface con- jugate to the surface in which P2 and P3 lie. But by construction this last-named surface is not a plane but a sphere having its centre at P^ and the optical system occupying the aperture Si. .S3 is not corrected to give a flat image in this region. If we make the necessary correction to yield a flat field it is clear that we shall incidentally render the point Pi non-aplanatic, and it follows therefore that no optical system can be fully corrected so as to be * This second proposition does not appear ;to be so generally understood as the first. A regular proof of it is given in a note — Note I. — in the appendix to a p.iper on the Helmholtz Tlieorv of the Microscope, which I had the honour of laying before the Society in 1903 (Journ. E.M.S., 1903, p. 420). Highly Magnified Images. By J. W, Gordon. 5 uplanatic and yield a flat image in two planes not conjugate to one another. Now it is manifestly impossible to compute the light phase in a region where the optical system is non-aplanatic, for in that case the phase is wholly indeterminate, and hence it is im- possible to make the image formation in the plane through P2 dependent upon that in the plane through Px, or vice versa. Coming now to what has been accomplished in the way of constructing a theory of the image formed by a Microscope, the fundamental proposition is worked out in Sir Geo. Airy's paper, and may be formulated thus : — I. The image formed by any aperture of a luminous point is ■an illuminated area, the shape and dimensions of which depend upon the form and size of the aperture. II. The focussed image of such a point is an antipoint, the shape of which is derived from the shape of the aperture by a rule of inverse resemblance, so that the antipoint is narrow across any diameter across which the aperture is broad, and vice versa. This rule of inversion results, in the case of a symmetrical aperture, in an approximate reproduction by the disc of the antipoint of the form of the aperture turned through an angle of 90°. III. In the case of a circular aperture, transmitting a beam in which the light arrives at the aperture in the form of plane wave' fronts, the form of the antipoint is a circular disc surrounded by 1*2 A, rings, the disc having a radius of „-. , and the dark rings sur- ° ° 2 sin u ° rounding it being situated at radial distances which tend to become equal to 0 . - for the nth dark ring. In these expressions X = _j S1H '10 the wave-length, u = the divergence angle of the focussed beam, and n is any integer. The inner rings have, as here shown in the case of the first ring, a somewhat greater radius than^ — = — .* °' ° 2 sin. u IV. Sir Geo. Airy calculates and gives in the form of a table the comparative amplitudes of the light undulation at selected zones in the circular antipoint. Plotted down, his amplitudes are proportional to the ordinates of the curve in fig. 2, where the calculated results are shown by the points of intersection of the curve with the scale rulings. The intermediate values are deter- mined graphically by carrying a continuous curve through the calculated points. This curve, and the table given by Sir Geo. Airy in the paper cited, are open to the criticism that they express only the semi- * This is the accepted description of the antipoint formed by a circular aperture, and is given here upon the authority of Sir Geo. Airy. The present writer submits considerations bearing upon it in a note subjoined to this paper (below, p. 25). 6 Transactions of the Society. amplitude, and consequently show negative values for the cal- culated amplitude in certain parts of the light curve. For the mere determination of relative magnitudes this is unimportant, since semi-amplitudes must have the same proportions inter se that the corresponding amplitudes have. But when we go further and ask what is the resulting amplitude if two adjacent and isophasal antipoints encroach the one upon the other, it then becomes im- portant to realise that the negative values in Airy's curve do not i n n-<» / \ 0 8 / \ 0-7 j 1 \ O-fi r- I / V fl-A 1 1 / \ 0-4- | / \ 0-3 / \ CVS 1 / \ 1 0-1 f 0 0- I _^ 0-2 i 0-3 "1 0-* -3 A 2 siu u -2 A 2 sin u -K 0 Fig. 2. 2 sin u 2\ 2 sin u 3A 2 sin a count against the positive. The coincident amplitudes have then to be compounded according to the relative retardation of the one as compared with the other ; whether expressed as positive or nega- tive quantities on Airy's curve makes no difference for this purpose. The following diagram will make this clear. Here, in fig. 3, we have the full amplitude curve of the " false disc," and it will be observed, that at every point it has a positive and a negative half, each equal in point of mere magnitude to the other. Hence the full ordinate is in this curve proportional at every point to Airy's ordinate, but on the other hand no one has either a positive or a negative value, and any two may be compounded indifferently either by addition or by subtraction. This corresponds to nature, for, in fact, two ordinates are to be compounded by addition when they have a phase difference of n X, n being any integer, and [are to be compounded by sub- Highly Magnified Images. Bg J. W. Gordon. 7 traction of the lesser from the greater when they have a phase 9 1 difference of ^— X. The general expression of which these two are particular examples, and by which any two amplitudes At and A2 having a phase difference ***' 7r may be compounded is : A. • (1) A(1 + 2) = A: 4- cos ^ 2 7r A2 . or, more generally still, if we assume that both the components At Fig. 3. and A2 are affected with retardation relatively to the phase of the resulting disturbance, we may write these retardations ?~ 2 tt /v and — 2 2 7r respectively. Then the two amplitudes in question A. may be compounded thus A(1 + 2) — < Aj cos ^ 2 7r + A2 cos ^ 2 7T > . . (2) Sir Geo. Airy's table contains the constants A1; A2, etc., required in this equation, and clearly its calculated value would be largely 8 Transactions of the Society. affected if certain of the constants employed were affected with a negative sign and others not. For this purpose, therefore, the emendation of Sir George Airy's table is of importance. Of the antipoint formed by a star in the image plane ot a telescope, Sir Geo. Airy's theory affords a sufficient explanation subject only to very small corrections, and that, in truth, is all that its author set himself to explain. But as it stands in the 'Philosophical Transactions,' the theory is not directly applic- able to the image formed by a Microscope, and this for two reasons : . . . , , 1. The Microscope receives upon its objective not plane but spherical wave-fronts of incident light ; and 2 The object on the stage of the Microscope, even when very minute, is not infinites imally small, like the disc of a star seen in the heavens, but is always of finite dimensions and usually ot sensible magnitude. In order to adapt the Airy theory to the case ot the Micro- scope both these new conditions must be investigated— that is to say the law of diffraction from spherical wave-fronts must be ascertained and substituted for the law of diffraction from plane wave-fronts as the basis of the theory, and the diffraction fringe formed about a small finite area must be substituted for the anti- point curve as the boundary region between light and dark areas. So the problem stood when, in 1874, Prof. Helmholtz; con- tributed his paper to ' Poggendorff's Annalen.' The paper was a composite, put together confessedly under great pressure ot time and apparently comprising, to judge by internal evidence, three constituent fragments tumbled together without sufficient or effectual editing. It is proper to recall these circumstances when discussing Helmholtz' paper, for they explain its limitations; they explain, for example, how it should have come about that Prof Helmholtz, while he solved the first half of the problem, and showed how to adapt Airy's theory to an instrument re- ceiving spherical wave-fronts, left the second half unattached, and incautiously assumed that the diffraction fringe of the smallest visible luminous area would be indistinguishable from the section of an antipoint. Such shortcomings are the results ot precipi- tation, which betrayed even the great Helmholtz into serious l°But it is his solution of the first part of the problem which concerns us, and this is so elegant that, formidable as the problem itself looks, the solution can be stated in a few words if we confine ourselves to results, referring the reader to other sources ot information for the demonstration. • There is another point affecting the form of the curve discussed in Note I. (below, p. 30 (6) ), in respect of which it may turn out that Sir Geo. Airy « resulta require correction. Highly Magnified Images. By J. W. Gordon. 9 Let e in fig. 4 be a point on the stage of a Microscope. Let P be the principal plane of the objective. Let A be an aperture which limits the diameter of the transmitted beam, and let rj be the point in the image plane conjugate to e. The question is to find an expression for the diameter of any given zone in the antipoint formed about ij by the aperture A. Fig. 4. Helmholtz' solution of the problem may be stated thus : Let A in the following diagram (fig. 5) be the given aperture, liaving rectilinear boundaries; a. . a, the axis of collimation, and rj the "point upon that axis to which the transmitted wave-front converges Also let al. . ,a1} intersecting the axis a. . .a at an angle 6, be the axis along which the diffracted beam in question would be Fig. 5 . deflected if the wave-fronts passing the aperture were not spheri- cal but plane wave-fronts. Then, by the known law of diffraction, sin 6 = y> the symbol being used to express in terms of X the retardation of the most retarded ray in the diffracted beam. Now it is plain that the axis alt . .ax will intersect the perpendicular plane through r) — which may be called the focal plane — at a point rji so situated that its axial distance 7} . . . r)i = tan 0 (e . . . rj) . . . , (3) 10 Transactions of the Society. In like manner the aperture A may be expressed in terms of the divergence angle u thus A = 2 tan u (c . . . rj) . . . . (4) and dividing (3) by (4) we obtain for a parallel beam of light the following equation between the diameter of the aperture and the diameter of the unfocussed antipoint — V • • • Vi tan 0 /"">\ — — . a . . . V-*/ A 2 tan u V. Helmholtz deduces for the case of the spherical wave-front focussed upon rj a law from which it may be inferred that in that case the expression (5) becomes p_= jin0 (6) A 2 sin u where p is written for the radius of the antipoint, or rather of that zone in the antipoint which is formed by the focussing of those diffracted beams which have the retardation = , and is, therefore, a general expression for (77 . . . rjx). This last expression can be further simplified. For in the case of an aperture with straight parallel edges, the value of 6 in a plane perpendicular to the edge is known to be, as above stated, such that , sin 0 - ?., A whence is equal to one complete cycle of phase change, and may therefore be expressed by one wave length. Thus we obtain the well-known expressions P — s— • — or p = 1*2 . -, 2 sin u 2 sin u according as the aperture is limited by a rectilinear or by a circular boundary. 1 -2 \ * The expression - is very approximately correct, if we adopt Sir Geo. 2 sin u Airy's equation for the antipoint light curve, for the inner zone3 (say those within the boundary of the false disc) of the circular antipoint— with which alone we shall be concerned in the present paper. In the outer zones the circular anti- poirt tends to conform to the dimensions of the rectilinear antipoint, that is to say,. A 2 sin u Highly Magnified Images. By J. W. Gordon. 11 From this result several very important inferences may be drawn. Thus, since the expression is independent of the 2 sin u dimensions of the aperture, we may infer that — VI. The dimensions of the antipoint depend only upon the divergence angle of the focussed beam, and are in no way determined by the magnitude of the aperture causing diffraction. This sounds surprising, for we know that the sine of the diffraction angle is inversely proportional to the diameter of the aperture, and are apt to assume that the dimensions of the antipoint will vary in a similar fashion. But a little reflection suggests that the divergence angle must have more to do with the diameter of the antipoint than has the breadth of the aperture, for, the divergence angle remain- ing unchanged, the distance of the aperture must be proportional to its diameter. Fig. 6 illustrates this relation. Here, whether we take the aperture to be A1} A2 or A3, it is Fig. U. plain that the sine of the diffraction angle multiplied by the dis- tance of the aperture from the point rj will be a constant quantity = •— ? — ; in other words, the antipoint will be un- 2 sin u changed whatever change may take place in the length of the beam, provided that its divergence angle remains unchanged. From this principle Helmholtz deduces a very elegant result. Since the antipoint depends only upon the divergence angle of the focussed beam, it can make no difference to it, and no difference therefore to the state of resolution of the image at what point in the system the diaphragm is placed, by which the beam is defined and diffraction caused. Therefore the actual dimensions of the antipoint will be determined by that aperture which has the smallest optical projection upon the principal plane of the entire optical system. Furthermore, it is clear that there can only be one such aperture, and therefore, whether we consider the beam to be transmitted upward towards the ocular and out through the eye- 12 Transactions of the Society. lens, or downwards towards the objective and out through the front lens, in either case we shall have to deal with the same limiting aperture, and both the actual antipoint in the real image and the theoretical antipoint produced in the object by Reverted beam will depend simply on the divergence angles in the front and back of the instrument respectively. We thus see that a simple numerical relation can be established between conjugate antipoiuts, but for the fuR significance oi this proposition we must consider it in the light of another, which also we owe to Helmholtz and find in this paper, and which connects conjugate images by the same law. For Helmholtz shows that i any Optical system-no matter how simple or how complicated -yields a correct (i.e. a flat and aplanatic) image ot a plane object, the law of magnification in that system will be— YII The conjugate images will be proportioned to one another inversely in the ratio of the sines of the divergence angles ol the Fir,. 7. beams by which they are severally formed. Diagrammatically, if in fig. 7 e be an object (or an image) and 77 its conjugate image sin ue € " sin «t) (9) It is evident that a similar rule with regard to antipoints can be deduced from equation (8). For , putting p, and pv tor the diameters of the conjugate antipoints, we have

an(i sm u cannot be greater than 1. If then we 1*2 write 2 p = 1 • 2 X = — inch, we shall have the smallest anti- 50,000 point that can by any possibility be obtained with green light of the wave-length mentioned. "What, then, must be the minimum separation of two bright objects which are by means of such an antipoint to be separately delineated ? This is the much discussed and profoundly interesting problem of the limit of resolving power. Professor Helmholtz, although he approached this problem, as we have seen, by a series of most masterly attacks upon what may be called its outworks, did not drive his attack home or succeed in capturing the citadel itself. It is not difficult to realise what re- mained to be done. The form, dimensions and illumination of the antipoint being taken to be known, it becomes in the next place necessary to consider how the overlapping of adjacent antipoints will affect the appearance of the field in which they lie. This, clearly, is a problem of great complexity, for antipoints may overlap in all imaginable degrees, from complete coincidence, as one extreme case, to complete separation as the opposite extreme. Moreover, any number of antipoints may overlap, and with varying degrees of encroachment upon the common area, thus giving rise to still further complexity. Helmholtz did not essay the regular solution of this problem ; it appears, indeed, from a postscript appended to his paper, that the necessary time was not at his command. But he thought that the extreme case could be very simply stated, and in effect he stated it as follows. Let Ax A2 in the following diagram (fig. 8) be two adjacent antipoints winch encroach upon one another. What is the smallest distance between their centres at which they can be discerned as separate objects ? The figure shows pairs of antipoints. The members of the first pair may be assumed to be indistinguishably merged in one another. The mem- bers of the third pair may be taken to be unmistakably distinct. If we assume the second pair to be at the limit of resolving-power, what will be the calculated distance of their centre points from one another? This would be the exact statement of the problem of the resolving limit as Helmholtz conceived it. But putting aside Highly Magnified Images. By J. W. Gordon. 15 refinements, he selects a case well, as lie supposed, within that limit, and propounds it thus. Taking a median section of the paired Fig. 8. antipoints, as shown by the section lines in the figure, he first draws their light intensity curves calculated by Sir George Airy's formula, next he adds together the ordinates of the overlapping parts of the curves, and so obtains the total light intensity curves •■shown by broken lines in fig. 9.* When the distance between Fig. 9. the two centres = p or < p, the total curve will show, as in the first and second pairs of the figure, no more than one maximum, whereas the widely separated members of the third group will yield two maxima as shown. Hence Helmholtz concluded that a centre to centre distance = p would be too small for the representation of the .two adjacent points as separate objects. This rule would of 1 *2 \ course ^ive a limit of c = — =— in the case of a circular aperture 2 sin u L if we write c for the centre to centre distance now under discussion, * The curves shown are actually reduced copies of Airy's Amplitude curve. The resulting inaccuracy is not conspicuous, and will not, it is hoped, occasion the reader any difficulty. 1G Transactions of the Society. but Helmholtz, not putting this forward as an exact solution, did not in fact state it with so much precision. He was content to say, using a merely approximative figure, the limit of resolving power must necessarily be > c = . . This is the well-known limit 2 sm u which on his authority and that of Prof. Abbe has been adopted by almost all subsequent writers upon die Microscope as the ulti- mate and necessary limit beyond which its performance can never go. It is a curious circumstance that both Helmholtz and Abbe should have fixed upon this expression. It is not, as has just been shown, the true result of Helmholtz' theory, but a figure arbitrarily selected as lying within the true limit, and Abbe was led to it by considering the rather fanciful question as to how a picture could be formed of an object illuminated by a beam of light having a divergence angle = 0. It is a mere coincidence, but a very strange one, that two such widely different attempts to solve the problem should both lead to the same result, and that an erroneous result. It is perhaps less surprising that the error so authenticated should have passed undetected and even unchallenged until 1896. In the last-named year Lord Eayleigh published a paper in which the whole subject was reviewed, the inadequacy of Prof. Abbe's treatment of it was pointed out, and a very pertinent inquiry started as to whether Helmholtz' method of obtaining the values of his total light curves (see fig. 9 above) took due account of the phase relations of contiguous antipoints. So long as we concern ourselves only with light intensities (ignoring the light amplitudes) no question of phase relation and resulting inter- ference can arise ; and it is commonly assumed by physicists that unless two beams of light originate in the same incandescent particle they must be independent as to phase, and cannot, there- fore, exhibit the phenomena of regular interference. This is only very imperfectly true, and Lord Piayleigh in this paper showed that — IX. If two beams of light, although originating in independent sources of light, follow very closely adjacent and nearly parallel paths, so that they interpenetrate one another, they will modify one another where they interpenetrate, and may thereby become attuned to one another almost as if they had had a common origin, and so as to be capable of exhibiting all the phenomena of interference.* It now appears that the results of overlapping must be more complex than Helmholtz had assumed, and Lord Eayleigh illustrates this fact by taking three typical cases. He assumes (1) that the over- * This interference of light beams from independent sources would seem to have been illustrated by a very elegant experiment devised by Dr. Johnstone Stoney. and demonstrated by him at a Meeting of the British Association. See Rep. B.A., 1901, p. 574. Highly Magnified Images. By J. W. Gordon. 17 lapping antipoints are attuned and to the same phase ; (2) that they are attuned, but with a phase difference A = - ; and A (3) that they are independent as to phase. The result of con- sidering case (2) is very remarkable, for it then appears that, how- ever close the centres may be, the antipoints will be seen, if at all, as separate objects. If they were to coincide exactly it is obvious that the light of the one would quench that of the other, and if they were separately of equal brightness the one to the other they would become invisible. In any case, if the centres be separated by a distance, how small soever, the middle point between those centres must be a point of darkness and, there- fore, a dark boundary must separate the two illuminated areas. Here then we have an unlimited resolving power. It thus appears that — X. The limit of resolving power is not simply a question of the propinquity of luminous objects, but depends in a material degree upon the phase relations of the light by which they are severally rendered visible, and from this it follows as a practical inference that the expedient of controlling the phase relations of adjacent antipoints — if we can find the means of applying it — will give us command of a resolving power beyond the Helmholtz limit, and possibly beyond any limit that can be assigned. To this point we shall have occasion to recur upon a later page in this paper. There is still another point in respect of which Helmholtz' result invites criticism. As already stated, the limit which he named was not put forward as an exact or calculated limit, but as a result of which actual practice must always and necessarily fall short, and fall short by a considerable measure. He took the anti- point as the extreme case of a very small surface, and argued that if two antipoints could not be separated from one another, the two finite surfaces on the confines of which these antipoints lay must in like manner be inextricably fused together. There is here a very singular oversight, the nature of which may be exhibited by a diagram. In fig. 9 {ante, p. 15) any one of the six curves shown represents the light amplitude curve of an antipoint, but that of a luminous area in which antipoints stand side by side and close to one another, overlapping as completely as may be, will be represented by the curve of the following figure (fig. 10). It is clear that the full brightness of the luminous area is not developed at its very edge, but at a distance = _ . - measured inward from the J ° ' 2 sin u edge. Moreover, the light intensity here, even if the antipoints have no determinate phase relation inter se, will be double the intensity at the true focus of a single antipoint, and if, therefore, we Feb. 15th, 1905 c 18 Transactions of the Society. have in place of the two antipoints postulated by Helmholtz two luminous areas having each a transverse diameter at least = . ° sin u these areas may be clearly distinguishable, even though their X adjacent edjres are separated by a distance •< 0 J ° l J 2 sin u The problem of resolving power which thus emerges, when the case is considered of two small luminous areas uf finite dimen- sions, having each a diameter of not less than measured away ' ° sin u J from the bounding edge, engaged the attention of Lord Eayleigh in 1903, and one particular case of it was treated in a paper which he communicated to this Society, being the last of the paper.s enumerated at the head of this article. Lord Eayleigh assumes two such areas separated by a dark bar, and calculates by the method of his former paper what in that case would be the minimum breadth of such a dark bar, which would visibly separate the field into two luminous areas. XL The result varies ac- cording to the reciprocal phase relation of the adjacent lumi- nous edges. If these have a constant phase difference A () = ^ X the bar will be a visible boundary, however narrow. But if the phase difference A () = 0, that is to say, if the same wave-front extends beneath the bar and illuminates both the separated areas — the worst case — then the bar must have a minimum breadth = fe X. If, on the other hand, there is no phase relation, and therefore no regular interference, the bar will still be visible, although it has a breadth no greater than ^ X. Here, at last, we begin to get into touch with fact. The conditions which Lord Eayleigh stipu- lates for in this paper are such conditions as may possibly arise in practice. Luminous areas and dark bars of the small but finite dimensions named are objects which the microscopist is actually concerned at times to see, whereas a luminous point — the word " point " being used in a mathematical sense — is a figment of the scientific imagination and a single antipoint is what no man has seen or ever will see. Fig. 10. Highly Magnified Images. By J. W. Gordon. 19 But Lord Rayleigh's results, although eminently suggestive and ■stimulating to further investigation of this profoundly interesting •subject, are by no means exhaustive. The dark bar is not the essential and ultimate element of the microscopic picture. The black dot is even more familiar and more profoundly important to the microscopist. He would like to know how small it may lie and yet remain visible, and he would like to know also how its appearance is modified by the laws of antipoint structure. The investigation of the case of the dark bar has yielded results so striking and so full of promise that he grows naturally impatient to have the case of the black dot similarly examined. The dark bar has only one finite dimension, the black dot two finite dimensions, and therefore it offers a problem of considerably increased complexity for solution. But on the other hand the solution is of higher value in at least an equal measure, for whereas the dark bar is an element in certain pictures only, the black dot is an element in all, and the most significant element of some of the pictures which have the highest significance for microscopists and for humanity. The problems connected with the black dot constitute thus at the present time the great terra incognita of the theory of the Microscope. But exploration in this region, promising as it is of results of the most profound significance and of the greatest prac- tical importance, will certainly miscarry if it proceeds upon a false postulate, and in this connection there is a question concerning the structure of the antipoint which has apparently escaped attention down to the present time, but which must needs be asked and answered as a preliminary to any secure advance. In all these investigations, thus far discussed, it has been tacitly assumed that the antipoint is itself monophasal. But this has never been proved and it does not stand to reason. It is quite possible that the successive zones of the antipoint differ not only by a gradual change of light intensity but also by a gradual change of phase, and if this be so it will have a most pronounced effect upon the phenomena of overlapping antipoints. The discussion of this question from the theoretical standpoint involves too much detail to be incorporated here, and is therefore relegated to a note.* But the experimental proof may well be noticed in this place. Let it be assumed, then, that the structure of a given antipoint involves not only a variation of light intensity according to Airy's law but also a gradual change of phase resulting in a retardation equal to ^A, between the centre of the false disc and its boundary. Such an antipoint may be represented diagrammatically by fig. 11, where the false disc of the antipoint is arbitrarily cut up into five concentric zones, and the symbol cf> by its inclination indicates the corresponding change of phase. It is clear at once that two such * See Note on p. 25 below. C 2 2d Transactions of the Society. antipoints, placed so as to overlap one another, would yield total amplitude curves very unlike those which we have been consider- ing, so that all the results so tar reached must be considered precarious if this new hypothesis be entertained. There are also certain phenomena highly characteristic of this graduated antipoint of which the monophasal anti- point affords no kind of explanation. To these we may now proceed. It is necessary for this purpose to investigate the law according to which a polyphasal surface such as that of fig. 11 must be propagated, and for this purpose we may provisionally* have recourse to the well-known principle of Huyghens. Let E. . .E of fig. 12 be such a surface, and let the derived surface r...v be drawn parallel to it and at a distance = X from it. Then the surface r . . . r will exactly reproduce the surface E . . . E as shown, the final phase in every ray being equal to the initial phase + \. If we trace another surface, r* . . .ri} midway between these two, we shall have a third surface in which the phase on any given ray is intermediate between the initial and the final phases. Similarly, if we select a fourth plane, r{. . ,ry intermediate between the last named and E. . .E, w$ Fig. 11. <0- ^Nsf^tfr i ! "1* * Fig. 12. shall there find the phase value intermediate between the initial and halfway phases. It will be clear without formal proof that the lines <£ . . <£ . . <£ of the diagram indicate monophasal surfaces, the existence of which in the position so delineated is implied by the existence in the initial plane of a polyphasal surface, having the postulated graduation of phase values in its various zones. We thus" see that a surface having this structure, itself the * "Provisionally," because the polyphasal surface cannot be propagated strictly according to Huyghens' law, i.e. not with the velocity of light ; but for short distances the assumption is allowable. \ Highly Magnified Images. By J. W. Gordon. 21 result of diffraction from a wave-front, will in its turn give rise by further diffraction to a inonophasal surface or true wave-front, a wave-front which, in the case supposed, would have a conical form. It will be interesting to consider what are the phenomena to which such a conical wave-front would give rise. Let P of fig. 13 be such a conical wave-front, and suppose, first, that the observer's eye is focussed on the plane p, situated a Fig. 13. Fig. 14. little below the apex of the cone. It is clear that the conical wave-front, optically projected backward on to the focal plane, will in that case produce a nebulous light in the middle of the field fading off towards the outer edge, where the illuminated zones are largest, and forming a strongly marked boundary at the inner edge, where a dark spot occupies the actual centre of the field. It may be observed that this nebula is, in fact, an expanded antipoint. Fig. 14 is actually drawn from such a nebula with the black dot at its centre. Next suppose the focal plane to be carried up to the position p2 shown in fig. 15. The part of the cone above the focal plane will be optically projected down upon it, and the part below will be propagated up to it, with the result that the nebula will pz Fig. 15. Fig. 16. be diminished in extent, enhanced in brightness, and its centre occupied by a strong point of concentrated light. The black dot has changed into a white dot. Fig. 16 is a drawing of a white dot produced in this way. Finally, assume the focal plane to be carried up to the position jh of fig- 17. Here the nebula becomes still larger, and, being more diffused, weaker towards its outer edge. The inner edge will, however, still be strong, and will clearly mark off ■a black dot in the centre, so that we have returned, not indeed in the structure of the image, but almost exactly in point of appearance, to the condition of things illustrated by fig. 14. 22 Trait surf ions of the Society. Very interesting results emerge if we consider what will happen if some part of the conical wave-front be blotted out. For example, we may suppose the apex to be cut off by an opaque X7 \ V / / \ / 1 V I \ ' V / V fc T-PS Fig. 17. Fig. 18. object introduced into that part of the field, as in fig. 18. In that case it is plain that we shall not have a bright dot at the level of p2, but a projection, having reduced diameter, of the opaque object surrounded by a nebula of diminished breadth. This will sud- denly change into a bright dot when the plane p5 is passed, to be again reversed into a black dot as before at the level of j)x. The microscopist will recognise in these descriptions a close resemblance to certain phenomena very familiar in high power microscopy, where objects come into view having dimensions com- mensurable with the dimensions of the antipoint, but for practical application the theory must be so extended as to include the common case in which we have to deal with sources of illumination of finite extent and in which the individual antipoint is merged^ and the boundaries between light and dark areas are traced by diffraction fringes. The great problem then may be formulated thus : What is the structure of a diffraction fringe if we assume that the antipoint, instead of being monophasal, has the phase structure of fig. 11, in which successive zones exhibit successive phases in a regular series ? The mathematical solution of this problem is too intricate to be developed here, and therefore my own contribution to it is embodied in a note. The result of the note is a rough approxima- tion only to the desired solution. It may even be that the problem is not susceptible of a complete solution, but if it be I must leave the task of solving it to other and abler hands. For immediate purposes the broad result suffices that in a diffraction fringe, as in the antipoint, we have a polyphasal surface which may be divided into zones parallel to the true boundary, and when so divided will exhibit the successive phases in due serial order. A typical diffrac- tion fringe is represented diagrammatically in fig. 19, and it will be observed that the fringe extends for a distance equal to the radius Highly Magnified Images. By J. W. Gordon. 23 of the antipoint on each side of the true boundary, and that whereas the light intensity curve shows an uninterrupted progression from edge to edge of the fringe, it is not so with the phase change. On -e- § dp 0 § § = (7) To facilitate the writing out of these values, let the following symbols be adopted with reference to Fig. 23 : s = sin u ; c = cos u : n = ; N= J — --^ p) = s {nc + s). P P The following diagram (fig. 24) will aid the determination of this coefficient. Here Dx . . D2 = A. measured on the edge of the beam AAi/. Dn is the middle point of the segment, and Dn . . rji is the axis passing through the points D« and rjl. Therefore, cx . . £., is the projection along this axis of D1 . . 1)2 = cos a X. In D2. take such that D., = J)1 . . D2. Then Dx . . £3 will be a monophasal surface, since every point in this surface is distant from the corresponding point in Dl . . D2 by a length, measured along the axis Dn . . •>?!, equal to the distance be- tween that corresponding point and D. Therefore, every point in D: . . t3 is isophasal with D1. Moreover, e1 . .c4, drawn parallel to Dj . . t3, is also a plane wave-front. It follows that el . . e2 represents a polyphasal sur- face, and that the phase range in ci • • e2 = (1 — sm a) - ^i ancl accord- ing to the well known expression for the efficiency of a polyphasal radiant surface — (5) _ 2 sin {(1 — sin a) ir] _ sin {(1 — sin a) tt} (1 — sin a) 2 ir (1 — sin a) -k = sm { — = — 7rl IN ( (N - j (N - n) 7T We have so far brought into the reckoning the phase changes due to the finite length of the small surface 8 S, but not those due to its finite breadth. It is, however, obvious that the breadth of 8 S will not be uniform, and not sensibly uniform, as we pass upward from the normal point towards the aperture A . . A, except, perhaps, in the case of an extremely short beam. In any ordinary case it will vary, and will vary very nearly in the proportion of the length of D (= n c p). We may therefore say, without sensible error, that the angle subtended at the point ■)]1 by the radiant wedge is for practical purposes invariable. Let this angle =2/3. Then from a horizontal line, equal to the breadth of ■8 S, through the point D„, the extreme difference of optical paths to -q^ will be (sec /? — 1) n c p, and the corresponding phase range (sec (3—1) n £ 2 ir. Let this angle be written n 0, and we shall obtain for the whole impulse emitted from 8 S when resolved along the Dn . . rjx axis. Highly Magnified Images. By J. W. Gordon. 29 ,-s ■ IN — n ) N sin n 0 v J IN f(N — «.)ir »0 where # is a small angle that cannot be mathematically determined, but must be ascertained by observation. 6. The Economy factor. If every point upon the surface ct . . e2 received its light from a separate ray in the principal beam, the efficiency would be fully represented by the expression just found for (5). But we are integrating over a single element of the light cone, and the original impulse is travelling to a certain extent in the same direction as the diffracted light which it gives off. Thus the light source is, so to speak, economised, and a light source of shorter length than A suffices to yield all the diffracted light which we have derived from Dx . . D2. Thus since the phase range in the surface cx . . e2 is only (1 — sin a) 2 7r, it is evident that the effective length of edge is (1 — sin a) A. Therefore (6) = 1 — sin a = — — — . v ' N We may now collect these various results into one expression, as. follows : . , m . d r . A d R M0 , . . A^= ^ •V''(ne + ,) v • l(N - ri)ir [ N N - n sin n 6 X Sm\ X "1 (N -»»)„■• X -•" 0 ' = m . d E . A . M0 . • . \nc + s . I sin . &-*>* . **"!L It may be noted here that the expression m d R A M0 denotes the radiation upon the focal point from a small surface A SA (equal in area to the topmost segment of the radiant wedge) in the wave-front which passes the aperture A . . A. It may, therefore, be fitly taken for the unit of radiation for the given system, and expressed by the symbol Mx. Accordingly the last expression may be written — „.- /nc-\-s 1 . (N — n)-7r sin n0\ . ^. A^ = s.M1^ ^—.-.snP -N ; .- Q ) . (10) The successive terms of this series are to be taken upon the principle of assigning one term to every segment of one wave-length measured from the normal point along the edge of the beam facing the point j/1s and therefore the values of n must be so chosen that— 1 3 5 J)1 = nx c p = A ; 1)2 = n2 c p = '-X; D3 = w3 cp = ' A, etc. AAA It is plain that if n be taken very small N = 1 nearly, and, therefore, Is - ■ n sin — == — it tends to = 0 as n approaches 0. Also if n becomes very X ji large, N — n tends to become = 0, so that in that case also sin — - approximates to 0. 30 Transactions of the Society. The successive values of (10) obtained by giving successive values to n in that expression are not capable of being simply added together, for here the undulation is resolved in a direction perpendicular to the DM . . vi axis ; which varies in position with the change of n. It is desirable, therefore, to obtain a resolution of these impulses in certain specified directions, and we may, for this purpose, select rectangular axes coinciding with the line through the normal point and the point yjl and with the edge ray through 8 S respectively. So resolved, A if/ will obviously yield two resultants, as follows, if we write x and y for these two axes in the order named. Aif/X = sin ttAif; A if/,, = cos a A if/, that is to say, in place of (10) we obtain two equations as follows— xf/x = 2 (A V* ) = s . Mx 2 ( -J?-- • ^ ^ . smv — ^J— . , _, , . . N ,, _, /nc 4- s 1 • CN — n)ir sin n 6\ I or, more compendiously, A^=^A2 Transactions of the Society. gradual distribution of phases parallel to the edge of the boundary, ruing from a phase equal to the external phase of the individual anti- point at the outer edge of the diffraction fringe to a value which is the average of the phases in one half of the antipoint over the boundary itself. This is obvious, for the light on the outermost edge is unmixed, and the light at every point on the boundary is the summed light of one half of the antipoint. Proceeding inward from the boundary we find the phase still increasing, for the region near the boundary is lighted up by something more than half the antipoint, and the addi- tional light consists in more than the total average proportion of the light of the innermost zones of the antipoint. But when we get to a point equal to the radius of the antipoint within the true boundary, we reach a region where the light on every point is the integral of all the light from a single antipoint. Here, then, the light phase must haw returned to the phase on the boundary, since the average phase of the com- plete antipoint must be the same as the average of the semi-antipoint, seeing that one half of every zone enters into the semi-antipoint, and the proportional value of every zone in relation to the whole illu- mination is therefore the same in both cases. This consideration points, to the existence of a doubly conical wave-front with unequal surfaces,. and yields at once a forecast of certain very striking phenomena which are, as the foregoing paper shows, very strikingly verified by experiments (See above, p. 23.) SUMMARY OF CURRENT RESEARCHES RELATING TO ZOOLOGY AND BOTANY (principally invertebrata and cryptogamia), MICEOSCOPY, Etc.* ZOOLOGY. VERTEBRATA. a. Embryology.! Mendel's Law and the Heredity of Albinism.}: - - W. E. Castle and G. M. Allen find that complete albinism, without a recorded ex- ception, behaves as a recessive character in heredity. Partial albinism is a mosaic condition, in which the dominant pigment-forming character and the recessive albino character are visible in different parts of the same individual. Albinism apparently complete may in reality conceal traces of the pigment-forming character, either in an active or in a latent condition. Albinos that are thus constituted are in reality mosaics of the con- trasted characters, but with the pigment-forming character (ordinarily dominant) occurring in a condition of partial or complete latency. When bred to other albinos they uniformly produce albinos, hence they may for convenience be distinguished as impure recessives. In guinea- pigs and rabbits the impurity of recessive individuals is, in certain cases at least, visible ; in mice it apparently is not. Cross-breeding is able to bring into activity latent characters or latent elements of a complex character. This is probably the true ex- planation of many cases of reversion. Conversely, it is able to cause one or another element of a complex character to become latent and to remain so under close breeding. This probably explains how races of black or yellow mice may be obtained by crossing wild grey mice with albinos. The Mendelian doctrine of gametic purity is fully substantiated by * The Society are not intended to be denoted by the editorial " we," and they do not hold themselves responsible for the views of the authors of the papers noted, nor for any claim to novelty or otherwise made by them. The object of this part of the Journal is to present a summary of the papers as actually published, and to describe and illustrate Instruments, Apparatus, etc., which are either new or have not been previously described in this country. t This section includes not only papers relating to Embryology properly so called r but also those dealing with Evolution, Development, Reproduction, and allied subjects. t Mark Anniv. Vol.. 190:;, pp. S79-98. Feb. loth, 1905 D 34- SUMMARY OF CURRENT RESEARCHES RELATING TO experiments in breeding mice, guinea-pigs, and rabbits, but with the important qualification stated in the preceding paragraph — a qualifica- tion which really enhances the practical utility of Mendel's doctrine in its everyday application by breeders. Radium Effect on Development of Amphibia.* — A. Schaper has proved experimentally that radium rays have a definite inhibitory effect upon cell-division in the frog, etc., also on embryonic differentiation, growth, and regenerative processes. These effects are observable only after a longer or shorter latent period. On frog larvae radium emana- tions had an injurious and finally fatal effect. Abnormal Eggs in Fowls.f — J. Kunstler discusses eggs with two separate shells, eggs with a double shell, double eggs, eggs without yolk, dwarf eggs, and so on. A frequent factor is a lack of tone in the oviduct, the usual movements are disturbed, the egg returns on its path. Foreign bodies may ascend from the cloaca and become surrounded by a shell. A mass of albumen may be enveloped in a shell ; and so on. Polymorphism of Spermatozoa.} — A. Gravel brings together some of the cases of dimorphic spermatozoa, — in Paludina vivipara, Notom- mata sieboldii, Asellus aquaticus, Pygccra bucephala, Staphylimbs, Cybister roeselii. In Ascaris rnegalocephala there are said to be four forms of spermatozoa, but only one form is capable of fertilisation. Gravel has studied the spermatozoa of Balanus perforatus in which giant forms occasionally occur, apparently in individuals separated widely from one another. These giant spermatozoa may be adapted to cross-fertilisation at a distance ; being stronger, they can move more rapidly, and further. Factors of Morphogenesis. § — Tad. Garbowski discusses Trichoplax adhcerens and other Mesozoa, the processes of gastrulation and ceeloni- formation, and the scope of physiological morphology. He rejects the homology of the germ-layers, the gastraea -theory, the ccelom-theory, and much more. He insists that a scientific interpreta- tion of the pedigrees of animals must be based on an observational and experimental study of the formative processes which actually occur in morphogenesis. (Estrous Cycle in Ferret.|| — F. H. A. Marshall finds that the female ferret is moncestrous, and may have one, two, or three sexual seasons within a year. The " heat " periods, however, are usually restricted to the spring and summer months. During the oestrous cycle the non- pregnant uterus experiences in succession periods of rest, of growth, of degeneration, and of recuperation. The changes occurring during these periods afford proof of the homology between the menstrual cycle of the primates and the oestrum of the lower mammals. Ovulation occurs probably at the commencement of the oestrous period, but only as a * Anat. Anzeig., xxv. (1904) pp. 326-37. t Mem. Soc. Sci. Bordeaux, ser. 6, iifc (1903) pp. 65-72 (7 figs.). X Tom. cit., pp. 273-9. § Morpbologische Studien, Als Beitrag zur Methodologie zoologischer Probleme. 4 to. Jena (1903) vii. and 189 pp., 6 pis. |! Quart. Journ. Micr. Sci., xlviii. (1904) pp. 323-45 (3 pis.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 35 result of sexual intercourse. Since coition and ovulation take place lifter the pro-oestrum, it is clear that the degeneration stages of the pro- ■cestrum cannot be of the nature of an undoing, in consequence of the absence of a fertilised ovum, of preparations made during the earlier growth stages. Implantation of Ovum in the Gopher.* — T. G. Lee gives an account of the fixation of the ovum in this rodent (Spermophilus tridecemlineatus), which differs from its relatives, and, further, from any other mammals yet described in the nature and history of the temporary "fixation-mass " formed by the trophoblast. Development of Pulmonary Arteries in Roe-deer. f — T. Sakurai finds that the pulmonary arteries arise first from both pulmonary arches as in man, but gradually the left passes over to the right pulmonary arch approaching the right artery. The portion of the right pulmonary arch between the angle of division of the arches and the origin of the left pulmonary artery forms the common origin of both pulmonary arteries. Development of Mammalian Kidney .% — J. Janosik has investigated certain early stages of the urogenital system in the pouched marmot. He finds the first certain appearance in embryos with ten distinct and one incipient mesoblastic somites. It arises opposite the seventh somite proximally as a grouping of somatopleure and splanchnopleure cells against the somites ; the ccelome is slightly indented into this group. The section situated between the twelfth and fifteenth or sixteenth somites in embryos showing these, is regarded as transitional to the mesonephros. The origin of this division of the mesonephros takes place as follows. The middle plates detach themselves both from the mesoblastic somites and from the ccelomic epithelium, and from them there arises a cellular strand which falls into separate cell masses not segmentary arranged. In these cell masses a lumen arises, which is transformed into a vesicle from which a small canal grows out. On the median end of each of these canals a glomerulus is formed, while the lateral end opens into the Wolffian duct. Thus connections arise similar to those known to occur in birds. Regeneration of Tail-tissues in Anuran Larvae. § — P. Wintrebert gives the results of experiments on the larva of Alytes. He finds that regeneration of the tail depends upon the reconstitution of the sup- porting apparatus, more especially the axis of central support round which the embryonic mesenchyme can be organised. The median " lophiodermic raphe " of the limbs constitutes a sufficient apparatus of support to admit of the regeneration of the cord. The connective fibrous neural and aortic canals are powerless, with the organs they inclose, to supply the place of the missing cord or to regenerate it. They may in fact by their re-union oppose its extension and thus limit * Mark Anuiv. Vol., 1903, pp. 417-35 (2 pis.}, t Anat. Anzei-., xxv.(1904) pp. 321-6. t Arch. Mikr. Anat., lxiv. pp. 214-34 (2 pis.). § Comptee Rendus. cxxxix. (1904) pp. 432-4. D 2 36 SUMMARY OF CURRENT RESEARCHES RELATING TO the regeneration of the tail. It is hence suggested that in animals the- absence of regeneration in an organ may be caused by the stoppage of development of the supporting tissue due to the fibrous growth of the cicatrix. Development of Amphibian Excretory System.*—!). P. Filatow discusses the development, structure, and functions of the pronephrie glomus, and the development of the mesonephric tubules. He explains certain differences in the first stages of the tubules in Urodela and Anura, referring particularly to the process of separating the connecting group of cells from the lateral plate, and the mode of approach of the group to the duct. In the Anura the group is first detached before- approaching the duct, while in Urodela the process of separation is pro- longed, with the result that a different formation appears. He thinks- that this explanation may account for peculiarities of the tubule forma- tion in other animal groups. Development of Ventral Nerves in Selachii.t — H. V. Neal dis- cusses the spinal ventral nerves in the spiny dogfish {Squalus acanthias). Positive conclusions in regard to some important questions have been reached. (1) The neuraxones of the spinal ventral nerves of Selachians develop like those of the Amniota as. processes of neuroblast cells. In their growth they are secondarily surrounded by sheath-cells. (2) Me- dullary cells, but not those that form the neuraxones, migrate into the ventral nerves in the early stages of development. (3) The migrant medullary cells form the neurilemma sheaths, but take no part in the formation of the neuraxones or ganglia of the ventral nerves. (4) The epineurium and perineurium sheaths are in chief part added to the embryonic nerve from the adjacent mesenchyme. In his summary the author states that neuroblasts and spongioblasts are undifferentiated in the early stages of the ventral nerve ; the first neuraxones are formed before the migration of the cells Avhich produce them ; the " germinative cells " of this are simply mitotic cells • no neuroblasts migrate from the wall of the neural tube ; their migration is entirely within the wall, and is the passive result of the multiplica- tion of cells near the lumen of the tube ; neuraxones of spinal ventral nerves are formed exclusively by medullary cells ; the cells of ventral nerves are not concerned with the formation of neuraxones ; they form the neurilemma and possibly also the connective-tissue sheaths of the nerves, to which mesenchymatous cells probably also contribute ; the cells of the forming ventral nerve are migrant medullary elements, to which are subsequently added cells from the adjacent mesenchyme ; the first connection of ventral nerve and myotome is not an intimate neuro- muscular attachment ; there is no primary cellular connection such as has been postulated by Sedgwick. Torus longitudinalis of Teleost Brain4 — P. E. "Sargent discusses this archaic portion of the mesencephalic roof formed in the Teleosts * Anat. Anzeig., xxv. (1904) pp. 33-47. t Mark Anniv. Vol., 1903, pp. 291-31:; (3 pis.). ; Tom. cit., pp 399-416 (1 pi.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 37 from the mesial and primitive portion of the tectum opticum, con- stricted off, and, as it were, left behind in the enormous development of the tectum in this aberrant group. In its early development in the ganoids it is the result of purely mechanical causes, the rapid growth in the adult of the "nucleus magnocellularis " producing a downward bending of the mesencephalic roof on either side of the median plane. Mechanical causes are still plainly operative in the Siluridre, but in other Teleosts the torus appears, at an early stage of ontogenetic development, as the result of phylogenetic causes. Though the torus longitudinalis is a structure which first attains an independent and definite form in the Teleosts, and in that group only, its essential elements are perhaps the most archaic of the mesencephalic roof. The structure and functions are also discussed. Development of Body Cavity and Gonads in Salmonidae.* — U. Bold has studied this in trout and salmon embryos. He finds that its first appearance in the trout is on the 25th day after fertilisation. It arises as a cleavage between somato- and splanchnopleure in the region of the lateral head plate. On the 28th day the body cavity has increased in the cranial, and especially in the caudal direction ; its development is closely connected with that of the gut. At :58 days, growth in length has ceased, whilst lateral development, coincident with yolk absorption, has considerably increased. In salmon embryos of 40 days (twenty segments) the body cavity of the tail is completely separate from that of the yolk-sac. Later the yolk-sac body cavity in the region of the 14th to 18th trunk segments is drawn into the trunk body cavity ; the yolk-sac, which has collapsed from the 18th segment onwards, forms for a time a long mesenteric formation, through which the ventral body partition is joined to the ectoderm. Later it is completely absorbed. In trout the first genital cells were not found before the 25th, and in salmon the 31st day. There are two stages of development of the genital organs. The first, that of the genital ridge, was observed in the salmon on the 60th day. The second, that of the genital fold, arises from the ridge, and may be recognised in the salmon on the 85th day. In its anterior part it never extends beyond the 4th, and in its posterior or caudal, never beyond the 38th. Three kinds of cells arise from ccelome >cells, viz. indifferent, follicle, and genital cells. Relation of Nervous System to Developing Musculature.f — R. G. Harrison has investigated this subject experimentally. The spinal cord of embryos of Rana was removed before histological dif- ferentiation in either muscular or nervous tissue had begun. This did not hinder the differentiation of the contractile substance in the normal manner, nor the grouping of the individual fibres into muscles. Larvse were reared under continued narcosis of acetone-chloroform, which stops all voluntary movements, including those of respiration, while the heart- beat is scarcely affected. The functions are rapidly restored by removal from the drug. Larvas reared in this way and imbedded side by side * Morphol. Jahrb., xxxii. (1904) pp. 505-86 (1 pi.). t Amer. Journ. Anat., iii. (1904) pp. 197-220. 38 SUMMARY OF CURRENT RESEARCHES RELATING TO with normally retired forms showed no marked contrast in the muscular tissue. The significance of these results is discussed. b. Histology. The Histology of the Cell.* — E. Rohde discusses very fully the insufficiency of present cell theory, the independence of the nucleus, the relation of the nucleus and cell body of the Metazoa (and Infusoria) to the central body (Biitschli) of bacteria, and other cell problems. A brief enumeration of some of his points on the first head may be given. Embryonic syncytia occur and frequently play a great part in histo- genesis. Especially instructive in the genesis of different tissue is the fact that cells clearly formed but undifferentiated blend into a syncytium from which diverse tissues are developed. An illustration of this is found in the development of the oesophagus of Ascuris. The (esophagus consists of a thoroughly uniform fundamental substance wdiich simul- taneously generates first a thick cuticle ; secondly, powerful supporting fibres of different systems ; thirdly, well developed muscle fibrils, which are said to be diagonally striped. Proof of another kind is found in the fact that many formations regarded as cells are the product of several quite different cells, e.g. Tubularian egg-cells, according to Doflein. Labbe regarded the ovum in this case as a plasmodium, which arose by the blending of several oocytes. Schneider observed the same in Synapta. Relations between Nucleus and Cytoplasm.f — Stanislas Maziarski describes three kinds of more or less pseudopodium-like processes which extend towards the base of the cell from the nucleus into the cytoplasm in the hepato-pancreatic tubules of various marine Isopods {Hymothoa, Nerocile, Anilocra). The prolongations may absorb substances from the cytoplasm, or may conduct products from the nucleoplasm to the cytoplasm. In any case, they point to close inter-relations between the two. Comparative Histology of Ducts and Accessory Glands of Male Gonads.:}: — R. Disselhorst is the author of the fourth part of Oppel's treatise on the comparative histology of Vertebrates. He deals with the minute structure of the ducts and accessory glands of the male reproductive system. Fifteen sections deal with these in fishes, am- phibians, reptiles, birds, and the chief orders of mammals. Two final sections sum up results, and give a short sketch of the history of the subjects. Then there are some physiological notes. This part main- tains the high standard of its predecessors, for which the editor was responsible. Epithelium of the Epididymis.§ — Zenon Jeleniewski has studied' this in cat, dog, mouse, rat, guinea-pig, and hedgehog. The epithelium * Zeitschr. wiss. Zool. Ixxviii. (1904) pp. 1-148 (7 pis.). + Bull. Internal Acad. Sci. Craeovie, 1-904, pp. 345-66 (2 pis.). * Lehrbueh der vergleicbenden mikroskopiscb.cn Anatumie der "Wirbeltiere. Herausgegeben von Prof. Albert Oppel. Vierter Teil. Ausfiihrapparat und Anhangs- driisen tier in'annlichen Ge.schlecbtsorgane. Prof. K. Disselborst. Jena (1904) x. and 432 pp., 435 figs, and 7 pis. § Anat. Anzeig. xxiv. (1904) pp. 630-40 (8 figs.). ZOOLOGY AXD BOTANY, MICROSCOPY, ETC. 39 of the beginning of the epididymis — the vasa efferentia and coni vasculosi — consist of ciliated cells, which from time to time secrete and lose their ciliary apparatus, regaining it after the secretory process is over. These cells contain " diplosomes" which are quite distinct from the centrosomes visible at the poles of the achromatin-spindle of dividing cells. The secretory activity leads to the gradual disintegration of the cells, which are then replaced. Many other histological details are communicated ; we have simply noted the salient points. Peculiar Structures in Hepatic Cells.* — Eugenie Koiransky gives a detailed account of peculiar rod-like or strand-like structures observed within the cells of the liver in frog, newt, and salamander. They are often substantial, and proceed from the nucleus towards the periphery of the cell, which they often reach. It is maintained that there is in secretion a shunting and migration of chromophilous substance towards the capillaries along protoplasmic strands, controlled by the kinetic potencies of the protoplasm, and that this is followed by a granular disruption, a chemical change, and a final solution of the substance in the vicinity of the capillaries. Position of Glycogen in Liver Cells.f — 0. Petersen points out that great care needs to be exercised in explaining alcohol-fixed pre- parations with reference to the position of glycogen within the cells. For this the method of freezing sections is more reliable. In cases of lateral penetration of alcohol the glycogen lies on the same side of all the cells, viz. remote from the side of penetration, as if pushed in front of the alcohol. Islets of Langerhans in Teleostei. :|: — J. Rennie has investigated the pancreas of a large number of bony fishes, and finds that these islets are a common character in the group. In a number of species there is an encapsuled islet ("principal islet") of relatively large size, of constant occurrence, and with definite relations, whose association with the pancreas is frequently extremely slight. In some forms it was the only body of this nature found. The smaller islets which do not appear to be constant in number, probably originated as accessory bodies, but are now established as definite organs. It is concluded that these islets are blood glands, whose relation with the pancreas is secondary. This has been brought about in Teleostei mainly by the tendency of the diffuse pancreas to envelop or invade other tissues. In the case of these so-called islets in the compact pancreas of Teleostei, and also of higher animals, the closer relation is due to the common embryonic origin of the two tissues. The primitive condition is that ' exhibited by Teleostei with diffuse pancreas, where the islets are both morphologically and functionally separate. Granular Cells in Epidermis of AmmocoBtes.§ — N. Loewenthal makes some notes on these cells. He describes the thread-like continua- * Anat. Anzeig., xxiv. (1904) pp. 435-56 (6 figs.). + Op. cit., xxiv. (1904) pp. 72-5. t Quart. Journ. Mior. Sci.,xlviii. (1901) pp. 379-40;") (3 pis.). § Anat. Anzeig., xxv. (1904) pp. 81-94. 40 SUMMARY OF CURRENT RESEARCHES RELATING TO tions which are directed to the upper surface of the epidermis. They can he traced within the cell up to the granular zone. In favourable cases there can be distinguished on the cud part of the continuation a spindle-shaped enlargement and delicate wavy threads ("terminal thread-apparatus"), which pass through the granular part of the cell. lie also describes amitotic divisions and constrictions in the nuclei of these cells. Structure of Human Hypophysis.* — V. Scaffidi finds that the human hypophysis exhibits two fundamental kinds of cell which are sharply distinguished from one another, viz. one stainable with I )range G. and the other with Acid fuchsin. The cyanophile cells of Schonemann are to be regarded as fuchsinophile elements in an advanced phase of elimination of plasma granules. The nuclear masses and the isolated nuclei (the definite characters according to which they are recognisable as belonging to the fuchsinophile cells) must be regarded as an ex- pression of the last phase of this elimination process. Probably the other nuclei which are surrounded by narrow fringes of protoplasm (to which the qualities of the above do not belong) may be considered as fuchsinophile cells in a stage of reconstruction. Two forms of cell colourable with Orange G are distinguishable, to which two different functional phases can be ascribed. Both the fundamental types (Orange (1 and Acid fuchsin) have probably the function of elaborating definite substances which together represent the secretion of the gland. Research Methods on Human Brain.f — P. Flechsig gives a con- cluding paper containing critical observations on research methods on the cerebral cortex. Contraction of Smooth Muscle Cells. £ — E. Forster states that these cells contract in such a way as to coil up spirally. This is true for smooth muscle cells, for heart muscle, and for the diagonally striped cells of amphibia. The nucleus shares passively in this spiral con- traction, so that it is rod-like when the cell is passive and wound spirally as the cell contracts. The extent of contraction of the cell may be known from the degree of the nuclear spiral. The " Stauchung" *' Faltehmg" " Schlangelung" of the nucleus spoken of by various authors, and the " nuclein-spiral " described, is nothing other than the spiral contraction here explained. Lymph Hearts of Rana.§ — M. H. Hover finds that the lymph hearts, like the blood hearts, are very perfectly developed organs, in which the entrance and exit is exactly regulated by a system of valves. The circumstance that there are several lymph hearts on each side has probably its explanation in the phylogenetic development of the Anura. The larvse are provided on each side with several lymph hearts, and Weliky has shown that the Urodela possess a large number of these segmentally arranged . * Arch Mikr. Anat., lxiv. (1904) pp. 235-57 (1 pi.). + Her Sachs. Gus. Leipzig, lvi. (1904) pp. 177-248. J Anat. Auzeig., xxv. (1904) pp. 338-55. * Bull. Intern. Aca>l. Sci. Cracovie, v. (1904; pp. 22S-37. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 41 Comparative Histology of Cartilaginous Cells.* — Joannes Chatin has a brief note on the extraordinary polymorphism of cartilage cells, which are usually described as ovoid or spheroidal except in rare cases. The fact is that it is a very variable element, occurring in spheroidal, "cylindrical, claviform, ovoid, angular, multiloba te, branched, stellate, and •other shapes, all connected by intermediate phases. c. General. Phototropism in Animals.f — Em. Radl has made many experiments, especially with Arthropods, on the wide-spread phenomenon of photo- tropism. Many animals, from Ccelentera to Molluscs, orientate their body in relation to the direction of light; many move actively to or from the light, orientating themselves meanwhile. It is a primitive reflex, and though it is not definitely proved, the author says, in Protozoa, it occurs familiarly in unicellular plants. Many interesting subjects are discussed — the behaviour of animals on a rotating turn- table, the compensatory head-movements of insects, nystagmus in insects, and the flight of moths and the like into the flame. The phototropic phenomena are considered in relation to other tropisms, and in connec- tion with the general problem of orientation. Kadi's general position is that, under the influence of external and internal forces, working, so to speak, in opposed couples, the organism comes to assume a position of static and also physiological equilibrium in reference to the direction of the light. Coloration in Mammals and Birds.J — J- L. Bonhote seeks to show that the colour of a bird or mammal is primarily due to " activity of nutrition and function." This he terms " vigour," which is dependent on (a) climate, containing two factors, temperature and food, and (b) the rise and fall of sexual activity. AVhere conditions for high vigour exist, the majority of the animals will be brightly coloured. Tlie individual vigour of various species and groups will differ, and one animal may be able to maintain a full vigour under conditions which would be im- possible to another. This will account for some of the Polar animals becoming strongly coloured, e.g. musk ox, raven, penguin. Shortly before the moult in many animals the colour of the pelage fades, beginning along certain definite areas and from certain centres, termed " pcecilomeres ;" this bleaching is physiological, and the patches so pro- duced thus owe their inception to internal rather than external causes. Relation of Oxidation to Functional Activity.§ — Sir John Burdon- S.niderson opened a discussion on this subject at the British Association Meeting at Cambridge. He particularly contrasted the chemical pro- cesses of gland function and muscle function. Whereas the former is not in any marked degree katabolic, the dominant process in the oxida- tion which is inseparably associated with the performance of muscular •function is katabolic. Oxygen seems to play two parts in metabolic * Comptes Rendus, cxxxix. (1904) pp. 489-91. t UntersuclmngenuberdenPhototropisimisderTiere. 8vo. Leipzig (1 903) 1S8 pp. ! Journ. Linn. Soc. (Zool.) xxix. (1904) pp. 185-7. $ Nature, lxx. (1904) pp. 590-3. 42 SUMMARY OF CURRENT RESEARCHES RELATING TO processes, one of which is prominent in muscle, and is responsible for the final oxidation of explosive material, while the other, which is more accentuated in glands, is akin to a building-up process, as it is involved in the elaboration of new material. Outlines of Zoology.* — R. Latzel has prepared a fourth revised edition of a class-hook which has had wide and prolonged favour in Germany, Graher's " Leitfaden der Zoologie." It is a terse and accurate synopsis of the general characters of the various classes of animals, somewhat too all-embracing and informative to be educationally inspiring, but of service, doubtless, as an index reritm in association with more vital studies. It is very copiously illustrated, and the coloured plates are admirable. Eyes of Vertebrates.! — 0. Schnaudigel takes an interesting com- parative survey of the eyes throughout the Vertebrate series — discussing, for instance, peculiar cases like eyes of cave animals and deep-sea fishes, and indicating the chief structural differences observed in a comparison of lenses, accommodation-apparatus, and retina in various types. The Mammalian Cribrum.J — W. Blendinger has investigated this structure in a series of Mammals. In origin it consists of lateral, more or less vertical folds, the cribral sacs. On the embryonic cribrum there arise three main side sacs, pro-, meso-, and metacribrum, the entrance to which is perpendicular to the main axis of the nasal canal. In later stages of growth two intermediary sacs are added, the epi- and para-- cribrum. The growth of all the five continues in a lateral and dorso- ventral direction ; the posterior end of the entrance to each is flanked by an olfactory torus. These are termed endoturbinal tori ; the corre- sponding sacs are distinguished as pro-, epi-, etc., turbinals. The form of the sacs is, in varying degrees in different species, further complicated by homologous side pockets, bursa-dorsalis, -externa, and -ventral is, which again form secondary niches. Between all the side spaces arise cartilaginous and ossifying partitions, the endo- and ecto-turbinal lamella?. The sinus maxillaris is a product of the procribrum, the other pneumatic hollows arise partly out of the procribrum and partly from the other cribral sacs. The paper is accompanied by historical and critical observations by Dr. A. Fleischmann. Whalebone Whales of Western North Atlantic.§ — V. W. True discusses these in a memoir, the size of which is worthy of the subject. The conclusions reached are :— (1) that the species in the Western North Atlantic are the same as those in the Eastern North Atlantic ; (2) that these are the Bowhead, or Greenland Right whale {Baloma mystketus), the Black whale (B. glacial is), the Humpback (Megaptera nodosa), the Sulphurbottom (Balc&noptera musculus), the common Finback (B. physalus), the Little Piked whale (B. acato-rostrata), and probably the Pollack whale (B. borealis) ; (3) that the range of the Humpback extends * Graber's Leitfaden der Zoologie fur hohere Lehranstalten. Bearheitet von, Dr. Robert Latzel. 4th revised edition, Svo. Leipzig (1901) 232 pp., 474 figs.,. 4 coloured plates, and a map of distribution. + Ber. Senckenbert:. Nat. Ges. 1903, pp. 187-202. * Morpbol. Jahrb., xxxii (1904) pp. 451-504 (2 pis). § Smithsonian Contributions to Knowledge, xxxiii. (1904) pp. 1-332 (50 pis.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 43 south ward at least as far as 18° North Lat. ; and (4) that the probability of the identity of the North Pacific species writh those of the North Atlantic is strengthened by the evidence collected. As evidence is strengthened regarding the specific identity of the whales of the North Atlantic and North Pacific, the belief that the same species of large whales range all over the globe is also strengthened. It is well known that whales closely resembling Megaptera nodosa, B. acuto- rostrata, B. musculm and B. physalus — to mention no others — occur in the South Atlantic and the Antarctic seas, and also, the second and last, at least, about New Zealand. But even if it should be proved that the species of large whalebone whales are cosmopolitan, it does not follow that the individuals constituting these several species range throughout the globe. The probabilities are much against such world-wide move- ments, and in the case of the Plight whale it appears to have been demonstrated by Maury that individuals do not cross the equator. The memoir is sumptuously illustrated. The Roman Mole.* — L. Camerano has made an elaborate compari- son between the Roman mole {Talpa romana Oldfield Thomas), the common mole Talpa europtm, and T. ectca Savi. His detailed measure- ments of many parts illustrate minutiose taxonomic work. He has no- doubt that T. romana is a very distinct species. The common mole occurs in various parts of Italy, but does not differ from that of other countries. Variations with fused eyelids occur ; this is normal in T. cceca, and the taxonomic value of T. cc&ca requires further study. New Order of Ungulate Mammals.f — C. W. Andrews has come to the conclusion that the remarkable genus Arsinoitherium (from the Eocene of Egypt) must be referred to a new sub-division of the TJngulata of equal value with the Amblypoda and Proboscidea, to both of which a certain degree of relationship may exist. For this new order the name Barypoda is proposed, in allusion to the massive character of the limbs. For another genus Barytherium, it seems safest to erect a sub-division of the Amblypoda, the Barytheria, equivalent in value to the Dinocerata. Forest Pig of Central Africa. £ — Oldfield Thomas notes that R. Meinertzhagen has procured two skulls and some portions of skin of the "forest pig" reported by Sir Henry Stanley and Sir Harry Johnston. The trophies show that the animal represents a most in- teresting new genus connecting the aberrant wart-hog {Phaco cheer us) with the more ordinary Suidae, such as Sus and Potamochmrus. It may be regarded as an early stage in the specialisation of the wart-hog. The name proposed is Hylochozrus meinertzluujenl. Material for the Study of Ruminants. § — Einar Lonnberg makes a contribution to the comparative anatomy of the wild ruminants, — the black-buck of India (Antilope cervicapra), Cephalopus ogilbyi, C. me- lanorhocus, and C. silvicultor, Boselaphus tragocamelus, and Anoa. In * Mem. R. Acad. Sci. Torino, liv. (1904) pp. 81-128 (1 pi.). t Geol. Mag., 5th decade, i. (1903) pp. 481-2. X Nature, lxx. (1904) p. 577. § Nova Acta R. Soc. Sci. Upsala, xx. (1904) Sect. ii. Art. 2, pp. 1-61 (2 pis.). 44 SUMMARY OF CURRENT RESEARCHES RELATING TO some instances the adaptations of the intestinal canal to the