m r^l a a a : m a A HANDBOOK V OF SYSTEMATIC BOTANY lo A HANDBOOK OF SYSTEMATIC BOTANY BY DR. E. WARMING Professor of Botany in the University of Copenhagen WITH A REVISION OF THE FUNGI BY DR. E. KNOBLAUCH, Karlsruhe TRANSLATED AND EDITED BY M. C. POTTER, M.A. F.L.S. Professor of Botany in the University of Durham College of Science, Newcastle-upon-Tyne Author of "An Elementary Text-book of Agricultural Botany' WITH 610 ILLUSTRATIONS 3Lonti0n SWAN SONNENSCHEIN & CO NEW YORK : MACMILLAN & CO 1895 BUTLER & TANNER, THE SET/WOOD PRINTING WORKS, FEOME, AND LONDON. PREFACE. THE present translation of Dr. E. Warming's Haandbog i den Systematiske Botanik is taken from the text of the 3rd Danish Edition (1892), and from Dr. Knoblauch's German Edition (1890), and the book has been further enriched by numerous additional notes which have been kindly sent to me by the author. Dr. Warming's work has long been recognised as an original and important contribution to Systematic Botanical Literature, and I have only to regret that the pressure of other scientific duties has delayed its presentation to English readers. Dr. Warming desires me to record his high appreciation of the careful transla- tion of Dr. Knoblauch, and his obligation to him for a number of corrections and improvements of which he has made use in the 3rd Danish Edition. In a few instances I have made slight additions to the text ; these, however, appear as footnotes, or are enclosed in square brackets. In the present Edition the Thallophytes have been revised and rearranged from notes supplied to me by Dr. Knoblauch, to whom I am indebted for the Classification of the Fungi, according to the more recent investigations of Brefeld. The Bacteria have been revised by Dr. Migula, the Florideae rearranged after Schmitz, and the Taphrinacese after Sadebeck. The main body of the text of the AlgfE and Fungi remains as it was originally written by Dr. Wille and Dr. Rostrup in the Danish Edition, though in many places considerable alterations and additions have been made. For the sake of comparison a tabular key to the Classification adopted in the Danish Edition is given in the Appendix. In the Angiosperms I have retained the sequence of orders in the Danish original, and have not rearranged them according to w. B. v I VI PREFACE the systems more familiar to English students. In any rearrange- ment much of the significance of Dr. Warming's valuable and original observations would have been lost, and also from a teacher's point of view I have found this system of great value. Although at present it may not be completely satisfactory, yet as an attempt to explain the mutual relationships, development and retrogression of many of the orders, it may be considered to have a distinct advantage over the more artificial systems founded upon Jnssieu's Divisions of Polypetala?, Gamopetala?, and Apetalse. With reference to the principles of the systematic arrangement adopted, I may here insert the following brief communication from the author (dated March, 1890), which he has requested me to quote from the preface of Dr. Knoblauch's edition : — " Each form which, on comparative morphological considerations, is clearly less simple, or can be shown to have arisen by reduction or through abortion of another type having the same fundamental structure, or in which a further differentiation and division of labour is found, will be regarded as younger, and as far as possible, and so far as other considerations will admit, will be reviewed later than the ' simpler,' more complete, or richer forms. For instance, to serve as an illustration : EPIGYNY and PEKIGYNY are less simple than HYFOGXY ; the Epigynous Sympetalie, Chori- petalte, Monoctyledones are, therefore, treated last, the Ilydro- charitacem are considered last under the Helobiet?,etc. ZYGOMOIM'HY is younger than ACTINOMORPHY ; the Scilaminece and Gynandrce therefore follow after the LiliijJora', the Scrophulariacere after the Solanacecc, Linaria after V&rbascum, etc. FORMS WITH UNITED LEAVES indicate younger types than those with free leaves ; hence the SympetalcB come after the Choripetaltv, the Silenece after the Alsinex, the Nal 'cacetv after the Stcrculiacex and Tiliacecc, etc. " ACYCLIC (spiral-leaved) flowers are older than cyclic (verticillate- leaved) with a definite number, comparing, of course, only those with the same fundamental structure. The Veronica-type must be considered as younger, for example, than Digitalis and Antir- PRKKACE. VII rli-inum, these again as younger than Scrophularia • Verbascum, on the contrary, is the least reduced, and therefore considered as the oldest form. Similarly the one-seeded, nut-fruited Ranunctdacew are considered as a later type (with evident abortion) than the many-seeded, folicular forms of the Order ; the Paronychiece and Chenopodiacece as reduced forms of the Alsinece type ; and the occurrence of few seeds in an ovary as generally arising through reduction of the many-seeded forms. The Cyperacece are regarded as a form derived from the Jimcacece through reduction, and associated with this, as is so often the case, there is a complication of the inflorescence ; the Dipsacacece are again regarded as a form proceeding from the Valerianactce by a similar reduction, and these in their turn as an off-shoot from the Caprifoliacece, etc. Of course these principles of systematic arrangement could only be applied very generally ; for teaching purposes they have often required modification." In preparing the translation considerable difficulty has been experienced in finding a satisfactory rendering of several terms which have no exact equivalent in English. I may here especially mention the term Vorblatt (Forblad) which I have translated by the term bracteole, when it clearly applied to the first leaf (or leaves) on a pedicel ; but in discussing questions of general morphology a term was much needed to include both vegetative and floral shoots, and for this I have employed the term " Fore- leaf." Also, the term " Floral-leaf " has been adopted as an equivalent of "Hochblatt," and the term "bract" has been limited to a leaf subtending a flower. I have followed Dr. E. L. Mark in translating the word " Anlage " by "Fundament." At the end of the book will be found a short appendix giving an outline of some of the earlier systems of Classification, with a more complete account of that of Hooker and Bentham. In a book of this character it is almost impossible to avoid some errors, but it is hoped that these will be comparatively few. In correcting the proof-sheets I have received invaluable assist- ance from Dr. Warming and Dr. Knoblauch, who have kindly Vlll PREFACE. read through every sheet, and to whom I am greatly indebted for many criticisms and suggestions. I have also to thank Mr. I. H. Burkill for his kind assistance in looking over the proofs of the Monocotyledons and Dicotyledons, and Mr. Harold Wager for kindly reading through the proofs of the Algce and Fungi. My thanks are also especially due to Mr. E. L. Danielsen, and I wish to take this opportunity of acknowledging the very considerable help which I have received from him in translating from the Original Danish. M. C. POTTER. January, 1895. TABLE OF CONTENTS. BEING THE SYSTEM OF CLASSIFICATION ADOPTED IN THE PEESENT VOLUME. (The Alc/CE and Fungi re-arranged in co-operation with Dr. E. Knoblauch, the other Divisions as in the 3rd Danish Edition.) DIVISION I. THALLOPHYTA ... 4 A. Sub-Division. Myxomycetes, Slime-Fungi 5 B. Sub-Division. Algae. ......... 8 Class 1. SYNGENETKLE 14 ,, 2. DINOFLAGELLATA 16 ,, 3. DIATOMEJE 18 ,, 4. SCHIZOPHYTA 22 Family 1. Schizophyceos 22 „ 2. Bacteria 26 Class 5. CONJUGATE 41 ,, 6. CHLOROPHYCE.E 46 Family 1. Protocoecoidese 47 ,, 2. Confervoidese ....... 53 „ 3. Sipboneee 59 Class 7. CHAEACE.E 64 ,, 8. PH^EOPHYCE^; (OLIVE-BROWN SEVSVEEDS) .... 68 Family 1. Pba3osporea3 68 ,, 2. Cyclosporese 73 Class 9. DICTYOTALES 76 ,, 10. RHODOPHYCEJE (RED SEAWEEDS) 77 Family 1. Bangioidese 77 ,, 2. Florideffi 78 C. Sub-Division. Fungi 84 Class 1. PHYCOJIYCETES 96 Sub-Class 1. Zygomycetes 96 ,, 2. Oomycctes 100 Family 1. Eutoinophthorales 102 2. Cbytridiales 102 ,, 3. Mycosiphonales 104 / TABLE OF CONTENTS. PA OH Class 2. MESOMYCETES ... ... . 108 Sub-Class 1. Hemittsci 108 ,, 2. Hemibasidii ..... . 109 Class 3. MYCOJIYCETI s (HIGHER FUNGI) . .... 114 Sub-Class 1. Ascvmycetes . • 114 Series 1. Exoasci ... . . 116 „ 2. Carpoasci ... .118 Family 1. Gjumoascales 118 ,, 2. Perisporiales . .... 119 ,, 3. Pyrenomycetes 125 ,, 4. Hysteriales ....... 132 ,, 5. Discomycetes .... . 132 6. Helvellales . . ... 136 Ascolichenes • 136 Sub-Class 2. Basidiomycetes ... . 144 Series 1. Protobasidoinycetes . . • 145 ,, 2. Autobasidiomycetes . • 157 Family 1. Dacryomycetes . • 159 ,, 2. Hynienoinycetes . . 159 3. Phalloideffi . • 172 ,, 4. Gasteromycetes . . • 173 Basidioliclienes . • 176 Fungi Imperfecti . .176 DIVISION II. MUSCINE^ (MOSSES) . . 181 Class 1. HEPATIOE • 188 Family 1. Marcbautiese ... . 190 ,, 2. Antbocerotese .191 ., 3. Jungermanmere ... • 191 Class 2. Musci FRONDOSI. .... . 192 Family 1. Spbagnete . .193 ,, 2. Schizocarpeae . • ,, 3. Cleistocarpeas . . • ,, 4. Stegocarpete ... • 195 DIVISION III. PTERIDOPHYTA . . 198 Class 1. FILICIN.E .... • 205 Sub-Class 1. Filices . . • 205 Family 1. Eusporangiatse. . . • 210 ,, 2. Leptosporangiatfe . . • 212 Sub-Class 2. Hydroptendece . • 215 Class 2. EQUISEIIN.E (HOESETAILS) . Sub Class 1. Isosporous Equiset line „ 2. Heterosporous Equisttince . • 225 Class 3. LYCOPODIN.E (CLUB MOSSES) . . • 226 Sub- Class 1. Lycopodiece ... • 226 ,, 2. Selayinellea 228 TAI',I,E OF CONTENTS. TRANSITION FROM THE CRYPTOGAMS TO TOE PHANEROGAMS Asexual Generation of the Cormopbytes . Sexual Generation ; Fertilisation .... DIVISION IV. GYMNOSPERM^E Class 1. CYCADEJE (CYCADS) ...... „ 2. CONIFER.E (PlXE-TREES) ..... Family 1. Taxoideas ...... ,, 2. Piiiouleffi ...... Class 3. GXETE.E Fossil Gymnosperms ..... DIVISION V. ANGIOSPERM^ Cl IPS 1. MONOCOTYLEDONES .... . . Family 1. Helobieas ...... ,, 2. Glumifiora} ...... „ 3. Spadicifloraa ..... „ 4. Euautioblastas . . . ,, 5. LiliifloriB ...... „ 6. Scitamineas ..... ,, 7. Gynandrae ...... ClaSS 2. DlCOTYLEDONES ...... Sub-Class 1. Choripctiiltc ...... Family 1. Saliciflorte ...... ,, 2. Casuariniflorre ..... ,, 3. Quercifloras ..... „ 4. Juglandifloraj ..... ,, 5. Urticiflorse . ..... „ 0. Polygonifloraa ..... ,, 7. Curvembryaj ..... ,, 8. Cactiflorce ,, 9. Polycarpicas ..... ,, 10. Rhosadinaa ...... ,, 11. Cistiflorag ...... 12. Gruinales ...... ,, 13. Columniferaj ..... „ 14. Tricoccos ,, 15. Terebinthiua) ,, 16. Aesculinas ...... ,, 17. Frangulinte ,, 18. Tliymelasinas ,, 19. Saxifragiua) ..... ,, 20. Bosiflorse ,, 21. Legumiuosaa ..... ,, 22. Passiflorinas ..... ,, 23. Myrtiflora3 ...... „ 24. Umbellifloraa ,. 25. Hysterophyta ..... PAGE . 234 . 234 . 243 . 251 . 252 . 255 . 259 . 262 . 270 . 271 . 273 . 274 . 278 . 283 . 297 . 308 . 309 . 323 . 328 . 334 . 337 . 337 . 339 . 340 . 349 . 351 . 358 . 363 . 375 . 377 . 393 . 406 . 416 . 421 . 430 . 435 . 439 . 443 . 448 . 451 . 456 . 466 . 475 . 482 . 490 493 Xll TABLE OF CONTENTS. Sub-Class 2. Sympetalce A. Pentacyclicic . Family 26. Bicornes . ,, 27. Diospyrina: ,, 28. Primulinffl B. Tetracycllccc . Family 29. Tubiflorte ,, 30. Personata? ,, 31. Nuculifera3 32. Contorts; . 33. Eubiales . „ 34. Dipsacales ,, 35. Campannlinffi . 36. Aggregates APPENDIX INDEX PAGE . 504 . 506 . 506 . 510 . 511 . 514 . 514 . 517 . 531 . 541 . 548 . 556 . 560 . 564 . 574 593 COEEIGENDA. Page 9, line 12 from top, for Hydrodicton read Hydrodiclyon. ,, 14, lines 1 and 2 from top, for as in the preceding case read in tltis case. ,, 14, ,, 2 and 15 from top, for zygote read oosporc. ,, 88, line 15 from bottom, for Periphyses read periphyses. ,, 124, ,, 7 ,, ,, for CJucromyces read Choiromyces. ,,142, ,, 2 „ ,, and in Fig. 137, for Bnomyves read Bccomyccs. ,, 152, ,, 2 ,, top, for Pints read Pi/nts. ,, 152, ,, 5 ,, „ for Crategus read Cratagus. „ 216, Fig. 215, for Salcina read Salvinia. ,, 306, line 6 from top, for Pista read Pistia. ,,316, ,, 26 „ ,, after Dracaena insert a comma. ,, 337, ,, 13 ,, ,, for end read beginning. ,, 483, ,, 11 ,, bottom, for Lagerstnvmia read Lagcrstrameria. For a, 6 and ii read as, ce and ue throughout. The following are not officinal in the British Pharmacopoeia : — page 316, Dractcna (Dragon's-blood), Smilax glalra ; p. 321, " Orris-root " ; p. 326, species of Curcuma, Alpinia qfficinarum; p. 333, Orr/tj's-species ("Salep"). On page 296, par. 4, only Pearl Barley is offic. iu the Brit. Phar. CLASSIFICATION OF THE VEGETABLE KINGDOM. The Vegetable Kingdom is arranged in 5 Divisions. Division I. — Thallophyta, Stemless Plants, or those which are composed of a " thallus," i.e. organs of nourishment which are not differentiated into root (in the sense in which this term is used among the higher plants), stem, or leaf. Vascular bundles are wanting. Conjugation and fertilisation in various ways; among most of the Fungi only vegetative multiplication. In contradistinction to the Thallopbytes all other plants are called " Stem- plants" (" Cormophyta "), because their shoots are leaf-bearing stem?. The name Thallophyta (Stemless-plants) is to some extent unsuitable, since many of the higher Alga? are differentiated into stem and leaf. The Thallophytes are again separated into 3 sub-divisions, namely : Sub-Division A.— Myxomycetes, Slime-Fungi, with only 1 class. Sub-Division B. — Algse, with 10 classes : Class 1. Syngeneticaa. ,, 2. Dinoflagellata, Peridinea. ,, 3. Diatomese, Diatoms. ,, 4. Schizophyta, Fission Algae. ,, 5. Conjugate. ,, 6. Chlorophycene, Green Algse. ,, 7. Characeae, Stone-worts. ,, 8. Phteophycea?, Brown Alga1. ,, 9. Dictyotales. ,, 10. Rhodophycere, Red Algaa. Sub-Division C. — Fungi, with 3 classes: Class 1. Phycomycetes. ,, 2. Mesomycetes. „ 3. Mycomycetes, Higher Fungi. Division II. — Bryophyta or Muscineae, Mosses. These have leaf-bearing shoots, but neither true roots nor vascular w. B. B 2 CLASSIFICATION OF THE VEGETABLE KINGDOM. bundles. The lowest Mosses have, however, a thallus. Fertili- sation is accomplished by means of self-motile, spirally coiled spermatozoids, through the agency of water. From the fertilised oosphere a " fruit-body " (capsule) with unicellular organs of reproduction (spores) is produced. The spore on germination gives rise to the vegetative system, which bears the organs of sexual reproduction ; and this system is divided into two stages —the protonema, and the leaf-bearing plant produced on it. Alternation of generations : I. The protonema and the entire nutritive system which bears the organs of sexual reproduction. II. The capsule-like sporangium, with spores. 2 Classes : 1. Hepatica?, Liverworts. 2. Musci, Leafy Mosses. Division III. — Pteridophyta or Vascular Cryptogams, Fern -like Plants having- leaf-bearing shoots, true roots, and vascular bundles with tracheides and sieve-tubes. Fertilisation as in the Mosses. From the fertilised oosphere the leaf -bearing shoot arises, which bears on its leaves the reproductive organs, the spores, in capsule-like sporangia. From the germination of the spore a small prothallium is formed, which bears the sexual reproductive organs. Alternation of generations : I. Prothallium with organs of sexual reproduction. II. Leaf-bearing shoot with capsule-like sporangia. 3 Classes: 1. FilicinaB, True Ferns. 2. Equisetina?, Horsetails. 3. Lycopodinse, Club-mosses. Division IV. — Gymnospermae. The vegetative organs are in the main similar to those in the 3rd Division ; special shoots are modified into flowers for the service of reproduction. From the oosphere, which is fertilised by means of the pollen-tube, the leaf -bearing plant is derived; this passes the first period of its life as an embryo in the seed, and continues its development when the germination of the seed takes place. The organs correspond- ing to the spores of the two preceding Divisions, are called respec- tively the pollen-grain and embryo-sac. The pollen-grains are multicellular ; i.e. they contain an indistinct prothallium. In the embryo-sac a prothallium, rich in reserve material (endosperm), CLASSIFICATION OF THE VEGETABLE KINGDOM. 3 with female organs of reproduction, is developed BEFORE FER- TILISATION. The pollen-grains are carried by means of the wind to the ovules; these enclose the embryo-sac, and are situated on the open fruit-leaf (carpel), which has no stigma. Alternation of generations : I. Prothallium = Endosperm in ovule. II. Leaf-bearing plant, with flowers which produce the pollen- sac and ovule. 3 Classes : 1. Cycadeae. 2. Coniferae. 3. Gnetaceee. Division V. — Angiospermae. The members of this group are very similar to those of Division IV. The ovules are, however, encased in closed fruit-leaves (ovary), which have a special portion (stigma) adapted for the reception and germination of the pollen- grains. The pollen-grains are bicellular, but with only a mem- brane separating the two nuclei ; they are carried to the stigma by animals (chiefly insects), by the wind, or by some other means. Endosperm is not formed till AFTER FERTILISATION. Alternation of generations in the main as in the Gymnosperms, but less distinct ; while the sexual generation, the prothallium, with the organs of fertilisation, is also strongly reduced. 2 Classes:1 1. Monocotyledones. Embryo with one seed-leaf. 2. Dicotyledones. Embryo with two seed-leaves. For a long time the vegetable kingdom has been divided into CRYPTOGAMS (so called because their organs of reproduction remained for some time undis- covered), and PHANEROGAMS or Flowering-plants which have evident sexual organs. The first three divisions belong to the Cryptogams, and the third and fourth divisions to the Phanerogams. This arrangement has no systematic value, but is very convenient in many ways. The Cryptogams are also known as Spore-plants, since they multiply by unicellular organs (spores), and the Phanerogams in contradistinction are called Seed-plants (Spermaphyta), since they multiply by seeds, multicellular bodies, the most important part of which is the embryo (a plant in its infancy). Mosses, Ferns, and Gymnosperms are together known as Arche- goniatre, fiuce they possess in common a female organ of distinct structure, the Archegonium. 1 See Angiospernise. THALLOPHYTA. DIVISION I. THALLOPHYTA. The thallus in the simplest forms is unicellular; in the majority, however, it is built up of many cells, which in a few instances are exactly similar ; but generally there is a division of labour, so that certain cells undertake certain functions and are constructed accordingly, while others have different work and corresponding structure. Vessels or similar high anatomical structures are seldom formed, and the markings on the cell-wall are with few exceptions very simple. The Myxomycetes occupy quite an isolated position ; their organs of nourishment are naked masses of protoplasm (plasmodia). As regards the external form, the thallus may be entirely without special prominences (such as branches, members), but when such are present they are all essentially alike in their origin and growth, that is, disregarding the hair- structures which may be developed. A shoot of a Seaweed or of a Lichen, etc., is essentially the same as any other part of the plant ; only among the highest Alga? (Characete, certain Siphonese, Sar- gaxsum, and certain Red Seaweeds) do we find the same differ- ences between the various external organs of the plant body as between stem and leaf, so that they must be distinguished by these names. Roots of the same structure and development as in the Seed- plants are not found, but organs of attachment (rhizoids and haptera) serve partly the biological functions of the root. SYSTEMATIC DIVISION OF THE THALLOPHYTES. To the Thallophytes belong three sub-divisions — Slime-Fungi, Alga?, and Fungi. Formerly the Thallophytes were divided into Alga?, Fungi, and Lichens. Biit this last group must be placed among the Fungi, since they are really Fungi, which live symbiotically with Alga3. The Slime-Fiingi must be separated from the true Fungi as a distinct sub-division. The Algce possess a colouring substance, which is generally green, brown, or red, and by means of which they are able to build up organic compounds from carbonic acid and water. The Bacteria, especially, form an exception to the Alga? in this respect ; like the Fungi and Slime-Fungi they have as a rule no such colouring material, but must have organic car- bonaceous food ; these plants form no starch, and need no light MYXOMYCETES. O for their vegetation (most Fungi require light for fructification). The Myxomycetes, Bacteria, and Fungi derive their nourish- ment either as saprophytes from dead animal or vegetable matter, or as parasites from living animals or plants (hosts), in which they very often cause disease. A remark, however, must be made with regard to this division. Among the higher plants so much stress is not laid upon the biological relations as to divide them into " green " and " non-green"; Cuscuta (Dodder), a parasite, is placed among the Convolvulaceje, Neottia and Corallorhiza, saprophytes, belong to the Orchidacea3, although they live like Fungi, yet their relations live as Alga?. In the same manner there are some colourless parasitic or saprophytic forms among the Alga?, and stress must be laid upon the fact that not only the Blue-green Alg.'v, but also the Bacteria, which cannot assimilate carbonic-acid, belong to tlie Alga? group, Schizophycese. The reason for this is that systematic classifications must be based upon the relationship of form, development, and reproduction, and from this point of view we must regard the Bacteria as being the nearer relatives of the Blue-green Alga?. All the Thallophytes, which are designated Fungi (when the entire group of Slime-Fungi is left out), form in some measure a connected series of development which only in the lower forms (Phycomycetes) is related to the Algre, and probably through them has taken its origin from the Alga? ; the higher Fungi have then developed independently from this beginning. The distinction of colour referred to is therefore not the only one which separates the Algne from the Fungi, but it is almost the only characteristic mark by which we can at once distinguish the two great sub- divisions of the Thallophytes. The first forms of life on earth were probably " Protista?," which had assimi- lating colour material, or in other words, they were Algre because they could as-imilate purely inorganic food substances, and there are some among these which belong to the simplest forms of all plants. Fungi and Slime-Fungi must have appeared later, because they are dependent on other plants which assimi- late carbon. 1 Sub-Division I.— MYXOMYCETES, SLIME-FUNGI. The Slime-Fungi occupy quite an isolated position in the Vegetable Kingdom, and are perhaps the most nearly related to the group of Rhizopods in the Animal Kingdom. They live in and on organic remains, especially rotten wood or leaves, etc., on the surface of which their sporangia may be found. They are organisms without chlorophyll, and in their vegetative condition are masses of protoplasm without cell-wall (plasmodt'a). They multiply by means of spores, which in the true Slime-Fungi3 1 According to the recent investigations of Winogradsky some micro-organisms (Nitrifying-bacteria) can build organic from inorganic matter. Sachs' hypothesis that the first organisms must necessarily have contained chlorophyll is there- fore untenable. 2 Myxogasteres, Engler's Syllabus, p. 1. 6 MYXOMTCETES. are produced in sporangia, but in some others * free. The spores are round cells (Fig. 1 a) which in all the true Slime-Fungi are surrounded by a cell-wall. The wall bursts on germination, and the contents float out in the water which is necessary for germination. They move about with swimming and hopping motions like swarmspores (e, /), having a cilia at the front end and provided with a cell-nucleus and a pulsating vacuole. Later on FIG. 1.— o-l Development of " Fuligo " from spore to Mj-xamoeba ; a-m are magnified 390 times ; m is a Myxamoeba, of Ltjcogala epidendron ; I' three Myxamoabfe of Physarum album about to unite; o, a small portion of plasmodiuni, magnified 90 times. they become a little less active, and creep about more slowly, while they continue to alter their form, shooting out arms in various places and drawing them in again (g, h, i, k, I, m) ; in this stage they are called Myxamcebce. The Myxamceba grows whilst taking up nourishment from the material in which it lives, and multiplies by division. At a later stage a larger or smaller number of Myxamcebae may be seen to 1 Acrasiete aud Plasrnodiopkorales, Hid. MYXOMYCETES. coalesce and form large masses of protoplasm, plasmodia, which in the "Flowers of Tan" may attain the size of the palm of a hand, or even larger, but in most others are smaller. The plas- modia are independent, cream-like masses of protoplasm, often containing grains of carbonate of lime and colouring matter (the latter yellow in the Flowers of Tan). They creep about in the decaying matter in which they live, by means of amoeboid movements, internal streamings of the pro- FIG. 3. — Pour sporangia of Stenwnitis fuscn, fixed on a branch, a The plasmodium. FIG. 2. — The plasmodiinn fa) of Stemonitis fusea, com- mencing to form into sporangia (b) ; drawn on. July 9. The dark-brown sporangia were completely formed by the next morning ; e-e shows the development of their external form. toplasm continually taking place ; finally they creep out to the surface, and very often attach themselves to other objects, such as Mosses, and form sporangia (Fig. 2). These are stalked or sessile and are generally cylindrical (Fig. 3), spherical or pear-shaped (Fig. 4); they rarely attain a larger size than that of a pin's head, and are red, brown, white, blue, yellow, etc., with a very delicate wall. In some genera maybe found a " Capillitium " (Fig. 4 cp), or net- work of branched fine strands between the spores. Flowers of FIG. 4. — Sporangium of Ar- cyria incarnata. B closed; 0 open ; p wall of sporangium ; cp capilitium. 8 ALG.E. Tan (Fuligo septicd) has a fruit-body composed of many sporangia (an yEthalium), which has the appearance of flat, irregular, brown cakes, inside the fragile external layer of which a loose powder, the spores, is found. It generally occurs on heaps of tanners' bark, and appears sometimes in hot-beds in which that material is used, and is destructive by spreading itself over the young plants and choking them. All the motile stages may pass into resting stages, the small forms only surrounding themselves with a wall, but the large ones at the same time divide in addition into polyhedral cells. When favour- able conditions arise, the walls dissolve and the whole appears again as a naked (free-moving) mass of protoplasm. To the genuine Slime-Fungi belong : Arcyria, Trichia, Didymium, Physarum, Stemonitis, Lycogala, Fuligo, Spumaria, Reticularia. Some genera wanting a sporangium- wall belong to the Slime- Fungi : Ceratiomyxa, whose fruit-body consists of polygonal plates, each bearing stalked spores ; Dictyostelium, in which the swarm-stage is wanting and which has stalked spores. Plas- modiophora brassicce preys upon the roots of cabbages and other cruciferous plants, causing- large swellings. PL alni causes coral-shaped outgrowths on the roots of the Alder (Altius). Phytomysea Jeguminosariim may be found in small knobs (tubercles) on the roots of leguminous plants. It is still uncertain whether it is this Fungus or Bacteria which is the cause of the formation of these tubercles. Sub-Division II. — ALG/E. Mode of Life. The Algte (except most of the Bacteria) are themselves able to form their organic material by the splitting up of the carbonic acid contained in the water, or air in some cases, and for this purpose need light. The majority live in water, fresh or salt, but many are present on damp soil, stones, bark of trees, etc. With the exception of the Bacteria, no saprophytes have actually been determined to belong to this group, and only very few true parasites (for instance, Phyllosiphon arisari, Mycoidea, etc.), but a good many are found epiphytic or endophytic on other Alga?, or water plants, and on animals (for instance, certain Schizophycece and Protocnccoidece ; Trichopliilus ivelckeri in the hairs of Bradypus, the Sloth), and several species in symbiotic relation to various ALG;E. 9 Fungi (species of Lichen), to Sponges (e.g. Trentepohlia spongio- phila, Struvea delicatula), and to sundry Infusoria and other lower animals as Radiolarias, Hydra, etc. (the so-called Zoochlorella and Zooxantella, which are perhaps partly stages in development of various Green and Brown Alga>). Vegetative Organs. The cells in all the Alga? (excepting certain reproductive cells) are surrounded by a membrane which (with the exception of the Bacteria) consists of pure or altered cellulose, sometimes forming a gelatinous covering, at other times a harder one, with deposits of chalk or silica formed in it. The cell-nucleus, which in the Schizophyta is less differentiated, may be one or more (e.g. Hydrodicton, Siphonece) in each cell. Except- ing in the majority of the Bacteria, colour materials (of which chlorophyll, or modifications of it, always seems to be found) occur, which either permeate the whole cytoplasm surrounding the cell- nucleus, as in most of the coloured Schizophyta, or are con- tained in certain specially formed small portions of protoplasm, (chromatophores). The individual at a certain stage of development consists nearly always of only one cell ; by its division multicellular individuals may arise, or, if the daughter-cells separate immediately after the division, as in many of the simplest forms, the individual will, during the whole course of its existence, consist of only a single cell (unicellular Alga?). In multicellular individuals the cells may be more or less firmly connected, and all the cells of the individual may be exactly alike, or a division of labour may take place, so that certain cells undertake certain functions, and are constructed accordingly ; this may also occur in parts of the cell in the large unicellular and multinuclear Alga? (Siphonea?, p. 62). The cells in most of the Alga? belong to the parencliymatous form ; these, however, in the course of their growth, may very often become somewhat oblong; in many Alga? (particularly Fucoidea? and Floridea>) occur, moreover, hyphce-like threads, which are very long, often branched, and are either formed of a single cell, or, more frequently, of a row of cells, having a well-pronounced apical growth. The parenchymatous as well as the hyphae-like cells may, in the higher Alga? (especially in certain Fucoidea? and Floridea?), be further differentiated, so that they form well- defined anatomico-physiological systems of tissue, i.e. assimilating, conducting, storing, and mechanical. With regard to the external form, the thallus may present no 10 ALG.E. differentiation, as in many unicellular Alga3, or in multicellular Alga? of the lower order, which are then either equally developed in all directions (e.g. Pleurococcuf, Fig. 47), or form flat cell-plates (Merismopedium) or threads (Oscillaria, Fig. 21). The first step in the way of differentiation appears as a difference between apex and base (Sivularia, Porphyra) ; but the division of labour may proceed so that differences may arise between vegetative and reproductive cells (CEdogonium, Fig. 54) ; hairs and organs of attachment (rhizoids and haptera), which biologically serve as roots, are developed, and even leaves in certain forms of high order, belonging to different classes (e.g. Caulerpa, Fig. 59 ; Characeoe, Fig. 61 ; Sargassum, Fig. 72 ; and many Floridea?). The nonsexual reproduction takes place vegeiatively, in many instances, simply by division into two, and more or less com- plete separation of the divisional products (Diatomaceae, Desmi- diaceoe (Fig. 36), many Fission-plants, etc.), or by detached portions of the thallus (e.g. Caulerpa, Ulra lacttica, etc. ; among many Schizo- phyceSB, small filaments known as hormogonia are set free), or asexually by special reproductive cells (spores) set free from the thallus ; these may be either stationary or motile. The stationary reproductive cells (spores) may either be devoid of cell-wall (te- traspores of the Florideie), or may possess a cell-wall ; in the latter case they may be formed directly from the vegetative cells, gene- rally by the thickening of the walls (akinetes), or only after a process of re-juvenescence (aplanospores) . Aplanospores, as well as akinetes, may either germinate immediately or may become resting-cells, which germinate only after a period of rest. THE MOTILE ASEXUAL REPRODUCTIVE CELLS are spherical, egg- or pear-shaped, naked, swarmspores (zoospores), which have arisen in other cells (zoosporangia), and propel themselves through the water by means of cilia ; or they are Phyto-Amceba?, which have no cilia and ci'eep on a substratum by means of pseudopodia. The cilia, which are formed from the protoplasm (in the Bacteria, however, from the membi'ane), are mostly situated at the pointed and colourless end, which is directed forwards when in motion, and are 1, 2 (Fig. 5 B), 4 or more. Both the cilia in the Brown Alga? are attached to one side (Fig. 65); they are occasionally situated in a circle round the fi'ont end (GEdogonium, Fig. 6 a, and Derbesia), or are very numerous and situated in pairs dis- tributed over a large part or nearly the whole of the zoospore (Vauclieria). Besides being provided with one or more nuclei 11 (Vaucheria), they may also have a red "eye spot" and vacu- oles, which are sometimes pulsating, i.e. they appear and re- appear at certain intervals. The swarmspores move about in the water in irregular paths, and apparently quite voluntarily, revolving round their longer axes ; but they come to the sur- face of the water in great numbers either because of their dependence on light, or driven by warm currents in the water, or attracted by some passing mass of food material. The swarmspores germinate, each forming a ue\v plant, as their movement ceases they surround themselves with a cell-wall, grow, and then divide ; in Fig. 6 6, two may be seen in the con- dition of germination, and about to attach themselves by means of the front end, which has been developed into haptera (see also Fig. 5 B, lowest figure). FIG. 5. — Cludopliora glomerata. A The lower cells are full of swarmspores, whilst from the upper one the greater part have escaped through the aperture m. B Free and germinating swarmspores. FIG. 6. — (Edoqonium : a (free), b germinating swarm- spores. The sexual reproduction here, probably in all cases, con- sists in the coalescence of two masses of protoplasm, that is, in the fusion of their nuclei. The simplest and lowest form is termed conjugation, orisoga- mous fertilisation, and is characterized by the fact that the two coalescing cells (termed gametes) are equal, or almost equal, in shape and size (the female gamete in the Cutleriacece, e.). The female (parthenogenesis) or male (androgenesis) sexual cell may, sometimes without any preceding fertilisation, form a new individual (e.g. Ulothrix zonata, Cyhndrocapsa, etc.). Systematic division of the Algae. The Algae are divided into the following ten classes : 1. STNGENETICJ: ; 2. DIXOFLAGELLATA, or PERIDINEA; 3. DIATO- MACEJ; ; 4. SCHIZOPHYTA, FlSSION-ALGJE ; 5. CONJUGATE ; 6. CHLORO- PHYCEJ:, GREEN-ALGJ-;; 7. CHARACE^;, STONEWORTS; 8. PH^OPHYCE^E ; 9. DlCTYOTALES ; 10. RHODOPHYCE^. Among the lowest forms of the Algae, the Syngeneticaa, the Dinoflagellata, and the unicellular Volvocaceae (Chlamydomonea?), distinct transitional forms are found approaching the animal kingdom, which can be grouped as animals or plants according to their method of taking food or other characteristics. Only an artificial boundary can therefore be drawn between the animal and vegetable kingdoms. In the following pages only those forms which possess chromatophores, and have no month, will be con- sidered as Alga?. Class 1. Syngeneticae. The individuals are uni- or multi-cellular, free-swimming or motionless. The cells (which in the multicellular forms are loosely connected together, of ten only by mucilaginous envelopes) are naked or surrounded by a mucilaginous cell- wall, in which silica is never embedded. They contain one cell-nucleus, one or more pulsating SYNGENETIC.E. 15 \ PIG. 11. — Syncrypta volvox : the multi- cellular individual is surrounded by a mucilaginous granular envelope. vacuoles, and one to two band- or plate-like chrornatophores with a brown or yellow colour, and sometimes a pjrenoid. Reproduction takes place by vegetative division, or asexually by zoospores, akinetes (or aplanospores ?). Sexual reproduction is un- known. They are all fresh water forms. To this class may perhaps be assigned the recently arranged and very little known orders of Calcocytacece, Murracytacece, Xanthellacece, and Dictyochacece, which partly occur in the free condition in the sea, in the so-called " Plankton," and partly symbiotic in various lower marine animals. The Syngeneiicce are closely re- lated to certain forms in the animal kingdom, as the Flagellatse. Order 1. Chrysomonadinaceae. In- dividuals, uni- or multi-cellular, swim- ming in free condition, naked or sur- rounded by a mucilaginous covering. The cells are generally oval or elongated, with 2 (rarely only 1) cilia, almost of the same length, and generally with a red " eye-spot " at their base, and with 2 (rarely 1 only) band-shaped chromatophores. Eeproduction by the longitudinal divi- sion of the individual cells either during the swarming, or during a resting stage ; in the multicellular forms also by the liberation of one or more cells, which in the latter case are connected together. A. Unicellular: Chromulina, Cryptogleiia, Microglena, Nephroselmis. B. Multicellular: Uroglena, Syncrypta (Fig. 11), Synnra. Among the unicellular Chrysomouadinaceae are probably classed some forms which are only stages in the development of the multicellular, or of other Syngeneiicce. Order 2. Chrysopyxaceae are unicellular, and differ mainly from the pre- ceding in being attached either on a slime-thread (titylo- chry sails), or enclosed in an envelope (Chrt/sopyxis, Fig. 12). They have two cilia, and multiply by longitudinal (Chrysopyxis) or transverse division, and the swarming of one of the daughter-individuals (zoospore). Division may also take place in a motionless stage (pulmella-staye). Order 3. Dinobryinaceae. The individuals are ori- ginally attached, uni- or multi-cellular ; each individual cell is distinctly contractile, and fixed at the bottom of a cup-shaped, open envelope. Cilia 2, but of unequal length. Asexual reproduction by zoospores, which are formed by straight or oblique longitudinal division of the mother-cell, during a palmella-stage which is pro- duced in the winter aplauospores. Epipyxls, Dinolryon. FIG. 12.— Chrsopyx-is m envelope, EC ckromatophure, cv contractile vacuole. 16 DINOFLAGELLATA. Order 4. Hydruracese. The individuals are attached, without cilia, multi- cellular, branched, and with apical growth. The cells are spherical, but in the final stage almost spindle-shaped, and embedded in large masses of mucilage. Asexual reproduction by zoospores which are tetrahedric, with 1 cilia, and by resting akinetes. Hydrurus is most common in mountain brooks. Class -2. Dinoflagellata. The individuals are of a very variable form, but always uni- cellular, and floating about in free condition. The cell is dorsi- ventral, bilateral, asymmetric and generally surrounded by a colour- less membrane, which has no silica embedded in it, but is formed of a substance allied to cellulose. The membrane, which exter- nally is provided with pores and raised borders, easily breaks up into irregularly- shaped pieces. In the forms which have longitudinal and cross furrows, two cilia are fixed where these cross each other, and project through a cleft in the membrane ; one of these cilia projects freely and is directed longitudinally to the front or to the rear, the other one stretches crosswise and lies close to the cell, often in a furrow (cross furrow). The chromatophores are coloured brown or green and may either be two parallel (ExuvieUa), or several radially placed, discs, which sometimes may coalesce and become a star-shaped chromatophore. The colouring material1 (pyrrophyl) consists, in addition to a modification of chlorophyl, also of phyco- pyrrin and peridinin ; this colour is sometimes more or less masked by the products of assimilation which, consist of yellow, red or colourless oil (?) and starch. Cell-nucleus one : in Polydinida several nuclei are found ; contractile vacuoles many, which partly open in the cilia-cleft (Fig. 13 gs). In some an eye-spot, coloured red by hasmatochrome, is found. Pyrenoids occur perhaps in ExuvieUa and AmpTiidinium. THE REPRODUCTION takes place as far as is known at present, only by division. This, in many salt water forms, may take place in the swarming condition, and, in that case, is always parallel to the longitudinal axis. The daughter-individuals, each of which retains half of the original shell, sometimes do not separ- ate at once from each other, and thus chains (e.g. in Ceratium} of several connected individuals may be formed. In others, the division occurs after the cilia have been thrown off and the cell-con- tents rounded. The daughter-cells then adopt entirely new cell-walls. A palmella-stage (motionless division-stage) sometimes appears to D1NOFLAGELLATA. 17 take place, and also aplanospores (?) with one or two horn-like elongations {e.g. in Peridinium cinctum and P. tabulatum) ; at germination one, or after division, two or more, new individuals may be formed. Sexual reproduction has not been observed with certainty. The Dinoflagellata move forward or backward, turning round their longitudinal axes ; in their motion they are influenced by the action of light. The motion possibly may be produced only by the transverse cilium, which vibrates rapidly ; whilst the longitudinal cilium moves slowly, and is supposed to serve mainly as a steering apparatus. They live principally in salt water, but also in fresh. Besides the coloured forms, which are able to make their own organic compounds by the splitting up of the carbonic acid contained in the water, there are a few colourless forms (e.g. Gymnodinium s£u'raZe),orsuch as do not possess chromatophores (Polykrikos) ; these appear to live saprophytically, and may be able to absorb solid bodies with which they come in contact. Dinoflagellata occur in the "Plank- ton " of the open sea, where they form together with Diatomacea? the basis for the animal life. It is known with certainty that some salt water forms (like the Noctiluca, which belongs -to the animal kingdom and to which they are perhaps related) produce light, known as phosphorescence. FIG. 13. — A and B Gltnodiniuin cinctum. A Seen from the ventral side, B from behind ; fg transverse cilium ; g longitudinal cilium ; ch chromatophores ; a starch ; 11 cell- nucleus ; 13 vacuole ; oc eye-spot ; C Ceratium tetraceros from the ventral side ; i- the right, I the posterior horn ; If longitudinal furrow ; gs cilium-clef t ; D vacuole ; g longitudi- nal cilium. (A and B mag. 450 times, C 337 times.) Dinqflagellata (Peridlnea, Cilioflagellata) are allied through their lowest form (Exuoiella) to the Syugeneticas and especially to the order Chrvsompnadinaceae. They may be divided into three orders. Order 1. Adinida. Without transverse or longitudinal furrows, but en- closed in two shells, and with two parallel chromatophores in each cell. Exuviella, Prorocentrum. Order 2. Dinifera. With tranverse and generally longitudinal furrow. Many radially-placed, disc-formed chromatophores. The most common genera are — Ceratium (Fig. IB), Peridinium, Glenodinium (Fig. 13), Gymnodinium, Dlnophysis. OrderS. Polydinida. With several transverse furrows, no chromatophores, and several cell-nuclei. Only one genus — Polykrikos. W. B. C 18 DIATOM KM. The order PoJydinida deviates in a high degree from the other Dinorlagellata, not only by its many tranverse furrows, each with its own transverse cilium, and by the absence of chromatopbores, but also in havjng several cell-nuclei and a kind of stinging capsule, which otherwise does not occur within the whole class. It may therefore be questionable whether this order should really be placed in the vegetable kingdom. Class 3. Diatomeae. The individuals — each known as a frustule — assume very various forms and may be unicellular or multicellular, but present no differentiation ; many similar cells may be connected in chains, embedded in mucilaginous masses, or attached to mucilaginous stalks. The cells are bi-lateral or centric, often asymmetrical, slightly dorsiventral and have no cilia ; those living in the free condition have the power of sliding upon a firm substratum. The cell contains 1 cell-nucleus and 1-2 plate-shaped or several disc- shaped chromatophores. The colouring material " Melinophyl " contains, in addition to a modification of chlorophyl, a brown colouring matter, diatomin. 1 or 2 pyrenoids sometimes occur. Starch is wanting and the first product of assimilation appears to be a kind of oil (?). The cell-walls are impregnated with silica to such a degree that they are imperishable and are therefore able to contribute in a great measure to the formation of the earth's crust. The structure of their cell-wall is most peculiar and differs from all other plants (except certain Desmidiaceoe) ; it does not consist of a single piece but is made up of two — the " shells " — (compare Exuviella and Prorocentrum among the Dinoflagellata) which are fitted into each other, one being1 a little larger than the other and embracing its edge, like a box with its lid (Fig. 14 B). The two parts which cor- respond to the bottom and lid of the box are known as valves. Along the central line of the valves a longitudinal rib may often be found, interrupted at its centre by a small cleft (perhaps homologous with the cilia-cleft of the Dinoflagellata), through which the protoplasm is enabled to communicate with the exterior (Fig. 14 A). It is principally by reason of the valves, which bear numerous fine, transverse ribs, striae or warts, etc. (Figs. 14, 15, 17), that the Diatomete have become so well known and employed as test objects in microscopical science. When the division takes place, the two shells are separated a little from each other, and after the cell-contents have divided into two masses, two new shells are formed, one fitting into the larger valve, the other one DIATOMEJ:. 19 \ into the smaller valve of the original frustule. The latter cell (frustule) is thus, upon the whole, ^ -g smaller than the mother-cell, and as the cells do not increase in size, some frustules are smaller than the ones from which they are derived, and thus, by repeated divisions, it follows that smaller and smaller frustules are pro- duced. This continued diminution in size is, however, compensated for by the formation, when the cells have been reduced to a certain minimum, of auxospores, 2-3 times larger. These may either be formed asexually by the protoplasm of a cell increasing, round- ing off and surrounding itself with a new wall (e.y. Melosira} or after con- jugation, which may take place with various modifications: 1. Two indi- viduals unite after the secretion of a quantity of mucilage, and the valves then commence to separate from each other, on the side which the two indi- FlG- ^--P^nuiaria .- B, from . , . the edge, shows the valves fitting viduals turn towards each other. The together; .4, a valve. FIG. 15. — Various Diatomacese. A Diatoma vulgare. B Tubellaria flocculosa. 0 Navicula tumida (lateral views). D Gomphonema const ric twin, (lateral views). E Navicula u-estll (lateral views). protoplasmic bodies now release themselves from their cell-wall, and each rounds off to form an ellipsoidal mass ; these two pro- 20 toplasmic masses (gametes) coalesce to form a zygote, tlie cell- nuclei and chromatophores also fusing together. The zygote in- creases in size, and surrounds itself with a firm, smooth, siliceous wall — the perizonium. The auxospores, whichever way they arise, are not resting stages. The germination of the zygote com- mences by the protoplasm withdrawing itself slightly from the cell-wall and constructing first the larger valve, and later on the smaller one ; finally the membrane of the zygote bursts (e.g. Himantidiuni). 2. The conjugation occurs in a similar manner, but the protoplasm of the cells divides transversely before conjugation into two daughtei'-cells. Those lying opposite one another conjugate (Fig. 16) and form two zygotes. The for- mation of the perizonium, and germination take place as in the preceding instance (e.g. Epithemia). 3. Two cells place them- selves parallel to each other, and each of the two cell-contents, I) FIG. 16. — Conjugation of Cijinbella variabilis. A, The protoplasm in the tvro cells has divided into two masses ; B these masses coalesce in pairs; the cells (B C) enclosed in a mucilaginous matrix. C D Auxospores and their formation. without coalescing, becomes an auxospore. The formation of the wall takes place as in the preceding case. This is found in the Naviculege, Cymbellere, the Gomphonemeae (e.g. FruStulia, Cocconema). The Diatomacese may be found in salt as well as in fresh water (often in such masses that the colour of the water or mud becomes yellow or brown ; in the same manner the genera Chcetoceros, Rhizosolenia, Coscinodiscus, and several others, form large slime- masses, " Plankton " on the surface of the sea), on damp soil and in dust blown by the wind. They occur as fossils in the recent formations, often in large deposits (siliceous earth, mountain meal), as in the cement lime in Jutland, the alluvial deposits beneath Berlin, in clay strata beneath peat bogs, in guano, etc. 21 These accumulations of fossilized diatoms are used in the manu- facture of dynamite and in various manufactures. The Diatomaceae appear nearest to, and must be placed as a group co-ordinate with the Dinoflagellata, as they doubtless may be supposed to derive their origin from forms resembling Exuviella, and to have lost the cilia. The resemblances to the Desmidiaceo? which are striking in many respects, can only be conceived as analogies, and cannot be founded upon homologies, and it is therefore impossible to regard them as proof of genetic relation- ship. The family contains only one order. FIG. 17. — Various Diatome®. A Synedra radians. B EjntJiewu'a turgida (from the two different sides). C Cymbella cuspidata. D Cocconeis pediculus (on the right several situated on a portion of a plant, oil the left a single one more highly magnified). Order 1. Diatomacese. This order may be divided into two sub-orders, viz. — Sub-Order 1. Placochromaticae. The chromatophores are discoid, large, 1 or 2 in each cell ; the structure of the valves is bilateral and always without reticulate markings. The follow- ing groups belong to this sub-order : Gomphonemex, Cynibellea>, Amphorece, Achnanthece, Cocconeidea3, Naviculece, Amphiplenrew, Phi- yiotropidea', Amphitropidece, Nitzchiece, Surirayece, and Eunotiece. Sub-Order 2. Coccochromaticse. The chromatophores are granular, small and many in each cell. The structure of the cells is zygomorphic or centric, often with reticulate markings. The following groups belong to this sub-order : Fragilariece, Meridiece, Tabellariece, Licmophorece, Biddulphiece, AngulifercB, Eupodiscece, Coscinodiscece and Melosirece. 22 SCHIZOPHYTA. Class 4. Schizophyta, Fission-Algae. The individuals are 1 — many celled ; the thallus consists in many of a single cell, in others of chains of cells, the cells dividing in only one definite direction (Figs. 18, 21). In certain Fission-Alga? the cell-chain branches (Fig. 30) and a difference between the an- terior and the posterior ends of the chain is marked ; in some, the cells may be united into the form of flat plates by the cell-division taking place in two directions ; and in others into somewhat cubi- cal masses, or rounded lumps of a less decided form, by the divisions taking place in three directions ; or less defined masses may be formed by the divisions taking place in all possible directions. The cell- walls rarely contain cellulose, they often swell con- siderably (Figs. 20, 22), and show distinct stratifications, or they are almost completely changed into a mucilaginous mass in which the protoplasts are embedded, e.g. in Nostoc (Fig. 22), and in the "Zoogloea" stage of the Bacteria (Fig. 27). Sexual reproduction is wanting. Vegetative reproduction by division and the separa- tion of the divisional products by the splitting of the cell- wall or its becoming mucilaginous ; among the Nostocacea?, Lyngbyaceie, Scytonemacese, etc., " Hormogonia " are found ; in Ghamcesiphon and others single reproductive akinetesare formed. Many Fission- Alga? conclude the growing period by the formation of resting akinetes or aplanospores. The Schizophyta may be divided into 2 families : 1. SCHIZOPHYCES;. 2. BACTERIA. Family 1. Schizophyceae,* Blue-Green Algse. All the Blue-green Alga? are able to assimilate carbon by means of a colouring material containing chlorophyll (cyanophyll) ; but the chlorophyll in this substance is masked by a blue (phycocyan), or red (phycoerythrin, e.g. in Trichodesmium erythrceum in the Red Sea) colouring matter which may be extracted from them in cold water after death. The colouring matter, in most of them, per- meates the whole of the protoplasm (excepting the cell-nucleus), but in a few (e.g. Glaucocys/is, Phragmonema), slightly developed chromatophores are to be found. Where the cells are united into filaments (cell-chains) a differentiation into apex and base (Rivu- lariacece) may take place, and also between ordinary vegetative cells and heterocysts; these latter cannot divide, and are dis- * Myxophyceas, Cyauophycere. SCHIZOPHYTA. tinguished from the ordinary vegetative cells (Fig. 22 h~) by their larger size, yellow colour, and poverty of contents. Branching sometimes occurs and is either true or spurious. FIG. IS. — Microcoleus lyngbyanus; a portion of a filament, the thick sheath encloses only one cell-chain ; in one place a cell is drawn out by the movement of the cell-chain; I the cell-chain has divided into two parts (" hormongonia ") which commence to separate from each other. The cell-chain in the spurious branching divides into two parts, of which either one or both grow beyond the place of division (Fig. 18) and often out to both sides (e.g. Scytonema), the divisions however, always take place transversely to the longitudinal direction of the cell-chain. In the true branching a cell elon- gates in the direction transverse to the cell-chain, and the division then takes place nearly at right angles to the former direction ( Sirosiphoniacece). FIG. 19. — Cj/Iindi'ugf) central poitinii of a filament. SCHIZOPHVTA. 25 Order 3. Chamaesiphonaceae. The individuals are 1- many-celled, attached, unbranched filaments with differentiation into apex and base, without heterocysts. Multiplication by re- productive akinetes; resting akinetes are wanting. Dermocarpa, Clastidium, Chamcesiphon, Godlewskia, Phragmonema. Order 4. Nostocaceae. The individuals are formed of mul- ticellular, unbranched filaments, without differentiation into apex and base ; heterocysts present. Reproduction by synakinetes and resting akinetes. Some genera are not mucilaginous, e.g. Cylindrospermum (Fig. 19). The cell-chains in others, e.g. Nostoc, wind in between one FIG. 22. — Nostoc verrucostim. A The plant in its natural size ; an irregularly folded jelly-like mass. B One of the cell-chains enlarged, with its heterocysts (ft), embedded in its mucilaginous sheath. another and are embedded in large structureless jelly-like masses, which may attain the size of a plum or even larger (Fig. 22) ; sometimes they are found floating in the water, sometimes attached to other bodies. Other genera as follows : Aphanizo- menon and Anabc&na (in lakes and smaller pieces of water) ; Nodularia is partly pelagic. Some occur in the intercellular spaces of higher plants, thus Nostuc-forms are found in Anthocerus, Blasia, Sphagnum, Lemna, and in the roots of Cijcas and Gunnera ; Anabvena in Azolla. Order 5. Rivulariaceae. The individuals are multicellnlar filaments, with differentiation into apex and base ; spurious branching, and a heterocyst at the base of each filament. Re- production by synakinetes and resting akinetes, rarely by simple reproductive akinetes. Rivulama, Glceotrichia, Isactis, Caluthrix. Order 6. Scytonemaceae. The individuals are formed of mnlticellular filaments with no longitudinal division ; differen- tiation into apex and base very slight or altogether absent ; 26 BACTERIA. branching spurious ; heterocysts present. Reproduction by syna- kinetes, rarely by resting akinetes and ordinary reproductive akinetes. Tolypothrix, Scytonema, Hassalia, Microchcete. Order 7. Sirosiphoniaceae. The individuals are formed of multicellular threads with longitudinal divisions ; true branching and heterocysts, and often distinct differentiation into apex and base. Reproduction by synakinetes, rarely by resting akinetes and ordinary reproductive akinetes. Hapalosiphon, Stigonema, Capsosira, Kostocopsis, Mas/igocolens. Family 2. Bacteria.* The Bacteria (also known as Schizomycetes, and Fission-Fungi) are the smallest known organisms, and form a parallel group to the Blue-green Algae, but separated from these Algae by the absence of their colouring material ; chlorophyll is only found in a few Bacteria. The various forms under which the vegetative condition of the Bacteria appear, are termed as follows : 1. GLOBULAR FORMS, cocci (Figs. 27, 30 c) : spherical or ellip- soidal, single cells, which, howevei-, are usually loosely massed together and generally termed "Micrococci." 2. ROD-LIKE FORMS : more or less elongated bodies ; the shorter forms have been styled "Bacterium" (in the narrower sense of the word), and the term "Bacillus " has been applied to longer forms which are straight and cylindrical (Figs. 28, 29, 30 E). 3. THREAD -LIKE FORMS : unbranched, long, round filaments, resembling1 those of Oscillaria, are pos- sessed by Leptothrix (very thin, non-granu- lar filaments ; Fig. 30 ^4, the small filaments) and Beggiatoa (thicker filaments, with strong, refractile grains or drops of sulphur (Fig. FIG. 23. — Spirillum sanguineutn. Four specimens. One has two cilia at the same end, the sulphur grains are seen internally. * The Bacteria are more usually included under Fungi. It seems better, how- ever, to place them under the Algae in a separate class with the Suhizophyceae. BACTERIA. 27 31); often self-motile). Branched filaments, with false brandling like many Scytonemacece, are found in Cladothrix (Fig. 30 B, G}. 4. SPIRAL FORMS : Rod-like or filamentous bodies, which more or less strongly resemble a corkscrew with a spiral rising to the left. In general these are termed Spirilla (Fig 23) ; very attenu- ated spirals, Vibriones (standing next to Fig. 30 M) ; if the filaments are slender and flexible with a closely wound spiral, (Fig. 24). 5. The MERISMOPEDIUM- FORM, consisting of rounded cells arranged in one plane, generally in groups of four, and produced by divisions perpen- dicular to each other. 6. The SARCINA-FORM, con- sisting of roundish cells which are produced by cellular divi- sion in all the three directions of space, united into globular or ovoid masses ("parcels") e.g. Sarcina ventriculi (Figs. 25, 26). All Bacteria are unicellular. In the case of the micrococci this is self-evident, but in the " rod," " thread," and " spiral " Bacteria, very often numerous cells remain united together and their indi- vidual elements can only be recognised by the use of special re- agents. FIG. 24. — Spirochxte obermeieri, in active motion (b)aiid shortly before the termination of the fever (c); o blood corpuscles. a d FIG. 25. — Soi-ciua ventnculi. One sur- face only is generally seen. Those cells which are drawn with double contour are seen with the correct focus, and more distinctly than those cells lying deeper drawn with single contour. FIG. 26. — Sarchia mmuta : a-d succes- sive stages of one individual (from 4-10 p.m.) ; / an individual of 32 cells. The condition termed " Zooglcea," which reminds us of Nostoc, is produced by the cells becoming strongly mucilaginous. A number of individuals in active division are found embedded in a mass of mucilage, which either contains, only one, or sometimes more, of ^O BACTERIA. the above-named forms. The individuals may eventually swarm out and continue their development in an isolated condition. Such mucilaginous masses occur especially upon moist vegetables (potatoes, etc.), on the surface of fluids with decaying raw or cooked materials, etc. The mucilaginous envelope is thrown into folds when the Bacteria, with their mucilaginous cell-walls, multiply so rapidly that there is no more room on the surface of the fluid. The cells of the Bacteria are constructed like other plant-cells in so far as their diminutive size has allowed us to observe them. The cell-wall only exceptionally shows the reactions of cellulose (in Sarcina, Leuconostoc ; also in a Vinegar-bacterium, Bacterium xylinum) ; a mucilaginous external layer is always present. The body of the cell mostly appears to be an uniform or finely granu- lated protoplasm. Very few species (e.g. Bacillus virens) contain chlorophyll ; others are coloured red (purple sulphur Bacteria) ; the majority are colourless. Bacillus amyloLacter shows a reaction of a starch-like material when treated with iodine before the spore-formation. Some Bacteria contain sulphur (see p. 37). The body, which has been described as a cell-nucleus, is still of a doubtful nature. Artificial colourings with aniline dyes (especially methyl-violet, gentian-violet, methylene-blue, fuchsin, Bismarck-brown and Vesuvin) play an important part in the investigations of Bacteria. MOVEMENT. Many Bacteria are self-motile; the long filaments of Beggiatoa exhibit movements resembling those of Oscillaria. In many motile forms the presence of cilia orflagella has been proved by the use of stains ; many forms have one, others several cilia attached at one or both ends (Fig. 23) or distributed ii-regularly over the whole body ; the cilia are apparently elongations of the mucilaginous covering and not, as in the other Algas of the proto- plasm. In Spirochcete the movement is produced by the flexibility of the cell itself. Generally speaking, the motion resembles that of swarm-cells (i.e. rotation round the long axis and movement in irregular paths) ; but either end has an equal power of proceeding forwards. The swarming motion must not be confounded with the hopping motion of the very minute particles under the microscope (Browiiian movement). VEGETATIVE REPRODUCTION takes place by continued transverse BACTERIA. 29 division ; hence the name " Fission-Fungi " or " Fission-Algae," has been applied to the Bacteria. SPORES. The spores are probably developed in two ways. In the ENDOSPOROUS species (Figs. 28, 29), the spore arises as a new cell inside the mother-cell. The spores are strongly refractile, smaller than the mother-cell, and may be compared to the aplanospores of other Algne. In addition to these there are the ARTHROSPOROUS species in which the cells, just as in Nostoc and other Blue-green Algge, assume the properties of spores without previously undergoing an endogenous new construction, and are able to germinate and form new vegetative generations (Fig. 27). The formation of spores very often commences when the vegetative development begins to be restricted. FIG. 27.— Leuconostoc mcsentevioides : a a zoogloea, natural size ; b cross section of zoogloea ; c filaments with spores ; d mature spores ; e-i successive stages of germina- tion ; in e portions of the ruptured spore-wall are seen on the external side of the muci- laginous covering, (b-i magnified 520.) The spores germinate as in Nostoc by the bursting of the external layer of the cell-wall, either by a transverse or longitudinal cleft, but always in the same way, in the same species (Fig. 28, example of transverse cleft). DISTRIBUTION. Bacteria and their germs capable of development, are found everywhere, in the air (dust), in surface water, and in the superficial layers of the soil. The number varies very much in accordance with the nature of the place, season, etc. They enter, together with air and food, into healthy animals and occur always in their alimentary tract. 30 BACTERIA. GROWTH AND REPRODUCTION depend upon the conditions of temperature. There is a certain minimum, optimum and maxi- mum for each species ; for instance (in degrees Centigrade)— VIG. 23. — Bacillus megaterium : a outline of a living, vegetative cell-rod ; b a living, motile, pair of rods ; p a similar 4-celled rod after the effects of iodine alcohol ; c a 5-celled rod in the first stages of spore-formation ; d-f successive stages of spore- formation in one and the same pair of rods (in the course of an afternoon) ; r a rod with mature spores ; g'-;/3 three stages of a 5-celled rod, with spores sown in nutritive solution ; Ji'-fi3, i,fe, I stages of germina- tion ; m a rod in the act of transverse division, grown out from a spore which had been sown eight hours previously. (After de Bary ; a mag. 250, the other figures 600 times). Bacillus subtilis B. anlhracis Spirillum cholerce asiaticce Bacterium tuberculosis Minim. + 6 15 8 Opt. c. 30 20-25 37 28 37-38 FIG. 29. — Bacillus amj/lobacter. Motile rods, partly cylindrical and without spores, partly swollen into various special shapes and wilh spore-forma- tion in the swelling, s Mature spore, with thick mucilaginous envelope. (After de Bary ; mag. 600 times, with the excep- tion of s, which is more highly magnified.) Maxim. + 50 43 40 (but grows only feebly if under 16°). 42 The functions of life cease on a slight excess of the maximum or minimum temperature, numbness setting in when either of these limits is passed. Crenothrix-ila.resLda provided with muci- laginous envelopes may, according to Zopf, sustain a tempera- ture of — 10°. Some Bacteria are said to be able to resist the exposure to as low a temperature as — 110° for a short time. It is not known at what degree of cold the death of the Bacteria oc- curs : the greatest degree of heat which the vegetative cells can BACTERIA. 31 withstand is about the same as that for other vegetative plant- cells, namely, about 50-60° C. Certain Bacteria, e.g. B. tliermo- philus, grow and thrive vigorously at 70° C. Many spores, on the contrary, are able to bear far higher temperatures (in several species a temperature for some duration of above 100°, those of Bacillus subtilis, for instance, can withstand for hours a tempera- ture of 100° in nutrient solutions ; the spores remain capable of development after exposure to a dry heat of 123° C.). The Desiccation of the air, if prolonged, kills many forms when in the vegetative condition. The spores however can bear a much longer period of dryness, some even several years. OXYGEN. Some species cannot live without a supply of free oxygen (Aerobic), e.g. the Vinegar-bacteria, the Hay-bacilli, the Anthrax-bacilli, the Cholera- Microspira. Other species again thrive vigorously without supply of free oxygen, and are even checked in their development by the admission of air (Anaerobic), e.g. the butyric acid Bacterium (Glostridium butyricum = Bacillus amy- lobacter). A distinction may be drawn between obligate and facultative aerobics and obligate and facultative anaerobics. Several Bacteria, producing fermentation, may grow without the aid of oxygen when they are living in a solution in which they can produce fermentation ; but, if this is not the case, they can only grow when a supply of oxygen is available. A great number of the pathogenic Bacteria belong to the facultative anaerobics. A luminous Bacterium (Bacillus phosphorescens) which in the presence of a supply of oxygen gives a bluish-white light, has been found in sea- water. Phosphorescent Bacteria have fre- quently been observed upon decaying sea-fish, as well as on the flesh of other animals ; by transferring the Bacteria from cod fish to beef, etc., the latter may be made luminous. Organic carbon compounds are indispensable for all Bacteria, (except, as it appears, for the nitrifying organisms), as they can only obtain the necessary supplies of carbon from this source. The supplies of nitrogen, which also they cannot do without, can be ob- tained equally as well from organic compounds as from inorganic salts, such as saltpetre or ammonia-compounds. The various "ash- constituents " are also essential for their nourishment. While Moulds and Yeast-Fungi grow best in an acid substratum, the Bacteria, on the other hand, generally thrive best in a neutral or slightly alkaline one. 32 BACTERIA. In sterilization, disinfection, and antisepsis, means are employed by which the Bacteria are killed, or. checked in their development, for instance, by heat (ignition, cooking, hot vapours, hot air, etc.), or poisons (acids, corrosive sublimate). The process of preserv- ing articles of food, in which they are boiled and then hermeti- cally sealed, aims at destroying the Bacteria, or the spores of those which already may be present in them, and excluding all others. As the Bacteria are unable to assimilate carbon from the car- bonic acid of the air, but must obtain it from the carbon-com- pounds already in existence in the organic world, they are either saprophytes or parasites. Some are exclusively either the one or the other, obligate saprophytes or parasites. But there are transitional forms among them, some of which are at ordinary times saprophytes, but may, when occasion offers, complete their development wholly or partly as parasites — facultative parasites ; others are generally parasitic, but may also pass certain stages of development as saprophytes — facultative saprophytes. All chlorophyll-free organisms act in a transforming and dis- turbing manner on the organic compounds from which they obtain their nourishment, and while they themselves grow and multiply, they produce, each after its kind, compounds of a less degree of complexity, i.e. they produce fermentation, putrefaction, sometimes the formation of poisons, and in living beings often disease. Those organisms which produce fermentation are called ferments ; this word, however, is also employed for similar transformations in purely chemical materials (inorganic ferments or enzymes). Many organic (" living ") ferments, among which are Yeast- cells and Bactei'ia, give off during their development certain inorganic and soluble ferments (enzymes) which may produce other transformations without themselves being changed. Dif- ferent organisms may produce in the same substratum different kinds of transformation ; alcoholic fermentation may for instance be produced by different species of Fungi, but in different pro- portions, and the same species produces in different substrata, different transformations (e.g. the Vinegar-bacteria oxydize diluted alcohol to vinegar, and eventually to carbonic acid and water). In the study of Bacteria it is absolutely necessary to sterilize the vessels employed in cultivation, the apparatus, and nutrient solutions, i.e. to free them from Bacteria germs and also to preserve the cultures from the intrusion of any foreign germs ("pure-cultures"). A firm, transparent, nutritive medium is BACTERIA. 33 frequently employed. This may be prepared by adding to tbe nutrient solu- tions (broth) either gelatine, or — when the Bacteria are to be cultivated at blood-heat — serum of sheep's or calf's blood, agar-agar or carragen ; serum alone may in itself serve as a nutrient medium. The so-called " plate-cul- tures " are frequently employed, i.e. the germs are isolated by shaking them with the melted liquid nutrient gelatine, which is then spread on a glass plate and allowed to coagulate ; when later on the individual germs grow into colonies, these remain separate in the solid substratum and it is easy to pursue their further development. Similar plate-cultures may also be cultivated in test-tubes and on microscopic slides. The slides and glass plates must be placed in " moist chambers" free from Bacteria. By sowing a few cells (if pos- sible one) by means of a fine platinum wire, pure cultures for further investi- gation may be obtained. In order to prove the relationship between pathogenic Bacteria and certain diseases, the experimental production of pathogenic Bacteria by the inoculation of Bacteria from pure cultures into healthy animals, is very important. It has not so far been possible to establish a classification of the Bacteria, as the life-history of many species has not yet been sufficiently investigated.1 The opinions of botanists are at variance, in many cases, with regard to the forms of growth of a particular kind. Some species are pleomorphic (many- formed) while others possess only one form. The following Bacteria are Saprophytes : — Gladothrix dichotonia is common in stagnant and running water which is impregnated with or-ganic matter; the cell-chains have false branching. According to Zopf, Leptothrix ochracea is one of the forms of this species which, in water containing ferrous iron (e.g. as FeC03), regularly embeds ferric-oxide in its sheath by means of the activity of the protoplasm. Leptothrix ochracea and other Iron-bacteria, according to Winogradsky (1888), do not continue their growth in water free from protoxide of iron ; while they multiply enormously in water which contains this salt of iron. The large masses of ochre-coloured slime, found in meadows, bogs, and lakes, are probably due to the activity of the Iron-bacteria. Those forms which, according to Zopf's views, represent the forms of development of Cladothrix dichotoma are placed together in Fig. 30. A represents a group of plants, seventy times magnified, attached to a Vaucheria. The largest one is branched like a tree, with branches of ordinary form ; a specimen with spirally twisted branches is seen to the right of the figure, at the lower part some small LeptotJirix-like forms. B shows the 1 See Marshall Ward, " On the Characters or Marks employed for Classifying the Schizomyceles," Annals of Botany, 1892. W. B. D 3-4 BACTEKIA. manner of branching and an incipient Cocctts-formation. C a Coccus-mass whose exit from the sheath has been observed. D the FIG. 3/0.—Cladothrix dicliotoma. same mass as G after the course of a day, the Cocci having turned into rods. E a group of Cocci in which some have deve- loped into shorter or longer rods. F one of these rods before BACTERIA. 35 and after treatment witli picric acid, which causes the chain-like structure to become apparent. G a portion of a plant with con- spicuous sheath, two lateral branches are being- formed. JET part of a plant, whose cells have divided and form Cocci. The original form of the cells in which the Cocci are embedded may still be recognised. I. Leptothrix-Gla,m.Qa.ta with conspicuous mucilaginous sheath, from which a series of rods is about to emerge ; the rod near the bottom is dead, and has remained lying in the sheath. K part of a plant which is forming Cocci, those at the top are in the zoogloea-stage, at the base they are elongating to form rods and Leptothrix-fil&meui,B. L a portion of a branched Cladothrix, which divides into motile Bacillus-forms ; the rays at the free ends indicate the currents which the cilia produce in the water. M a spirally-twisted, swarming filament, before and after division into halves. N part of a tree-like zoogloea with Cocci and short rods. — All of these spirilla, zoogloea, etc., which Zopf has con- nected with Clad, dichotoma, are according to Winogradsky, inde- pendent organisms. Micrococcus urece produces urinal fermentation (transformation of urinal matter into ammonium carbonate) ; aerobic ; round cells generally united to form bent chains or a zoogloea. — Several other kinds of Bacteria have the same action as this one : in damp soil containing ammonia-compounds, saltpetre-formations are pro- duced by M. nitrificans and several different kinds of Bacteria. Micrococcus prodigiosus is found on articles of food containing starch ; " bleeding bread " is caused by this Bacterium, which has the power of forming a red pigment ; it also occurs in milk, and produces lactic acid. Leuconostoc mesenterioides is the frog-spawn Bacterium (Fig. 27) which is found in sugar manufactories, and has the power of producing a viscous fermentation in saccharine solutions which have been derived from plants, e.g. in beetroot-sugar manu- factories, where large accumulations of mucilage are formed at the expense of the sugar, with an evolution of carbonic acid. The cell-rows, resembling somewhat a pearl necklace, have thick mucilaginous cell-walls, and form white " Nostoc "-lumps. The mucilage eventually deliquesces and the cells separate from each other; arthrospores ? — -Similar viscous deteriorations occur in beer and wine, which may then be drawn out into long, string like filaments — " ropiness." Bacterium aceti, the Vinegar-bacterium, oxidizes alcohol into 36 BACTERIA. acetic acid (acetous-fermentation) and forms a greyish covering of Bacteria ("Vinegar-mother") on the surface of the liquid ; the acetic acid formed, becomes by continued oxidization by B. aceti, again transformed into carbonic acid and water. Aerobic; short cylindrical cells, often united into chains, or to form a zoogloaa ; sometimes also rod- and spindle-shaped. The Vinegar- bacteria and other kinds with ball- or rod-forms sometimes become swollen, spindle-shaped, or oval links ; they are supposed to be diseased forms1 ("Involution-forms"). Bacillus laciictts (Bacterium acidi lactici, Zopf) is always found in milk which has stood for some time, and in sour foods (cabbage, cucumbers, etc.) ; it turns the milk sour by producing lactic acid fermentation in the sugar contained in the milk ; the lactic acid formed, eventually causes the coagulation of the casein. It re- sembles the Vinegar-bacteria, occurring as small cylindrical cells, rarely in short rows; not self-motile. — Several other Bacteria appear to act in the same way, some occurring in the mouth of human beings ; some of these Bacteria give to butter its taste and flavour. The kefir-grains which are added to milk for the preparation of kefir, contain in large numbers a Bacterium (Dispora caucasica') in the zoogloea-form, a Yeast-fungus, and Bacilhis lacticus. Kefir is a somewhat alcoholic sour milk, rich in carbonic acid ; it is a beverage manufactured by the inhabitants of the Caucasus, from the milk of cows, goats, or sheep, and is sometimes used as a medicine. In the production of kefir, lactic acid fermentation takes place in one part of the sugar contained in the milk, and alcoholic fermentation in another part, and the casein which had become curdled is partially liquefied (peptonised) by an enzyme of a Zoogloea-bacterium. IlacUlns amylobacter (Bacillus buiyricus) , the Butyric-acid-bac- terium (Fig. 29), is a very common anaerobic which produces fermentation in sugar and lactic-acid salts, and whose principal product is butyric acid. It destroys articles of food and (together with other species) plays a part in the butyric acid fermentation Avhich is necessary in the making of cheese ; it is verv active wherever portions of plants are decaying, in destroying the cellu- lose in the cell-walls of herbaceous plants, and is thus useful in the preparation of flax and hemp. The cells are self-motile, generally cylindrical, sometimes united into short rows ; endo- 1 According to Hausen these are net disease formr, bat occur regularly under certain conditions, e.g. temperature. BACTERIA. 37 N «> \< S sporous; the spore-forming cells swell, assume very different forms, and show granulose reaction. The germ-tube grows out in the direction of the long axis of the spore. Bacillus snbtilis, the Hay-bacillus, is developed in all decoctions of hay ; a slender, aerobic, self-motile Bacillus ; endosporous (aplano- spores) ; the spore-wall ruptures transversely on germination. Crenothrix kilhuiana occurs in the springs of many baths, in wells, in water or drain-pipes. Beggiatoa (parallel with the Blue-green Alga Oscillaria). Long filaments formed of cylindrical cells which are attached by one of the ends, but which are nearly always free when observed. The filaments, like those of Oscillaria, describe conical figures in their revolutions, the free filaments slide upwards and parallel with one another; sheaths are wanting ; strongly refractive sulphur drops are found in the *| ^ r\ interior. The Beggiatoas are the most W H y\ iriai IE a prevalent Sulphur-bacteria. They occur, very commonly in large numbers, wher- ever plant or animal remains are de- caying in water in which sulphuretted hydrogen is being formed ; thus, for ex- ample, B. alba (Fig. 31) occurs frequently as a white covering or slimy film on mud containing organic remains. B. mirabilis is remarkable for its size and its strong peristaltic movements. The Sulphur-bacteria oxidize the sulphuretted hydi-ogen, and accu- mulate sulphur in the shape of small granules of soft amorphic sulphur, which in the living cell never passes over into the crystalline state. They next oxidize this sulphur into sulphuric acid, which is immediately rendered neutral by ab- sorbed salts of calcium, and is given off in the form of a sulphate, thus CaC03 is principally changed into Ca SO4. In the absence of sulphur the nutritive processes are suspended, and consequently death occurs either sooner or later. The Sulphur- bacteria may exist and multiply in a fluid which only contains traces of organic matter, in which organisms devoid of chlorophyll are not able to exist. The Beggiatoas very frequently form white, bulky masses in sulphur wells and y 8 FIG. 31. — Beggiatoa alba: a from a fluid containing abund- ance of sulphuretted hydrogen ; I) after lying 24 hours in a solu- tion devoid of sulphuretted hydrogen ; c after lying an additional -48 hours in a solution devoid of sulphuretted hydro- gen, by this means the trans- verse walls and vacuoles have become visible. 38 BACTERIA. in salt water, the traces of organic material which the sulphur water contains proving sufficient for them. The cellulose-fermenta- tion, to which the sulphur wells iu all probability owe their origin, mainly procures them suitable conditions for existence. The Ca C03 and H2S, formed during the cellulose fermentation by the reduction of CaS04 is again changed into CaSOj and CO2 by the Sulphur-bacteria (Winogradsky, 1887).— Other Sulphur-bacteria, the so-called purple Sulphur-bacteria, e.ij. B. roseo-persicina, Spirillum sanguineum (Fig. 23), Bacterium sulfuratum, etc., have their protoplasm mixed with a red colouring matter (bacterio-purpurin) which, like chlorophyll, has the power, in the presence of light, of giving off oxygen (as proved by T. W. Englemann, 1888, in oxygen-sensitive Bacteria). The three purple Sulphur-bacteria mentioned, are, according to Winogradsky, not pleomorphic kinds but embrace numerous species. Many Spirilli (Spirillum tenue, S. nndula, S.plicatile, and others) are found prevalent in decaying liquids. Bacteria (especially Bacilli) are the cause of many substances emitting a foul odour, and of various changes in milk. Parasitic Bacteria live in other living organisms ; but the relation between "host" and parasite may vary in considerable degree. Some parasites do no injury to their host, others produce dangerous contagious diseases ; some choose only a special kind as host, others again live equally well in many different ones. There are further specific and individual differences with regard to the predisposition of the host, and every individual has not the same receptivity at all times. THE HARMLESS PARASITES OF HUMAN BEINGS. Several of the above mentioned saprophytes may also occur in the alimentary canal of human beings ; e.g., the Hay-bacillus, the Butyric-acid- bacillus, etc. ; but the gastric juice prevents the development of others, at all events in their vegetative condition. Sarcina ven- triatli, "packet-bacterium," is only known to occur in the stomach and intestines of human beings, and makes its appearance in cer- tain diseases of the stomach (dilation of the stomach, etc.) in great numbers, without, however, being the cause of the disease. It occurs in somewhat cubical masses of roundish cells (Fig. 25). LESS DANGEROUS PARASITES. In the mouth, especially between and on the teeth, a great many Bacteria are to be found (more than fifty species are known), e.g. Leptothrix buccalis (long, brittle, very thin filaments which are united into bundles), Micrococci in large lumps, Spirochtvte cohnii, etc. Some of them are known to be injurious, as they contribute in various ways to the decay of the teeth (caries dentiuvn) ; a Micrococcns, for instance, forms lactic acid BACTERIA. 39 in materials containing sugar and starch, and the acid dissolves the lime salts in the external layers of the teeth : those parts of the teeth thus deprived of lime are attacked by other Bacteria, and become dissolved. Inflammation in the tissues at the root of a tooth, is probably produced by septic materials which have been formed by Bacteria in the root-canal. DANGEROUS PARASITES. In a large number of the infections dis- eases of human beings and animals, it has been possible to prove that parasitic Bacteria have been the cause of the disease. Various pathogenic Bacteria of this nature, belonging to the coccus, rod, and spiral Bacteria groups, are mentioned in the following: — Pathogenic Micrococci. Staphylococcus pyogenes aureus pro- duces abscesses of various natures (boils, suppurative processes in internal organs). The same effects are produced by — Streptococcus pyogenes, which is the most frequent cause of malig- nant puerperal fever ; it is perhaps identical with — Streptococcus erysipelatis, which is the cause of erysipelas in human beings. Diplococcus pneumonia (A. Friinkel) is the cause of pneumonia, and of the epidemic cerebro-spinal meningitis. Gonococcus (Neisser) is the cause of gonorrhea and inflammation of the eyes. Pathogenic Rod- Bacteria. Bacterium cholerce gallinarum, an aerobic, facultative parasite which produces fowl-cholera among poultry ; it is easily cultivated on various substrata as a sapro- phyte. The disease may be conveyed both through wounds and by food, and may also be communicated to mammals. Bacillus anthraci*, the Anthrax bacillus (Fig. 32), chiefly attacks mammals, especially herbivorous animals (house mice, guinea-pigs, rabbits, sheep, cattle), in a less degree omnivorous animals (includ- ing human beings), and in a still less degree the Carnivores. Aerobic. Cylindrical cells, 3-4 times as long as broad, united into long rod-like bodies, which may elongate into long, bent, and twisted filaments. Not self-motile. Endosporous. Germination takes place without the throwing off of any spore-membrane (com- pare Hay-bacillus p. 37 which resembles it). Contagion may take place both by introduction into wounds, and from the mucous membrane of the intestines or lungs, both by vegetative cells and by spores ; in intestinal anthrax, however, only by spores. The Bacillus multiplies as soon as it has entered the blood, and the anthrax disease commences. The Bacilli not only give off poison, 40 BACTERIA. but also deprive the blood of its oxygen. Vegetative cells only occur in living animals. This species is a, facultative parasite which in the first stage is a saprophyte, and only in this condition forms spores. Bacillus tuberc^llosis produces tuberculosis in human beings, also in domestic animals (perlsucht). It is a distinct parasite, but may also live saprophytically. It is rod-formed, often slightly bent, and is recognised principally by its action with stains (when stained with an alkaline solution of methyl-blue or carbolic fuch- •° PI --*, 0 =8 -\\ ^ \ . i -'= o. iSk ^-B : : S- M: -I FIG. 32.— Anthrax bacillus (Bacil- lus anthracis) with red (b) and white (a) blood-corpuscles. FIG. 33. — Anthrax bacillus. The formation of the spores ; magnified 450 times. sin, it retains the colour for a long time even in solutions of mineral acids, in contrast with the majority of well-known Bacteria): it probably forms spores which are able to resist heat, dryness, etc. Bacillus lepne produces leprosy ; Bacillus mallei produces glanders ; Bacillus tetani, tetanus (the tetanus bacillus is very common in soil ; anaerobic) ; Bacillus diphtheria, diphtheria ; Bacillus typhosus, typhoid fever, etc. Pathogenic Spiral Bacteria. Spirochwte oberm&ieri (Fig. 24) produces intermittent fever (febris recurrens) ; it makes its appearance in the blood during the attacks of fever, but it is not to be found during intervals when there is no fever. Obligate parasite. Spirillum cholerce asiaticcB (Microspira comma) without doubt produces Asiatic cholera ; an exceedingly motile spirillum, which is also found in short, bent rods (known as the "Comma-bacillus"), CONJUGATE. 41 it lives in the intestines of those attacked by the disease, and gives off a sti*ong poison which enters the body. It is easily ciiltivated as a saprophyte. A great many circumstances seem to show that a number of other infectious diseases (syphilis, small-pox, scarlet-fever, measles, yellow-fever, etc.) owe their origen to parasitic Bacteria, but this has not been proved with certainty in all cases. It has been possible by means of special cultivations (ample supply of oxygen, high temperature, antiseptic materials) to pro- duce from the parasitic Bacteria described above (e.g. the fowl-cholera and the anthrax Bacteria) physiological varieties which are distinct from those appearing in nature and possess a less degree of " virulence," i.e. produce fever and less dangerous symptoms in those animals which are inoculated with them. The production of such physiological varieties has come to be of great practical importance from the fact that they are used as vaccines, i.e. these harmless species produce in the animals inoculated with them immunity from the malignant in- fectious Bacteria from which they were derived. This immunity is effected by the change of the products of one or more of the Bacteria, but we do not yet know anything about the way in which they act on the animal organism. The white blood corpuscles, ac- cording to the Metschnikoff, play the part of " Phagocytes " by absorbing and destroying the less virulent Bacteria which have entered the blood, and by so doing they are gradually enabled to overcome those of a more virulent nature. Class 5. Conjugatae. The Algae belonging to this class have chlorophyll, and pyre- noids round which starch is formed. The cells divide only in one direction, they live solitarily, or united to form filaments which generally float freely (seldom attached). Swarm-cells are want- ing1. The fertilisation is isogamous (conjugation) and takes place by means of apJanogametes. The zygote, after a period of rest, produces, immediately on germination, one or more new vegetative FIG. 31. — a and i> The same blood-cell of a Frog: a in the act of engulfing an anthrax-bacillus ; b after an interval of a few minutes when the bacillus has been ab? orbed. 42 CONJUGATE. individuals ; sometimes akinetes or aplanospores are formed in addition. They only occur in fresh or slightly brackish water. Order 1. Desmidiaceae. The cells generally present markings on the outer wall, and are mostly divided into two symmetrical halves by a constriction in the middle, or there is at least a symmetrical division of the protoplasmic cell-contents. The cell- wall consists nearly always of two layers, the one overlapping the other (Fig. 35 0). The cells either live solitarily or are united into unbranched filaments. The mass of protoplasm formed by the fusion of the two conjugating cells becomes the zygote, which on germination produces one (or after division 2, 4 or 8) new vegetative individual. The chromatophores are either star-, plate-, or band-shaped, and regularly arranged round the long axis of the cell. A FIG. 35. — A Cell of Gi/wiiozy.oa brebistonii, external view showing the distribution of the pores. B A portion of the membrane of Slaurastrum licorne with pores containing proto- plasmic projection?. 0 Cell-wall of Hyalotheca inucosa during cell-division ; the central part, being already formed, shows the connection with the divisional wall. The Desmidiaceee are not able to swim independently, many species, however, show movements of different kinds by rising and sliding forward on the substratum. These movements, which are partly dependent upon, and partly independent of light and the force of gravitation, are connected with the protrusion of a mu- cilaginous stalk. The mucilage, which sometimes surrounds the whole individual, may acquire a prismatic structure, it is secreted by the protoplasmic threads which project through certain pores definitely situated in the walls (Fig. 35 A, B). VEGETATIVE MULTIPLICATION takes places by division. A good example of this is found in Cosmarium botrytis (Fig. 36 A-D). The nucleus and chromatophores divide, and simultaneously the central indentation becomes deeper, the outer wall is then ruptured making a circular aperture through which the inner wall protrudes forming a short, cylindrical canal between the two halves to which it is attached (Fig. 36 C). After elongation the canal is divided by a central transverse wall, which commences as a ring round its CONJUGATE. inner surface and gradually forms a complete septum. The divid- ing wall gradually splits, and the two individuals separate from each other, each one having an old and a new half. The two FIG. 36.— Cosmo rinm botrytis. A-D Different stages of cell-division. daughter-cells bulge out, receive a supply of contents from the parent-cells, and gradually attain their mature size and develop- ment (Fig. 36-B-D). Exceptions to this occur in some forms. CONJUGATION takes place in the simplest way in Mesotcenium, where the two conjugating cells unite by a short tube (conjugation-canal), which is not developed at any particular point. The aplanogametes merge together after the dissolution of the dividing wall, like two drops of water, almost without any trace of preceding contraction, so that the cell-wall of the zygote generally lies in close contact with the conjugating cells. The conjugating cells in the others lie either transversely (e.g. Cosmarium, Fig. 37 d ; Staurastrum, etc.), or parallel to one another (e.g. Penium, Closterium, etc.), and FIG. 37. — Cosmarium menegliinii : a-c same individual seen from the side, from the end, and from the edge ; d-f stages of conjugation ; g-i germination of the zygote. emit a short conjugation-canal (Fig. 37 d) from the centre of that side of each cell which is turned towards the other one. These canals touch, become spherical, and on the absorption of the divid- ing wall the aplanogametes coalesce in the swollen conjugation- canal (Fig. 37 c), which is often sin-rounded by a mucilaginous envelope. The zygote, which is often spherical, is surrounded by a thick cell-Avail, consisting of three layers ; the outermost of these CONJUGATE. sometimes bears thorn-like projections, which in some species are simple (Fig. 37/), in others branched or variously marked; in some, however, it remains always smooth (e.g. Tetmemorus, Desmidium*). Deviation from this mode of conjugation may occur within certain genera (e.g. Closterium, Penium). Upon germina- tion the contents of the zygote emerge, surrounded by the inner- most layers of the wall (Fig. 37 g, h\ and generally divide into two parts which develope into two new individuals, placed trans- versely to each other (Fig. 37 i) ; these may have a somewhat more simple marking than is generally possessed by the species. FIG. 38. — Destnidiacese. A Closterium moniliferum ; Ji Pennon crastiu&culum ; C Micrasterias truncata .(front and end view) ; D Euastruin, elegans ; E Stauraktrum muticum (end view). The most frequent genera are : — A. Solitary cells : MESOT^NIUM, PENIUM (Fig. 38 £?), CYLINDKOCVSTIS, EUASTRUM (Fig. 38 D), MICRASTEEIAS (Fig. 38 C), COSMAHIUM (Fig. 36, 37), XANTHIDIOJI, STAURASTRUJI (Fig. 38 E), PLEUROX.ENIOM, DOCIDIOM, TETJIEMORUS, CLOSTERIUM (Fig. 38 A), SPIROT^NIA. B. Cells united into filaments : SPH.EROZOSMA. DESMIDICM, HYALOTHECA, GYMNOZYGA, ANCYLONEMA, GONATOZYGON. Order 2. Zygnemaceae. Cell-wall without markings. The cells are cylindrical, not constricted in the centre, and (generally) united into simple, unbranched filaments. The whole contents of the conjugating cells take part in the formation of the zygote, which on germination grows out directly into a new filament. Spirogyra is easily recognised by its spiral chlorophyll band ; Zy/jnema has two star-like chromatophores in each cell (Fig. 40) ; both these genera are very common Alga? in ponds and ditches. CONJUGATE. 45 The conjugation among the Zygnemacete takes place in the following manner : the cells of two filaments, lying side by side, or A n FIG. 39. — Spirogyra longata. A At the commencement of conjugation, the conjugation- canals begin to protrude at a and touch one another at J> ; the spiral chlorophyll band and cell-nuclei (fc) are shown. B A more advanced stage of conjugation; a, a' the rounded female and male aplanogametes : in b' the male aplanogamete is going over to and uniting with the female aplanogamete (b). two cells, the one being situated above the other in the same fila- ment (Fig. 41), push out small protuberances opposite each other (Fig. 39 A, a, b) ; these finally meet, and the dividing wall is ab- sorbed so that a tube is formed connectin one cell with the other ; S- FIG. 40.— A cell of Zygnema. S Pyrenoid. FIG. 41. — Zygnema insigne, with zygote. the protoplasmic contents round off, and the whole of these contents of one of the cells glides through the conjugation-tube and coalesces with that of the other (Fig. 39 5), the aggregate mass then rounds off, sur- rounds itself with FIG. 42.— Germinating zygote of Spirogyra jugalis -. the a cell-Wall, and be- young plant is still unicellular; the end which is still in comes a ZV^ote A the wall of the zygote is elongated and root-like; the chromatophore divides and forms the spiral band. distinct difference 46 CHLOROPHYCE^. may be found between the cells in the two filaments, those in the one whose protoplasmic contents pass over being cylindrical, while those of the recipient one are more barrel-shaped, and of a larger diameter. The former may be regarded as a male, the latter as a female plant. The zygote germinates after a period of rest, and grows out into a new filament (Fig. 42). Order 3. Mesocarpaceae. The cell-walls are glabrous, uncon- stricted in the centre, and united into simple unbranched filaments. The chromatophore consists of an axial chlorophyll-plate, with several pyrenoids. The zygote is formed by the coalescence of two cells (Fig. 43) (sometimes three or four), but the whole proto- plasmic contents of the cells do not take part in this process, a portion always remaining behind ; the aplanogametes coalesce in the conjugation-canal. The zygote thus formed appears incapable of germination until after 3-5 divisions. Of the cells so formed, FIG. 43. — Nowjeotia calcarea. Cells showing various modes of conjugation : at m tripar- tition ; pg quadripartition ; s quinquipartition of the zygote. only one is fertile, the sterile cells, according to Pringsheim, con- stituting a rudimentary sporocarp. The germinating cells grow out into a new filament. In this order, conjugation has been ob- served between two cells of the same filament. The Mesocarpacese thrive best in water which contains lime. Class 6. Chlorophyceae (Green Algae). These Algse are coloured green by chlorophyll, seldom in com- bination with other colouring matter, and then especially with red. The product of assimilation is frequently starch, which generally accumulates round certain specially formed portions of protoplasm termed pyrenoids. The thallus is uni- or multi-cellular; in the higher forms (certain Siphonea?) the organs of vegetation attain differentiation into stem and leaf. The asexual reproduction takes place in various ways ; the sexual reproduction is effected by con- jugation of motile gametes, or by oogamous fertilisation. The PROTOCOCCOIDE^. 47 swarm-cells (zoospores, gametes, and spermatozoids) are con- structed symetrically, and have true protoplasmic cilia, these generally being attached to the front end of the swarm- cells. Most of these Alga? live in water (fresh or salt); some are found upon damp soil, stones, or tree- stems, and some live enclosed in other plants. The Class is divided into three families : — 1. PROTOCOCCOIDEJ; : Volvocaceae, Tetrasporacea?, Chloro- sphasraceas, Pleurococcaceaa, Protococcaceas, Hydrodictyaceae. 2. CONFERVOIDE^E : Ulvacea?, Ulothricaceae, Cha?tophoracea?, Mycoideacea3, Cylindrocapsaceaa, (Edogoniacege, Coleochaetacea-, Cladophoraceas, Gomontiacea?, Sphn?ropleacea3. 3. SIPHONED : Botrydiacea?, Bryopsidacea?, Derbesiaceae, Vau- cheriacea?, Pbyllosiphonacea3, Caulerpacese, Codiaeese, Valoniaceae, Dasycladacese. Family 1. Protococcoideae. The Alga1 which belong to this group are uni- or multi-cellular with the cells more or less firmly connected, sometimes in a definite, sometimes in an indefinite form (Fig. 47). Colonies are formed either by division or by small unicellular individuals be- coming united in a definite manner ; the colonies formed in this latter way are termed C&nobia. Apical cells and branching are absent. Multiplication by division ; asexual reproduction by zoo- spores, rarely by akinetes. Sexual reproduction may be wanting, or it takes place by isogamous, rarely by oogamous fertilisation. Some are attached by means of a stalk to other objects (Chara- cium, Fig. 49), others occur as " Endophytes " in the tissues of certain Mosses or Phanerogams, e.g. Chlorochytrium lemncu, in Lemna trisitlca ; Endosphcera, in the leaves of Potamogeton, Mentha aquatica, and Peplis portula ; Phyllobium, in the leaves of Lynmachia num- inularia, A/uga, Chlora, and species of Grasses ; Scotinosphcera in the leaves of Hypnum and Lemna trisulca ; the majority, however, live free in water and in damp places. Many species which were formerly considered to belong to this family have been proved to be higher Alga? in stages of development. Order 1. Volvocaceae. The individuals in this order are either uni- or multi-cellular, and during the essential part of their life are free-swimming organisms. They are generally encased in a mucilaginous envelope, through which 2-6 cilia project from every 48 PROTOCOCCOIDEJ:. cell. The vegetative reproduction takes place by the division of all, or a few, of the cells of the individual ; in some a palmella-stage is found in addition. The sexual reproduction takes place by isogamous or oogamous fertilisation. The Volvocacese may be considered to include the original forms of the Chloro- phycete, because, among other reasons, the motile stage is here the most promi- nent ; they also form the connecting link between the animal Flagellata, and forms intermediate to the Syngeneticcc may perhaps be found amongst them. Three series of green Algee may be supposed to have taken their origin from the Volvocacea? : CONJUGATED (Desmidiacece) which have lost the swarming stage, but whose conjugation is the nearest to the fertilisation in Chlannjdomonas pulvis- cuhis : the PKOTOCOCCACE.S: in which the vegetative divisions have disappeared, while the swarming stage continues to be present, though of shorter duration ; and TETRASPORACE^E, in which the vegetative divisions are more prominent, whilst the swarming stage is less so. A. UNICELLULAR INDIVIDUALS. The principle genera are : Chla- mydomonas, Sphcerella, Pliacotns. — Sphterella nivalis is the Alga which produces the phenomenon of " Red Snow," well known en high mountains and on ice and snow fields in the polar regions. The red colouring matter which appears in this and other green Alga?, especially in the resting cells, is produced by the alteration of the chlorophyll. Phacotus lenticidaris has an outer covering incrusted with lime, which, at death, or after division, opens out into two halves. Species may be found among Chlamydomonas, in which conjuga- tion takes place between gametes of similar size without cell-wall, but in C. pulvisculus conjugation takes place between male and female aplanogametes which are surrounded by a mucilaginous envelope. B. MULTICELLULAR INDIVIDUALS. The most important genera are Gonium, Stephanosplicera, Pandor- inn, Eudorina, Volvox* — Gonium has 4 or 16 cells arranged in a definite pattern in a flat plate Fig. 44.— Gonium pectornle. /T-,. ,.x -^ , . -.-r-,. . „< (Fig. 44). Pandonna (Fig. 45), has 16 cells arranged in a sphere (Fig. 45 A). The vegetative reproduction takes place in this way : each cell, after having rounded off, and after the withdrawal of the cilia, divides itself PROTOCOCCOIDE^:. 49 into 16 new ones (Fig. 45 B), each forming a new individual, which soon grows to the size of the mother-individual. It was in this Alga that the conjugation of self-motile gametes was first discovered by Pringsheim, 1869. When conjugation is about to take place, each cell divides into sixteen, as in vegeta- tive reproduction, but the 16 x 16 cells all separate from one another (Fig. 45 C, female gametes, and D, male gametes), and FIG. 45. — Pandorina worum. swarm solitarily in the water. The male are, most frequently, smaller than the female, but otherwise they are exactly alike ; they are more or less pear-shaped, with a colourless anterior end, 2 cilia, a red " eye-spot," etc. After swarming for some time they approach each other, two and two, generally a large and a smaller one, and come into contact at their colourless end ; in a few moments they coalesce and become one cell (Fig. 45 E, F), this W. B. E 50 PROTOCOCCOIDEjE. has at first a large colourless anterior end, 4 cilia, and 2 " eye- spots" (Fig. 45 G), but these soon disappear and the cell becomes uniformly dark-green and spherical, and surrounds itself with a thick cell-wall, losing at the same time its power of motion : the zygote (Fig. 45 H) is formed, and becomes later on a deep red colour. On the germination of the zygote, the protoplasmic cell- contents burst open the wall (Fig. 45 J), and emerge as a large swarmspore (Fig. 45 K) which divides into 16 cells, and the first small individual is formed (Fig. 45 i, M). Eudorina is like Pandorina in structure, but stands somewhat FIG. 46.— Volvox gfobator, sexual individual : a antheridia which have formed sperniato- zoids ; b oogonia. higher, since the contrast between the conjugating sexual cells is greater, the female one being a motionless oosphere. The highest stage of development is found in Volvox (Fig. 46). The cells are here arranged on the circumference of a sphere, and enclose a cavity filled with mucilage. The number of these cells may vary from 200-22,000, of which the majority are vegetative and not reproductive, but some become large, motionless oospheres (Fig. 46 b) ; others, which may appear as solitary individuals, divide and form disc- shaped masses of from 8-256 small spermato- PROTOCOCCOIDEjE. 51 zoids (Fig. 46 a). After the oosphere has been fertilised by these, the oospore surrounds itself by a thick, sometimes thorny cell- wall, and on germination becomes a new individual of few cells. A few cells conspicuous by their larger size may be found (1—9, but generally 8) in certain individuals, and these provide the vegeta- tive reproduction, each forming by division a new individual. Order 2. Tetrasporaceae reproduce both by vegetative divisions and swarmspores, some have also gamete-conjugation. The principal genera are : Tetraspora, Apioci/stis, Dactylococcus, Dictyuspharium, Chloranyium. Order 3. Chlorosphaeraceae. Chlurosphara. Order 4. Pleurococcaceae. In this order the swarm-stages O and sexual reproduction are entirely absent. Vegetative repro- duction by division. The principal genera are : Pleurococcus (Fig. 47), Scenedesmus (Fig. 48), . Raphidium, Oocystis, ScMzochlamys, Crucigenia, Selenastrum. — Pleurococcus vulgaris (Fig. 47) is one of the most common Algae throughout the world, occurring as o'reen coverings on tree-stems, and damp walls, and it is one of the most common lichen-gomdia. B FIG. -17. — Pleurococcus vulgaris. FIG. 48. — ScciictlcsiiiHS quadricauda. Order 5. Protococcaceae. The cells are motionless, free or affixed on a stalk (e.g. Characium, Fig. 49), either separate or loosely bound to one another ; they never form multicellular individuals. Multiplication by division is nearly always wanting. Reproduction takes place by swarmspores, which have 1 or 2 cilia, and sexual reproduction in some by gamete- conjugation. The principal genera are : Chlo- rococcum, Ghlorochytfium, Chlorocystis, Scotino- sphc&ra, Endosplicera, PhylJobium, Characiurn, Ophwcytium, Sciadium. Order 6. Hydrodictyacese. The indi- viduals are unicellular but several unite after the zoospore-stage into definitely formed families (coenobia). Ordinary vegetative division is wanting, but FIG. 49. — Characiwm strictum. A The cell-son- tents have divided into many swarrnspores. B Swarmspores escaping. 52 PROTOCOCCOIDE^E. asexual reproduction takes place by zoospores (or by motionless cells without cilia), which unite and form a family similar to the mother-family, inside the mother-cell, or in a mucilaginous enve- lope. Where sexual reproduction is found it takes place by gamete-conjugation. The principal genera are : Pediastrum (Fig. 50), Cwlastrum, Hydrodictyon (Fig. 51). The coanobiuin of Hydrodictyon reticulatum (Water-net) is formed of a large number of cells which are cylindrical, and attached to one another by the ends (Fig. 51). The asexual reproduction takes place by zoospores, which are formed in large numbers (7,000-20,000) in each mother-cell, within which they move about for a time, and then come to rest and arrange them- selves into a new net (Fig. 51 A) which is set free by the dissolu- tion of the wall of the mother-cell, grows, and becomes a new B FIG. 50. — Pediastrum agperwm. FIG. 51. — Hydrodictyon reticulatum. A A cell where the zoospores are on the point of arranging themselves to form a net. B A cell with gametes svyarming out. coenobium. The sexual reproduction takes place by gamete-conju- gation. The gametes are formed in the same manner as the zoo- spores, but in larger numbers (30,000-100,000), and swarm out of the mother-cell (Fig. 51 B). The zygote forms, on germination, 2-5 large zoospores, each with one or two cilia, these generally swarm about for a time, and after a period of rest become irregular thorny bodies (polyhedra) ; their contents again divide into zoo- spores, the thorny external coating of the polyhedra is cast off, and the zoospores, surrounded by the dilated internal coating, unite to form a small family, which produces several others in the manner described. CONFER VOIDED. OO Family 2. Confervoideae. The individuals are always multicellular, the cells firmly bound together and united into unbranched or branched filaments, expansions, or masses of cells which grow by intercallary divisions or have apical growth. In the first seven orders the cells are uninuclear, but the cells of the remaining three orders contain several nuclei. Asexual reproduction by zoospores, akinetes or aplanospores. Sexual reproduction by isogamous or oogamous fertilisation. The Confervoidea?, through the Ulvaceaj, are connected with the Tetra- sporacefe, and from the Coleochccttrcefe, which is the most highly developed order, there are the best reasons for supposing that the Mosses have taken their origin. The Clndophoracea: show the nearest approach to the Sipliontie. Order 1. Ulvaceae. The thallus consists of one or two layers, of parenchymatous cells, connected together to form either a flat membrane (JMonnstroma, Ulva) or a hollow tube (Enteromorplia), and may be either simple, lobed, or branched. Reproduction takes place by detached portions of the thallus ; or asexually by zoospores or akinetes. Gamete conjugation is known to take place in some members of this order, the zygote germinating without any resting-stage. The majority are found in salt or brackish water. Order 2. Ulothricaceae. The thallus consists normally of a simple unbranched filament (sometimes a small expansion con- \ FIG. 52. — Ulothrix zonnta: a portion of a filament with zoospores, which are formed two in each cell (zoosporangium); the dark spots are the red "eye-spots"; 1, 2, 3, 4, denote successive stages in the development of the zoospores ; b a single zoospore, v the pulsating vacuole ; c portion of a filament with gametes, sixteen are produced in each gnmetangium ; d free gametes, solitary or in the act of conjugation ; e the conjugation is completed, and the formed zygote has assumed the resting-sta.ge. sisting of one layer of cells is formed, as in Schizomeris and Prasiola which were formerly described as separate genera). Asexual reproduction takes place by means of zoospores (with 54 CONFERVOIDE.E. 1, 2, or 4 cilia), akinetes or aplanospores ; the last named may germinate immediately, or only after a period of rest. Sexual re- production takes place by the conjugation of gametes of about the same size, each having two cilia (Fig. 52 d). The zygote of Ulothrix, on germination, produces a brood of zoospores which swarm for a time and then elongate to become £7/o^/m',£-filaments (alternation of generations). The gametes may also germinate without conjugation in the same manner as the zoospores. The principal genera are : Ulothrix, Hormidium, Conferva, Micro- spora. — Ulothrix zonata is very common in running fresh water. Nearly all the species of Hormidium occur on damp soil, tree- stems and stones. Order 3. Chaetophoraceae. The thallus consists of a single, branched, erect or creeping filament of cells, often surrounded by mucilage. The cells have only one nucleus. Asexual reproduc- tion by zoospores with 2 or 4 cilia, by akinetes, or aplanospores. In many, conjugation between gametes with 2 cilia may be found. They approach on one side, Ulothricaceae, and on the other, My- coideacea?. The principal genera are : Siigeoclonium, Draparnahlia, Cluvtophora, Enloderma, Aphanochtvte, Herposteiron, Phceuthamnion, Cltlorotylium, Trichophihis, Gongrosira, TrentepohJia. Most of the species of Trentepoklia are coloured red by the presence of a red colouring material, which occurs in addition to the chlorophyll. They are aerial Algae which live on stones (T. julithus, "violet stone," so named on account of its violet-like odour in rainy weather), on bark and old wood (T. umbrina'), or on damp rocks (T. aurea). Trichophilus icelckeri lives in the hair of Bradypus. Order 4. Mycoideaceae. The thallus is discoid, consisting of one or more cell-layers, and is always attached. Asexual reproduction by zoospores with 2 or 4 cilia. Sexual reproduction in some species by the conjugation of gametes with 2 cilia. This order forms the connecting link betweeu Cluctop]ior(tct Zoospore. E Spermatozoid. to an oogonium, germinates, and gives rise to a filament of a very few cells— dwarf-male (A, B, ?»). The spermatozoids are formed in the upper cell of the dwarf-male («i), and are set free by the summit of the antheridium lifting off like a lid. On the germina- tion of the oospore (C), which takes place in the following spring, 4 zoospores are produced (F) (i.e. the sexual generation) ; these swarm about for a time, and ultimately grow into new filaments. Order 7. Coleochsetacese. The thallus is always attached, and of a disc- or cushion-shape, formed by the dichotomous branching of filaments of cells united in a pseudo-parenchy- matous manner. Each cell has only one nucleus. Asexual re- production by zoospores with 2 cilia (Fig. 55 D), which may arise in all the cells. Sexual reproduction by oogamous fertili- sation. The spermatozoids resemble the swarmspores, but are 58 .CONFERVOIPEJ:. smaller (E), and originate singly (in the species figured) in small conical cells (c, d in A\ The oogonia are developed at the extremities of certain branches : they are bottle-shaped cells with very long and thin necks (trichogyne), open at the end (a in A); at the base of each oogonium is a spherical oosphere. The sper- matozoids reach the oosphere through the trichogyne, or through an aperture in the wall when the trichogyne is absent, and fertili- sation having taken place, the oogonium becomes surrounded by a cell-layer (envelope), which grows out from the cells near its base (b in A), and in this way a kind of fruit is formed (B) (spermocarp, cystocarp) . The oospore, next spring, divides and forms a parenchymatous tissue (homologous with the Moss-sporophyte) ; this bursts open the envelope (C), and a zoospore (homologous with the spores of the Moss-capsule) arises in each of the cells, and produces a new Goleochcete. We have then, in this case, a still more distinct alternation of generations than in GEdogonium. Only one genus, Coleochcete, is known, but it contains several species, all living in fresh water. Order 8. Cladophoraceae. This order is probably derived from the Ulothricacea?. The thallus consists of a single, un- branched or branched filament, generally with an apical cell. The cells have each 2 or more nuclei. Asexual reproduction by zoospores with 2 or 4 cilia, and by akinetes. Conjugation of gametes with 2 cilia is found in some genera. They occur in salt as well as in fresh water. The principal genera are: Urospora, Chcetomorpha, Ithizoclonium, Cladophora; of the last named genus the species C. lanosa and C. rupestris are common in salt water ; C. fracta and C. glomerata in fresh water. Order 9. Gomontiace*. Gomontia polyrrhiza, the only species hitherto known, is found on old calcareous shells of certain salt water Molluscs. Order 10. Sphceropleaceae. The thallus consists of free, un- branched filaments, with very elongated multinuclear cells. The ve-etative cells form no zoospores. Sexual reproduction by oogamous fertilisation (see page 13, Fig. 10 B). The oospore has a thick wall (Fig. 10 D) studded with warts, and assumes a colour resembling red lead. It germinates only in the following spring, and produces 1-8 zoospores, each with 2 cilia (Fig. 10 E), which grow into new filaments. Only one species, Sphceroplea unnulina, is known. SIPHONED. 59 Family 3. Siphoneae. The thallus has apical growth, and in the vegetative condition consists generally of one single (in the Valoniacese most frequently of more) multinuclear cell, which may be much branched, and whose separate parts in the higher forms (e.g. Bryopsi*, Fig. 57 ; Caulerpa, Fig. 59, etc.) may be differentiated to perform the various physiological functions (as root, stem and leaf). Vegeta- tive multiplication by detached portions of the thallus (gemmae) ; asexual reproduction by zoospores, akinetes, or aplanospores. Sexual reproduction by gamete-conjugation, rarely by oogamous fertilisation. The zygote or oospore germinates as a rule without any resting-stage. Most of the Siphonene occur in salt water or on damp soil. FIG. 56. — Botrydium granulatum : a an entire plant forming1 swarmspores ; b swarm- spores; c an individual with gametangia ; d, gamete; e,f,g conjugation; h zygote seen from above ; i the same in a lateral view. Many (e.g. Dasycladact'W) are very much incrusted with lime, and occur, in the fossilized condition, in the deposits from the Cretaceous period to the present time. The Siphonete are connected by their lowest forms (Botrydiacew or Valonia) with the Protococcacea?, but show also, through the Valoniacese, points of relationship to the Cladophoracece. Order 1. Botrydiaceae. The thallus in the vegetative condi- tion is unicellular, club-shaped, with a small single (Codiolwrn) or repeatedly dichotomously branched system of colourless rhizoids (Botrydium, Fig. 56 a), by which it is attached to objects immersed in salt water (Codtolum) or to damp clay soil (-Botrydium). Asexual reproduction by zoospores with one (Botrydium) or two 60 SIPHONED. cilia, and by aplauospores. The sexual reproduction is only known in Botrydium, and takes place in the following manner: in the part of the thallus which is ahove ground and in an active vegetative condition, several round cells (Fig. 56 c) are formed, which may be green or red according as they grow under water, or exposed to the strong light of the sun. These cells must be considered as "gametangia" as they produce many gametes (d) provided with two cilia. The zygote (h, i) formed by the conju- gation (e, /, g) may either germinate immediately, or become a thick-walled resting-cell of an irregular, angular form. Order 2. Bryopsidacese. The thallus in the vegetative condition is uni- cellular, and consists at the lower extremity of branched rhizoids. while the upper portion is prolonged into a stem-like structure of un- limited growth, producing, acropetally, branches and leaf-like structures. The latter have limited growth, and are separated by a cross wall from the stem, and be- come gametangia, or drop off. The gametes have two cilia, and are of two kinds : the female, which are green and large and the male, which are of brownish colour and smaller. Zoospores or anj- other method of asexual reproduction are unknown. Only one genus, Bryopsis, living in salt water. OrderS. Derbesiacese. Only one genus, Derbesia, living in saltwater. The zoospores, which are formed in a few lateral, swollen zoosporangia, possess one nucleus which has arisen through the coalescence of several, and they resemble the zoospores of ffidogonium by having a circle of cilia attached at the base of the colourless spot. Order 4. Vaucheriacese. The thallus consists, in the vegetative condition, of a single irregularly or dichotomously branched cell, without differentiation into stem or leaf ; root-like organs of attach- ment may however occur. Asexual reproduction by zoospores, which are formed singly in the extremity of a branch cut off by a transverse wall. They contain many nuclei, and bear small cilia situated in pairs, which give the appearance of a fine " pile " covering the whole or a great part of the surface. Akinetes, FIG. 57. — Bryopsis plumosa. A the plant, natural size. K A portion (enlarged) which shows the growing point (w), and the leaves derived from it in acropetal succes- sion. SiPHONEJS. 61 aplanospores, and phytoamosbae (naked masses of protoplasm, without cilia, which creep like an amoeba on a substratum) may occur under certain conditions. The sexual reproductive organs are formed on short lateral branches, and are separated from the vegetative cell (Fig. 58 A) by cell-walls. Numerous spermatozoids, each with two cilia, are developed in the coiled antheridium (A, b). The oogonium is a thick, egg-shaped, often oblique cell, with its protoplasm rounded into an oosphere, which has a hyaline " receptive-spot" (A, a) im- mediately beneath the aperture formed in the wall of the oogonium. A slimy mass, which serves to receive the spermatozoids, is formed in some species in this aperture. The spermatozoids when liber- ated swim towards and enter the oosphere, which then immedia- A B FIG. 58.— Vawcheria sessilis. A Fertilisation ; b the antheridia ; a the oogonia ; a the receptive spot. B Oospore. tely surrounds itself with a thick cell-wall. The mature oospore (-B) contains a large quantity of oil. At germination the outer cell-wall bursts and a new plant is formed. There is only one genus, Vaucheria, with species living in salt as well as in fresh water and on damp soil. Order 5. Phyllosiphonaceze are parasites in the leaves and stalks of Flowering-plants. Order 6. Caulerpaceae. The thallus has distinct dift'erentation into root, stem and leaf-like members (Fig. 59) ; it is unicellular. Within the cell, strong, branched threads of cellulose extend from one side to the other serving as stays to support the thallus. Reproduction takes place by detached portions of the thallus; no other modes of reproduction are known. This order may most approximately be classed with the Bryopsidacece. The genus Caulerpa consists of more than seventy species which inhabit the tropical seas. Order 7. Codiaceae. The thallus has various forms, but with- 02 SIPHONED. out distinct differentiation in stem- or leaf-structures, sometimes (e.g. Halimeda) it is very much incrusted with lime. In the early stages it is unicellular (later, often multicellular), very much branched, with the branches, at any rate partly, so united or grown in amongst one another (Fig. 60) that an apparently pai-enchymatous cellular body is formed. Akinetes or aplanospores are wanting; zoospores (or gametes ?) may be developed in some species, however, in special swollen sporangia. Fertilisation similar to that in Bryopsis occurs perhaps in Codium. They are rill salt water forms. Order 8. Valoniaceae. The thal- lus is generally multicellular, without differentation into stem- or leaf-struc- tures, but the cells are sometimes united together and form a leaf-like reticulate expansion (e.g. Anadyomene). Zoospores are known in some, and they are then formed directly in the vegetative cells. In others (e.g. Valonia), a mass of protoplasm, which maybe separated through the damag- ing of a cell, can surround itself with FIG. 59. — Cnulcrpa, prolifera (natural size). a cell-wall, and grow into a new plant. No other modes of reproduction are known. The most important genera are : Valonia, Siphonocladus, Chamadoris, Strucea, Microtiictyon, Anadyomene. They are all salt water forms. As already pointed out, the Valoniaceer occupy a somewhat central position among the Siphoneze, and present points of similarity and contrast with the liotrydiacfa; and the Bryopsidacetc through Valonia, with the Dasycladaceee through C)iama>doris, and also with the Cladophoracete through Siphonocladus, and Slruvea. SIPHONED. 63 Order 9. Dasycladaceae. The thallus consists of an axile longitudinal cell, destitute of transverse walls, attached at the base by root-like organs of attachment, and producing acropetally whorls of united, single or branched, leaf-like structures with limited growth. Asexual reproduction is wanting. Sexual re- production by conjugation of gametes which arise in separate, fertile leaves/either directly or from aplanospores, which develope into gametangia. The principal genera are : Acetabularia, Dasy- cladus. Neomeris, Cymopnlia. All marine. The curiously shaped Acetalndaria mediterra- nea grows gregariously on limestone rocks, and shells of mussels in the Mediterranean ; it re- sembles a minute um- brella with a small stem, sometimes as much as nine centimetres in height, and a shade which may be more than one centimetre in di- ameter. The cell-mem- brane is thick, and incrusted with carbonate and oxalate of lime. Only the lower, root- like part of the thallus, which penetrates the calcareous substratum- survives the winter, and may grow up into a new plant. The sterile leaves, which drop off early, are dichoto- mously branched and formed of cylindrical cells separated from each other by cross-walls, but they are not grown to- gether. The shade is formed by a circle of 70-100 club-shaped rays (fertile leaves) grown together, in each ray 40-80 aplano- spores are formed, which become liberated at the breaking of the shade, and later on are changed to gametangia (compare Botry- dium} which open by a lid and allow a large number of egg- shaped gametes with two cilia to escape. Gametes from various FIG. 60.— Halimeda opuntia. Plant (natural size). B Part of a longitudinal section. 64 CHARACEJ:. gametangia conjugate with one another; the product of the conju- gation swarms about for some time, rounds off, and then surrounds itself with a cell-wall. The zygote germinates after a period of rest and then produces a sexual plant. The aplanospores (game- tangia) thus represent the sexual generation. Class 7. Characese. The thallus has a stem with nodes and internodes ; and whorls of leaves, on which may be developed the antheridia and oogonia, are borne at the nodes. Vegetative reproduction by bulbils and accessory shoots. Zoospores are wanting. The antheridia are spherical, and contain a number of filaments in which the spirally coiled spermatozoids, each with two cilia, are formed. The oogonium is situated terminally, and is at first naked, but becomes later on surrounded by an investment, and forms after fertilisation the so-called " fruit." The oospore, after a period of rest, germinates by producing a " proembryo," from which the young sexual plant uri.ses as a lateral branch. The Characeaa are distinguished by the structure of their vegetative system as well as by the spirally- coiled spermatozoids, and stand as an isolated group among the Thallophytes, of which, however, the Siphonete appear to be their nearest relations. They were formerly, but wrongly, placed near the Mosses. The class contains only one order, the Characese. Order 1. Characeae. Alga? with a peculiar odour, often incrusted with lime, and of a brittle nature. They generally grow gregariously in large masses at the bottom of fresh and brackish water, and are from a few inches to more than a foot in height. The stem has long internodes which in Nitella are formed of one cylindrical cell; in Chara of a similar cell, but closely surrounded by a cortical layer of smaller ones. The protoplasm in contact with the cell- wall exhibits in a well-marked degree the movement of rotation (cyclosis), carrying the chlorophyll corpuscles along with it. The internodes are separated from each other by a layer of small cells (nodal cells) from which the leaves are produced. The leaves are borne in whorls of from 5-12 which regularly alternate with one another as in the higher verticillate plants ; a branch is borne in the axil of the first formed leaf of each whorl (Fig. Gl A, «). The leaves are constructed in the same manner as the stem ; they are divided into a series of joints, but have only a limited CHARACE.E. 65 power of growth ; their terminal cell, too, is not enclosed by a cortex. Leaflets are borne at their nodes. The growth of the stem is unlimited, and proceeds by means of an apical cell (Fig. 62 s). The apical cell divides into a segment-cell and a new apical cell. The segment-cell then divides by a transverse wall into two cells, one lying above the other ; the lower one, without FIG. 61.— Charafragilis. A Portion of a plant, natural size. B Portio'i of a leaf I, with leaflets £'-£" ; a antht-ridium ; c oogonium. C A shield.— Nitella Jlexilis. D Filament from antherkliuru with sperm itozoids. E Free spermatozoids. any further division, becomes one of the long, cylindrical, inter- nodal cells (Pig. 62 in), and the upper one (Fig. 62 n) divides by vertical walls to form the nodal cells. The cortical cells (Fig. 62 r) which surround the long internodal cells of Chara, are derived from the divisions of the nodal cells ; the cells covering the upper portion of an internodal cell being derived from the W. B. F 6 CHARACE^:. node immediately above it, and those in the lower part of the intemode from the node below it. The organs of reproduction are very conspicuous by their colour and form. They are always situated on the leaves, the plants being very frequently monoecious. The antheridia (Fig. 61 B, a) are modified leaflets or the terminal cell of a leaf; they are spheri- cal and become red when mature. Their wall consists of 8 " shields," i.e. of plate-like cells, 4 of which cover the upper half, and are triangular ; the 4 round the lower half, to which the stalk of the antheridia is attached, being quadrilateral, with sides of unequal length. The shields (Fig. 61 C) have dentated edges, FIG. 62. — Chara fragilis : s apical cell ; FIG. 63. — Oogonium of Chara : fc n, n nodal cells; in internodal cells; II, "crown"; u receptive spot; s sperma- II leaves ; r, r the cortical cells. tozoids. with the teeth fitting into one another, and their faces ornamented with ridges. From the centre of the internal face of each shield (C) a cylindrical cell, the manubrium, projects nearly as far as the centre of the antheridium ; at the inner end of each of the manu- bria a spherical cell, the capitulunt, is situated. Each capitulum bears six secondary capitula, from each of which four long coiled filaments (C, D) project into the cavity of the antheridium. These filaments are divided by transverse walls into from 100-200 discoid cells, in each of which a biciliated, coiled spermatozoid is developed (D, E) from the nucleus. The spermatozoids escape from their mother-cell and are set free by the shields separating from one other. CHARADES. 67 The female organ of reproduction (Fig. 61 -Z?, 63) is a small modified shoot, whose apical cell functions as an oogonium, its protoplasm forming the oosphere, which has a colourless receptive- spot at the summit (Fig. 63 «). The oogonium is situated on a nodal cell, from which 5 cells grow out in a circle and coil round the oogonium, covering it with a close investment. These cells divide once or twice at the top, so that 5 or 10 small cells are cut off, which project above the oogo- nium and form the so-called " crown " (Fig. 63 fc). The crown either drops off at fertilisation, or its cells separate to form a central canal for the passage of the spermatozoids. The wall of the oosphere l above the receptive spot be- comes mucilaginous, and allows the spermatozoid to fuse with the oosphere. The oospore, on germination (Fig. 64 sp), becomes a small filamentous plant of limited growth (Fig. 64 •/, d, q, pi) — the proembryo — and from this, as a lateral outgrowth, the sexual generation is pro- duced. The order is divided into two sub- orders : — A. NITELLEJ;. The crown consists of 10 cells ; cortex absent : Nitella, Toly- pella. B. CHARES. The crown consists of 5 cells ; cortex present : Tolypellopsis, Lam- prothamnus, Lychnotliamnus, Char a. Chara crinita is parthenogenetic ; in large districts of Europe only female plants are found, yet oospheres are formed capable of germination. About 40 species of fossilized Chara, determined by their carpogonia, are known in the geological formations from the Trias up to the present day. FIG. 64. — Chara fragilis. Ger- minating oospore (sp); i, d, g, pi, form together the proembryo rbizoids (w") are formed at d ; w' the so-called tap-root; at g are the first leaves of the sexual plant, which appears as a lateral bud. 1 Before fertilisation the cosphere divides and cuts off at the base one or more cells (polar bodies?), termed " wendungszellen." C8 PHJ:OSPOREJ<:. Class 8. Phaeophycese (Olive-Brown Seaweeds). The Phaeophycea? are Alga?, with chromatophores in which the chlorophyll is masked by a brown colour (phycophcein). The pro- duct of assimilation is a carbohydrate (fucosan), never true starch. In the highest forms (FucAicece}, the thallus presents differentiation into stem, leaf, and root-like structures. The asexual reproduction takes place by means of zoospores. The sexual reproduction is effected by the coalescence of motile gametes, or by oogamous fertilisation. The swarm-cells are monosymmetric, each moved by two cilia which are true protoplasmic structures, and generally attached laterally (Fig. 65). The PhaaophyceaB are almost entirely salt-water forms ; a few species of Lithoderma live in fresh water. The class is divided into two families :— 1. PH^OSPORE^: : 1 Sub-Family, Zoogonicse; 2 Sub- Family, Acinetae. 2. CYCLOSPORE.S! : Fucaceaa. Family 1. Phseosporese. The family consists of multicellular plants, whose cells are firmly united together to form a thallus ; this, in the simplest cases, may be a branched filament of cells (Ectocarpus), or, in the highest, may resemble a stem with leaves (Laminariacece) , while all transitional forms may be found between these two. The thallus grows by intercalary divisions (e.g. Ectocarpiis\ or by an apical cell (e.rj. Sphacelaria) ; pseudo-parenchymatous tissue may sometimes be formed by cells, which were originally distinct, becoming united together. The size of the thallus varies ; in some species it is quite small — almost microscopical, — while in the largest it is many metres in length. The vegetative cells in the lower forms are nearly uniform, but in those which are moi'e highly developed (Laminariacece and Fucacecc}, they are FIG. t«>.— bwaruispore of Cutler ia sometimes so highly differentiated that mechanical, assimilating, storing and conducting systems may be found ; the last named systems are formed of long cells with perforated, transverse walls, which bear a strong resemblance to the sieve-tubes in the higher plants. The colouring matter in the living cells (" phasophyl ") contains 69 chlorophyll; but tliis is concealed by a brown (" phycophoein "), and a yellow (" phycoxanthin ") colouring material, and hence all these Algae are a lighter or darker yellow-brown. Starch is not formed. Asexual reproduction takes place, (1) by zoospores which arise in unilocular zoosporangia, and are raonosymmetric, with two cilia attached laterally at the base of the colourless anterior end (Fig. 65), the longer one being directed forwards and the shorter backwards ; or (2) by aplanospores (?). Sexnal reproduction has only been discovered in a few cases, and takes place by means of gametes (oogamous fertilisation perhaps FIG. 66. — Ectocarpus tiliaulosug. I a-f A female gamete in the various stages of coming to rest. II A motionless female gamete surrounded by male gametes. Ill a^e Stages in the coal- escence of male and female gametes. PIG. 67. — Zttiiardim'a collavis. A Male gametangia (the smaller celled) and female gatnetaiigia (the larger celled). C Female gamete. D Male gamete. JJ, E Fertilisation. F Zygote. G Germinating zygote. occurs in the Tilopteridse). The gametes have the same structure as the zoospores, and arise in multilocular gametangia ; these, like the zoosporangia, are outgrowths from the external surface, or arise as modifications from it. The conjugating gametes may be similar {e.g. Ectocarpus pusillus), or there may be a more or less pronounced difference of sex, an indication of which is found in Ectocarpus siliculosus (Fig. 60). When the gametes in this species have swarmed for a time, some, which are generally larger, 70 are seen to attach themselves by one of the cilia, which by degrees is shortened to form a kind of stalk (compare the upper gamete in Fig. 66 II) ; these are the female gametes, which now become sur- rounded by a number of males endeavouring to conjugate with them, but only one succeeds in effecting fertilisation. The protoplasm of the two gametes coalesces (Fig. 66 III), and a zygote (e) is formed. The male gametes which do not conjugate may germinate, but the plants derived from them are much weaker than those produced by the zygotes. Strongly pronounced sexual differences are found in the Cutleriacese, in which order the male and female gametes arise in separate gametangia (Fig. 67 J.). The male gametes (Fig. 67 P) are much smaller than the female gamete (Fig. 67 C1) ; the latter, after swarming for a short time, withdraws the cilia, and is then ready to become fertilised (Fig. 67 I), E\ thus we have here a distinct transition to the oogamous fertilisation which is found in the Fucacere. Alternation of gene- rations is rarely found. 1. Sub-Family. Zoogonicae. Reproduction by means of gametes and zoospores. Order 1. Ectocarpaceee. The thallns consists of single or branched filaments with intercalary growth, extending vertically from a horizontal, branched filament or a disc, but sometimes it is reduced to this basal portion only. Zoosporangia and gametangia (for fertilisation see Fig. 66) are either outgrowths or arise by the transformation of one or several of the ordinary cells. The most common genera are : Ectocarpus and Pylaiella. Order 2. Choristocarpacese. ChoristocarpuSjDiscosporaiigmm. Order 3. Sphacelariaceae. The thallus consists of small, parenchymatous, more or less ramified shoots, presenting a feather-like appear- ance. In the shoots, which grow by means of an apical cell (Fig. 68 S), a cortical layer, surrounding a row of central cells, is present. Sporangia and gametangia are outgrowths from the main stem or its branches. Sphacelaria, Chsetopteris are common forms. Order 4. Encoeliaceae. Punctaria, Aspero~ v , coccus, Plnillitis fascia, it IG. 6!-.— Apex of tbe thallus of Clurtopteris plumosa. S Api- Order 5- Striariaceae. Striana, Phlteo- cal cell. spora. 71 Order 6. Dictyosiphonaceae. Dictyosiphon. Order 7. Desmarestiaceae. Desmarestia aculeata is common. Order 8. Myriotrichiaceae. Mijriotrichia. Order 9. Elachistaceae. Elachista fucicolu is a common epiphj'te on species of Fiicus. Order 10. Chordariaceae. The shoot-systems are often surrounded by mucilage. Chordaria ; Leathesia difformis occurs as rounded, brown-green masses of the size of a nut, generally attached to other Seaweeds. Order 11. Stilophoraceae. Stilophora rhizodes is common. Order 12. Spermatochnaceae. Spermatochnus paradoxus is common. Order 13. Sporochnaceae. Sporoclmus. Order 1-4. Ralfsiaceae. Ralfsia verrucosa is common as a red-brown incrus- tation on stoues and rocks at the water's edge. Order 15. Lithodermataceae. Some species of the genus Lithodcrma occur in fresh water. Order 16. Laminariaceae. The thallus is more or less leathery, and has generally a root-like lower part (Fig. 69) which serves to attach it, and a stalk or stem-like part, terminated by a large leaf- like expansion. Meristematic cells are situated at the base of the leaf, and from these the new leaves are derived. The older leaf thus pushed away by the intercalary formation of the younger ones, soon withers (Fig. 69). Gametes are wanting. Zoosporangia are developed from the lower part of a simple, few-celled sporangio- phore, which is an outgrowth from a surface-cell and has a large club-formed apical cell. The spo- rangia are aggregated into closely packed sori, which cover the lower part of the terminal leaf, or occur on special, smaller, lateral, fertile fronds (Alaria). Most of the species belonging to this order live in seas of moderate or cold tem- perature and occur in the most northern regions that have yet been explored, forming their organs of reproduction during the cold and darkness of the arctic night. Laminaria is destitute of a midrib and has only one terminal leaf. FIG. 69. — Lammdria digitnta (much reduced in size) . 72 L. digitata has a broad leaf, which, by the violence of the waves, is torn into a number of palmate strips (Fig. 69). L. saccharina has a small, undivided leaf. At aria has a midrib and special fertile fronds. A. esculenta occurs plentifully on the west coast of Nor- way and on the shores of Great Britain. Chorda filum, a common seaweed, is thick, unbranched, and attains a length of several metres, without any sti-ong demarcation between stalk and leaf. Some attain quite a gigantic size, e.g. Macrocystis pyrifera, whose thallus is said sometimes to be more than 300 metres in length. The Lessouia-STpecies, like the above, form submarine forests of seaweed on the south and south-west coasts of South America, the Cape, and other localities in the Southern Hemisphere. USES. The large Laminarias, where they occur in great numbers, are, like the Fuci, used for various purposes, for example, in the production of iodine and soda, and as ail article of food (Laminaria saccharina, Alaria exculenta, etc). Laminaria mu-L-harina contains a large quantity of sugar (maniiit) and is in some districts u-;ed in the preparation of a kind ol syrup ; in surgical operations it is employed for the distension of apertures and passages, as for instance the ear-passage. It is by reason of the anatomical peculiarities and structure of the cell-walls, that they are employed for this purpose. The cell-walls are divided into two layers, an inner oue which has very little power of swelling, and an outer one, well developed and almost gelatinous — the so-called "intercellular substance'' — which shrivels up when dried, but can absorb water and swell to about five times its &i/e. The stalks of Laininuria clustoiii are oflicinal. Order 17. Cutleriacese. The thallus is formed by the union of the originally free, band-shaped shoots. The growth is inter- calary. Sexual reproduction by the conjugation of male and female gametes. An asexual generation of different appearance, which produces zoospores, arises from the germination of the zygote. Cutleria, Zaiiardinia. Sub-Family 2. Acinetae. Branched, simple cell-rows with intercalaiy growth. The organs of reproduction are partly uni- and partly multi-cellular ; in the unicellular ones a cell without cilia is formed, which may be destitute of a cell-wall, but has one nucleus (oosphere ?), or which has a cell-wall and contains several (generally four) nuclei (aplanospores ?) ; in the multicellular, monosymmetric swarm-cells with two cilia (spermatozoids r*) are formed. The fertilisation has not been observed. Order 1. Tilopteridaceae. Haplospora, Tilopteris. CYCLOSPOREJ!. 73 Family 2. Cyclosporeae. The individuals are rnulticellular, with growth by an apical cell. The thallus — often bilateral — is differentiated into a root- like structure (attachment-disc), and stem, sometimes also into leaves (Sargassum). Sometimes a differentiation occurs into various tissue-systems, viz. an external assimilating tissue, a storing tissue, a mechanical tissue of thickened, longitudinal, parenchyma- tous, strengthening cells, and a conducting tissue of sieve-cells, or of short sieve-tubes with perforated walls. Colouring material, as in Phaeosporege. Vegetative reproduction can only take place by means of detached portions of the thallus (Sarg>issum\ which are kept floating by means of bladders (Fig. 70 A, a, Fig. 72). Zoo- spores are wanting. The sexual reproduction takes place by oogamous fertilisation. The oogonia and antheridia are formed inside special organs (conceptacles), and are surrounded by paraphyses. The concep- tacles (Fig. 70 JJ, Fig. 71 b) are small, pear-shaped or spherical depressions, produced by a special ingrowth of the surface cells of the thallus, and their mouths (ostioles) project like small warts ; they are either situated near the end of the ordinary branches of the thallus (Fucus serratus, Fig. 71 a) which may be swollen on this account (Fucus vesiculosus, Fig. 70 A, 6), or on special short branches (AscopTvyllum, Sargassum). The vertical section of a coiiceptacle is seen in Fig. 70 B (see also Fig. 71 &) where, in addition to the paraphyses, oogonia only are seen (F. vesiculosus is dioecious— male plant, yellow-brown; female plant, olive-brown); but in some species antheridia, together with oogonia, are pro- duced in the same coiiceptacle. The oogonia are large, almost spherical cells, situated on a short stalk, in each of which are formed from 1-8 (in Fucus, 8; in Ascophyllum, 4; in Halidrys, 1 ; in Pelvetia, 2) rounded, immotile oospheres. The wall of the oogonium ruptures, and the oospheres, still enclosed in the inner membrane, are ejected through the mouth of the conceptacle, and float about in the water, being finally set free by the bursting of the inner membrane. The antheridia are oblong cells (Fig. 70 G, a), many of which are produced on the same branched antheridio- phore (Fig. 70 C) ; the numerous spermatozoids are provided with 2 cilia and are very small (Fig. 70 D, two antheridia sur- rounded by spermatozoids, one being open). The spermatozoids, still enclosed by the inner membrane of the antheridium, are 74 CYCLOSPOREJ;. similarly set free, and fertilisation takes place in the water, numerous spermatozoids collecting round the oosphere (Fig. 70 E), which is many times larger, and by their own motion causing it' to rotate. After fertilisation, the oospore surrounds itself with a & :^Mg^*fr*s! •:f^-»^&&&**r?* D F FIG. 70. — Fttcits vesiculosus. A Portion of thallus with swimrciDg bladders (n) and conceptacles (6). S Section of a female conceptacle ; li the mouth; 31 the inner cavity; s ooponia. C Antheridiophore; a antheridium; y sterile cells. D Anthcridia out of which the eparmatozoicls are escaping. E Fertilisation. F Germinating oospore. cell-wall and germinates immediately, attaching itself (Fig. 70 to some object, and by cell-division grows into a new plant. CYCLOSPORE^:. 75 Order 1. Fucaceae. The following species are common on our coasts : Fucus vesiculosus (Fig. 70) has a thallus with an entire margin, and with bladders arranged in pairs ; F. serratus (Fig. 71) without bladders, but with serrated margin ; Ascophijllum nodosiim has strap-like shoots, which here and there are swollen to form bladders ; Halidrys siliquosus has its swimming bladders divided by transverse walls; Himanthalia Zorea, which is found on the west coast of Norway, and the south, coast of England, has a small perennial, button-shaped part, from the centre of which proceeds the long and sparsely branched, strap-like, annual shoot, which FIG. 72. — Sargafsum baccifernm. A portion of the thallus, natural size. FIG. 71.— Fucus serratus. a Portion of a male plant -which has been exposed to the action of the open air for some time ; small orange-yellow masses, formed by the anther- idia.are seen outside the mouths of the male cnneeptacles (nat.size). b Cross section through the end of a branch of a female plant, showing the female conceptacles ( x 4). bears the conceptacles. The Gulf-weed (Sargassiim bacciferum, Fig. 72) is well known historically from the voyage of Columbus ; it is met with in large, floating, detached masses in all oceans, and is found most abundantly in the Atlantic, off the Canary Islands and the Azores, and towards the Bermudas. The stalked, spherical air-bladders are the characteristic feature of this genus. The thallus is more highly developed than in Fucus, and there is a contrast between the stem and leaf-like parts. The 76 DICTTOTALES. portions which are found floating are always barren, only those attached are fertile. USES. The Fucaeeae, like the Laminariaceae, are used as manure (the best kinds being Fucus vtsicnlosu* and Aicophijllum nodosum), for burning to pro- duce kelp, and as food for domestic animals (^scopliyllum nodosum is especially used for this purpose). Class 9. Dictyotales. The plants in this class are multicellular, and brown, with apical growth, new cells being derived either from a flat apical cell, or from a border of apical cells. The thallus is flat, leaf- or strap-shaped, attached by haptera, which are either found only at the base, or on the whole of the lower expansion of the thallns. The cells are differentiated into the following systems of tissues : an external, small-celled layer of assimilating cells, generally one cell in thickness, and an internal, large-celled layer of one or only a few cells in thickness, forming the mechanical and conducting tissues. All the reproductive cells are motionless. Asexual re- production by naked, motionless spores (tetraspores) which are formed 1-4 in each tetrasporangium, the latter being outgrowths from the surface cells of special, sexless individuals. Zoospores are wanting. The sexual organs are of two kinds, oogonia and antheridia, which are formed from the surface cells, either on the same or different individuals. The oogonia are spherical or oval, and are generally placed close together ; each contains one oosphere, which on maturity is ejected into the surrounding water, and is then naked and motionless. The antheridia are formed of longitudinal cells, united in groups, whose contents by repeated divisions — transverse and longitudinal — are divided into a large number of small, colourless, motionless sperm at ia — - round or elongated — which are set free by the dissolution of the wall of the antheridium. The process of fertilisation has not yet been observed. The Dictyotales, in having tetraspores and spermatia, deviate considerably from the Pha9ophycea3, but may be classed near to the Tilopterida?, in which there are asexual spores with 4 cell- nuclei, which may be considered as an indication of the formation of tetraspores. Order 1. Dictyotaceae. Dictyota dichotoma which has a thin, regularly dichotoruously divided thallus, occurs on the coasts of the British Isles Padina is found on the south coast. BANG10IDE.E. 77 Class 10. Rhodophyceae (Red Seaweeds). The plants comprised in this class are multicellular ; they are simple or branched filaments, or expansions consisting of 1 to several layers of cells; the thallus maybe differentiated (as in many Floridece), to resemble stem, root, and leaf. The cells con- tain a distinctly differentiated nucleus (sometimes several), and distinct chromatophores, coloured by rhodophyll. The chloro- phyll of the chromatophores is generally masked by a red colour- ing matter (phycoerythrin), which may be extracted in cold, fresh water ; or rarely by phycocyan. Pyrenoids occur in some. Starch is never formed in the chromatophores themselves, but a modifi- cation — Floridea? starch — may be found in the colourless proto- plasm. Asexual reproduction by motile or motionless spores (tetraspores) which are devoid of cilia and of cell-wall. Swarm- spores are never found. Sexual reproduction is wanting, or takes place by the coales- cence of a spermatium and a more or less developed female cell. The spermatia are naked masses of protoplasm, devoid of cilia and chromatophores. The female cell (carpogonium) is enclosed by a cell-wall, and after fertilisation forms a number of spores, either with or without cell-walls (carpospores), which grow into new individuals. The Rhodophycea3 may be divided into two families : 1. BANGIOIDE.E. Family 1. Bangioidea.. The thallus consists of a branched or unbranched cell-filament, formed of a single row or of many rows of cells, or of an expan- sion, one or two layers of cells in thickness, but without conspic- uous pores for the intercommunication of the cells. The growth of the thallus is chiefly intercalary. The star-like chromatophores contain chlorophyll and are coloured blue-green with phycocyan, or reddish with phycoerythrin ; all these colouring' matters are occasionally found in the same cell (Bangia-species). Asexual reproduction by tetraspores, without cilia, but capable of amoeboid movements. Sexual reproduction is wanting, or takes place by the coalescence of a spermatium with a carpogonium, which is only slightly differ- entiated from the vegetative cells, and is devoid of a trichogyne. 78 FLORIDEJ:. The carpospores are destitute of cell-wall and arise directly by the division of the fertilised oosphere. The Bangioidete occur chiefly in salt water. Order 1. Goniotrichacese. — The thallus consists of a branched cell- filament without rhizoids. Tetraspores are formed directly from the entire contents of the mother-cell, without any preceding division. Fertilisation unknown. Asterocystis, Goniotrichum. The GoniotrichacecK, through the blue-green Asterocystis, are allied to the Myxophycese, and through Goniotrichum to the Porphyraeeee. Order 2. Porphyraceae. — The thallus is formed of an expansion consisting of a layer of 1-2 cells, which, at the base, are attached to the substratum by means of a special form of haptera (Porphyra, Diploderma) ; or of uubranched (very rarely slightly branched) filaments, attached at the base by haptera (Bangia) : or it extends from a prostrate cell-disc (various species of Erythro- trichia). Tetraspores are formed after one or more divisions of the mother-cell, either from the whole or only a part of its contents ; they possess arnceboid movements, or have a jerky, sliding-forward motion. The antheridia have the same appearance as the vegetative cells, but divide several times, and several spermatia are formed, either simultaneously from the whole contents (Porphyra, Bangia), or the spermatia are successively formed from a part of the contents of the antheridium (Erythrotrichia). The carpogonium is with- out a trichogyne, but the oosphere has a colourless spot which may sonae- times rise a little above the surface of the thallus, and may be considered as an early stage in the development of the trichogyne. The spermatia form a canal through the membrane of the carpogonium, and their contents coal- esce with the oosphere at its colourless spot. The fertilised oosphere divides on germination into a number of carpospores, which are set free as naked, motionless masses of protoplasm, which grow and give rise to new individuals (alternation of generations). Family 2. Floridese. The thallus has one or more apical cells, grows principally by apical growth, and may be differentiated into root, stem, and leaf. The chromatophores vary in form, but have a red or brownish colour, due to chlorophyll and phycoerythrin. Asexual repro- duction by motionless tetraspores, which generally arise by the division into four of the contents of the tetrasporangium. The carpogonium has a trichogyne, and the carpospores, which are formed indirectly from the fertilised oosphere, possess a cell- wall. The thallus may assume very different forms. In the simplest species it is filamentous and formed of single, branched rows of cells (Callithamnion, etc., Fig. 73). Ceramium has a filamentous, thallus, generally dichotomously forked (Fig. 75), or sometimes 79 pinnately branched, which, at the nodes, or throughout its entire length, is covered by a layer of small cortical cells. Polysiphonia (Fig. 74) has a filamentous, much branched thallus, made up of a central cylindrical cell, surrounded by a layer of other cells, cortical cells, which in length and position correspond to the central ones. In many of the Red Alga? the vegetative organs are differentiated into stems and leaves, the former having, as in Chara, unlimited growth in length, whilst the latter soon attain their full development. Choiidrus has a fleshy, gelatinous thallus, without nodes ; it is repeatedly forked into flat branches of vary- ing thickness. Farcellaria has a forked thallus with thick branches FIG. 73. — CaUitJmmnion elegans : a a plant with tetraspores ( x 20) ; b apex of a branch with tetraspores ( x 250). Fis. 74. — Polj/si'pTioni'a variegata : a a portion of a male plant with aiitheridia; b spermatia ; c trans- verse section of thallus. and without nodes. The thallus of Delesseria (Fig. 76) consists of branches, often bearing leaf-like structures, with a midrib and lateral ribs springing from it. These ribs persist through the winter, and at the commencement of the succeeding period of vegetation the lateral ribs become the starting points for new- leaves. In Corallina the thallus is pinnately branched, and divided into nodes and internodes. The name has been given to this genus from the fact that the thallus is incrusted with carr bonate of lime to such a degree that it becomes, very hard, and the 80 FLORIDE^!. whole plant adopts a coral-like appearance. Other genera which are similarly incrusted, and have a leaf-like or even crustaceous thallus (such as Melol>esia, Lithothamnion), are included in this family. In some instances the cells of the thallus may be found differ- entiated into more or less well defined tissues, so that it is possible to find special assimilating, mechanical, and conducting tissues, the last named in some cases having the double function of con- ducting and of serving as a reservoir in which starch is found as a reserve material. The cells of the Floridese, which are formed by the division of a mother-cell into two daughter-cells of unequal FIG. 75. — Ccramium diaplianum (uat. size). FIG. 76. — Delesseria sanguinea (about size, have always larger or smaller pits in the cell-walls, and the thin cell- wall separating two pits from each other is perforated by a number of small holes. These pits are particularly developed in the conducting tissues, but sieve-tubes are very rarely to be found. Tetraspores may be wanting (e.g. Lemanea) or may often arise on special, non-sexual individuals. In some (e.g. Bntrachospir- mum) only one tetraspore is formed in each tetrasporangium, but the number is generally four, which may be formed tetrahedrally (Fig. 73) or by divisional walls perpendicular to each other, or even in a single row. The tetrasporangia in some species are free (Fig. 73), but in the majority they are embedded in the thallns. The sexual reproduction (discovered by Thuret and Bornet, FLOR1DE.E. 81 1867) differs in the essential points from that of all other plants, and approaches most nearly to the sexual reproduction of the Bang-widen;. The sexual cells are developed from the terminal cells (never nodal cells) of the branched cell-filaments, which constitute the thallus. The mother-cells of the spermatia (spermatangia) are generally arranged in a group, in the so-called antlieri'Hci (Figs. 74, 77 A, a). On becoming ripe the membrane of the spermatangium ruptures and the spermatia emerge as spherical or ovoid, naked (a little later they may possess a cell- wall) masses of protoplasm which are not endowed with the power of motion, and hence are carried passively by the current of the FIG. 77. — A Lejolisia mediterranea : rhaptera; s longitudinal section through a cystocarp ; p the empty space left by the liberated spore (0- -B-.E Nemalion multifidum: a antheridia ; b procaruium with trichogyne, to which two spermutia are adhering. water in which they may happen to be, to the female cell. This latter is analogous with the oogonium of the Green Algre. The female reproductive organ is termed the procarpium, and consists of two parts, a lower swollen portion — the carpogonium (Fig. 77 b in A and B) — Avhich contains the cell-nucleus, and an upper filamentous prolongation — the trichogyne (Fig. 77 B) — which is homologous with the colourless receptive spot of the oosphere of the Green Algre, and the Porphyracece. In the sexual reproduc- tion of the majority of the Floridea?, a very important part is played by certain special cells, rich in cell-contents — the auxiliary u. B. G 82 cells. These are either dispersed in the interior of the thallns, or are arranged together in pairs with the cell-filament which bears the carpogonium, and are generally united with this to form an independent multicellular procarpium. The sperrnatia attach themselves firmly to the trichogyne and surround them- selves with a cell-wall. The dividing wall at the point of contact is perforated, and the nucleus of the spermatium probably travels through the trichogyne to the swollen part of the procarpium —the carpogonium — and fuses with its nucleus. After fertilisation the trichogyne withers (Fig. 77 0), but the lower portion'of the procarpium, constituting the fertilised oosphere, grows out and forms in various ways, first a tuft of spore-forming filaments known as gonimoblasts, and finally the carpospores. These latter form a new asexual generation (compare the germination of the oospore of OEdogonium and Goleochcete'). The gonimoblasts may arise in three ways : — 1. In the Nemalionales, branched filaments grow out from the oosphere and form an upright, compressed or expanded tuft of spore-forming filaments. 2. In the Cryptoneiuiales, several branched or uubranched filaments (ooblas- tema-filaments) grow out from the oosphere, and conjugate in various ways with the auxiliary cells. The gonimoblasts are then formed from the single cells produced by the conjugation. 3. In the Gigartinaies and Rhodymeniales the oosphere conjugates with an auxiliary cell by means of a short ooblasterna-filament, and from this auxiliary cell a gonimoblast is produced. The motionless carpospores, which sometimes in the early stages are naked, and afterwards invested with a cell-wall, are developed from the terminal cells (and perhaps also from some of the other cells) of the branches of the goniuio- blast. The gonimoblasts constitute sharply defined parts of the plant in which the carpospores arise. These parts are called cystocarps and are either naked (Fig. 77 E), or surrounded by a covering (pericarp or involucre, Fig. 77 A) formed in different ways. On this account the Florideac were formerly divided into GYMNOSPORE/E (Batrachospermum, Nemalion, Cerainiuni, etc.) and ANOIO- SPORE.E (Fnrcellaria, Lejolisia, Delesseria, Melobesia, etc.). The Floridese are divided into four sub-families :— Sub-Family I. Nemalionales. The fertilised oosphere produces directly the gonimoblast. Order 1. Lemaneaceae. Algas of brownish colour and living in fresh water. They lack tetraspores, and the very sparingly bra7iched fertile filaments, composed of many rows of cells, grow out from a pro-embryo, which consists of a single row of cells bearing branches. Lemanea Jluviatilis, often found on rocks and stones in quickly flowing streams. FLORIDE^E. 83 Order 2. Helminthocladiacese. Tetraspores are generally wanting (e.g. in Nentalioit) or arise one in each tetrasporangiuui (e.g. Batrachospermum) and it is only in Liagora that four cruciate tetraspores are formed. CMntranxia corymbifera consists of simple, branched cell-rows, and is an independent species. Several other Cliantransia-forms, living in fresh water, are "proembryos" of species of the genus Batrachotpermum. The germinating carpospore grows out into filaments and forms a so-called proembryo which, if not shaded, attains only a small size, but when growing in shady situations presents a much greater development. These highly developed proembryos have been described as species of Chantransia. The proembryo can reproduce by division, or by tetra- spores which are developed singly in the sporangia; in B. vayum and B. spuru- lunx which do not possess fully developed female reproductive organs, the pro- embryos serve almost entirely to reproduce the species. The young Batracho- spermum-plant arises from the end of an upright filament of the proembryo. The proembryo is generally persistent, and continually produces new Batraeho- spennums. These latter bear the sexual reproductive organs and also whorls of branches : the central row of cells is enclosed by cells growing from the base of the whorls of branches, and from these cortical cells secondary proembryos are developed. In this alternation of shoots there is really no alternation of generations, since the proembryo and the shoots with the sexual reproductive organs are parts of the same thallus. Several species of Batrachospermum have a bluish green or verdigris colour. Nemalion multijidum has a brown-red thallus, slightly branched, which is attached to rocks near the water's edge. Order 3. Chaetangiaceae. Galuxaura Las a thallus thickly incrusted with lime. Order 4. Gelidiaceae. Naccaria, Gelidium. Sub-Family 2. Gigartinales. The fertilised auxiliary cell grows towards the thallus, to produce the gonimoblasts. Procarpia generally present. Order 5. Acrotylaceae. Acrotylus. Order 6. Gigartinaceae. 6-igartina, Phyllophora, Ahiifeltia ; Chondrus crispus, with dark red, dichotomously branched thallus, is common on the coasts of Scandinavia and Great Britain. Order 7. Rhodophyllidaceae. Ehodophyllis, Euthora ; Cystoclonium pur- purascens is common, and sometimes the ends of its branches may be modified into tendril-like haptera. Sub-Family 3. Rhodymeniales. The fertilised auxiliary cell forms the gommoblast on the side away from the thallus. Procarpia are abundantly produced. Order 8. Sphaerococcaceae. Gracilariu. Order 9. Rhodymeniaceae. Rhodytneiua palinata is a common species. Lomentaria, Chylocladla, Plucamium. Order 10. Delesseriaceas. Deletseria sanguined ; D. alata and I), sinuosa aie handsome forms which are not uncommon. Order 11. Bonnemaisoniaceae. Bonnemaisonia. Order 12. Rhodomelaceae. Rhodoinela, Odonthalia ; Polysiphonia, of which many species are to be found on the coasts of Great Britain, has a filamentous, richly branched thallus consisting of a central row of cells sur- 84 FUNGI. rounded by a varying number of cortical cells of similar size — the so-called " siphons." Order 13. Ceramiaceae. Pretty Algfe, often branched dichotomously, or unilaterally pinnate. Spermothamition, Grijfithsiu, Callithamnivn, Ccramium, Ptilota. Sub-Family 4. Cryptonemiales. The cells formed by the coalescence of the auxiliary cells and the ooblastema-filameuts, produce the gouimoblasts. The carpogunium-jilaments and the auxiliary cells are scattered siugly in the thallus. Order 14. Gloiosiphoniaceas. Gloiopeltis. Order 15. Grateloupiaceas. Halymenia, Cryptoncmia. Order 16. Dumontiaceas. Dumontiii, DuJretniaya. Order 17. Nemastomacese. Furcellaria, which has dichotomously branched, round shoots, is common on the coasts of Great Britain. Order 18. Rhizophyllidaceae. PolyiJes, Rhizophyllis. Order 19. Squamariaceas. The Alga- belonging to this order form crust- like coverings on stones, mussel-shells, and on other Algffi, but are not them- selves incrustated : Petrocflis, Cruoria, Peyssonellia, Order 20. Corallinaceas. Partly crustaceous, partly erect, branched Alga?, thickly iucrusted with lime, so that a few species (LitliotJiamnia, also called NulUpora') occur in fossilized condition from Jurassic to Tertiary periods. 3Jelubaia, Lithophyllum, Lithothamnion, Corallina. USES. " Carragen " is the tliallus of Cfiondms cri«pus (Irish Moss) and Gigartina mamillosa. It is a common article of food on the coasts of Ireland, and swells to a jelly when cooked. It is officinal. Rhodymenia palmetto, is generally eaten as food in Ireland and in some places on the west coast of Norway ; it is also used as food for sheep and hence is termed " Sheep-seaweed. " Agar-Agar is the jelly obtained from species of Gelid ium and Gigartina growing in China and Japan. Sub-Division III. FUNGI. Mode of Life. The Fungi have no chlorophyll, and are thus unable in any stage of their existence to assimilate carbon ; they must therefore live as saprophytes or parasites. There is, however, no strong line of demarcation between these ; many Fungi com- mence as true parasites, bat only attain their full develop- ment upon or in dead plants or animals (Rhytisma, Empusa). Many saprophytes may occasionally appear as parasites, and are then designated "facultative parasites ' (Nectria cinnabarinn, Lophodermium piiumtri), in contradistinction to those AY Inch only FCNGI. 85 appear as parasites, " obligate parasites" (Mildew, Brand- and Rust- Fungi, Cordyceps). The parasites which live on the surface of the host-plant are termed epiphytic (Mildew, Fiisicladium} ; and those living in its tissues are termed endopliytic (Ustilago, Peronospora). Epizoio (Oidium tonsnrans, Laboulbenia) and endnzoic Fungi (Cordyce/'>si Eiitomnplithora), are distinguished, in the same manner, as those which live on the surface or in the interior of animals. The Funo-i o designated pathogenic are especially those which produce disease in human beings and in animals. Most of the diseases of plants are attributed to the parasitic Fungi. These force their way into the host-plant by piercing the outer wall of the epidermis, as in the Potato-disease; or by grow- ing in through the stomata, e.g. the summer generations of the Rust of Wheat ; or they can only penetrate through a wound, e.g. Nectria. Some effect an entrance into the host- plant by the secretion of a poisonous matter or ferment, which, softens and destroys the cell-walls (Sderotinia). Some Yeast and Mould Fungi secrete ferments (enzymes), which, for example, convert cane-sugar into a sugar capable of fermentation. The relation of the parasitic Fungus to the host-plant is mainly of two kinds. In the one case, the cell-contents are desti'oyed, the protoplasm is killed, and the cellular tissue becomes discoloured and dies (Peronospora, Armillaria mellea, Polyporus) ; in the other case, the parasite has an irritating effect on the cellular tissue, whereby the affected organ grows more rapidly and be- comes larger than normal, producing hypertrophy. Such malfor- mations are termed Fungi-galls (Mycocecidia) ; in this manner " witches' brooms " are produced by jEcidium, " pocket-plum " by Taphrina, and other deformities by Exobasidium and Cystnpus candi'lus. This hypertrophy may either be produced by a vigorous cell-multiplication, which is most frequently the case, or by the enlargement of the individual cells (Synchytrium, Calyptospora). The relation between host and Fungus among the Lichens is of a very peculiar nature, termed " symbiosis." Vegetative Organs. The vegetative parts of a Fungus are termed its mycelium.1 This is formed of a mass of long, cylindrical, branched cells resembling threads (and hence termed hyphen), which have a continued apical growth. The mycelium, in its early development, shows a well-marked difference between the 1 From the Greek /j.vKt)s = Fungus, hence " myc 'logy." 86 FUNGI. two main groups of true Fungi : in the Pliy corny cetes, or Algal Fungi, the mycelium has no transverse walls, and is therefore unicellular, while in the Mesomycetes and My corny cetes it is pro- A'ided with dividing walls, which grad^^ally arise during growth, in the youngest hypha? ; intercalary transverse walls may also be formed at a later period. In the hyphas of some of the Higher Fungi (Hymenomycetes), connections may be formed between two contiguous cells of the same hypha, by a protuberance growing out from an upper cell just above the transverse wall, and forming a junction with the cell below. These are known as clamp-connec- tions; they appear to be of use in affording communication be- tween the two cells. The hyphse of Fungi, where they come in contact with one another, often growT together, so that H-formed combinations (fu- sions) are produced, which give rise to very compact felted tissue. When the hypha? are not only closely interwroven, but also united and provided with many transverse walls, the mycelium assumes the appearance of a tissue with isodiametric cells, and is then termed pseudo-parencJiyma. The hyphse-walls are sometimes very much thickened, and composed of several layers, and the external layers, by the absorption of water, may often swell very much and become mucilaginous. In some instances the walls are colour- less, in others coloured, the most frequent colour being brown. The cell-contents may also be coloured, and in that case are gene- rally yellow; this colour is chiefly connected with the fat (oil) which may be found in abundance in the Fungi, whilst starch is invariably absent in all the true Fungi. The mycelium assumes many different forms ; sometimes it appears as a thread-like, cobwebby, loose tissue, less frequently as firm strands, thin or thick membranes, horn-like plates or tuber- like bodies. The thread-like mycelium may, in the parasitic Fungi, be intercellular or intracellular, according as it only extends into the interstices between the cells or enters into the cells proper. In the first case there are generally found haustoria, or organs of suction (e.g. among the Peronosporacece ; Taphrina, on the contrary, has no haustoria) ; but haustoria are also found among the epiphytic Fungi (e.g. Erysiphacea^). Intracellular naycelia are found in the Rust-Fungi, in Claviceps purpurea, EutomopJithora, etc. In spite of its delicate structure, this mycelium may live a long time, owing to the circumstance that it continues to grow peri- pherally, while the older parts gradually die off ("fairy rings"). FUNGI. 87 String-like mycelia may be found, for example, in Phallus, Coprinus, and are formed of hyphse, which run more or less parallel to each other. Membrane-like mycelia are chiefly to be found in Fungi growing on tree-stems (Polyporacea? and Agari- cacea3) ; they may have a thickness varying from that of the finest tissue-paper to that of thick leather, and may extend for several feet. The peculiar horny or leather-like strands and plates which, for instance, appear in Armillaria mellea, are known as Rhizomorpha ; they may attain a length of more than fifty feet. The tuber-like mycelia or sclerotia play the part of resting mycelia, since a store of nourishment is accumulated in them, and after a period of rest they develope organs of reproduction. The sclerotia are hard, spherical, or irregular bodies, from the size of a cabbage seed to that of a hand, internally white or greyish, with a brown or black, pseudo-parenchymatous, external layer. Sclerotia only occur in the higher Fungi, and are found both in saprophytes, e.g. Coprinus, and in parasites, e.g. CJaviceps (Ergot), Sclerotinia. Reproduction. SEXUAL REPRODUCTION is found only among the lower Fungi which stand near to the Algae, the Algal-Fungi, and takes place by the same two methods as in the Algte, namely by conjugation and by the fertilisation of the egg-cell in the oogonium. The majority of Fungi have only ASEXUAL reproduction. The most important methods of this kind of reproduction are the sporangia- fructification and the conidio-fructijication. In the SPORANGIO-FKUCTIFICATION the spores (endospores) arise inside a mother-cell, the sporangium (Fig. 80). Spores without a cell-wall, which move in water by means of cilia and hence are known as swarmspores or zoospores, are found among the Oomycetes, the sporangia in which these are produced being called swarm- sporangia or zoosporangia (Figs. 86, 87, 91, 94). In the CONIDIO-FRUCTIFICATION the conidia (exospores) arise on special hyphse (conidiophores), or directly from the mycelium. When conidiophores are present, the conidia are developed upon them terminally or laterally, either in a basipetal succession (in many Fungi, for example in Penicillium, Fig. Ill, Erysiphe, Cystopus), or acropetally (in which method the chains of conidia are often branched ; examples, Pleospora vulgaris, Hormodendron cladosporioides) . All conidia are at first unicellular, sometimes at a later stage they become two-celled or multicellular through the formation of partition-walls (Piptocephalis) . The conidia with 88 FUNGI. thick, brown cell-walls, and contents rich in fats (resting conidia), can withstand unfavourable external conditions for a much longer period than conidia with thin walls and poor in contents. The SPORANGIA arise either from the ordinary cells of the mycelium (Protomyces\ or are borne on special hyphre. They are generally spherical (Mucor, Fig. 80 ; Saprolegniacese), egg-, pear-, or club-shaped (Ascoriiycetes), more rarely they are cylindrical or spindle-shaped. While among the Phycornycetes the size, form, and number of spores are indefinite in each species, in the Ascomy- cetes the sporangia (asci) have a definite size, form, and number of spores. The spores of the Ascomycetes are known as asco- spores. The sporangio-fructification is found under three main forms. 1. FREE SPORANGIOPHORES which are either single (Mucor, Fig. 78), or branched (Thamnidium). 2. SPORANGIAL-LAYERS. These are produced by a number of sessile or shortly-stalked sporangia, being formed close together like a palisade (Taphrina, Fig. 105). 3. SPORANGIOCARPS. These consist usually of many sporangia enclosed in a covering, they are found only in the Carpoasci, and are also known as ascocarps. The parts of an ascocarp are the covering (peridiutn), and the hymenium, which is in contact with the inner wall of the peridium, and is generally made up of asci, and sterile, slender hyphje. The latter either penetrate between the asci and are branched and multicellular (paraphyses, Figs. 103 d, 123, 125, 129), or clothe those parts of the inner wall which bear no asci (Periphyses ; among many peronocarpic Ascomycetes, e.g. Chwfomium, Sordaria, Stictosphce.ra lioffmanni). The ascocarps are produced directly from the mycelium, or from a stroma, that is a vegetative body of various forms, in which they may be embedded (Figs. 116 B, C). Among the conidio-fructifications there are, in the same way, three divisions. 1. FREE CONIDIOPHORES (Fig. 109). The form of the conidiophores, the shape, and number of its spores are various. Iii the most highly developed Fungi, the Basidiomycetes, there are, however, special more highly developed conidiophores, the basidia, which have a definite form ana spores of a definite shape and number. The conidia borne on basidia are called busidiozpores. 2. CONIDIAL-LAYERS. (a) The SIMPLEST case of this is found when the conidiophores arise directly from the mycelium, parallel .FUNG[. 89 to one another, and form a flat body (e.g. Exobasidium vaccinii, Hypochnus ; among the Phycomycetes, Empusa nniscce and Cystopus). (b) In a HIGHER form the conidial-layers are thick, felted threads (stroma) inserted between the mycelium and the hymenium (i.e. the region of the conidiophores). Examples are found in a section of the Pyrenomycetes (Fig. 122). (c) The HIGHEST form has the basiJiaJ -layer, that is a conidial-layer with more highly developed conidiophores (basidia). The basidial-layer, with stroma, and the hymeniurn (region of the basidia), forms the basidio-fructifica- tion, which is branched in the Clavariacea?, and hat-shaped in other Hymenomycetes (in these groups the hymenium is confined to the lower side of the pileus). The hymenium of the conidial-layer and basidial-layer is com- posed entirely of conidiophores, or of conidiophores and sterile hyphre (paraphyses) which are probably always unicellular. Paraphyses are found in Entomophthora radicans, and in certain Basidiomycetes (e.g. Corticium'). 3. CONIDIOCARPS (pycmdia). A special covering surrounds the conidia-foi-ming elements. The inner side of this covering (peridium) bears the hymenium, i.e. those elements from which the conidia are abstracted. The conidiocarps arise either imme- diately from the hyphoe or from a stroma in which they are generally embedded. Conidiocarps are entirely wanting in the Phycomycetes. On the other hand they are found among the Ascomycetes and Basidiomycetes, and in the latter group the conidiocarps contain more highly differentiated conidiophores (basidia) and are known as hasidiocarps. Conidiocarps with simple conidiophores, are found only among the Basidiomycetes, in the Uredinacese, and in Craterocolla cerasi. In the Ascomycetes (Figs. 120 cZ, e ; 117 a, b ; 123 a ; 124? 6) the conidiocarps are visible, as points, to the naked eye, while the basidiocarps of the Basidiomy- cetes (Figs. 170, 171, 173-176, 178-180) vary from the size of a pea to that of a child's head. The " spermogonia " of the Ascomycetes and Lichenes, are conidiocarps with small conidia (microconidia) which germinate sometimes more slowly than other conidia, and formerly were erroneously considered as male repro- ductive cells, and called spermatia. The conidia of the Fungi are not primitive structures. The comparison of the sporangia and conidia among the Zygomycetes, and among the species of the genus Peronospora shows, that the conidia are aberrant formations, and that they have arisen through 90 FUNGI. the degeneration of the sporangium, which, by the reduction of its spores to one, has itself become a spore. In the genera Thamnidium and Clxetocladium the gradual diminution of the sporangia, and the reduction of the number of spores can be distinctly followed. In Thamnidium the number of spores is often reduced to one, which is free in the sporangium. In Chatocladinm however the sporangia are typically one-spared, the spore is always united with the sporangium, and the two become a single body, the so-called conidium, which is in reality a closed sporangium. How close is the connection between the sporangia and conidia of Thamnidium and Chtetocladium, is seen from the fact that, in the conidial stage of Chcetocladium the same whorl-form of branching appears as in the sporaugial stages of Thamnidunn ch(etocladloides, and also, that the conidia of Ch. frexen- ianum throw off the former sporangium-wall (exosporium), while Ch. jonexii germinates without shedding its exosporium. The Phycomycetes have doubt- less sprung from Water-Alga? and inherit the sporangia from them. On this supposition, as the Phycomycetes assumed a terrestrial mode of life, the sporangia would become adapted to the distribution of the spores by means of the air, the sporangia would become small, contain dust-like spores, and would eventuall}' become closed-sporangia, i.e. conidia. The conidia are a terrestrial method for the multiplication of Fungi. In the Hemiasci and the Ascomycetes the sporangia are still preserved, but in every instance they are adapted to terrestrial spore-distribution, their spores being set free on the destruction of the sporangium-wall (generally shot out) and distributed through the air. For further examples of spore-distribution see below, p. 91-93. The reproduction of Fungi is accomplished not only by spores and conidia, but also sometimes by chlamydospores. These are fundaments * of sporangiophores and conidiophores, which have taken on a resting condition in the form of a spore, and are able to germinate and produce carpophores. In the formation of the chlamydospores the hyphre accumulate reserve materials at the expense of the neighbouring cells ; in the undivided hyphse of the Phycomycetes transverse walls are formed, and finally the chlamy- dospores are set free by the decay of the empty cells connecting them with the mycelium. One must distinguish between oidia and true chlamydospores. The former are more simple, the latter are a somewhat more differentiated form of carpophore fundaments, which serve for propagation in the same manner as spores. In CJilamydomucor racemosns the chlamydospores grow out into the air and form differentiated carpophores. In the Autobasidiomy- cetes they only gei'minate vegetatively, and not with the forma- tion of fructifications. From Cldamydomucor up to the Auto- basidiomycetes the successive development of the fructification, 1 This term is adopted as a translation of the German " anlage." FUNGI. 91 which is interrupted by the formation of the chlamydospores, degenerates more and more. Among certain Ustilaginere the chlamydospores (brand-spores) no longer germinate with the pro- duction of fructifications. In the Uredinacea?, only one of the three chlamydospore-forms has the property of producing fructifications on germination; the other forms only germinate vegetatively, like ordinary spores, and in the same manner as the chlamydospores of the Autobasidiornycetes. In the Hemibasidii, and the Uredin- acea?, in Protomyces, the chlamydospores are the chief means of reproduction. They are found also among the Ascomycetes. The sporangia and the conidia of the Fungi have their common origin in the sporangia of the Phycomycetes. The asci (and the Ascomycetes which are characterised by these bodies) are descended from the sporangia-forming, lower Fungi ; the basidia (and the Basidiornycetes) from those which bear conidia. The sporangia of the Phycomycetes are the primitive form and the start- ing point for all the reproductive forms of the Fungi. The chlamy- dospores appear besides in all classes of Fungi as supplementary forms of reproduction, and are of no importance in determining relationships. Although the expression "fruit" must essentially be applied to true Phanerogams, yet, through usage, the term " fruit- forms " is employed to designate the forms or means of reproduction of Fungi, and the organs of reproduction are known as organs of fructification, the sporangiophores and conidiophores as fruit -bearers (carpopliores), and the sporangiocarps, conidiocarps, and basidiocarps as "fruit-bodies." The majority of Fungi have more than one method of reproduction, often on various hosts (Uredinaceae). Species with one, two, or more than two methods of reproduction are spoken of as having monomorphic, dimorphic, or pleomorphic fructification. Monomorphic, e.g. the Tuberaceas ; dimorphic, Mttcor, Pipto- cepJialis, Saprolegniacea?, Penicillium crustaceum ; pleomorphic, Pucciiriu graminis, Capnodium salicinum (in the last species there are five methods of reproduction : yeast-like conidia, free conidiophores, conidiocarps with small and large conidia, and ascocarps). The liberation and distribution of the spores and conidia. The spores and conidia, on account of their small size and lightness, are spread far and wide by currents in the air, but in addition to this method, insects and other animals frequently assist in disseminating them. The liberation of the conidia is occasionally effected by the complete shrinking away of the conidiophore, but more frequently by abstriction from the conidio- phores, either by their gradually tapering to a point, or by the y-i FUNGI. dissolution of a cross-wall (generally of a mucilaginous nature). The individual links of conidia-chains are detached from one another in the same way, or often by means of small, intercalary cells, which are formed at the base of the individual links, and becoming slimy, dissolve upon the maturity of the spores. Special contrivances for ejecting the spores and conidia may often be found. In Peronospora the cylindrical fruit-hyphaa in the dry condition become strap-shaped and also twisted. These are very hygroscopic, and the changes of form take place so suddenly, that the spores are violently detached and shot away. In Empusa a peculiar squirting mechanism may be found (Fig. 85). Each club- shaped hypha which projects from the body of the fly, bears a conidium at its apex ; a vacuole, which grows gradually larger, is formed in the slimy contents of the hypha, and the pressure thereby eventually becomes so great that the hypha bursts at its apex, and the conidiam is shot into the air. By a similar mechan- ism, the spores of many of the Agaricaceae are cast away from the parent-plants. In the case of Pilobnlus (Fig. 84) the entire sporangium is thrown for some distance into the air by a similar contrivance, the basal region of the sporangium having, by the absorption of water, been transformed into a slimy layer which is readily detached. Sphcerobolus, a Gasteromycete, has a small, spherical fruit-body (basidiocarp), the covering of which, when ripe, suddenly bursts, and the basidiospores contained in it are forcibly ejected. The spores ichich are enclosed in asci are, in some instances, set free from the mother-cell (ascus) prior to their complete develop- ment (Elaphomycet, Enrotiuni). In the case of the majority of the Pyrenomycetes and Truffles, the asci swell by the absorption of water into a slimy mass, which gradually disappears, so that the spores lie free in the fruit-body ; they either remain there till the fruit- body decays, as in those which have no aperture (Perisporiaceae, Tuberaceae), or the slimy mass, by its growth, is forced out through the aperture of the sporocarp, taking the spores with it (Nectria). The ejection of the spores by mechanical means takes place in a number of Ascomycetes, and should many spores be simultane- ously ejected, a dust-cloud may be seen with the naked eye to arise in the air from the fruit-body. This is the case in the larger species of Pe:iza, Helvella, Rhytisma, when suddenly exposed to a damp current of air. A distinction is drawn between a simultaneous ejection of all the spores contained in the ascus, and an ejection at FUNGI. 93 intervals (successive), when only one spore at a time is thrown out. The first of these methods is the most frequent, and is brought about by the ascus being lined with a layer of protoplasm, which absorbs water to such a degree that the elastic walls are extended at times to double their original size. The spores are forced up against the free end of the ascus, a circular rupture is made at this point, and the elastic walls contract, so that the fluid with the spores is ejected. Special means may in some instances be found to keep the spores together, and compel their simultaneous ejection. Thus, a tough slime may surround all the spores (Suc- cobolus), or a chain-apparatus, similarly formed of tough slime ; or there may be a hooked appendage from each end of the spores which hooks into the appendage of the next spore (Sordaria). The paraphyses occurring between the asci in many Ascomycetes, also play a part in the distribution of the spores, by reason of the pressure they exercise. The asci in some of the Pyrenomycetes, which are provided with jar-shaped fruit-bodies, elongate to such an extent that, without becoming detached from their bases, they reach the mouth of the fruit-body one at a time, burst and disperse their spores, and so make room for those succeeding. An ejection of the spores at intervals from the ascus is rarer. It takes place, for instance, in Pleospora, whose asci have a double wall. The external wall, by absorption of water, at last becomes ruptured, and the internal and more elastic membrane forces itself out in the course of a few seconds to one of two or three times greater , O length and thickness, so that one spore after another is forcibly ejected from a narrow aperture at the end of the ascus. Germination of spores (conidia and chlamydospores). In many spores may be found one or more germ-pores, i.e. thinner places, either in the inner membrane (uredospores, Sordaria) or in the external membrane (teleutospores in Rust-Fungi), through which the germination takes place. Generally this does not occur till the spores have been set free : in some Ascomycetes germination commences inside the ascus (Taphrina, Sclerotitiia ) . The different ways in which the spores germinate may be classified into three groups. I. THE ORDINARY GERMINATION occurs by the spore emitting a germ-tube, which immediately developes into a mycelium. In spores with a double wall it is only the inner membrane which forms the germ-tube. In swarmspores a single wall is formed after the withdrawal of the cilia, and this, by direct elongation, 94 FONGl. becomes the germ-tube. The protoplasm accumulated in the spore enters the hypha, which, in pure water, can only grow as long as the reserve nourishment lasts. 2. GERMINATION WITH PROMYCELIUM differs only by the circum- stance that the hypha developed from the germ-tube has a very limited growth, and hence it does not immediately develope into a mycelium, but produces coniclia (Rust- and Brand-Fungi). This promycelium must only be regarded as an advanced development of a conidiophore or basidium. 3. THE YEAST-FORMATION of conidia consists in the production of outgrowths, very much constricted at their bases, from one or more places. Each of the conidia formed in this manner may again germinate in the same way. When sufficient nourishment is present, a branched chain of such conidia is formed, and these are finally detached from one another. Yeast-like buddings from the conidia are produced in various Fungi, e.g. Ascoidea, Protomyces, Ustilaginese, Ascomycetes, Tremellaceae, etc. In the Ustilaginese these conidia are an important element in the development. The budding conidia of Exobasidium forms a "mould" on the nutritive solution. The yeast-like conidia are not to be con- founded with the " Mucor-yeast " (comp. Mucoraceae). For Sac- charomyces see Appendix to the Fungi, page 176. In a compound spore (i.e. when a mass of spores are associated together) each spore germinates on its own account. There are sometimes, however, certain among them which do not germinate, but yield their contents to those which do. The length of time for which conidia can retain their power of germination is shortest (being only a few weeks) in those having thin walls and containing a large supply of water (Peronosporaeefe, Uredinacese). In many spores a resting period is absolutely neces- sary before they are able to germinate (resting spores). It has been observed in some spores and conidia, that the faculty of germinating may be preserved for several years if the conditions necessary for germination remain absent (Ustilaginese, ISurotium, Penicillium) . The optimum, minimum and maximum temperatures required for the germination of the spores has been decided in the case of a good many Fungi. A large portion of the most common Fungi have their optimum at 20°C., minimum at 1— 2°C, maximum at 40°C. In the case of pathogenic Fungi the optimum is adapted to the temperature of the blood. Fungi living in manure, whose ZYGOMYCETES. 95 spores are often adapted to germinate in the alimentary canals of warm-blooded animals, have an optimum corresponding to the temperature of these animals, but with a little margin. Systematic Division. — The lowest class of the Fungi is that of the PHYCOMYCETES, which have an unicellular mycelium, sexual and asexual reproduction, and have doubtless sprung from spo- rangia-bearing, lower Green Alga?. From the Phycomycetes (and certainly from the Zygomycetes) spring two well defined branches, each with numerous distinct species; to the one branch belong the HEMIASCI and the ASCOMYCETES, to the other the HEMIBASIDII and the BASIDIOMYCETKS. Ascomycetes and Basidiomycetes may be united under the title of MYCOMYCETES or HIGHER FUNGI. The Hemiasci and the Hemibasidii constitute the class of MESOMYCETES. The Hemiasci are an intermediate form between Zygomycetes and Ascomycetes ; the Hemibasidii a, similar group between the Zygo- mycetes and Basidiomycetes. Mesomycetesand Mycomyceteshave only asexual reproduction ; sexual reproduction is wanting. Their mycelium is multicellular. Up to the present time about 39,000 species have been described. Review of the divisions of the Fungi : — ciass L— Phycomycetes (Algal-Fungi). Sub-Class 1. Zygomycetes. Sub-Class 2. Oomycetes. Family 1. ENTOMOPHTHOKALES. Family 2. CHYTRIDIALHS. Family 3. MYCOSIPHONALES. class ii. Mesomycetes. Sub-Class l. Hemiasci. Sub-Class 2. Hemibasidii (Brand-Fungi). ciass in.— Mycomycetes (Higher Fungi). Sub-Class 1. Ascomycetes. Series 1. Exoasci. Series 2. Carpoasci. Family 1. GYMNOASCALES. -\ Family 2. PEHISPORIALES. ?• Angiocarpic Exoasci. Family 3. PYKENOMYCETES. J Family 4. HYSTERIALES 1 TT • • T< * - Hemi-angiocarpic Exoasci. family 5. DISCOMYCETES. J Family 6. HELVELLALES. Gymnocarpic (?) Exoasci. Additional : ASCOLICHENES. Lichen-forming Ascomycetes. 96 ZYGOMTCETES. Sub-Class 2. Basidiomycetes. Series 1. — Protobasidiomycetes. Partly gymnocarpic, partly angiocarpic. Series 2. Autobasidiomycetes. Family 1. DACRYOMYCETES. Gymnocarpic. Family 2. HYIIENOJIYCETES. Piirtly gymuocarpic, partly hemi- angioca'pic. Family 3. PHALLOIDE^E. Herniangiocarpic. Family 4. GASTEROMYCETES. Angiocarpic. Additional : BASIDIOLICHENES. Licben-foruiiug Basidiomycetes. Additional to the Fungi : FUNGI IMPERFECTI. Incompletely known (Saccharomyees, Oidium-loims, etc.). Class 1. Phycomycetes (Algal-Fungi).1 This group resembles Vaucher.ia and the other Siphoneae among the Algre. ORGANS OF NUTRITION. The mycelium is formed of a single cell, often thread-like and abundantly branched (Fig. 78). Vegetative propagation by chlamydospores and oidia. Asexual reproduction by endospores (sometimes sicarmspores) and conidia. Sexual re- production by conjugation of two hypha? as in the Conjugates, or by fertilisation of an egg-cell in an oogonium. On this account the class of the Phycomycetes is divided into two sub-classes : ZVGOMYCETES and OOIIYCETES. Sub-Class I. Zygomycetes. Sexual reproduction takes place by zygospores, which function as resting-spores, and arise in consequence of conjugation (Fig. 81); in the majority of species these are rarely found, and only under special conditions. The most common method of reproduction is by endospores, by acrogenous conidia, by chlamydospores, or by oidia. Swarmspores are wanting. Parasites and saprophytes (order 6 and 7). The zygospores are generally produced when the formation of sporangia has ceased; e.g. by the suppression of the sporangial- hyphre (Mucor wucedo), or by the diminution of oxygen; Pilobolus crystaliinus forms zygospores, when the sporangia are infected with saprophytic Piptocepltalis or Pleotraclielus. A. Asexual reproduction only by sporangia. Order 1. Mucoraceae. The spherical sporangia contain many spores. The zygospore is formed between two unicellular branches (gametes). 1 Also termed Water-Fungi (Wasserpilzeii). ZYGOMYCETES. 97 The unicellular mycelium (Fig. 78) of the Mucoracese branches abundantly, and lives, generally, as a saprophyte on all sorts of dead organic remains. Some of these Fungi are known. to be cap- able of producing alcoholic fermentation, in common with the Sac- charomyces. This applies especially to Chlamydomucor racemosus (Mucor racemosus}, when grown in a saccharine solution, and de- prived of oxygen; the mycelium, under such conditions, becomes divided by transverse walls into a large number of small cells. FIG. 78. — Mucor m'iccdo. A mycelium which has sprung from one spore, whose position is marked by the * : a, b, c are three sporangia in different stages of development ; a is the youngest one, as yet only a short, thick, erect branch ; b is commencing to form a sporangium which is larger in c, but not yet separated from its stalk. Many of these swell out into spherical or club-shaped cells, and when detached from one another become chlamydospores, which abstrict new cells of similar nature (Fig. 79). These chlamydo- spores were formerly erroneously termed " mucor-yeast," but they must not be confounded with the yeast-conidia (page 94). They are shortened hypha?, and are not conidia of definite size, shape, and point of budding. Oidia are also found in Clilamydomucor. w. B. H 98 ZYGOMYCETES. The Mucoracere, in addition to the chlamydospores and oidia, have a more normal and ordinary method of reproduction ; viz., by spores which are formed without any sexual act. Mucor has round sporangia ; from the mycelium one or more long- branches, sometimes several centimetres in length, grow vertically into the air; the apex swells (Figs. 78, 80) into a sphere which soon becomes separated from its stalk by a transverse wall ; in the interior of this sphere (spor- angium) a number of spores are formed which eventually are set free by the rupture of the wall. The transverse wall protrudes into the sporangium and forms the well-known columella (Fig. 80 d, e). The formation of spores takes place in various ways among the different genera. SEXUAL REPRODUCTION by conjugation takes place in the follow- ing manner. The ends of two hyphse meet (Fig. 81) and become more or less club-shaped ; the ends of each of these are cut off by a cell- wall, and two new small cells (Fig. 81 A) are thus' formed, these coalesce and give rise to a new cell which becomes the very thick-walled zygote (zygospore), and germinates after FIG. 79. — Chlamydospores of Chlamydo- mucor racemosus (x 375 times.) FIG. 80.— Mucor ?ni