I'll' McGRAW-HILL PUBLICATIONS IN THE AGRICULTURAL AND BOTANICAL SCIENCES EDMUND W. SINNOTT, Consulting Editor COMPARATIVE MORPHOLOGY OF FUNGI McGRAW-HILL PUBLICATIONS IN THE AGRICULTURAL AND BOTANICAL SCIENCES Edmund W. Sinnott, Consulting Editor Adams — FARM MANAGEMENT Babcock and Clausen — GENETICS IN RELATION TO AGRICULTURE Babcock and Collins — GENETICS LABORATORY MANUAL Boyle — MARKETING OF AGRICUL- TURAL PRODUCTS Brown — COTTON Carrier — BEGINNINGS OF AGRICUL- TURE IN AMERICA Cruess — COMMERCIAL FRUIT AND VEGETABLE PRODUCTS Cruess and Christie — LABORATORY MANUAL OF FRUIT AND VEGETABLE PRODUCTS Eames and MaeDaniels — PLANT ANATOMY Emerson — SOIL CHARACTERISTICS Fawcett and Lee — CITRUS DISEASES Gardner, Bradford and Hooker — FRUIT PRODUCTION Gardner, Bradford and Hooker — ORCHARDING Gdumann and Dodge — COMPARATIVE MORPHOL- OGY OF FUNGI Hayes and Garber — BREEDING CROP PLANTS Heald— PLANT DISEASES BACTERI- Horlachei SHEEP PRODUCTION Hutcheson and Wolfe — FIELD CROPS Jones and Rosa — TRUCK CROP PLANTS Loeb — REGENERATION Lohnis and Fred — AGRICULTURAL OLOGY Piper and Morse — THE SOYBEAN Rice — THE BREEDING AND IM- PROVEMENT OF FARM ANIMALS Sharp — CYTOLOGY Sinnott — BOTANY Sinnott — LABORATORY MANUAL FOR ELEMENTARY BOTANY Sinnott and Dunn — PRINCIPLES OF GENETICS Swingle — A TEXTBOOK OF SYSTEM- ATIC BOTANY Thatcher — CHEMISTRY OF PLANT LIFE Thompson — ■ VEGETABLE CROPS Weaver — ROOT DEVELOPMENT OF FIELD CROPS Weaver and Bruner — ROOT DEVELOPMENT OF VEGETABLE CROPS McGRAW-HILL PUBLICATIONS IN THE ZOOLOGICAL SCIENCES A. Franklin Shull, Consulting Editor Fernald — APPLIED ENTOMOLOGY AT itch ell GENERAL PHYSIOLOGY Pearse — ANIMAL ECOLOGY Rogers — COMPARATIVE OGY Shull — HEREDITY PHYSIOL- Shull, Larue and Ruthven — ANIMAL BIOLOGY Shull, Larue and Ruthven — LABORATORY DIRECTIONS IN ANIMAL BIOLOGY Snodgrass — ANATOMY AND PHYSIOL- OGY OF THE HONEYBEE Van Cleave — INVERTEBRATE ZOOLOGY Wieman — GENERAL ZOOLOGY These two series were originally published as one under the title of McGraw-Hill Agricultural and Biological Publications. The late Dr. C. V. Piper was Consulting Editor from the inception of this series in 1917 until his death in 1926. A3 COMPARATIVE MORPHOLOGY OF FUNGI BY ERNST ALBERT GAUMANN Professor of Botany, Federal Technical High School, Zurich TRANSLATED AND REVISED BY CARROLL WILLIAM DODGE Assistant Professor of Botany, Harvard University First Edition McGRAW-HILL BOOK COMPANY, Inc. NEW YORK: 370 SEVENTH AVENUE LONDON: 6 & 8 BOUVERIE ST., E. C. 4 1928 Copyright, 1928, by the McGraw-Hill Book Company, Inc. PRINTED IN THE UNITED STATES OF AMERICA THE MAPLE PRESS COMPANY, YORK, PA. TO ROLAND THAXTER PREFACE TO THE AMERICAN EDITION In presenting this translation and revision of Gaumann's "Com- parative Morphology of Fungi" to the American public, it is desirable to state the principles which have guided in this work. An attempt has been made to secure a free translation, conveying the ideas expressed in as idiomatic English as possible rather than to follow the German closely. Whenever any ambiguity has appeared, the original papers have been consulted and followed. The theoretical discussions of phylogeny have been preserved, even though it is impossible for me to agree with some of the conclusions. The rearrangement of the orders is made with the author's approval, since the arrangement in the German edition followed the traditional arrangement rather than expressed the author's personal views. This arrangement being less traditional in America, the need for its preservation seemed less. This rearrangement has necessitated rewriting most of the orders of the Basidiomycetes, except the rusts and smuts. Throughout the book, such new literature (1925-1927) as I have found, has been incorporated without special mention or change of the discussion of the phylogeny. In a few cases, the abundant new literature has necessitated a complete rewriting of the discussion of the group in question. That of the Basioboleae was rewritten in the light of Miss Levisohn's paper and that of the Elaphomycetaceae as a result of my own observations. The papers of Wehmeyer on the stromatic Sphaeriales necessitated a complete revision of the Diatrypaceae and Diaporthaceae. Two new volumes of Thaxter's monograph of the Laboulbeniales, and Gaumann's misinterpretation of some of Thaxter's previous statements and figures, necessitated a new discussion of that order. Gaumann's phylogenetic discussion and my criticism of his statements have been relegated to smaller type at the close of the order, leaving the main discussion a statement of facts. The papers of Burt on the Thelephoraceae (sensu latiore) have opened up a wealth of new forms, here dealt with in the Corticiaceae, Cyphellaceae, Tremellaceae and Septobasidiaceae. The discussion of the Radulaceae (Hydnaceae of most authors) is based partly on Banker's excellent papers and partly on my own observations. The treatment of the Gasteromycetes (including the Plectobasidiales, the Podaxaceae and the Secotiaceae of Gaumann's treatment), except that of the Clathraceae and Phallaceae, has been completely rewritten in the light of recent ontogenetic papers and my own observations of the last decade, and I assume full responsibility for Vll viii PREFACE TO THE AMERICAN EDITION any opinions expressed therein. The papers of Faull on the Puccinias- treae and of B. O. Dodge on the rusts of Rubus have necessitated extensive alterations in the Uredinales. Personally, I feel too much weight has been attached to the differences between the sticho- and chiastobasidia; hence I am not at all in sympathy with the segregation of the Cantharellales as a separate order. There are no other constant morphological characters to separate the two types, but I have retained this segregation in a less exaggerated form as pre- senting a viewpoint which should stimulate further work to prove its truth or falsity. Obvious errors in synonymy have been corrected, with the first mention of a species usually followed by parentheses containing synonyms used in the original papers. To save space, authorities for names have been omitted in the body of the text and given in full, as accurately as I have been able to determine them, in the index. The bibliography has been assembled in a single chapter at the end of the book, again to save space, and has been verified insofar as the books and periodicals were readily available. In conclusion, I wish to express my gratitude to the following persons who have kindly loaned me unpublished manuscripts for inclusion in this edition: Professor J. H. Faull of Toronto, for his paper on the Pucciniastreae delivered at the International Congress at Ithaca, 1926; Dr. C. L. Shear and Dr. B. O. Dodge for their paper on Neurospora, delivered at the winter meeting of the Botanical Society of America at Philadelphia, 1926; Dr. L. E. Wehmeyer for his unpublished papers on the Diaporthaceae. Dr. Margaret B. Church kindly read the discussion of the Aspergillaceae and Dr. Roland Thaxter that of the Laboulbeniales, criticizing and adding new information as the result of his unpublished observations on this group. I deeply regret that Dr. Gaumann's illness has prevented his collaboration in this revision. Dr. Thaxter has kindly furnished the drawings for Figures 253 to 261, Figure 230 is reproduced from Heald's Manual of Plant Diseases, Fig- ure 234,2 from an unpublished drawing by Louis C. C. Krieger in the Farlow Library, the rest being the cuts used in the German edition, through the kindness of the publisher, Gustav Fischer of Jena. Finally, I wish to acknowledge my gratitude to my wife for her cooperation in preparing the manuscript for the press and reading the proof. C. W. Dodge. Cambridge, Massachusetts, December 1, 1927. PREFACE TO THE GERMAN EDITION By the introduction of cytological methods of investigation to mycology, we have arrived at a much clearer conception of many of the problems of comparative morphology. In general, the classification of fungi has remained the same, but its interpretation has been strengthened and deepened in many ways. The task of this book is to present these conceptions in the most concise form. To my teacher, Eduard Fischer, Professor of Botany in Bern, I dedicate it as a token of my gratitude. Many of the ideas presented here, I owe to his lectures and conversation. In the introductory chapters, the most important points of view and the basic forms are briefly discussed, assuming a knowledge of a textbook similar in content to that of Strasburger. This first part contains a brief summary of present knowledge. The remainder of the book describes modifications of the basic forms in the different groups. In order to shorten this presentation, we have dispensed with a discussion of the historical background of our knowledge. To anyone interested in this aspect of the question, we may recommend the excellent work of Vuillemin (1912). I have attempted, however, to present the divergent conceptions of various authors with the data on which they are based, and to deal with them justly. In order to facilitate special studies, I have included many references to recent works which contain summaries of the older literature. I would like here to express my thanks to all those who have aided me with information, material from their herbaria and libraries, by copies of their works, or permission to use their figures. I wish especially to thank my wife for her assistance in redrawing the figures and the artist, E. Tobler of Zurich, who provided some habit sketches. I am greatly indebted to the publisher, Dr. Gustav Fischer, who readily agreed to all my proposals for the preparation of this book. As all such books, this contains many omissions and errors; I admit them willingly and will be grateful to have any pointed out so that they may later be corrected. Dr. Ernst Gaumann, Botanist, Swiss Agricultural Experiment Station, Docent, Federal Technical High School. Oeklikon-Zurich, October, 1925. IX CONTENTS Page Preface to the American Edition vii Preface to the German Edition ix Chapter I. Introduction 1 II. The Thalltjs 3 III. Reproductive Organs 7 IV. Sexual Organs and Sexuality 11 V. Archimycetes 17 Olpidiaceae 17 Synchytriaceae 20 Plasmodiophoraceae 24 Woroninaceae 26 VI. Phycomycetes 30 VII. Chytridiales 33 Rhizidiaceae 35 Rhizophidieae 36 Entophlycteae 37 Harpochytrieae 39 Chytridieae 40 Rhizidieae 40 Hyphochytriaceae 45 Cladochytriaceae 45 VIII. Oomycetes 51 Monoblepharidaceae 54 Blastocladiaceae 58 Ancylistaceae 59 Saprolegniaceae 63 Leptomitaceae 70 Peronosporaceae 73 IX. Zygomycetes 92 Mucoraceae 94 Endogonaceae 113 Entomophthoraceae 117 Basidioboleae 117 Entomophthoreae 120 X. Ascomycetes 127 XL Hemiascomycetes — Endomycetales 137 Dipodascaceae 137 Endomycetaceae 139 Saccharomycetaceae 148 xi 31940 Xli CONTENTS Chapter pAGB XII. Taphrinales 159 Protomycetaceae 159 Taphrinaceae 161 XIII. Euascomycetes-Plectascales 166 Gymnoascaceae 168 Aspergillaceae 170 Onygenaceae 186 Trichocomaceae 187 Terfeziaceae 187 Elaphomycetaceae 188 XIV. Perisporiales 192 Erysiphaceae 192 Perisporiaceae 204 Englerulaceae 211 XV. Myriangiales . 212 Myriangiaceae 212 Plectodiscellaceae 215 Saccardiaceae 215 Dothioraceae 215 Pseudosphaeriaceae 219 XVI. Hypocreales 225 XVII. Sphaeriales 257 Sordariaceae 257 Sphaeriaceae 262 Ceratostomataceae 262 Cucurbitariaceae 263 Coryneliaceae 264 Amphisphaeriaceae 264 Lophiostomataceae 264 Mycosphaerellaceae 267 Gnomoniaceae 274 Diatrypaceae 277 Diaporthaceae 281 Xylariaceae 286 XVIII. DOTHIDEALES 291 Dothideaceae 291 Phyllachoraceae 294 XIX. Hysteriales 296 XX. Hemisphaeriales 298 Stigmateaceae 298 Polystomellaceae 301 Microthyriaceae 303 Trichothyriaceae 307 XXI. Phacidiales 308 XXII. Pezizales 315 Inoperculatae 317 CONTENTS xin Chapter Page Philipsiellaceae — Patellariaceae 317 Dermateaceae 318 Bulgariaceae 319 Cyttariaceae 320 Mollisiaceae 321 Helotiaceae 322 Geoglossaceae 325 Operculatae 329 Rhizinaceae 330 Pyronemaceae 332 Ascobolaceae 338 Pezizaceae 343 Helvellaceae 346 Discomycetous lichens 350 XXIII. Tuberales -354 XXIV. Laboulbeniales 364 Ceratomycetaceae 365 Laboulbeniaceae 367 Peyritschiellaceae 377 XXV. Basidiomycetes 396 XXVI. POLYPORALES 429 Tulasnellaceae 431 Vuilleminiaceae 433 Brachybasidiaceae 433 Corticiaceae 434 Cyphellaceae . . ' 440 Clavariaceae 441 Dictyolaceae 442 Radulaceae 442 Polyporaceae 445 Fistulinaceae 449 XXVII. Agaricales 451 Hygrophoraceae 456 Agaricaceae 457 Clitocybeae 457 Marasmieae 458 Schizophylleae 458 Tricholomateae 459 Amaniteae 459 Lactariaceae 460 Coprinaceae 461 Paxillaceae 463 Boletaceae 464 Hemigasteraceae 466 XXVIII. Gasteromycetes 467 Rhizopogonaceae ^oa Sclerodermataceae 470 Lycoperdaceae 4'^ xiv CONTENTS Chapter Page Tulostomataceae 479 Sphaerobolaceae 480 Nidulariaceae 482 Hydnangiaceae 485 Hymenogasteraceae 488 Hysterangiaceae 491 Clathraceae 497 Phallaceae 511 XXIX. Tremellales 520 Tremellaceae 520 Hyaloriaceae 526 Sirobasidiaceae 527 XXX. Cantharellales 529 Exobasidiaceae 530 Clavulinaceae 532 Cantharellaceae 533 XXXI. Dacryomycetales 535 XXXII. AURICULARIALES 540 Auriculariaceae 540 Septobasidiaceae 543 Phleogenaceae 549 XXXIII. Uredinales 553 Coleosporiaceae 569 Melampsoraceae 571 Cronartiaceae 572 Pucciniaceae 575 XXXIV. USTILAGINALES 596 Ustilaginaceae 599 Tilletiaceae 604 Graphiolaceae 608 XXXV. Fungi Imperfecti 614 XXXVI. Review of Fungus Classification 618 XXXVII. Bibliography 630 Index 671 Lj L I B R •* R Y ■ 3Q COMPARATIVE MORPHOLOGY OF FUNGI CHAPTER I INTRODUCTION There are two distinct phases in the cytological development of sexually reproducing organisms, the haploid phase with the single or x number of chromosomes, and the diploid phase with the double or 2x number. The former ends with fertilization, the latter with meiosis. A morphological change in the organism occurs parallel and in the same rhythm with this change in nuclear condition and is apparently correlated with it. Certain specialized cells or groups of cells which usually produce the characteristic organs of fertilization, always appear at the transition from haploid to diploid phase, while meiosis occurs at the transition from diploid to haploid phase. According to their cor- responding nuclear phase, these cells or groups of cells are called haplont (haploid soma) and diplont (diploid soma). In an ideal case this cyto- logical and morphological change of phase may be represented by the following diagram: r~ pc r i Haplont— >Gametangia— >Gametes— >Zygote— > Diplont— >Gonotocont— >Tetracytes— >Haplont Haploid phase Diploid phase Haploid phase Diagram I. Gametangia containing gametes are formed on the haplont. Plas- mogamy (a fusion between two sexual cells) which is followed sooner or later by caryogamy (a fusion of two sexual nuclei) takes place between pairs of gametes. These two processes are indicated as P and C in the above diagram. The product of fertilization is called a zygote as long as it remains unicellular; it develops into a diplont which forms gono- toconts (organs in which meiosis occurs). The products of meiosis, in so far as they are spores, are called tetracytes and develop into new hap- lonts. In the ideal case, haploid and diploid phases show a similar structure: haplont corresponds to diplont, gametangium to gonotocont, gamete to tetracyte. Fertilization and meiosis are the cardinal points in the life cycle, indicated in the diagram by vertical lines with the 1 2 COMPARATIVE MORPHOLOGY OF FUNGI appropriate letters above. The haploid phase is underlined by a narrow line, the diploid by a broad one. The extent of development of haplont and diplont are very different for different groups of organisms. On one extreme the thallus (vegeta- tive body) is haploid and the diplont is reduced to a zygote incapable of separate existence. There are many intermediate cases to the other extreme in which the thallus is diploid and the haplont is reduced to a few cells parasitic on the diplont. An intermediate condition is reached in forms in which haplont and diplont are two distinct thalli. Haplont and diplont here follow each other as two morphologically different generations. In this case we have alternation of generations. The haploid generation is called the gametophyte, the diploid, the sporophyte. These relations are further complicated in certain cases where an organ- ism regularly passes through several different, morphologically distinct stages of development within the same nuclear phase, e.g., the protonema and moss plant in the haploid phase of mosses and the larval, pupal and imago in the diploid phase of insects (Maire, 1900, 1902; Lotsy, 1907; Buder, 1916; Goeldi and E. Fischer, 1917; Kylin, 1917; E. Fischer, 1919; Svedelius, 1921, 1927). These different rhythms are not so strongly fixed in the fungi as in higher organisms. They have been modified and have displaced one another because of parthenogenesis, apogamy, apomeiosis, because of environmental changes or because of retardation or hindrance of fertili- zation or of meiosis. Since the comparison of these rhythms makes a desirable scheme in which to arrange morphological facts, it will be given the chief emphasis in this book. It is the aim of comparative morphology to follow the cytological development of the life cycle and to examine the ontogeny of thalli and fructifications by comparing them in both phases. CHAPTER II THE THALLUS The thallus (vegetative body) is naked and at times amoeboid in the simplest families of fungi; in the rest, it is surrounded by a cell wall and is usually in the form of septate hyphae. Under certain conditions of nutrition, as in solutions of small nutritive value, the hyphae grow by sprouting, in which process small protuberances are formed which enlarge, round off and are abjointed (cut off by a septum) from the mother cell, then continue to increase in size and sooner or later separate from the original groups of cells (Fig. 1, a, e,f). These are called sprout cells or occasionally, and less correctly, sprout conidia. In certain groups they form the only type of thallus known. Under unfavorable conditions of growth, the protoplasm contracts, rounds up and secretes a special, thick membrane; these resting cells are called gemmae. Under suitable conditions, they grow to normal thalli. In some groups the hyphal wall gives the chitin reaction, in others that of cellulose; in fructifications and resting cells it is usually strengthened by mineral incrustations, by secretions of resins, etc. At first it forms a hyaline membrane which becomes thicker, is further differentiated by secretions and deposits and usually colored by pigment deposits. An unquestioned relation between the fundaments of the wall, especially the septum, and mitosis has been proved only in a few cases; an especially characteristic example occurs in ascospore formation. As a rule the wall is gradually differentiated from the cytoplasm without nuclear aid, in endogenous spore formation simultaneous with cell elongation, in septal formation by furrowing (ring-like thickening of the walls like an iris diaphragm). For the maintenance of intercellular communication, the septa are usually pierced by a few openings through which pass protoplasmic threads In rapid growth, septal formation may be delayed, later it is made up for by simultaneous or successive septal formation. In certain groups, as in the Siphonales among the algae, the septa are wholly suppressed; the whole thallus is then a single ramose, multinuclear sac which becomes septate only in the formation of reproductive organs, in conditions of poor nutrition and in age. Since these sacs contain numerous undiffer- entiated energids, they are called coenocytic (polyenergid). The individual hyphae usually creep about and are intertwined in felt-like masses. Such a group of hyphae is called the mycelium. In 3 COMPARATIVE MORPHOLOGY OF FUNGI i FRusEHSiiiao'M- Fig. 1. — Monilia Candida. Formation of sprout cells, b, c, typical hyphae; a, e, f, sprout cells; d, oidia. ( X 1,000; after Hansen.) THE THALLUS 5 ectoparasitic, less often in parasitic, forms it may cling fast to the sub- strate by holdfasts known as appressoria (Fig. 215, 2). Usually it is able to absorb food over its whole surface; yet for the better fulfilment of this function, special hyphae or hyphal branches are developed in sapro- phytic forms as rhizoids (Fig. 55, 1) and in parasitic forms, haustoria (Fig. 120). Occasionally these structures function as holdfasts as well as food absorbers. It is still an open question whether the haustorium is a normal organ or whether it is not more often restricted in growth and deformed by the action of the host cells. In many cases the hyphae grow together in groups, intertwine, adhere and form a thick tissue which is called plectenchyma. If the single hyphal elements are still recognizable as such (Fig. 2, 6), they are called Fig. 2. — Claviceps purpurea. Section through a sclerotium. parenchyma; b, core tissue of prosenchyma; r, rind. o, peripheral layer of pseudo- (X 360; after Tavel.) prosoplectenchyma or prosenchyma; if the hyphae have lost their indi- viduality so that they lie beside each other (in sections) with the cells appearing isodiametric and continuous, as in the parenchyma of higher plants (Fig. 2, a), they are called paraplectenchyma or pseudoparenchyma. In sclerotia the plectenchyma appears tuberiform with a firmer pseudoparenchymatic rind and a looser prosenchymatic core. This structure serves to carry the organism over unfavorable conditions of growth and, with the return of normal conditions, germinates to the usual mycelium or to a fructification. Bulbils are small sclerotia formed of a few layers of cells, and are often present in large numbers. Rhizomorphs indicate a further step in the development of plecten- chyma. They arise chiefly from parallel hyphae and often have a definite apical growth from an apical meristem, as the root tips of cormophytes. Under suitable conditions, they may again spread out in sheets of myce- 6 COMPARATIVE MORPHOLOGY OF FUNGI Hum. In the higher forms, a dark, thick, irregularly intertwined rind and a loose, white core are differentiated from parallel hyphae. They serve, as will be shown in the Basidiomycetes, chiefly for transport of food. Fig. 3. — Armillaria mellea. Longitudinal section of tip of rhizomorph. a, loose hyphae; b, gelatinous, loosely interwoven hyphal layer; c, d, core layers; e, central cavity; /, apical meristem. ( X 300; after Hartig.) Occasionally the conducting function becomes less evident and they attain a more sclerotic character. The plectenchyma attains its highest development in fructifications where the differentiation is reminiscent of the cormophytes. CHAPTER III FRUCTIFICATIONS In most fungi, at a definite age and under favorable conditions of nourishment, the mycelium proceeds to the formation of fructifications. In the simplest unicellular families, as in the protozoa, the whole (unicellu- lar) thallus becomes transformed into a fructification. These forms are called holocarpic. The thallus (vegetative condition) and the fructifi- cation (reproductive condition) of the same individual show in some cases two successive phases of development; in other cases these phases are concealed and are only recog- nizable as different because of their functions. In the other fungi, the thallus and fructification are separate from each other both in time and space ; only a portion of the thallus is used for the forma- tion of the fructification, while the rest remains to serve its original vegetative function. These forms are called eucarpic. The products of the reproductive processes are chiefly spores. Spores are characteristically formed cells or groups of cells which separate from the mother plant and may grow independently to new individuals. They serve either for propagation (multiplication and dispersal) or overwintering (as hypnospores or resting spores). In the simplest case, they arise by the separation of hyphal cells (Fig. 263, 1), which grow into new hyphae. These individual cells are called oidia and fig. 4. — Saprolegnia are homologous to the cells of a sprout hypha, only «**»• . Zoosporangium & r ill discharging zoospores, o. the latter arise by sprouting rather than by the (After Kiebs.) breaking up of a hypha. From oidia, there is an imperceptible transition to definite spores, characteristic in form, color or sculpturing of the wall. In many cases they are cut off directly from the ordinary hyphae; in other cases they arise on special sporophores. If these sporophores form the spores endo- genously from particular sporogenous cells, sporangia, they are called sporangiophores, and the spores, if they are naked and motile, are called zoospores (Fig. 4), or, if they are enclosed and non-motile, sporangio- spores (Fig. 5, sp). If the sporophores cut off their spores exogenously, 7 8 COMPARATIVE MORPHOLOGY OF FUNGI they are called conidiophores and the spores themselves conidia (Fig. 6). A special type of thick-walled conidium is called a chlamydospore or, in the resting state of the mycelium, a gemma. Chlamydospores have an entirely different morphological significance in different orders, as we shall see in the course of this book. In the higher fungi, the hyphae forming the conidiophores show a tendency to come together into groups or fructifications. When these groups have the form of fascicles, they are called coremia ; if they form widespread cushions, they are called sporodochia in saprophytes and acervuli in parasites; the tissue from which they arise is known as their stroma. If the conidial hyphae join in groups of plectenchymatous structures in whose interior they cut off their spores, these structures are Fig. 5. — Mucor Mucedo. 1. Sporangium with spor- angial wall, m; sporangiospores, sp; and columella, c. 2. Sporangium rupturing intermediate substance, z. (After Brefeld.) Fig. 6. — Penicillium crusta- ceum. Conidiophores. St, ster- igma; Ph, phialide; M, metula; A, primary branch. (After Strasburger.) called pycnia (pycnidia) and the conidia themselves (for better differ- entiation from other conidia) are called pycnospores, pycnidiospores or stylospores. In case the pycnia arise by growth and division of a single portion of a hypha with the aid of neighboring branches of the same hypha, the method is called meristogenous. If they arise by the inter- twining and coiling of hyphae of different origin, however, their method is called symphyogenous. These distinctions have a limited value as these types pass into each other and are at times found in the same spe- cies, e.g., the pycnia of Phoma conidiogena are formed entirely meristo- genously with poor media and more symphyogenously with good media (Schnegg, 1915; Kempton, 1919; B. O. Dodge, 1923a). These different spore forms — oidia, gemmae, conidia, etc. — may be formed on a suitable part of the haplont (rarely also on the diplont in FR UCTIFICA TIONS 9 the Basidiomycetes) as soon as conditions of nutrition suffice. A limita- tion exists only in so far as the isolated sporophores usually occur earlier than the corresponding fructification. Where several spore forms occur in the same species, it is called polymorphic. Another group of spore forms is not primarily dependent for its initiation on the conditions of nutrition but on the rhythm of the change of nuclear condition: either because their formation follows fertilization or because meiosis generally takes place in the sporophore. In the first Fig. 7. — Coremia. 1. Stysanus thyrsoideas. 2. Acaulium nigrum. after Sopp, 1912.) (1 X 220; 2 X 40; case, they are connected with the beginning, in the latter with the end of the diploid phase. In the first case they are recognizable morphologically since they show encysted zygotes (the products of the sexual act) ; biologically they usu- ally develop as hypnospores. According to the morphological position of the cells which copulate, their morphological significance and name varies, as we shall see in individual cases. In the second case, they are morphologically recognizable since they form tetracytes (as daughter cells of gonotoconts). Apparently, since 10 COMPARATIVE MORPHOLOGY OF FUNGI they are products of meiosis, they have become constant in number, which is usually fixed at 8 or 4; biologically, in the higher forms they are hypno- spores. If the sporogenous cells which serve as gonotoconts form their spores endogenously through free cell formation, they are called asci and the spores ascospores (Fig. 81) ; if they are formed exogenously by cutting off spores, they are called basidia and their spores, basidiospores (Fig. 265, 7 to 14). " Fig. 8. — Septoria. Pycnium. (After Klebahn.) Both these sporophore types functioning as gonotoconts show the same collectivistic tendency as the sporophores of the haplont. They collect in groups or in layers on which they stand beside each other in palisades which are called hymenia. The hymenia develop in typical gymnocarpous or angiocarpous fructifications whose structure is always highly differentiated. As only in these highest groups do the gonoto- conts become sporophores and especially as the gonotocont fructifications are the only ones visible to the naked eye, the gonotoconts of the groups in question (asci and basidia) are called the perfect forms, the other spore forms are called imperfect or secondary spore forms. CHAPTER IV SEXUAL ORGANS AND SEXUALITY The sexual function involves two processes: (a) fertilization, i.e., a fusion of two nuclei, periodically recurring in the course of development and setting free specific stimuli for development; and (b) meiosis, i.e., a return to the single chromosome number. This rotation (haplont- fertilization-diplont-meiosis) forms the changes of nuclear condition mentioned in the introduction. A few fungi seem to exist without a change of nuclear condition; they seem to be accustomed to living an unlimited number of "generations" without reconstruction of their nuclei and to propagate themselves by imperfect stages only. These fungi with incomplete, or incompletely known, life cycles are called Fungi Imperfecti or Deuteromycetes. The fungi with complete life cycles are divided, as are all other sexual organisms, into monoecious (bisexual or hermaphroditic) and dioecious forms. In contrast to the higher plants, in these fungi the question of the division of sexes is limited to the haplonts, i.e., the thallus, and the monoecious forms are called homothallic or neutral and the dioecious forms, heterothallic. The former are indicated as ± , the latter as + or — . The + and — mycelia of the latter group may be distinguished from each other only dynamically (i.e., only physiologically, as a result of their sexual tendencies) or morphologically (e.g., in growth form, sexual dimorphism). The process of fertilization in fungi, as in algae and protozoa, may be demonstrated in many ways (Winkler, 1908; Hartmann, 1909, 1918; Guillermond, 1913; Ernst, 1918). The simplest normal type of fertili- zation, when two spatially separated, not closely related sexual cells fuse to form a new entity, is called amphimixis. If these sexual cells arise as daughter cells of a characteristic mother cell and are themselves characteristically formed, they are called gametes and the mother cells gametangia (Fig. 11, 13 to 15). The copulation of two specific gametes of this type is called merogamy. If the gametes are equivalent to each other, the copulation is called isogamous, if the gametes are different, their copulation is heterogamous. If in the latter case one gamete is motile, the other non-motile, the former is called sperm (sper- matozoid) and the latter, egg (Fig. 34). In the lower fungi, the gametes are doubtlessly derived from zoospores which are weakened by under- 11 12 COMPARATIVE MORPHOLOGY OF FUNGI nourishment and are no longer capable of independent development. They proceed in pairs to autophagy, and the product of their fusion acquires a new specific ability for development. Under the influence of tendencies which will be brought out in the course of the discussion, the individualization of the gametes in the gametangia ceases at a low stage and the contents of the gametangia remain polyenergid. Thereby the original copulation of gametes is suppressed and replaced by many secondary processes which compensate for the loss of the original merogamy. All these secondary processes of fertilization are called deuterogamy (secondary pairing). In this cate- gory fall the processes of the higher algae and phanerogams (except the lower gymnosperms) while in the animal kingdom the primitive mero- gamy has persisted up to the highest vertebrates. In deuterogamy the gametangia assume the function of their daughter cells, the gametes, and cause their coenocytic content to fuse without further differentiation (Fig. 50). A sexual act occurs between two sexual organs instead of between sexual cells, and sexual attraction passes from the latter to the former. This type is called gametangial copulation. It assumes close contact between two gametangia and has a biologically obvious consequence that one gametangium can fertilize only one other which must be located directly next to it; but it has the obvious advantage that it no longer remains to chance whether the two gametes find each other, for the gametangia provide that their nuclei reach each other and fuse. Viewed caryologically, the effectiveness of gametangial copulation becomes greater since most of the nuclei of both succeed in their activity and consequently the number of zygote nuclei increases; viewed numeri- cally, only a small fraction are effective, for the fate of whole gametangia depend on the occurrence or non-occurrence of a single sexual act and only one very strong coenocytic zygote results instead of many smaller unicellular zygotes. There is a special advantage for the gametangium, since at its maturity it is no longer dependent on a definite medium for the copulation of its gametes and consequently it has made possible an easier transition from water to land habitats, and to parasitism in the interior of other plants. Whether gametangia are formed on special branches or whether these branches as a whole complete the act of fertili- zation, they are called copulation branches. In the case of heterogamy they are distinguished as antheridium (male) and oogonium, archicarp or ascogonium (female). In the holocarpic forms, gametangial copulation naturally leads to the fusion of whole individuals (Fig. 26, 4 and 5) and is equivalent in a certain sense to self annihilation. This special case of gametangial copulation, in which two mature individuals copulate, is called hologamy. In the fungi, in contrast to certain flagellates, it has doubtlessly arisen secondarily from merogamy. SEXUAL ORGANS AND SEXUALITY 13 In the higher Ascomycetes, for reasons still unknown, the fundaments of the antheridium are gradually reduced; thereby cross-fertilization generally ceases and is replaced by self-fertilization, i.e., sl new group of deuterogamous processes between daughter cells of the same mother cell or between the nuclei of the same cell which are included in the term automixis. Automixis is represented in the fungi by two forms: parthenogamy and autogamy. Parthenogamy (parthenomixis of Winkler) is fertiliza- tion which takes place between two female cells, i.e., in the fungi usually between two cells of the archicarp (Fig. 227). In certain forms this parthenogamic fusion of two specialized cells is suppressed and replaced by pairing of nuclei within a single polyenergid cell of the archicarp (Fig. 229). This automictic fertilization within a cell is called autogamy. From these forms in which the sexual organs (or in any case the female organ) are apparently still typical in form, but no longer functional and serving only as the site of automictic processes, there is a series of intermediate stages to the other extreme in which the sexual organs are entirely suppressed, the sexual processes occurring outside in the thallus between any two sexually differentiated vegetative cells (Fig. 266, 1). The latter process is called pseudomixis (pseudogamy of Hartmann). Since the copulating cells are not morphologically distinguished from other vegetative cells and since only the release of specific developmental stimuli, which only appear later, marks this anastomosis of two vegeta- tive cells as a sexual process, pseudogamy is often distinguished with difficulty from the usual pseudosexual anastomoses which are brought about by food relations. Its true character is only recognizable cytol- ogically in the pairing of nuclei. If pseudogamy takes place between two sprout cells (Fig. 301, 10 and 11), they are called gametes; in order to avoid misunderstanding, this term should be reserved for merogamous gametes. The ambiguous term pedogamy, often used in other senses, may be used to indicate the pseudogamy between adult and young cells (Fig. 93, 17 to 23). The special case of pseudogamy between mother and daughter cell is called adelphogamy. Apomixis, the entire loss of fertilization, represents the last step in this series of reduction of natural sexuality in which growth from repro- ductive cells takes place vegetatively without cell or nuclear fusion or any external stimulus of development. If the new individuals (in the absence of fertilization) arise from haploid sexual cells, the process is called parthenogenesis; if they arise (in the absence of meiosis) from diploid sex cells, the process is called apogamy. For a better summary the different forms of fertilization are tabulated, as far as they concern fungi, according to the scheme of Hartmann : 14 COMPARATIVE MORPHOLOGY OF FUNGI 1. Amphimixis, the copulation of two sexual cells not closely related. A. Merogamy. Specific gametes which have arisen as daughter cells of gametangia and serve as sexual cells (e.g., Syjichytrium, Fig. 11). B. Gametangial copulation. Where the differentiation of gametes is suppressed {e.g., Phytophthora, Fig. 51). C. Hologamy. A special case of gametangial copulation, in holocarpic forms where the whole thallus is transformed into a gametangium and copulation takes place between two mature individuals (e.g., Polyphagus, Fig. 26). 2. Automixis. Self-fertilization following copulation of two closely related sexual cells or sexual nuclei. A. Parthenogamy. Copulation between two cells of the female sexual organ (e.g., Ascobolus citrinus, Fig. 227). B. Autogamy. Fusion of nuclei in pairs within a single cell of the female sexual organ, not accompanied by cell fusion (e.g., Humana granulata, Fig. 229). 3. Pseudomixis. Copulation between two vegetative cells. A. Pseudogamy. Between cells not closely related to each other (e.g., Peniophora Sambuci, Fig. 266, 1). B. Pedogamy. Pseudomictic copulation between mature and imma- ture cells (e.g., various yeasts). C. Adelphogamy. Pseudomictic copulation of mother and daughter cells (e.g., Zygosaccharomyces Chevalieri, Fig. 93, 17 to 23). 4. Apomixis. Vegetative development of sexual cells in the absence of copulation. A. Parthenogenesis. Apomictic development of haploid cells. B. Apogamy. Apomictic development of diploid cells. Besides the complication that the original processes of fertilization are replaced in the course of development by all sorts of substitutes, in the study of fungi there is another difficulty. The diagram of a life cycle, (p. 1) which at the instant of fertilization shows a complete transition from the haploid to the diploid phase, describes only the exceptional case in fungi. In the lower fungi, there is simple fertilization where a fusion of two sexual cells (plasmogamy) is followed normally and directly by a fusion of both haploid nuclei into a diploid zygote nucleus, a syncaryon (caryogamy) ; in most fungi, however, caryogamy is delayed and is only completed when the necessity for meiosis appears. Thus the sexual nuclei unite only to form a dicaryon in which the paired nuclei pass through their further development synchronously (conjugately); and in this condition possess the same ability to activate the somatic develop- ment as after complete caryogamy, although the nuclei remain spatially separate. Their relation corresponds to that of Cyclops in which the parent chromosomes remain separate up to the time of egg formation (synapsis!). But in the case of Cyclops they are surrounded by the same SEXUAL ORGANS AND SEXUALITY 15 nuclear membrane, while in the fungi they remain in their original nuclear membranes. With this retardation of caryogamy, there goes a spatial separation. The binucleate zygote continues its growth without completing the fusion of nuclei and develops, in the higher fungi, to a new thallus whose cells, virtually diploid, morphologically contain two sexually differenti- ated haploid nuclei. This new phase, intruded between plasmogamy and caryogamy, is called the binucleate phase. To distinguish it from the usual diploid phase we will underline it in the life-cycle diagrams with two thin instead of one heavy line. It is significant that in spite of this removal and retardation, caryog- amy must take place in definite organs. The organs in which the ferti- lization processes are completed and the dicaryon ends are called zeugites. As caryogamy is delayed until the necessity for meiosis appears, these zeugites function in most forms as gonotoconts. The diagram on page 1 might therefore be modified as follows: I ~P~ C R | Haploid thallus — >Sexual cells -^Diploid thallus— >Zeugites— >Gonotocont— >Tetracytes Diagram II. The two moments, the transformation of the cells which complete the sexual act and the division of the sexual act itself into plasmogamy and caryogamy, separated in time and space, so that reproduction is sepa- rated in time and space from the sexual act which brings it about, are both fundamental processes which, since the contributions of Bary and Brefeld, have made possible a deeper interpretation of the classification of fungi created by these two investigators. We shall give special attention to these processes in the rest of the book. Classification. — Fungi are considered as thallophytes without chloro- phyll. In this book, the bacteria and Myxomycetes are not considered. From these two latter classes, the fungi in the narrower sense are distin- guished by their diversity of fructifications, from the bacteria by the possession of true nuclei and from the Myxomycetes, excluding groups here considered under the Archimycetes, by the possession of cell walls at all stages of development. In contrast to the Myxomycetes, the other fungi are often called Eumycetes; in other terminology, however, this name is reserved for the Ascomycetes and Basidiomycetes, to dis- tinguish these two classes from the Phycomycetes. The classification of fungi rests upon the consideration of the life cycle and the development which their thalli and organs of fructification have attained in both portions of the life cycle. On this basis they may be divided into four classes: Archimycetes, Phycomycetes, Ascomycetes and Basidiomycetes. The Archimycetes and Phycomycetes are distinguished by the primitive character of the thallus, naked in the Archimycetes, or 16 COMPARATIVE MORPHOLOGY OF FUNGI surrounded by a cell wall in the Phycomycetes, and by the limitation of the diplonts to the zygote, in whose germination meiosis occurs ; thus the zygote is also gonotocont. The Ascomycetes are distinguished by the more highly developed thallus and, in typical forms, by the develop- ment of the zygote to a typical mycelium with meiosis shifted to special reproductive organs; in the Ascomycetes into "sporangia" with free cell formation, the asci; in the Basidiomycetes into "conidiophores" with exogenous abscission of spores, the basidia. Possibly in time it will be desirable to place at the beginning still a fifth class, the Myxomycetes, as these may be basically separated from the Archimycetes. CHAPTER V CLASS ARCHIMYCETES According to a proposal in a letter from E. Fischer, the fungi here called Archimycetes are the earlier Myxochytridiales. They include naked, often amoeboid forms which develop holocarpic reproductive organs by division of the whole thallus. They stand very close to the Myxomycetes and flagellates and chiefly differ from them in their parasitism. They are divided into four families: the Olpidiaceae and Synchyt- riaceae, whose zoospores are oval or pyriform with trailing flagella; the Plasmodiophoraceae, whose zoospores are amoeboid, with an apical flagellum ; and the Woroninaceae whose zoospores are reniform with two lateral flagella. The thallus forms a single sporangium in the Olpidia- ceae, a sporangiosorus in the Synchytriaceae and a multitude of spores or spore balls in the Plasmodiophoraceae. At present the relationships of these four families are still obscure. The Plasmodiophoraceae and Woroninaceae, are peculiar on account of their schizogonia; it is questionable, however, whether the formation of sori in the Synchytriaceae may not be an extreme reduction of schizo- gonia, if the nuclear divisions up to the formation of the protospores and their analogues are called the vegetative phase and the subsequent ones, which lead to zoospore formation, the reproductive phase. Previous studies, however, have given no basis for such considerations. Further, the zoospores of the Olpidiaceae and Woroninaceae, like the swarm spores of many Monadineae, before germination on the host are always sur- rounded by a membrane, and discharge their contents into the host cell leaving their empty membrane on its surface. The zoospore of the Synchytriaceae and possibly of the Plasmodiophoraceae withdraws its flagellum and then as a whole penetrates the host plant. How far this lack of a membrane may be evaluated phylogenetically is not yet clear. These four families are regarded as four different lines which have developed independently of each other from the Sporozoa-Flagellate- Myxomycete line. Since in the Woroninaceae and Plasmodiophoraceae, the distinguishing points have not yet been determined cytologically, a discussion of these relationships would be premature. Olpidiaceae. — This family is very simply organized and, as far as known, reproduction proceeds isogamously by aplanogametes. 17 18 COMPARATIVE MORPHOLOGY OF FUNGI In Olpidium Viciae, which in spring and early summer causes a disease of Vicia unijuga in Japan (Kusano, 1912), the uniflagellate zoospore swims about on the leaves of the host for as long as 24 hours, with short rest periods during which it may creep over the substrate in an amoe- boid manner (Fig. 9, 1). When it finally comes to rest it withdraws its flagellum, surrounds itself with a membrane, bores through the wall and discharges its thick naked protoplasm into an epidermal cell of the host, where it attaches itself to the nucleus as an amoeboid proto- plast (Fig. 9, 2 to 6). A period of promitotic (or amitotic?), later of mitotic, nuclear division follows, during which the protoplast is sur- rounded by a membrane and develops to a sporangium. At maturity Fig. 9. — Olpidium Viciae. 1. Zoospores. 2 to 5. Shedding of membranes and pene- tration of host cell. 6. Naked thallus of fungus in host cell. 7. Germinating zoosporan- gium. 8. Empty zoosporangium. 9. Copulation of two planogametes. 10. Young zygote before caryogamy. 11. Mature hypnospore. 12. Multinucleate hypnospore at the beginning of germination. (1 to 9 X 535; 10 X 600; 11, 12 X 1,200; after Kusano, 1912.) (after 5 to 10 days) this pierces the wall of the host cell by rostrate processes and through one of these discharges the zoospores (Fig. 9, 7 and 8). Under certain conditions, the zoospores behave as planogametes, especially in very ripe sporangia which have consumed the nutriment of the host cell and, while waiting for favorable conditions of nutrition, are passing through a period of hunger. Then they copulate in pairs during pauses in their amoeboid activity. The biflagellate zygote swims about (also with rest periods) and finally comes to rest, surrounds itself with a membrane and discharges its content into a host cell. A definite point of fusion is not present as in the planogametes of the Chlorophyceae; CLASS ARCHIMYCETES 19 apparently the plasma membrane may be ruptured at any point. A sexual differentiation is also lacking, indeed two gametes, after attempt- ing to copulate for a few minutes, may again separate. This inner differentiation rests rather on differences in age or turgor. The young diploid protoplast is binucleate (Fig. 9, 10). When it is mature it is surrounded by a membrane which in time differentiates into an exospore and endospore. Thereby the zygote has become a hypnospore. A fusion of both nuclei occurs in the following spring a few days before germination (Fig. 9, 11). This is followed by numerous mitotic divisions, of which the first is possibly a meiosis. The outer layer of the endospore swells, whereupon the inner layer of the endospore forms an emission collar through the wall of the host cell (Fig. 9, 12) and discharges the zoospore. Thus the life cycle corresponds to the following scheme (Goeldi and Fischer, 1916): R Zoospores P Binucleate ZoUporeS^™u£^oosporangia^Gam Diagram III. Haplont and diplont are motile in their young stages and independent in their life functions; accordingly they are true gametophytes and sporo- phytes. The former, which lacks the diplont may increase repeatedly by zoospores, while the specific duty of the latter is the formation of hypnospores. A similar life cycle is probably possessed by the numerous other equally parasitic species of Olpidium, as 0. Brassicae, a destructive parasite of seedlings of cabbage, possibly also of lettuce and tobacco. The young protoplasts are uni- nucleate. Under favorable conditions they may be naked, even in the stage with 32 nuclei. Then they are surrounded by a membrane and on the proximal side develop an emission collar which germinates at the tip (Nemec, 1912). The source and germination of hypnospores rangia. 2. Hypnospores within /-r-.- ,~ «n ■ , t n i epidermal cells. (X 110; after (Fig. 10, 2) is unknown. In youth, however, Woronint i878.) they are binucleate, suggesting a previous plas- mogamy (Nemec, 1922). Similar observations have been made on 0. Salicorniae on the roots of Salicornia herbacea (Nemec, 1911). Similar to Olpidium, but lacking an emission collar, is Olpidiaster radicis (Asterocystis radicis) parasitic on the secondary roots of many Fig. 10. — Olpidium Bras- sicae. 1. Germinating zoospo- 20 COMPARATIVE MORPHOLOGY OF FUNGI phanerogams and causing the wilt of flax seedlings in Flanders. Its zygotes are also binucleate in the young stages (Nemec, 1922). Reesia amoeboides on Lemna sp. in Germany has the same life cycle as Olpidium. It is the first form in which copulation of planogametes was observed by Fisch (1884), but until the work of Kusano, his work was considered erroneous. Monochytrium Stevensianum (Griggs, 1910) on Ambrosia artemisifolia in the United States appears to be similar, but its life cycle is incompletely known. Also noteworthy is the parti- ally known Pleolpidium which parasitizes fungal hyphae, such as P. irregulare on Pythium. In some respects it reminds one of the Woroni- naceae but differs from them in the uniflagellate zoospores. Dangeard (1889, 1895a) made similar observations for Sphaerita. Synchytriaceae. — In contrast to the Olpidiaceae, the thallus of this family does not change to a sporangium but to a sporangial sorus par- tially protruding from the original sheath. Further, their thalli remain uninucleate until the beginning of fructification so that the nucleus may attain a diameter of 25/x. Synchytrium, chiefly parasitic on phanerogams, is divided into three subgenera according to the method of spore formation: Pycno- chytrium where the summer spores (if they are produced) are as thick walled as hypnospores and germinate with a protruding sorus; Mesochytrium whose summer sori are thin walled but germinate as in Pycnochytrium; and Eusynchytrium which agrees morphologically with Mesochytrium, but forms zoospores inside the membrane of the initial cell. How far these differences are fundamental is still obscure; the protrusion of the sorus may be only the result of a brittleness of the exospore which cannot expand as rapidly as the sorus. In the subgenera Eusynchytrium and Mesochytrium, the protoplast is yellow or reddish yellow ; in Pycnochytrium, it varies according to the species and age, from reddish yellow to yellow or hyaline. In the subgenus Pycnochytrium, S. endobioticum causes the potato wart on Solanum tuberosum, also attacking S. nigrum and S. Dulcamara (Curtis, 1921). The zoospore swarms especially between 12 and 19°. After it comes to rest on the epidermis of the host, it withdraws its flagellum, throws it off and penetrates the host cell where its body is carried to the bottom of the cell by the streaming of protoplasm (Fig. 11, 1 to 4). The host cell swells under the influence of the parasite and becomes pyriform; repeated division of the neighboring tissue cells forms a tumor; the surrounding epidermal cells divide similarly and become woody so that a rosette is formed with the infected cell in the middle (Fig. 11, 5 and 6). The zoospore develops to a summer spore, also called prosorus or initial cell, and surrounds itself with a double wall, a thick golden-yellow exospore and a thin hyaline endospore (Fig. 11, 7). Its nucleus reaches CLASS ARCHIMYCETES 21 a diameter of 25/i. It completes its maturation by a triple expulsion of chromatin from the nucleolus into the nuclear vacuole. During, or shortly after, the third expulsion, the endospore pushes out a short pro- Fig. 11. — Synchytrium endobioticum. 1. Zoospores. 2, 3. Penetration of host cells. 4. Young protoplast within a hypertrophied epidermal cell. 5. Group of immature sum- mer spores; the single thickened cells within the rosettes are the infected epidermal cells. 6. Rosette. 7. Mature summer spore. 8 to 10. Germination of mature summer spores. 11. Young sorus, the future walls indicated by the denser protoplasm. 12. Mature zoosporangium with the fundament of the emission collar. 13 to 15. Copulation of two planogametes. 16, 17. Penetration of the zygote. 18. Young hypnospore. 19. Hypno- spore during maturation of the zoospore primordium. 20. Empty hypnospore. (1, 12, 19, 20 X 520; 2, 3, 14 to 16 X 1,270; 4, 7 to 10, 17, 18 X 270; 5 X 100; 6 X 115; 11 X 535; 13 X 1,110; after Curtis, 1921.) jection and in about 4 hours the whole content slips into the remaining space of the dead host cell (Fig. 11, 8 to 10). When the number of nuclei reaches the neighborhood of 32 by repeated mitotic division, the proto- plasm collects to denser zones (Fig. 11, 11), regardless of the position of 22 COMPARATIVE MORPHOLOGY OF FUNGI the nuclei, so that the prosorus is divided into 5 to 7, seldom into 9 por- tions. These portions are surrounded by hyaline membranes; they are the future zoosporangia in which, by further divisions, the number of nuclei increases to as many as 300 (Fig. 11, 12). At germination the rosette, along with the whole sorus, is pressed to the upper surface by the swelling of the tumor cells; similarly, by pressure on all sides, the sporangia are forced out of the sorus and the disorganised host cell, into the open (Fig. 11, 13) and liberate their numerous zoospores through a narrow slit. Zoospores from over-ripe sporangia behave as planogametes. A zoo- spore swims to another which has come to rest and fuses with it (Fig. 11, 13 to 15). It is improbable that zoospores from the same sporangium copulate, although zoospores from different sporangia of the same sorus may. The zygote, like a zoospore, penetrates the epidermal cell of the host (Fig. 11, 16 and 17); under its influence the latter divides repeatedly so that daughter cells and parasite are pushed several layers of cells deep into the host tissue (Fig. 11, 18). While the haploid zoospores cause only a hypertrophy of the host cell and the sori arising from them cause a hyperplasia of the neighboring epidermal cells, the diploid zygote or young hypnospore causes hyper- plasia of the host so that the resting spore is pushed deeper into the host tissue, but the neighboring epidermal cells remain undivided. Here is an example of the different specific effect of the haplont and diplont on the host, such as we shall find in the Uredinales. The diploid nucleus extrudes chromatin at least thrice ; a true meiosis has not yet been reported. The young hypnospore surrounds itself with a double wall; a third layer is laid down by the protoplasm of the host cell. After a long resting period, usually the next spring, numerous zoospores are formed by repeated nuclear division (Fig. 11, 19); because of the swelling of the innermost wall layer, the hypnospore bursts open and the zoospores are set free in their sorus (Fig. 11, 20). Closely related to this form is S. aureum which lives on more than 100 host plants in very diverse families (Rytz, 1907). A much-enlarged epidermal cell serves as host cell for the fungus. The neighboring cells, especially the epidermal cells, enlarge and occasionally divide to produce a hemispherical growth which often raises the host cell above the plane of the epidermis. The top of the host cell (i.e., the top of the wart) lies in a slight depression. According to observations in the natural habitats, the several strains of fungi formed because of different conditions of living and plant associations, differ on principal and auxiliary hosts, for the principal host may be comparatively regularly infected and the auxiliary hosts under definite, but still unknown conditions. Thus for the Lysimachia group (S. aureum), the chief host is Lysimachia nummularia; CLASS ARCHIMYCETES 23 the auxiliary hosts are from Potentilla, Valeriana, Hypericum, Epilobium and Myosotis; or in the alpine saxifrage groups (S. Saxifragae) the princi- pal host is »S. aizoides, the auxiliary hosts S. stellaris, S. moschata, Andro- sace chamaejasme, Hutchinsia, Leontodon, Viola, Ranunculus, etc. In Synchytrium Succisae, on Succisa pratensis, there is a division of labor between the summer sori and the resting spores; the summer sori remain thin walled and only the somewhat smaller hypnospores, in which the fungus winters over, possess a thick double-layered sheath (Rytz, 1907). In Synchytrium (Eusynchytrium) Taraxaci on Taraxacum sp. (Schroe- ter, 1875; Liidi, 1901), S. {Eusynchytrium) decipiens on tropical and temperate phanerogams (Tobler-Wolff, 1912) and S. (Eusynchytrium) Puerariae on Pueraria Thunbergiana in Japan (Kusano, 1907, 1908), the stage of the projecting blister is omitted; their zoospores arise in the Fig. 12. — Synchytrium aureum. Hypno- spore in an enlarged epidermal cell, sur- rounded by a small gall. ( X 93 ; after Rytz, 1907.) Fig. 13. — Synchytrium Saxifragae. Hy- pnospore, a; with sorus, b, which has already formed zoosporangia. (X 340; after Rytz, 1907.) initial cells themselves and swarm out of them through an opening. In S. decipiens, cleavage of the protoplasm produces uninucleate portions which form the young naked sporangia. They are called protospores (Harper, 1899). Their nuclei divide repeatedly so that every sporangium contains several nuclei. In this species, four chromosomes have been counted (F. L. and A. C. Stevens, 1903; Griggs, 1909). In »S. Taraxaci the protospore stage is omitted and the multinucleate protoplasm, as in S. endobioticum, is divided directly into multinucleate sporangia whose nuclear number further increases by division (Dangeard, 1891; Harper, 1899) ; this division takes place by cleavage from the periphery inwards, not by successive formation of membranes as in S. endobioticum. A fourth subgenus Woroninella is distinguished by the crateriform or aecidial habit of its open sori. So far only thin-walled summer spores, germinating as in the Eusynchytrium type, are known. Synchytrium Psophocarpi in tropical Asia is parasitic on Psophocarpus tetragonolobus, S. vidcanicum on Lespedeza cytisoides, S. aequatoriense in Ecuador on 24 COMPARATIVE MORPHOLOGY OF FUNGI Psoralea Mutisii and S. aecidioides (Uredo aecidioides) on Amphicarpa in the United States (Gaumann, 1927). Still insufficiently known and hence of uncertain position are Microm- yces (Dangeard, 1889) in Zygotonium in western France, Sorolpidium (Nemec, 1911, Guyot, 1927) in the cortical cells of Beta vulgaris (B.mari- tima) in Czechoslovakia and Anisomyxa (Nemec, 1913) in the cortical cells of roots of Plantago lanceolata in Czechoslovakia. All three agree in that their thalli break up into zoosporangial sori and that the zoospores are uniflagellate. The two latter appear to differ from Synchytrium in nuclear relationships. Plasmodiophoraceae. — In spite of many studies, there is still much doubt in the decisive points of the life cycle, particularly in regard to the peculiarities of nuclear division and the existence of caryogamy. Usually single organs of phanerogams are stimulated to form tumors within which spores are produced. At spore germination, which generally occurs in spring, there arises from each spore an amoeboid zoospore (myxamoeba) with an apical flagellum, which in Spo?igospora combines with the myxamoebae from other spores (Kunkel, 1915) and penetrates the host. In the first stages of the disease, one finds in the protoplasm of the host cell, one or more naked bodies of protoplasm (myxamoebae) which have penetrated (Fig. 14, 2). They grow markedly and by repeated promitotic nuclear division become multinucleate (schizont stage) and successively cut off daughter amoebae (meronts) as short blunt processes (Fig. 14, 3). With the divisions of the host cells, where such occur, the amoebae are again divided among the daughter cells; however they are also able to wander independently from cell to cell (Kunkel, 1918). The host cells gradually swell up and the schizogonia of the amoebae proceed until the exhaustion of the reserve stores. Then the amoebae of each host cell join to form a plasmodium, and their nuclei extrude a part of their chromatin (Fig. 14, 4 and 5). Their further phases are still insufficiently known. Prowazek (1905) for Plasmodiophora Brassicae, the cause of clubroot of cabbage, and Osborn (1911) for Spongospora subterranea, the cause of powdery scab of potatoes, have claimed that some nuclei come together in pairs and fuse, while the surplus nuclei degenerate and disappear; these statements, however, have not been confirmed. In any case there follows a generative period in which throughout the plasmodia, there occur two synchronous, nuclear divisions, one of which is meiotic (Fig. 14, 7); the plasmodia divide into uninucleate portions, surround themselves with a membrane and develop as spores (Fig. 14, 1, 8). These spores are generally comparatively thick walled and very resist- ant to external influences. In Plasmodiophora (Woronin, 1878; Naw- aschin, 1899; Prowazek, 1902, 1905; Maire and Tison, 1909; Favorski, CLASS ARCHIMYCETES 25 1910; Lutman, 1913) they lie singly within the host cell and are liberated on its decay; in Sorosphaera (Schwartz, 1910, 1911; Maire and Tison, 1909; Blomfield and Schwartz, 1910; Winge, 1913) they are arranged in hollow spheres; in Sorodiscus (Winge, 1913) they form ellipsoids; in Tetramyxa (Maire and Tison, 1911) they lie in tetrads; in Spongospora (Osborn, 1911; Kunkel, 1915) they are joined in spongy masses and in Ligniera (Maire, 1911; Schwartz, 1914; Fron and Gaillat, 1925; Cook, ■•■■ i&s-y* Fig. 14. — Spongospora subterranea. 1. Host cell with 8 spore balls. 2. Young amoeba in host cell. 3. Amoebae. 4, 5. Plasmodium formation. 6. Beginning of segmentation of the protoplasm. 7. Beginning spore formation. 8. Mature spores. (1 X 700; 2 to 6 X 600; 7, 8 X 1,830; after Osborn, 1911.) 1926, Guyot, 1927) in regular clumps. The last genus does not cause the development of tumors by the host, while all the others cause con- spicuous hypertrophies. Only Plasmodiophora and Spongospora cause disease of economic importance. An interpretation of the life cycle of the Plasmodiophroaceae is not yet possible. Except for the unconfirmed work of Prowazek and of Osborn, the location of caryogamy is unknown. Similarly the relation of the sporonts to plasmodia needs more careful investigation. Because of this obscurity, a discussion of the relationships of the Plasmodiophor- 26 COMPARATIVE MORPHOLOGY OF FUNGI aceae to the Myxomycetes and flagellates would be premature; probably they have arisen from these groups and have been much modified by their parasitism. Woroninaceae. — Since the position of this family is obscure, its classification here is provisional. It contains all biflagellate Archimy- cetes. The assignment of definite phylogenetic lines is postponed until a greater number of species is known. A representative of each of the more carefully investigated genera will be described. The zoospores of Olpidiopsis Saprolegniae on Saprolegnia are ovoid or reniform. The two flagella arise laterally somewhat toward the apex. eg ■:0- .-■<=>•: if *fe"v °-iT" Si' .fcra.-. i&i'' m a.'-s-.-i--':'? ^ „«>■', .'-^s..:'&^- Fig. 15. — Olpidiopsis Saprolegniae. 1. The zoospore has formed a membrane and allowed its content to slip into a hypha of the host. 2 to 5. Development of the young protoplast to a zoosporangium. 6, 7. Development of the zygote. 8. Host hypha with 3 empty zoosporangia and 2 hypnospores. (1, S X 1,000; 2 X 890; 3, 6, 7 X 670; 4, 5 X 1,370; after Barrett, 1912.) A few minutes after swarming they come to complete rest and after a short rest period, swim on. If they reach a filament of Saprolegnia, they show some amoeboid movement, and surround themselves with a wall, while the germ tube pierces the wall of the host hypha, into which the uninucleate cell content is ejected (Fig. 15, 1). By streaming, the naked protoplasm may be carried for a distance in the hypha; it grows rapidly, becomes multinucleate, and after two or three days surrounds itself with a wall and becomes a zoosporangium. At maturity several small vacuoles form and these then flow together into a large central vacuole CLASS ARCHIMYCETES 27 (Fig. 15, 3), push toward the periphery and, after completing a nuclear division, cut up the protoplasm next the wall into uninucleate zoospore initials. These grow with equal rapidity, fill out the sporangium and thereupon contract, perhaps by the expression of water. Finally they begin to swarm from the emission collar (A. Fischer, 1882; Schwarze, 1922). The formation of hypnospores in the poorly nourished hyphae is preceded by a sexual act. Around one larger multinucleate protoplast, one or more equally nucleate, smaller male protoplasts are placed (Fig. 15, 6). Each is surrounded by a membrane which in the female cell, except for the point of contact with the male, is thickened and echinulate while the male remains thin and smooth. At fertilization the separating wall dissolves and the whole content of the male cell passes into the female (Fig. 15, 7). If several male cells are present, apparently all can discharge their content into the female. Fig. 16. — Pscudol pidium Saprolegniae. a, swollen host hyphae with 3 sporangia; b, hypnospore. (X 320; after A. Fischer, 1882.) The empty male cell membranes remain connected to the zygote as " appendiculate cells." The further fate of the nuclei is unknown. The endospore becomes brown and thickened while the echinulate exposore remains hyaline. They germinate by zoospores which discharge through an emission collar (Barrett, 1912). Pseudolpidium Saprolegniae, also parasitic on Saprolegnia, in structure and habit resembles Olpidiopsis but differs in the absence of "appendicu- late cells" on the hypnospores (Fig. 166). An insufficiently known spe- cies found by Serbinov (1907) on algae, suggests Woronina and Rozella in the peculiarity of its young amoeboid protoplasts, which divide by constriction. The species of Wo7-onina are parasitic on algae and fungi. In W. poly- cystis, on Saprolegnia (A. Fischer, 1882), the zoospore on the host hyphae 28 COMPARATIVE MORPHOLOGY OF FUNGI o . Q 6 — c ...Q. <^ ,oa \Q° (To OO 9^A w£$QJ? oc : i * ® a b c m Fig. 17— Woronina polycystis. a, Hyphal tip of Saprolegnia with 5 cells each contain- ing a sporangia! sorus of the parasite, the uppermost about to discharge; b, Cystosorus, c in each of lower cells, a sporangiosorus, s, in the upper cells, c. Rozella septigena. Hyphal tip . o -Saproleama with 5 cells each entirely filled with a cylindrical zoosporangium. (a X 200, b and c X 300; after Cornu.) CLASS ARCHIMYCETES 29 surrounds itself with a membrane, and discharges the naked protoplast into the interior. This is carried to the tip of the hypha by the streaming protoplasm and there separated from the host by a septum. It grows rapidly at the expense of the host plant and after two days breaks up into polyhedral portions (the young zoosporangia) each of which rounds off and surrounds itself with a membrane. At maturity they form a short papilla which pierces the host wall and allows the zoospores to escape. With falling temperature in stagnant water, resting conditions appear. The individual sporangia are surrounded by a strong membrane, adapted to resting over unfavorable conditions. A. Fischer calls them sporangio- cysts. They are joined to a thick group (cystosorus) which is derived as a whole from a single protoplast (Fig. 176). At germination the spo- rangiocysts change into sporangia and, in a still unknown manner, dis- charge the zoospores into the open. /S Fig. 18. — Rozella scptigcna. Part of host hypha with the false oogonia, each contain- ing an echinulate hypnospore, d, containing the parasite; s, sporangium of the parasite. (X 400; after Cornu.) Rozella septigena lives exclusively on Saprolegnia hyphae, (A. Fischer, 1882). As in Woronina polycystis, the parasite, after penetration, passes with the streaming protoplasm to the apex where it divides repeatedly, so that the daughter individuals are separated occasionally by the septa of the host. Hence they lie behind one another in a row of single flabella (Fig. 17c). After approximately two days, each changes to a sporangium whose walls lie directly on that of the host hyphae. Thus a filament infected by Rozella has the appearance of a hypha which has cut off several gemmae. At germination the sporangium collects its protoplasm to a thick covering on the walls, and cleaves into single zoospores which swarm out through a papilla. The hypnospores arise in lateral outgrowths of the single flabellum; their wall is closely echinulate (Fig. 18). Their formation and germination are unknown. Belonging to the Woroninaceae or closely related to them is a series of interesting forms whose life cycles are imperfectly known, as Pyrrho- sorus marinus (Juel, 1901) and Pleolpidium inflatum (Butler, 1907). CHAPTER VI CLASS PHYCOMYCETES The Phycomycetes owe their name to the fact that they were long considered as degenerate algae. Because of their similarity to the Siphonales, they are sometimes called Siphonomycetes. The thallus, in contrast to that of the Archimycetes, is surrounded by a membrane. In the simpler forms, it is a uninucleate cell; in the higher forms a true mycelium with aseptate multinucleate hyphae; in the high- est forms, the hyphae are abjointed into uni- or multinucleate cells. In several families the hyphae may fragment and become a sprout mycelium. Sporangia and conidia are fructifications of the haplont. In the simplest forms, sporangia arise by a change of the thallus; in the forms with a better developed thallus, they are eucarpic, with special organs which occupy only a part of the thallus. In time, such a small part of the thallus is used for the formation of sporangia that these may be repeatedly formed on nearly all the hyphae of the plant; thus the repro- ductivity of an individual is increased many times. At maturity the sporangia are generally coenocytic. By the individ- ualization of single energids, they produce motile zoospores, or by the cleavage of the protoplasm into multinucleate portions, non-motile sporangiospores. By the combined effect of several factors, especially by the transition from submersed to terrestrial and finally to parasitic habits, the development is gradually inhibited before the daughter cells have individualized : the sporangia germinate as a whole with a coenocytic germ tube. Subsequently they assume the task of propagation instead of their daughter cells, and become successively spores and conidia. By this degeneration of sporangia to conidia, the number of propagative organs formed by an individual is greatly reduced. This numerical dis- advantage is offset by a considerable increase of branching of the conid- iophores, whereby the number of sporangia formed by an individual increases in geometric progression. Aplanes Braunii and Pythium Indigoferae, however, are on the point of giving up their degenerate asexual reproduction in favor of the sexual, and in many Entomophthoraceae and Endogonaceae, only the sexual reproduction is known. The preference for sexual reproduction at the cost of the degenerate asexual, will be met later in a greater degree in the Ascomycetes and Basidiomycetes. As sexual organs, gametangia and gametes are formed. In the lower forms, the gametangia arise like the sporangia by the transformation of 30 CLASS PHYCOMYCETES 31 the whole thallus; they are then only sporangia whose zoospores, possibly because of undernourishment, are no longer capable of further independ- ent development. In the higher forms, however, again like sporangia, they arise as special organs, antheridia, oogonia, etc., which finally engage only a small part of the thallus; in many of these forms, however, condi- tions of nourishment alone determine whether a fundament develops to a sporangium or gametangium. Only in the highest Phy corny cetes is the gametangium so highly specialized that it is unable to change into a sporangium, and degenerates in the absence of a mate. These close relationships between sporangia and gametangia increase, so that in the Phycomycetes, the gametangia undergo changes in the course of their phylogenetic development similar to those in sporangia; just as in sporangia, the individualization of spores is absent and the sporangia assume the task of the spores so in the gametangia, individual- ization of the gametes is lacking; hence the gametangia remain coenocytic and allow their contents to fuse without differentiation. Gametangial copulation appears between two coenocytic gametangia instead of copula- tion of gametes. These tendencies appear in the lowest holocarpic families and naturally lead to hologamy ; as the differentiation of gametes is absent, the whole thalli fuse and form a single coenocytic zygote. In the higher forms, gametangial copulation, except in Monoblepharis, is the only type of sexuality known. The original complexes which lead to suppression of individualization of gametes and copulation of coenocytic gametangia, have not yet reached pure gametangial copulation; their reduced activity in the nuclei leads, in the higher forms, to the appearance of privileged sexual nuclei, appearing in both the isogamous and the heterogamous series. Corresponding to this variation in development of gametangium and gametes, the zygotes are not entirely equivalent in the Phycomycetes. Externally they appear rather similar, as, almost without exception, biologically they are hypnospores; ontogenetically they may be divided into true zygotes and coenozygotes the product of two coenocytic gametangia. As a conidium corresponds to many zoospores and hence the probability of dispersal is numerically only a fraction of that represen- ted by the totality of these zoospores, a coenozygote corresponds to a large number of true zygotes and has, by analogy, only a fraction of the probability, represented by the totality of true zygotes, to rest over unfavorable times and to reach a favorable substrate. Hence it is significant that in the coenozygotes, the formation of fructifications appears first in the fungi. In the highest Oomycetes, the coenozygotes remain enclosed in the sheath of the female gametangium whose wall undergoes much thickening, and in the higher Zygomycetes they are im- bedded in a sheath of closely intertwined hyphae, rich in reserve materials. 32 COMPARATIVE MORPHOLOGY OF FUNGI Retardation of development, similar to that in the gametangia before the gametes were individualized, may be recognized in the zygotes and coenozygotes; in them caryogamy is first postponed and then shifted in place. These tendencies will be discussed more in detail in the Ascomycetes. The life cycle of most forms resembles that of the simpler Chloro- phyceae: the thallus and the fructification is haploid and the diplont is limited to a zygote at whose germination meiosis probably occurs. The systematic classification of the Phycomycetes is based on the developmental forms of the haplont and the structure of the sexual cells. Three orders are generally distinguished, the Chytridiales, the Oomycetes and the Zygomycetes. In the Chytridiales, the thallus is unicellular and poorly developed; in the Oomycetes and Zygomycetes it consists of a highly developed, generally ramose, aseptate, coenocytic mycelium. The Oomycetes are heterogamous; the content of their female gametangia changes into one or more egg cells which are fertilized by sperms or undifferentiated sexual cells (oogamy). The Zygomycetes are isoga- mous; the contents of their gametangia is not further differentiated, but mixes with the content of a second morphologically equivalent gametan- gium (zygogamy). The Chytridiales and Oomycetes are generally aquatic, the Zygomycetes terrestrial. The question of their origin and mutual relationships will be discussed later under the individual orders CHAPTER VII CHYTRIDIALES In the present work, the Chytridiales, often called Chytridineae, include the Mycochytridineae; they are parasitic or saprophytic, usually in water, rarely on land. In the lowest forms, the thallus consists of one or more spherical cells, parasitic within the host. In the higher forms it is extramatrical and sends pseudopodia-like haustoria into the substrate ; in the highest forms it develops a tubular coenocytic mycelium which may be differentiated into a basal part serving for nourishment and an apical portion serving for reproduction. Zoosporangia and hypnospores are known. The lowest forms are holocarpic; i.e., the whole thallus forms a fructification. The higher forms are eucarpic; i.e., fructifications are formed from only a portion of the thallus. Both the zoosporangia and the hypnospores germinate by zoospores, which are generally uniflagellate, exceptionally aflagellate; their emission takes place through openings in the mother-cell wall or by emission collars. In the individual details of their formation and libera- tion, particularly in the varied manner of their accumulation at the mouth of the emission collar, important ontogenetic problems are still hidden. In some species, the formation of hypnospores is preceded by a sexual act, which occurs between two zoospores which behave as piano- gametes or between two plants or between two daughter cells of the same plant which have been transformed into gametangia. The systematic position of the Chytridiales has been controversial. By Bary (1884), Brefeld (1889), Zopf (1890) and Petersen (1910), they are regarded as derivatives of the higher Phycomycetes, particularly of the Zygomycetes, which as a result of their parasitic and aquatic habits, have undergone considerable degeneration. By Bessey (1903), they are connected with the Cladophoraceae in which they had degen- erated beyond the Valoniaceae and Botrydiaceae. By Fisch (1884), Dangeard (1889), A. Fischer (1892), Serbinov (1907), Atkinson (1909a), Cavers (1915) and Scherffel (1925), they are considered as primitive organisms which, because of the regular appearance of flagellate, often amoeboid, zoospores and simple forms of sexuality, may not be explained by degeneration. While this last conception is becoming generally accepted, it does not suggest where the roots of the Chytridiales may be sought. Fisch (1884), 33 34 COMPARATIVE MORPHOLOGY OF FUNGI Lagerheim (1893), Kusano (1912) and Griggs (1912) suggest a deriva- tion from algae, especially the Phyllobieae, by adaptation to parasitism. Lotsy (1907) and Vuillemin (1907) consider the biflagellate forms at least, are derived from the Isokonteae, while the uniflagellate forms were much simpler and not related to the former. Dangeard, A. Fischer, Cavers and Scherffel finally emphasize their relationship with the Proto- zoa, especially with the Monadineae (Pseudosporeae) e.g., Aphelidium and Aphelidiopsis. It is possible that the Chytridiales include entirely heterogeneous elements which appear to converge because of the leveling influences of aquatic and parasitic habits. CHYTRIDIALES HYPHOCHYTRIACEAE Macrochytrium CLADOCHYTRIACEAE. Urophlyctis Physoderma Nowakowskiella Cladochytriu'm Amoebochytrium RHIZIDIACEAE Chytridieae Chytridium Dangeardia Entophlycteae Pseudolpidiopsis? Diplophlyctis Rhizophideae Zygorhizidium? Rhizidiomyces Rhizophidium Phlvctidium Rhizidieae Polyphagus Sporophlyctis Rhizophlyctis Saccomyces Rhizidium Harpochytrieae Harpochytrium CHLOROPHYCEAE Diagram IV. CHYTRIDIALES 35 The present systematic classification of the Chytridiales is only provisional. At present a large number of very old, slightly related forms are known. As it would be inconvenient to divide them into monotypic families, they have been grouped into larger families but it must be remembered that only a few of them are natural. As only in Central Europe and Eastern United States have they been extensively collected, it is probable that many of the present gaps will be filled. The above diagram follows essentially that given for the Mycochy- tridineae (A. Fischer, 1892; Minden, 1915). According to the height of development of the thallus, the Chytridiales are divided into three fami- lies; the Rhizidiaceae, Hyphochytriaceae and the Cladochytriaceae. The Rhizidiaceae are holocarpic; their thallus consists of processes (rhizoids) without nuclei and therefore always dependent on the central body which develops into a sporangium. The rhizoids penetrate the substrate like haustoria: they correspond approximately to the pseudopodia of the Rhizopoda. The Hyphochytriaceae and Cladochytriaceae are eucarpic: their thallus is formed as a true mycelium which is divided into principal and secondary axes. The latter possess peculiar swellings with still unknown functions, the turbinate cells. Whether and how these three families are connected is still obscure. It is possible that the Entophlycteae, Chytrideae and Rhizidieae, may be derived from Rhizophidieae-like forms and perhaps the Clado- chytriaceae and Hyphochytriaceae from the Rhizidaceae. Opinion is also divided on their relation to the four families of the Archimycetes ; thus Minden (1915) considers it possible that the Rhizidiaceae may be derived from the Olpidiaceae, while Serbinov (1907) considers both families phylogenetically distinct. The Archimycetes seem to be foreign to true fungi and connected with the Myxomycetes and Protozoa. Gaumann would derive the Chytridiales from the Chlorophyceae and consider them as a phylogenetic starting point for the greater part of the fungi. In spite of these obscurities and in order to give a preliminary exposi- tion of the system of the Chytridiales on page 34, these three families have been juxtaposed on the basis of their morphological similarities. Obviously this scheme in no way corresponds to the natural phylogenetic relationships. Rhizidiaceae. — This family includes chiefly parasitic forms. There are two distinct lines of development; either a species limits itself to one host individual (monophagy) and by reduction of the extramatrical parts, penetrates far into the host, i.e., passes from ecto- to endoparasitism, or the extramatrical part of the thallus develops as much as possible and infects a large number of hosts (polyphagy) thus increasing the amount of available nourishment. These latter forms are ectoparasitic. Tran- sitional forms are shown between the Rhizophidieae and Entophlycteae, where some forms of the Rhizideae show tendencies to polyphagy. 36 COMPARATIVE MORPHOLOGY OF FUNGI In order to classify the various genera they have been divided into subfamilies of which five will be discussed here. The Rhizophideae include a series of forms whose sporangia and hypnospores arise directly from the stronger zoospores. After a swarm period zoospores cling fast to the substrate, surround themselves with a membrane and push a process into the substrate and themselves swell to sporangia. In Phlyctidium brevipes on Spirogyra in North America this process is still short and scarcely able to penetrate the wall of the host cell. The zoospores disappear through an emission papilla at the top; if after a certain time they have not found a suitable substrate, they may shed their membrane (Atkinson, 1909). Rhizophidium pollinis (Zopf, 1887) is easily found on Pinus pollen in stagnant water (Fig. 19a) and oospores of the Peronosporaceae (Melhus, 1914). In the interior of the pollen grain the germ tube branches to a small rhizoid fascicle. The sporangium discharges its zoospores through Fig. 19. — Rhizophidium pollinis. A, zoosporangium on a pollen grain; B, Hypnospores and zoosporangia. {After Zopf, 1887.) several sharply limited, punctate germ pores whose membranes dissolve at maturity. In Rhizidiomyces apophysatus (Zopf, 1885), parasitic on the oogonia of many Saprolegniae, the germ tube on the inside of the oogonial wall swells up to an apophysis, out of which the rhizoids pass (Fig. 20, 1). The significance of this subsporangial sac is not yet clear. Directly before zoospore formation, the sporangia form a long emission collar which swells up like a sac at the tip (Fig. 20, 2). Into this sac the zoospore initials pass singly as small bits of protoplasm and are then liberated by the solu- tion of the sac (Fig. 20, 3). Hypnospores are unknown. Zygorhizidium Willei (Loewenthal, 1905) corresponding in the type of sexuality to the Rhizideae and in the manner of opening its zoosporangia to the Chytrideae, is parasitic on Cylindrocystis Brebissonii of the Meso- taeniaceae in Norway. The structure of its thallus corresponds to that of Rhizidiomyces, although its zoospores are not liberated by an emission collar but by the dehiscence of a lid (Fig. 21, 5). CHYTRIDIALES 37 The formation of resting spores is preceded by a sexual act by which a small male plant sends out an extramatrical copulation tube to a neigh- boring, larger, similar female plant into which the nucleus and most of the male cytoplasm migrates (Fig. 21, 6 to 8). The female plant sur- ,.„FlG- 20-—Rhizidiomyces apophysatus. 1. Oogonium of Saprolegnia with sporangia in different stages of development. 2. Beginning germination. 3. Beginning differentiation of zoospores. ( X 360; after Zopf, 1885.) rounds itself with a firm membrane and becomes a hypnospore, whose method of germination is unknown. The Entophlycteae continue the tendency of the Rhizophideae, first formulated by Atkinson (1909a), to penetrate deeper into the host cell. In Diplophlyctis intestina, a hemiparasite on Nitella, the zoospores, after . FlG" 21-~zWorhizidiumWillei. 1. Zoospore. 2. Young individual. 3 to 5 Evacua- tion of zoosporangium. 6. Male individual and copulation process. 7. Female individual 8. Plasmogamy. (X 1,500; after Lowenthal, 1905.) they have been surrounded by a membrane, form a germ tube and an intramatrical sac, called a germsphere by Zopf (1885). In contrast to Rhizidiomyces, however, the zoospores transfer their whole content into this bladder, whereupon the original zoospore membrane dissolves and disappears (Fig. 22, 1). The germsphere puts out a rhizoid which swells to an apophysis at its point of exit. While the rhizoid elongates and branches, the germsphere swells to a sporangium which at maturity 38 COMPARATIVE MORPHOLOGY OF FUNGI pierces the host membrane by an emission collar and emits amoeboid zoospores. In winter this germsphere is transformed as a whole into a thick- walled hypnospore (Fig. 22, 2) which germinates in the spring with zoospores liberated through an emission collar. Thus in Diplophlyctis, the whole development is shifted one step further into the host cell than in Rhizidiomyces. Pseudolpidiopsis Schenkiana, parasitic on Zygne- maceae, is systematically placed differently by various authors. Lotsy (1907) and Minden (1915) have placed it in the Olpidiaceae, although the original author, Zopf (1885, p. 169) expressly stated that in contrast \ j, Fig. 22. — Diplophlyctis intestina. 1. Fresh point of infection. The zoospore mem- brane has disappeared by solution. The germ sac has formed a short rhizoid which is about to swell to an apophysis at its point of attachment. 2. Thick-walled hypnospore with apophysis. Pseudolpidiopsis Schenkiana. 3. Fresh infection. The zoospore membrane has already gelified and the germ sac is about to swell to form a zoosporangium. 4, 5. Germinating zoosporangia. 6. Copulation of a small male and large female. 7. Germi- nating hypnospore; the male is still recognizable as an empty sac. (1, 2 X 600; 3 to 7 X 200; after Zopf, 1885.) to the Olpidiaceae, no naked protoplast penetrates the host cell and, therefore, he classed it in the Ancylistaceae. Whether it belongs to the Ancylistaceae or Rhizidiaceae will depend mainly on the number of flagella and type of fertilization. If the zoospores are uniflagellate, as Fisch and Zopf state, they belong to the Rhizidiaceae. If they are biflagel- late and if fertilization is oogamous, as Scherffel (1925) states, they belong to the Ancylistaceae. The latter solution is also suggested by its similarity to dwarf specimens of Myzocytium. As soon as the zoospores reach the host, they surround themselves with a membrane and put forth a germ tube which swells to a germ sac within the host cell. This matures to a zoosporangium while the swarm CHYTRIDIALES 39 spore membrane and infection tube degenerate. Zoospores soon develop in the zoosporangia, remain for a short time lying before the opening of the emission collar, there undergo some amoeboid alterations in form and finally swim away (Fig. 22, 4 and 5). In a related species, P. Oedogo- niorum, the whole content of the zoosporangium may pass out of the emis- sion collar and be differentiated into individual zoospores. In the sexual plants, the germ sac is divided into a smaller male and a larger female sexual cell (Fig. 22, 6). The content of the male passes over into the female. This as a whole (?) becomes a hypnospore, thickens its wall, so that the male cell, as in Olpidiopsis, remains attached as an empty cell. Germination follows by zoospores which escape through the emission collar (Fig. 22, 7). Fig. 23. — Harpochytrium Hyalothecae. 1. Young parasite on Spirogyra filament. 2. Mature individual. 3. Swarming of zoospores and lateral growth of zoosporangium. 4. Empty zoosporangium showing the beginning of proliferation. (After Atkinson, 1903.) The Harpochytrieae, because of their unusual habitat and the peculiar proliferation of the zoosporangia, known elsewhere only in the Clado- chytriaceae, are unique in the Chytridiales. In Harpochytrium Hyalothecae, which is parasitic or saprophytic on numerous green algae (Atkinson, 1903; Dangeard, 1903), the germinating zoospore forms a small germ tube which swells to a hapteroid structure between the lamellae of the cell wall of the host or within the cell (Fig. 23, 2). Rhizoids are absent. The young thallus is uninucleate. Nuclear division begins later and the plant divides into a short stipe cell and a long sporangium which discharges the zoospores through an opening at the tip (Fig. 23, 3). After evacuation, the stipe cell grows into the empty sheath of the sporangium, and develops a new sporangium, repeating the process several times. Resting stages are unknown. 40 COMPARATIVE MORPHOLOGY OF FUNGI Related to it, or perhaps identical with it, is the somewhat larger H. Hedenii which is found on Zygnemaceae in North America, Europe, Patagonia and Thibet. This disconnected area suggests great age. The Chytridieae agree in structure and development with the Rhizo- phidieae, but their resting spores develop intramatrically, as in Dan- geardia mamillata (Schroder, 1898) on Pandorina morum and Chytridium olla on oogonia of Oedogonium. Their sporangia open by a flat lid covered with blunt spines. The method of formation of hypnospores is unknown; their germination takes place through the formation of a simple tube which ruptures the wall of the host and forms a sessile, covered sporangium. Fig. 24. — Entophlyctis Cienkowskianum. 1. Cell of Cladophora with a sporangiferous plant. 2. Empty zoosporangium. Saccomyces Dangeardi. 3. Four-lobed haustorium. 4. Cell of Euglena with germinating zoosporangia. 5. Hypnospore. (1,2 X 200; 3 to 5 X 280; after Zopf, 1885, and Serbinov, 1907.) Of all these tribes, the Rhizidieae are the highest in development both in thallus and in sexuality; in the monophagic forms, the zoospores have partially lost their importance as central sacs and are replaced by germ sacs which simultaneously serve as sporangia. The monophagic forms are closely connected to the Rhizophidieae and Entophlycteae. In Entophlyctis Cienkowskianum, parasitic or hemi- saprophytic on filaments of Cladophora, the zoospores, as in Diplo- phlyciis, put forth a germ tube which swells to a germ sac and takes up all the protoplasm of the zoospores. In exceptional cases, the zoospore sheath may be retained as a knob as is the rule in other species, e.g., R. bulligerum. The germ sac develops to a spherical or pyriform sporangium discharging its zoopores through an emission collar which often projects far out into the water (Fig. 24, 2). In some species aplanospores are occasionally formed (Zopf, 1885). At the beginning of the cold season, CHYTRIDIALES 41 the sporangial sac changes into a thick-walled hypnospore whose germination is not yet known. Because of the type of its germination, Saccomyces Da?igeardii (Serbi- nov, 1907), which in Russia is parasitic on resting Euglena, is assigned to the polyphagic genera. Its thallus consists of a slightly developed, pyriform, extramatrical portion, a strengthened swarmspore body and a much-branched intramatrical rhizoid tuft (Fig. 24, 3). At the formation of the zoospores, the content of the extramatrical part passes out into a pyriform sac where, inside the membrane, it breaks up into zoospores (Fig. 24, 4), which in turn are freed by degeneration of the sac wall. Hypnospores are formed asexually instead of sporangia. Fig. 25. — Sporophlyctis rostrata. 1. Infected filaments of Draparnaldia glomerata. 2. Young individual. 3. Mature individual. 4 to 6. Akinete formation. 7 to 9. Copu- lation. (X 400; after Serbinov, 1907.) In the following species an extramatrical development of the thallus becomes prominent, so that the single individuals simultaneously pene- trate several plants of gregarious hosts, as in Bhizophlyctis Braunii which is parasitic or saprophytic on diatoms and desmids. A similar species is Sporophlyctis rostrata (Serbinov, 1907) whose thallus is extramatrical except for the last fine filaments which penetrate the host cell (Fig. 25, 1). The saccate portion of the strengthened zoospore is originally uninucleate, but becomes multinucleate by repeated nuclear divisions. At maturity, the whole content passes out into a sac (Fig. 25, 4) and there breaks up into uninucleate, non-motile akinetes which are liberated by the rupture of the membrane (Fig. 25, 6). Copu- lation precedes the formation of hypnospores. Two individuals fuse, the content of the male passing over into the female (Fig. 25, 7 to 9). The wall of the hypnospore consists of two layers. Otherwise its development is unknown. 42 COMPARATIVE MORPHOLOGY OF FUNGI The highest stage of development is reached by Polyphagus Euglenae, parasitic on resting stages of Euglena (Nowakowski, 1876: Dangeard, 1900; Wager, 1913). Its zoospores are very large, 5 to 13 X 3 to 5/x Fig. 26. — Polyphagus Euglenae. 1. Swarming zoospores. 2, 3. Thallus with pseudo- podia. 4. Beginning copulation. 5. Young zygote, female nucleus about to enter copula- tion tube. (1 to 3 X 670, 4, 5 X 510; after Wager, 1913.) (Fig. 26, 1). After they have come to rest and surrounded themselves with a membrane, they form the first rhizoids in 1}^ to 2 hours. These grow rapidly and in 3 hours become 5 to 6 times the diameter of the CHYTRIDIALES 43 central sac which is the original strengthened zoospore. In this condi- tion, the plant looks like a young heliozoan (Fig. 26, 2). On the other hand, if the zoospore germinates in contact with a Eugle?ia, the sac is sessile and the plant looks like a Rhizidium or a Chytridium. Later the rhizoids branch greatly and can infect as many as 50 Euglenae. The mm fm m mmm m Fig. 27. — Polyphagus Euglenae. 1. Young zygote with both nuclei. The male nucleus is still the smaller. 2 to 7. Germination of zygote with a zoosporangium. 8. Empty zoosporangium. (X 670; after Wager, 1913.) thallus always remains unicellular and uninucleate, but in course of time its membrane becomes very firm. At maturity, on the central sac there appears a spherical outgrowth which increases at about 50/c per hour and develops into a sac about 275/* long. It takes up the whole contents of the mother cell from which it is abjointed. During the vegetative period the original zoospore nucleus has reached dimensions similar to those of Synchytrium; it divides repeatedly until several hundred daughter nuclei may be formed. The 44 COMPARATIVE MORPHOLOGY OF FUNGI chromosome number appears to be from 10 to 12. After cleavage, the uninucleate portions of protoplasm become zoospores liberated by degeneration of the tube. Polyphagias stands on the dividing line between holocarpism and eucarpism. Physiologically it is still holocarpic. With the formation of the sporangium the plant has spent its life. Morphologically it is already eucarpic, for no longer the whole but only its central portion becomes a sporangium. At the sudden appearance of unfavorable conditions the single indi- viduals may become encysted so that the central sac is surrounded by a thick membrane. At the return of favorable conditions, they germinate by a sporangium as above described. If the store of nourishment (fresh Euglenae) is exhausted, the plants change to gametangia instead of germinating with sporangia. The smaller, male individual forms a long thin process. On meeting a female cell, this process swells to a sac which thickens its wall echinulately and absorbs the whole content of the male plant. The wall between the female cell and this sac is dissolved and the content of the female cell is discharged into the sac (Fig. 26, 4 and 5). The smaller male and the somewhat larger female nuclei do not fuse but remain diametrically opposite at the periphery. The male nucleus gradually attains the size of the female. Meanwhile the zygote has been separated from the gametangia by two walls, it rounds off and becomes a hypnospore (Fig. 27, 1), while the remains of both plants degenerate. The whole process lasts at most 12 hours. After a few months the zygote germinates by a zoosporangium into which both sexual nuclei pass and fuse (Fig. 27, 2 and 3), whereupon, possibly, meiosis follows at once. The life cycle may be represented by the following scheme: I ± Thallus— +Zoosporangiurn — ^Zoospores / P C R Zoospores ^+ Tli all us >- + Coenoganiete Hypnospores— ^oosporangium ^ — Thallus >-— Coenogamcte Diagram V. Thus from one zoospore there arises a unicellular thallus which can form a zoosporangium or a gametangium, with copulation between unicellular coenogametes. In this scheme it is uncertain whether the zoospores throughout the whole period of vegetation may be considered as + and — in the sense of heterothallism, or whether they and their thalli, as assumed in this scheme, are indifferent throughout, with sexual differentiation only in the formation of individuals behaving as gametan- gia. In contrast to Olpidium Viciae (p. 18) the diplont is here reduced to the hypnospore. CHYTRIDIALES 45 Hyphochytriaceae. — In this family, only one form has been described in detail, Macrochytrium botrydioides (Minden, 1916), saprophytic on rotting fruits in water. The plants possess a short, almost cylindrical main axis which spreads out at the base in rhizoids, and ends apically with a blunt process. Below the tip, a branch from the main axis swells clavately and later pushes aside the tip. This is abjointed from the rest of the plant, and develops a sporangium (Fig. 28, 1). At its germination, a lid is sharply cut off at the top and the spore mass swells, still surrounded by a membrane (Fig. 28, 2). When the bulging mass has attained about half the size of the sporangium, the membrane ruptures, liberating the uniflagellate zoospores (Fig. 28, 3). Their motion may be amoeboid with the flagellum trailing behind (Fig. 28, 4). Minden considers this a 4 I- Fio. 28. — Macrochytrium botrydioides. 1. Plant with sporangium. 2, 3. Swarming of zoospores. 4. Amoeboid zoospores. (After Minden, 1916.) biological adaptation to their special mode of life, in that often they can reach a substrate covered with other organisms (e.g., bacteria). Cladochytriaceae. — This family includes a number of saprophytic or parasitic forms which possess an evanescent, very slender, filamentous mycelium with peculiar swellings called turbinate cells (Sammelzellen). As a result of this higher stage of development of their thallus they stand far above the other Chytridiales. Since sexual processes, however, have not been demonstrated with certainty, it is still impossible to determine their exact position. Amoebochytrium rhizidioides (Zopf, 1885), growing in the slime of Chaetophora, is transitional between the Rhizideae and this family. The zoospores are aflagellate but capable of amoeboid movement. After they have come to rest, they surround themselves with a membrane and mature to large ramose mycelia. After 36 hours, the hyphae produce peculiar intercalary swellings, rich in protoplasm, which are abjointed 46 COMPARATIVE MORPHOLOGY OF FUNGI and become flask-shaped sporangia. The marked thickening of their membrane continues beyond the sporangial neck, affects part of the original hyphae and forms a peculiar tube (Fig. 29, 2). The mycelium collapses very early, thereby liberating the sporangia which germinate by a dissolution of the septum in the neck. Hypnospores are unknown. Cladochytrium and N owakowskiella are somewhat more highly dif- ferentiated. In Cladochytrium the zoosporangia open by gelification of a papilla, in N owakoivskiella by a lid. Cladochytrium tenue (Nowakow- ski, 1876) is parasitic or saprophytic in the tissues of aquatic angio- sperms, as Acorus, Iris, Glyceria. The mycelium consists of filaments 1 to 2fi thick, which penetrate the infected part of the host intracellu- larly in all directions and swell up inside the host cells into turbinate Fig. 29. Fig. 30. Fig. 29. — Amocbochytrium rhizidioides. 1. Germ tubes from zoospores which were unable to swarm. Below to the left, two young turbinate cells. 2. Zoosporangium show- ing thickening of the walls. (After Zopf, 1885.) Fig. 30. — Cladochytrium tenue. 1. Mycelium from Iris pseudacorus with several turbinate cells which later form zoospores. 2. Germinating and empty zoosporangium. (1 X 400; 2 X 270; after Nowakowski, 1876.) cells (Fig. 30, 1). Each changes as a whole into a zoosporangium or is divided by a septum into two daughter cells one or both of which become zoosporangia. Their germination generally takes place through an emis- sion collar which opens into water or into a neighboring host cell and liberates the swarm cells jointed into a sphere. Under special conditions, the sporangia germinate with germ tubes instead of zoospores. N owakowskiella ramosa was found by Butler (1907) on decaying wheat stems in India. The mycelium lives both intra- and extramatri- cally and is unusually well developed for the Chytridiales (Fig. 31, 1). Eight to ten thick- walled hyphae arise from a basal piece; they branch CHYTRIDIALES 47 (so that the places of forking are markedly swollen) and anastomose frequently. The terminal or intercalary sporangia arise by swelling and cutting off hyphal portions; the adjacent hyphal portions swell like apophyses. At germination, a piece of the exospore is thrown off as a lid by the swelling endospore and the uniflagellate zoospores are liberated by a germ sac or singly. In case the sporangia germinate in the interior of a host cell, the wall of the latter is pierced by an emission collar. In addition to sporangia, hypnospores have also been observed. A certain hypha undergoes longitudinal and transverse divisions so that Fig. 31. — Nowakowskiella ramosa. 1. Mycelium showing numerous anastomoses and swellings which will later develop zoosporangia. Below to the left, an intercalary zoosporan- gium with bilateral apophyses. 2. Zoospores. 3. Proliferating zoosporangium, the lid is still visible in the old one. 4, 5. Primordium of hypnospores. ( X 608 ; after Butler, 1907.) the outer cells change to thick-walled spores (Fig. 31, 4 and 5). Their germination is still unknown and their morphological significance still obscure. Both Physoderma and Urophlyclis are marked by the high develop- ment of their hypnospores which in Physoderma are spherical or ellip- soidal, in Urophlyctis flattened on one side. The peculiarities of their structure and development have been little investigated, so that their systematic classification offers great difficulties. In numerous species only the hypnospores are known. In Physoderma macuLare {Cladochyirium Alismatis) on leaves and stems of Alisma sp. (Clinton, 1902), the zoospores are uniflagellate; 48 COMPARATIVE MORPHOLOGY OF FUNGI they come to rest on the young leaves, make a few amoeboid movements and put a short rhizoid into the epidermis. The zoospore body develops shortly into an irregularly indented sporangium, sessile as in Rhizo- phidium. At maturity its content breaks up into numerous zoospores. A part of the walls swells, bursts open and liberates the zoospores. Under favorable conditions, a new sporangium may grow five or six times from the rhizoid into the emptied sheath. In the formation of hypnospores the content of the zoospores pass over into the rhizoid, which swells up at its end into a small cell. When this is mature, a smaller basal cell is abjointed on the side next the empty SW3, f* Fig. 32. — Physoderma Zeae-maydis. 1. Hyphae with turbinate cells. 2. Mature zoosporangium discharging zoospores by the removal of a lid. 3. Mature zoospore. 4, Amoeboid zoospore. 5. Hyphae with young, binucleate hypnospores. (After Tisdale, 1919.) zoospore membrane. The larger, rich in oil droplets and reserves, is divided into two or more daughter cells; these develop to hyphae which penetrate to neighboring cells of the host and there form similar swellings. On these swellings resting sporangia are formed in a manner as yet unknown. In Physoderma Zeae-maydis which, in North America, causes a disease of maize and teosinte, the hypnospores are liberated as a brown powder in the spring by the rupture of the epidermis of rotting leaves. Their optimum of germination is very high, 26 to 28°. At germination a por- tion of the exospore is raised like a lid (Fig. 32, 2), the endospore bulges out, finally ruptures and liberates 20 to 50 uniflagellate zoospores. These swim about 1 to 2 hours, come to rest, form amoeboid processes (Fig. 32, 4), surround themselves with a membrane and put forth into the CHYTRIDIALES 49 interior of the host a slender hypha which later branches considerably. The mycelium remains very slender; in the host cells the hyphae swell to turbinate cells (Fig. 32, 1), two to four of which may be joined. Where they are present singly they are rounded up and surrounded by a thick Fig. 33. — Urophlyctis alfalfae. 1. Advanced stage of infec- tion of host tissue. 2. Section of an epidermal cell with the primary turbinate cells. 3. Older stage with secondary turbi- nate cells. 4. Section of a turbinate cell; the nuclei have just migrated from a sporogenous cell into a young hypnospore. 5. A turbinate cell with mature and immature hypnospores. (1 X 280; 2 to 4 X 580; 5 X 560; after Jones and Drechsler, 1920.) wall. In multicellular structures one cell seems to discharge its content into a neighboring cell, which then becomes binucleate (Fig. 32, 5) and forms hypnospores on a lateral process. Further details are still unknown. At maturity the mycelium is entirely disorganised and the hypnospores are left free in the host cell (Tisdale, 1919). In Urophlyctis alfalfae on young shoots of various species of Medicago, especially M. sativa (Jones and Drechsler, 1920), the germ tube of the zoospores penetrates an epidermal cell and swells to a multinucleate turbinate cell (Fig. 33, 2). Peripheral uninucleate cells are separated from the protoplasm periclinally. Each of these cells develop to a long narrow hypha which later swells terminally into a turbinate cell (Fig. 50 COMPARATIVE MORPHOLOGY OF FUNGI 33, 3) and goes through several nuclear divisions. These processes are repeated (Fig. 33, 1). At maturity the turbinate cells have a crown of filamentous structures which may be regarded as haustoria. The axis of this tuft swells to a sac (Fig. 33, 5) into which the contents of the turbi- nate cells migrate. There some of the nuclei enlarge markedly and per- haps degenerate. The sac also bears a crown of those peculiar growths; at maturity, its membrane thickens, the growths fall off, the sac becomes a hypnospore and the whole mycelium disintegrates. At germination, the content of the resting spores is divided into a variable number of sporangia (up to 15 or more) which are liberated by regular slits in the wall. There they form emission collars and liberate the uniflagellate zoospores (Scott, 1920). As related species may be mentioned U. pulposa on leaves and stems of Chenopodium sp., U. Trifolii on the epigaeous ports of Trifolium sp., U. Ruebsameni on the roots of Rumex scutatus, U. Potteri (Bartlett, 1926) on Lotus corniculatus and U. pluriannulatus (Jones and Drechsler, 1920) on Sanicula Menziesii. CHAPTER VIII OOMYCETES In the Oomycetes there appears, instead of the uninucleate and centrally organized thallus of the Chytridiales, a well-developed poly- energid mycelium with characteristic hyphae adapted to independent existence. This independence in some families (e.g., the Saproleg- niaceae) goes so far that hyphal fragments may grow to new individuals. Furthermore, under unfavorable conditions, smaller portions of hyphae can thicken their walls and become gemmae. In the lower aquatic forms, asexual reproduction occurs exclusively by zoosporangia with zoospores which may be uni- or biflagellate. In Ectrogella and Saprolegnia, the zoospores are diplanetic, and in some other genera can shed their membranes. Diplanetism is the separation of the swarm period into two morphologically different phases, always in the same sequence, separated from each other by a resting period, while at the shedding of the membrane both swarm phases appear morphologi- cally similar. In diplanetism, the zoospores in the first period may be terminally flagellate, in the second laterally. At the shedding of the membrane, e.g., of a laterally flagellate zoospore, however, the naked protoplasm assumes its previous form, moves out of the membrane and begins a swarm stage (Fig. 39, 3 to 5). Even in these aquatic forms, at different parts of the system and independent of each other, e.g., Ancylistes, Aplanes, Araiospora and Pythium, there is a tendency to allow the zoosporangia to germinate with coenocytic germ tubes intead of with zoospores. As tube ger- mination, in contrast to zoospore germination, can occur in damp air, some of these forms were able to migrate to dry land, where they developed as parasites on phanerogams. Since the highest of these forms have lost their ability to form zoospores, the coenocytic zoosporangia develop directly to coenocytic mycelia. W* Along with the decline of differentiation of the sporangial content and the discharge of the unaltered protoplasm into a germ tube, there is a proportional increase in external differentiation of the sporangia themselves. In the lower forms, they are always connected with_ the^ sporiferous hyphae and morphologically almost indistinguishable frDm them, while in the higher forms, they are separated from the hyphae before spore formation, and either fall off and are independently dis- seminated, or become spores and conidia. 51 52 COMPARATIVE MORPHOLOGY OF FUNGI This process of transformation extends also to the sporiferous hyphae. Just as the sporangia lose their sporangial nature and become conidia, the sporiferous hyphae lose their hyphal character and become specialized conidiophores, with limited function. Parallel with this development goes a shifting of the relative values for classification, e.g., in the aquatic forms, as the Saprolegniaceae, the structure of the sporiferous hyphae plays no or only a subordinate part, while in the Peronosporaceae, the form of the conidiophores becomes an important systematic character. The gametangia are developed as antheridia and oogonia. In the lower forms they arise beside and between the sporangia, and thus show their homology with them. In the Saprolegniaceous Thraustotheca clavata, they change to sporangia if they find no mate (Weston, 1918). In the higher forms they are specialized exclusively as sexual organs; in some genera, the oogonia may develop parthenogenetically in the absence of antheridia. In internal differentiation, there are active morphogenetic forces like those in the zoosporangia. Just as in the latter, the individualization of the uninucleate zoospores is eventually suppressed and the whole content is discharged into a germ tube, so also in the gametangia, after a certain stage, a differentiation into uninucleate male and female gametes is suppressed. The oogonia and antheridia remain coenocytic, the latter germinating with a germ tube instead of with sperms. In the female gametangia, degeneration goes still further; in them a decreasing number of gamete nuclei are admitted for fertilization while the rest degenerate. Around the privileged, sexual nuclei, the protoplasm collects (and this is a specifically new structure for the Oomycetes, giving the group its name) to egg cells (oospheres), to which one or more male cells are attracted and joined by a copulation tube. The fertilized eggs develop to resting spores (oospores). At germination these change into zoospor- angia or germinate with germ tubes. As in Olpidium in the Archimycetes and in Pohjphagus in the Chytri- diales, caryogamy does not coincide with plasmogamy, but occurs only at the germination of the zygote, sometimes months after plasmogamy has occurred. Between plasmogamy and caryogamy is inserted a dicaryophase which physiologically is equivalent to the diplophase, but carries the possibility of entirely new developments. We will meet it again in the Zygomycetes. The classification rests next upon the structure of the zoospores; the uniflagellate and the biflagellate groups are usually treated separately. In the uniflagellate group two families may be distinguished, the Mono- blepharidaceae, with hyphae smooth and undifferentiated, and the Blastocladiaceae with constrictions and partial differentiation into main axis and secondary shoots. Furthermore, the Monoblepharidaceae OOMYCETES 53 have fertilization by sperms, while in the Blastocladiaceae the sexual organs are still unknown. In the biflagellate forms, there are three families: the Ancylistaceae, the Saprolegniaceae and the Peronosporaceae. The Ancylistaceae are OOMYCETES PEROXOSPORAOEAE Albugineae Albugo I Peronosporeae j Peronospora I Bremia i Plasmopara ! Sclerospora j Basidiophora Pythieae Phytophthora Pythium Pythiomorpha Pythiogeton SAPROLEGNIACEAE Aplanes Pythiopsis Thraustotheca Dictyuchus Achlya Isoachlva /. * Saprolegnia LEPTOMITEAE Ara iospora Rhipidium Leptomitus Apodachlya ANCYLISTACEAE Ertrogella Myzocytium Lagenidiuni Anevlistes BLASTOCLADIACEAE Jaraia? Allomyces Blastocladia Gonapodya MOXOBLEPHARIDACEAE Monoblepharis Diblepharis Myrioblepharis t CHLOROPHYCEAE Diagram VI. aquatic and parasitic on lower plants and animals, their thallus is reduced and limited to the formation of the reproductive organs. At least in Ancylistes the contents of the oogonium changes into a single egg cell. 54 COMPARATIVE MORPHOLOGY OF FUNGI The Saprolegniaceae are also aquatic but are generally saprophytic on animal and plant remains; their thallus is well developed. The oogonial contents collect at the wall, surrounding a large central vacuole, and split into several egg cells. The Peronosporaceae are endoparasitic in land plants. No central vacuole is formed in their oogonia, whose contents are differentiated into a vegetative periplasm and a gonoplasm which forms the single egg. The morphological relationships between these six families are represented on p. 53. Several parallel developmental series have been distinguished, where Gonapodya, Leptomitus, Apodachlya, Pythiopsis and Achlya take approximately the same level. On account of the slight differentiation of their oogonia and their diplanetism, the Saproleg- niaceae stand at the bottom of the biflagellate series. The Leptomita- ceae show great similarities to the Blastocladiaceae. This may be only a convergence phenomenon, as both groups live in stagnant water on decaying objects where other Oomycetes do not appear. Apparently the Peronosporaceae have arisen from Saprolegnioid forms; the organiza- tion, however, of the sporangia of the present known genera (as the simpler Pythieae) is lower than that of the modern Saprolegniaceae; on the other hand, the Pythieae, in their zoosporangial germination, still bear traces of earlier diplanetism and roughly correspond with Achlya. In this respect they are above Saprolegnia. The Ancylistaceae are connected to the Pythieae; both are partially endosparaltic and similar in their habits (Atkinson, 1909a). As regards their sexual organs, the Ancylistaceae would be better connected to the present Saprolegnia, and below the lowest Pythieae, as their oogonia are more primitive than those of other biflagellate Oomycetes. A short discussion of the mutual phylogenetic relationships of the Oomycetes, especially the derivation from the green algae, indicated in the scheme on page 53, will be deferred to the close of the order in con- nection with the Peronosporaceae. Monoblepharidaceae. — This family occupies a special position in the fungi, because of the motility of its zygotes, elsewhere known only in Olpidium, and because of fertilization by motile sperms. Monoblepharis is best known. It is found in Europe and North America on fallen twigs in water, especially in spring and fall. The zoospores formed in the spring germinate the following fall, and on twigs which have lain in water all summer, develop a new vegetation whose oospores then winter over and develop further the next spring. In summer they seem suppressed by algae. The thallus consists of rhizoids which penetrate the substrate, and of multinucleate, little-branched, extramatrical hyphae, only distinguishable from the otherwise similar but thicker hyphae of Saprolegnia by their faveolate protoplasm. At the beginning of unfavorable growth condi- OOMYCETES 55 tions, M. brachyandra forms moniliform gemmae with thick, brownish walls. Reproduction takes place by zoospores and oogonia with antheri- dia (Thaxter, 1895; Lagerheim, 1899; Woronin, 1904; Laibach, 1926). The zoospores develop as follows: In the upper, often somewhat thickened part of a hypha, protoplasm with numerous nuclei collects, and is abjointed from the vacuolate portion. By its cleavage, there are formed one or two series of uninucleate zoospore initials which become zoospores in an unknown manner and swarm through an opening at the tip of the sporangium (Fig. 34, a). After some time they come to rest, surround themselves with a membrane and germinate. Subsequently many lateral sporangia may grow out behind each other, so that generally Fig. 34. — Monoblepharis macrandra. a, Zoosporangium ; M. sphaerica. b to e, Fertilization; Og, oogonia; An, antheridia producing sperms; S, oospores. (After Woronin, 1904.) only a portion of the hyphae participates in sporangial formation; thus sporangial conditions result which give the impression of sympodial branching. In other cases proliferation occurs, i.e., a new sporangium arises beneath an old one and grows through its empty membrane. The antheridia are epigynous in Monoblepharis insignis, and M. brachyandra, hypogynous in M. spherica and M. macrandra (Fig. 34, 6). In the first, the antheridium, like a zoosporangium, is cut off as a terminal cell. The hypha below the septum forms a lateral outgrowth, the neck of the oogonium, and the oogonium itself is abjointed from the rest of the hypha. Thus the antheridium is borne on the oogonium. A new lateral outgrowth develops beneath the oogonium; its tip is separated as an antheridium while the remainder swells to an oogonium and is 56 COMPARATIVE MORPHOLOGY OF FUNGI abjointed from the sporiferous hypha. This process may be repeated as many as eight times, producing a chain of oogonia, each one of which bears a small antheridium. Sometimes the latter are not formed. In the hypogynous forms, the life cycle is essentially the same, except that the positions of antheridium and oogonium are reversed. In the antheridia as many as 32 sperms, corresponding to the nuclear number, are formed. They resemble zoospores but are only half as large. They swarm through an opening at the tip (Fig. 34, b and c). The processes which occur during the development and ripening of the oogonium are not well known. The oogonia are always uninucleate; their protoplasm forms an oosphere. Occasionally they mature later than the antheridia, e.g., M. brachyandra is protandrous; consequently self-fertilization is rare, although this species is not self-sterile. The tip of the mature oogonium, which in some species is drawn out into a papilla, gelifies. In M. insignis it opens intermittently, permitting part of the substance to escape. The sperms flock together, probably by chemotropism, and by amoeboid motion creep down the neck (Fig. 34, c). One of them fuses with the oosphere (plasmogamy). The zeugite then remains at rest. In some exogynous species as M. brachy- andra and M . sphaerica it moves, with revolution and amoeboid alterations of form, to the bottom of the oogonium, and thence again toward the tip whence it escapes (Fig. 34, d and e). Possibly this motility was caused by the male flagellum being thrown off rather late. Near the opening, it goes through a few amoeboid motions, becomes spherical, surrounds itself with a membrane which gradually thickens and becomes verrucose. In M. macrandra it leaves the oogonium entirely by its own motion and matures elsewhere. In the endogenous species, e.g., M. insignis, the oosphere remains in the oogonium and is there changed to a hypnospore. Caryogamy takes place comparatively late after the oosphere has left the oogonium, during the formation of the warts. After a rest of several months, germination with meiosis (?) occurs through a germ tube which perhaps develops to a zoosporangium. If the oosphere is not fertilized, it is surrounded in the oogonium by a membrane and develops parthenogenetically to a hypnospore. Conversely sperm fertilization admits the possibility of cross fertilization; thus Woronin considers M. macrandra, var. longicollis, a hybrid between M. poly- morpha and M . spherica. Two other genera which have been important in the discussion of the significance of the flagella for classification, Diblepharis with biflagellate zoospores, and Myrioblepharis with multiflagellate zoospores, should be considered in this family. In fitting the facts to the classification, Woronin (1904) suggests the possibility that the biflagellate zoospores belong to a parasite which has penetrated; in the second, Minden (1915) suggests a mixture of Pythium and protozoa. OOMYCETES 57 FlG 35.-Gonapodya siliquiformis. 1. Hyphae with proliferating zoosporangia. Allomyces arbuscula. 2. Plants with rhizoids, zoosporangia and some . hyP^Pore^ 3. Hypnospores. 4. Chain of mature zoosporangia which have formed germ Papi"^- Blastocladia Pringsheimii. 5. Plant, bearing sporangia and hypnospores. 6. Detail showing hair formation. (After Minden, 1916; Butler, 1911.) 58 COMPARATIVE MORPHOLOGY OF FUNGI Blastocladiaceae. — In the differentiation of the thallus into principal and secondary axes, this family is reminiscent of the Leptomitaceae, from which it differs by its typical uniflagellate zoospores. As sexual organs are unknown, its systematic position and classification are still obscure. In Gonapodya siliquiformis and G. polymorpha, on fruit and twigs lying in water, the mycelium is differentiated into principal and secondary axes (often indefinitely); the individual hyphae are divided by slight constrictions into more or less easily visible segments (Fig. 35, 1). The sporangia are terminal and ovoid and renew by proliferation. They open by an apical pore through which the zoospores pass out singly and swarm or creep away. The systematic position of this genus is doubtful, as zoospores of varied size and flagellar number have been reported in G. polymorpha. The other genera, also saprophytic and aquatic, are characterized by the differentiation of its thallus into a highly developed basal cell attached to the substrate by rhizoids and into true hyphae growing from the basal cell and generally ending in sporangia (Fig. 35, 2). The basal cell corresponds essentially to the turbinate cells of the Cladochytriaceae ; it arises from the body of a germinating zoospore while its germ tube develops to a rhizoid system. The sporangia are mostly solitary and terminal, in Allomyces also occasionally moniliform. Their content is split directly into single zoospore initials as in Monoblepharis, i.e., without the formation of a large central vacuole. Germination of most species takes place slowly in the form of a sac out of which the zoospores swarm. They generally creep around like amoebae. The number of their flagella varies from one to three, but in typical cases is one. In Allomyces arbuscula (Blastocladia strangulata) the zoosporangial branches still have constrictions as in Gonapodya (Butler, 1911; Barrett, 1912; Kanouse, 1927). In these constrictions several broad trabeculae, which permit a free circulation of cytoplasm are formed centripetally from the wall, chiefly in age and upon damage to the hyphae fuse into a false septum. The sporangia are ovoid with several emission collars. In forma dichotoma (Septocladia dichotoma) the constrictions are absent (Coker and Grant, 1922; Kanouse, 1927). In Mindeniella spinospora (Kanouse, 1927) the sporangia and oogonia are pedicellate and the oogonial walls echinulate. In Blastocladia, the false septa of trabeculae are absent and the sporan- gia are cylindrical with one emission collar. In B. prolifera, the sporangia proliferate as in Saprolegnia. The basal cell in B. ramosa, B. gracilis and B. tenuis is cylindrical and dichotomously branched, in B. globosa is subspherical, in B. rostrata B. Pringsheimii and B. prolifera is variously branched. In B. globosa, antheridial branches have been reported by Kanouse (1927) but the process of fertilization was not observed. Since OOMYCETES 59 these branches are rare, she suggests that the oospores probably develop parthenogenetically. In addition to the sporangia, characteristic hypnospores, which fall off at maturity and leave scars on the sporangiophores, have been observed, e.g., in B. Pringsheimii (Fig. 35, 5). In Allomyces arbuscula these hypnospores arise inside the terminal segment (Fig. 35, 3). Their morphological significance is still puzzling. Butler (1911) regards them as parthenogenetically developed oospores which find their analogues in the endogenous species of Monoblepharis. Finally the only parasite in this group, Jaraia Salicis (Nemec, 1911), on root tips of Salix purpurea in Czechoslovakia, lacks differentiation into primary and secondary shoots, and segmentation of the sporiferous hyphae. It possesses antheridia and oogonia; in the latter there arise as many as 50 rather thin-walled zoospores. Further investigation would give interesting results. Ancylistaceae. — At present only aquatic forms on pollen grains, algae and animals are known. Because of their simple thallus and holo- carpy, some authors place them in the Chytridiales; however, since they form oospores, they undoubtedly belong to the Oomycetes. Here also relationships are obscure, particularly because the exact processes before and after fertilization are insufficiently known. They are con- sidered by A. Fischer (1882), Schroeter and Scherffel (1925) as ascending forms which lead from the Archimycetes and Chytridiales to the Oomy- cetes. Scherffel bases this conception on his observations concerning the diplanetism of Ectrogella, which he connects directly to the shedding of the membrane as described for Phlyctidium (p. 36). It is a question whether Ectrogella forms true oospores or whether it does not rather behave as Zygorhizium, Pseudolpidiopsis, etc. (empty appendiculate cells in E. Licmophorae!). Further, their zoospores are not reniform with a true lateral insertion of flagella, as in the true Ancylistaceae, but pyriform with more or less terminal flagella. Hence it is quite possible that Ectrogella does not belong to the Oomycetes and, in spite of its two flagella, should be classified with the Chytridiales. In this case, the main support for deriving the Ancylistales from the Chytridiales would be removed ; also Ectrogella would take a more significant position in the Chytridiales as it would explain the peculiar collecting of zoospores at the mouth of the emission collar. Bary and Tavel, on the other hand, regard the Ancylistaceae as simple or simplified Pythiaceae. This conception appears nearer the truth, as in the better-known genera, with the exception of Ectrogella, the zoospores possess laterally inserted flagella. I prefer not to regard them an ascending line, as one cannot imagine how the less complex soil saprophytes, like the Aphragmium group of Pythium, have arisen from such parasites as Ancylistes and Myzocytium; but I prefer to consider 60 COMPARATIVE MORPHOLOGY OF FUNGI them a line gradually degenerated as a result of submersed parasitism. Hence the individual genera are considered in a series, descending in respect to zoospore germination: first Myzocytium, in which zoospore initials still arise within the sporangium, pass out as such into the germ sac and there develop their flagella; then Lagenidium, in which the proto- plasm partly flows out in a continuous stream through the emission collar into the germ sac, and only there differentiates into the individual spore portions; and finally Ancylistes where there is no differentiation of zoospores and the emission collar, as the infection tube seizes new hosts. These true Ancylistaceae are placed before Ectrogella. The better-known species of Ecirogella parasitize algae. The commonest species, E. Bacillariacearum on diatoms, chiefly on Synedra, is psychrophilic and occurs chiefly in spring and late fall. When a zoospore reaches a host, it surrounds itself with a wall, and forces its germ tube into a raphe. The thallus in time increases much in volume and forces the valves of the diatom apart. The protoplasm of the whole mature thallus collects at the wall (as in Olpidiopsis and the Saprolegnia- ceae) and splits into zoospores which are liberated by a short, papilliform emission collar. The zoospores have two short flagella of equal length inserted in a lateral depression below the tip ; thus they are isocont. After a short, not very intensive swarm stage, they come to rest and surround themselves with a wall. Later, in the form of secondary zoospores, they again slip out of this wall which they leave behind as an empty sheath. Thereafter they possess a long and a short flagellum (and thus are heter- cont) and are very actively motile. In other species, as in E. monostoma and E. Licmophorae, the first swarm stage is considerably shortened. The primary zoospores collect before the emission collar into a moriform group, shed their membranes and swim away as secondary zoospores. Unfortunately these relation- ships cannot be given diagrammatically in this book, as the work of Scherffel only appeared after the figures were finished. One can picture them approximately, however, if one imagines in Fig. 36, 9, a group of empty zoospore membranes before the emission collar, as shown for Achlya racemosa (Fig. 39, 1). E. monostoma and E. Licmophorae are thus related to E. Bacillariacea- rum, as in the Saprolegniaceae Achlya is to Saprolegnia. In E. Bacil- lariacearum, the shedding of the membrane of the primary zoospores occurs as in Saprotegnia, far from the zoosporangium; in E. monostoma and E. Licmophorae, as in Achlya, directly before its opening. This parallelism to the Saprolegniae goes farther in Ectrogella for in E. Dickso?iii {Eurychasma Dicksonii, Rhizophidium Dicksonii), the shedding of zoospore walls may take place in the interior of the zoospo- rangium, thus leaving the empty walls inside the zoosporangium, as in the net sporangium of Dictyuchus. OOMYCETES 61 Unfortunately in the aquatic Chytridiales, no studies of this sort have been carefully conducted, but the conjecture of Scherffel, that an entirely new point of view will be found, seems to be entirely justified. In Myzocytium proliferum on Zygnemaceae and M . vermicolum on anguillules (Zopf, 1885; Dangeard, 1906), the zoospores are slightly reniform and possess two lateral flagella. During their swarm period they undergo amoeboid alterations of form. They then come to rest, Fig. 36. — Myzocytium vermicolum. 1. Worm with two specimens of parasite. 2. Cell filament with two antheridia in the middle and an oogonium at each end. 3, 4. Antheridia and oogonia. 5 to 8. Development of oospores. 9. Individual oospore in worm. {After Dangeard, 1906.) surround themselves with membrane, force a germ tube into the host cell and there mature to a thick, cellular multinucleate mycelium. At the beginning of the formation of the fructification, the whole mycelium is divided by septa into multinucleate members, each of which becomes a zoosporangium (Fig. 36, 1). The protoplasm collects at the walls and splits into uninucleate zoospore initials which pass singly out through an emission collar and assemble at its mouth in a sac. Soon the flagella are visible, the sac bursts, and the zoospores swarm. Zoospores which 62 COMPARATIVE MORPHOLOGY OF FUNGI do not find an exit and remain in the zoosporangium may germinate there and pierce the walls. At the appearance of unfavorable conditions, antheridia and oogonia are formed in some segments instead of sporangia (Fig. 36, 2 to 4). The antheridium remains cylindrical and contains few, often only two, nuclei. The oogonia swell and become barrel shaped; usually there are about eight nuclei. At maturity all female nuclei except one degenerate; it is still uncertain whether this lies in a special oosphere. A neighbor- ing antheridium, generally of the same, rarely of another plant, forces a copulation tube through the wall of the oogonium, into which a single nucleus migrates and soon fuses with the female nucleus. An oospore Fig. 37. — Ancylistes Closterii. 1. Closterium with parasite. 2, 3. Fertilization. Mature zoospores. (After Dangeard, 1906.) with a double wall develops and probably germinates by zoospores which escape through the neck. Lagenidium Rabenhorslii (Zopf, 1885), causing an epidemic on the mats of Spirogyra, Mesocarpus, etc., and L. pygmaeum (Zopf, 1888) on Pinus pollen in water, agree essentially with Myzocytium, except that their mycelium is lobulate. The sporangia discharge undifferentiated protoplasm into a germ sac formed at the mouth of the emission collar. The sac begins to rotate, bursts and liberates the biflagellate zoospores. Occasionally in L. americanum there is no differentiation into zoospores, but the naked protoplasm swims away with many flagella (Atkinson, 1909). In Ancylistes Closterii on Closterium, the emission collar develops to a regular hypha into which the sporangia discharge their whole content. From time to time they are abjointed in the rear from the OOMYCETES 63 empty part. Thus the formation of zoospores is entirely suppressed and the undifferentiated sporangium germinates by a mycelial filament. Wherever this comes in contact with a Closterium it pierces the wall and grows into the interior. A. Closterii is generally dioecious. As in Myzo- cytium, there are few nuclei in the antheridium but many in the oogonium. They divide in the mature sexual organs. Then the antheridia form copulation tubes (Fig. 37, 2 and 3) through which the whole content migrates into the oogonium. The details of development and the germination of the oospores are not yet known, it is particularly uncertain whether nuclear fusion occurs between all nuclei or, as in Myzocytium, between privileged nuclei. § • >, A': ■ . Fig. 38. — Saprolegnia. Development of zoospores. A, Young zoosporangium whose peripheral protoplasm has a large number of nuclei; B, (section) uninucleate spore initials are formed in the peripheral layer by radial cleavage; C, D, spore initials contract, separate and round up. (After Davis, 1903.) Saprolegniaceae. — This family is mostly saprophytic, rarely parasitic on plant and animal substrates in water and soil. The mycelium is tubular, generally differentiated into slender, ramose, intramatrical hyphae and into thick, less-branched extramatrical hyphae, up to 200/j in diameter. The vacuolate protoplasm lies next the wall. Under favorable conditions, the resting hyphae change to gemmae. The hyphal tip swells to a short clavate organ stored with protoplasm, is abjointed, rounds off and thickens its wall. This process is repeated basipetally, so that a moniliform chain results. When the extramatrical hyphae have attained a certain age, their ends become clavate or spherical, filled with thick protoplasm and numerous nuclei, and are abjointed as zoosporangia (Rothert, 1892). The peripheral protoplasm splits without further nuclear division into 64 COMPARATIVE MORPHOLOGY OF FUNGI uninucleate portions (Fig. 38 A and B); these round off, acquire two flagella and swarm (Trow, 1899; Davis, 1903). In many forms (as in many species of Saprolegnia and Leptolegnia) the adjacent portion of the hypha penetrates the empty sporangium and there swells up or, if it has grown through the sporangium, it forms a second sporangium at its tip. This may be repeated several times. In other genera, as in Achlya, Aphano?nyces and Pythiopsis, the sporangia are renewed by lateral out- growth of a portion of the hypha next the empty sporangium. There, too, the process may be repeated, forming sympodially divided, verticillately or spirally arranged sporangia. In still other forms as Saprolegnia torulosa, and some species of Pythiopsis and Dictyuchus, the sporangia may be intercalary, catenulate or occasionally intermingled with oogonia. The behavior of swarming zoospores is very different in different genera. In Saprolegnia, they are ovoid (Fig. 4, s2) with two nagella at the pointed ends. After a time they come to rest and surround them- selves with a cellulose wall. They do not put forth a germ tube, but their naked protoplasm slips out of the wall as a reniform swarm spore with two nagella in a lateral indentation. The empty sheath degener- ates. Generally the second swarm stage lasts longer than the first. When it ends, the zoospores are again surrounded by a wall and develop to a mycelium. » This diplanetic basic form of the Saprolegnia type has been modified in the various genera by a suppression of one or both swarm stages. In Pythiopsis, the second swarm stage has disappeared, its zoospores come to rest immediately after the stage with two apical nagella and germinate with a hypha. In the Achlya-Thraustotheca series, as in the Ectrogella Bacillariacearum and E. Dicksonii series, the first stage is gradually suppressed. In Achlya (Fig. 39, 1), Plectospira (Drechsler, 1927) and Aphanomyces, the generally aflagellate zoospore initials (in some species they still seem to possess two terminal flagella) form a small cluster in front of the sporangial opening, shed their walls and swarm as reniform zoospores with lateral flagella, leaving the group of empty sheaths before the opening of the sporangium. In Dictyuchus, the zoospore initials no longer come out but surround themselves, while still in the sporangium, by a membrane out of which the spores swarm singly through an opening in the sporangial wall. The empty spore membranes remaining behind in the sporangium thus form a delicate, transient, net sporangium. In Thraustotheca, the zoospores, surrounded by a mem- brane, are liberated through a rupture in the sporangial wall or by its destruction (Fig. 39, 6). There, according to circumstances, they germinate with a laterally flagellate zoospore, a mycelium or a sporangium. In other forms, reduction has also affected the second swarm stage; thus in Achlya aplanes (Maurizio, 1894) the zoospore initials come out OOMYCETES 65 -piQ, 39. — Saprolegnieae. Degeneration of diplanetic zoospores. 1. Achlya racemosa. Sporangiferous hyphae. Both upper sporangia are empty while the lower contains zoo- spores already surrounded by a membrane (Reticulate sporangium). 2. Dictyuchus mono- sporus. Two superimposed zoosporangia, with reticulate structure, the upper empty, the lower just mature. 3. Exit of zoospore from zoosporangium. 4. Zoospore surrounded by membrane. 5. Resting zoospore has just slipped out of membrane. 6. T hraustotheca clavata. Liberation of sporangiospore balls. 7. Exit of zoospore from sporangiospore. 8. Aplanes Braunii. Sporangium with internally germinating zoospores. 9. Germination of zoospores before zoosporangium, 10 hours after their exit. (1 X 55, 2 X 370; 3 to 7 X 930; 8 X 33; 9 X 280; after Pringsheim, Weston, Bary and Maurizio.) 66 COMPARATIVE MORPHOLOGY OF FUNGI before the sporangial opening and are there surrounded by a membrane. No shedding of the membrane follows, and the resting zoospores germi- nate directly to a mycelium (Fig. 39, 9). This emission of naked proto- plasmic portions is reminiscent of diplanetism; but this character too disappears. In Aplanes the zoospore initials, while still in the spo- rangium, surround themselves with a wall and germinate there, piercing the sporangial wall with their germ tubes (Fig. 39, 8). In Geolegnia, the zoospore initials surround themselves with a thick wall and await the decay of the sporangial wall before germinating directly to mycelium (Harvey, 1925). Thus zoospore formation is entirely suppressed. It is noteworthy that these degenerate, functionless sporangia only appear occasionally in the mats; they are replaced by sexual reproduction. Thus Aplanes and Geolegnia seem to be on the point of entirely giving up degenerate asexual reproduction in favor of sexual. The sexual organs are developed (as in the Ancylistaceae) as anther- idia and oogonia. In Saprolegnia mixta (Klebs, 1889) and Achlya radiosa (A. decorata) (Obel, 1910), their formation may be hastened by lowering the concentration of the medium or by lack of phosphates. Couch (1926) reports Dictyuchus is heterothallic, physiologically differ entiated strains being necessary to secure production of antheridia and oogonia. The oogonia generally arise terminally on short branches of the main hypha, more seldom intercalary or incased in empty sporangia. Their wall is generally thicker than that of the vegetative hyphae, colorless or yellowish, smooth or covered with stellate projections. The antheridia develop on branches which are more slender and branched than the oogoniophores. If the antheridiophores arise on the same hyphae as the oogonia which they fertilize, the form is called andro- gynous, if they arise on other hyphae, they are called diclinous. Whether androgyny and diclinism correspond to true heterothallism still remains to be investigated. Homothallism has been definitely proved only for the androgynous S. monoica (Kniep, 1919). In certain species, the antheridia arise directly under the oogonia and on the same hypha (hypogyny). In still other species, they are entirely lacking or no longer functional, and the oospores develop parthenogenetically. Klebs (1899) and Kauffman (1908) determined that the forms of development may be entirely influenced by the chemical character of the nutrient solution; thus S. hypogyna, which normally forms hypogynous antheridia, may form them on branches in certain nutrient solutions. Dangeard (1891) and Claussen (1908) studied the ontogeny of S. monoica and Davis (1903) the oogonia of S. mixta. The antheridia and oogonia take large masses of nuclei from the hyphae and then are abjointed from the remaining part, the stipe. Before the septum is com- pleted, the cytoplasm and nuclei degenerate in the oogonium, progres- sively from the center toward the periphery. This process continues OOMYCETES 67 until only a thin protoplasmic wall layer with few nuclei remains (Fig. 40, A). The nuclei then undergo simultaneously a single mitotic division and degenerate; finally the protoplasm splits, rolls up around each of the remaining nuclei and forms uninucleate eggs, oospheres (Fig. 40, D). At first the egg nucleus shows a rostrate process with a definite centrosome. <^d Fig. 40. — Saprolegnia monoica. Egg development. A, young oogonium with periph- eral protoplasm; B to D, sections of the peripheral layer in different stages of develop- ment; c, normal nucleus with centrosomes; d, degenerating nuclei. (After Claussen, 1908.) Meanwhile the antheridium has approached the oogonium and partially surrounded it. About simultaneously with that of the oogo- nium, the nuclei divide once. Hereupon the antheridia pierce the oogonial membrane through pits. Within the oogonium the process divides, into several branches, each of which approaches an egg cell and discharges a nucleus into it. Nuclear fusion follows immediately. The fertilized egg surrounds itself with a two-layered, smooth, colorless membrane: it becomes an oospore with the character of a hypnospore. 68 COMPARATIVE MORPHOLOGY OF FUNGI In contrast to the Ancylistaceae, a new structure has arisen, especially in the female gametangium. Its content is no longer changed into a single multinucleate egg, but, as in the primitive gametangium, it is split into uninucleate daughter cells, here called oospheres. These may not be considered homologous to true female gametes, however, for their nuclei only represent the remaining privileged sexual nuclei. Morpho- logically the eggs are coenocytic; functionally, however, the female gametes have recovered atavistically to a certain degree their earlier individuality; to be sure, they no longer swarm, but each acquires a male nucleus for itself through a special branch of the fertilization tube. The process is the same as in Olpidium in which (if one considers them heterog- amous) several sexual acts occur between the gametes of two gametangia and several zygotes result. In the Saprolegniaceae a number of sexual acts between the two gametes of two gametangia occur and many zygotes (oospores) result; only the male gametes are no longer recogniz- able as individuals and the female gametes always remain in the game- tangia; thus the sexual acts are shifted back to the female gametangia where the zygotes remain enclosed. After maturity of the oospores, the oogonia remain connected with the mycelium until it disintegrates ; much later they, too, degenerate so that the oospores are liberated and germinate. Usually after a rest of 2 to 5 months, germination takes place with a germ tube where meiosis occurs. According to the nutrient content of the environment, it ends in a sporangium after a short time or develops to a mycelium. The rest period does not seem indispensable in all species; thus, in S. mixta, it may be shortened to 8 to 10 days by placing the oospores in pure water at 23 to 25°. Achlya americana (Trow, 1899), A. debaryana (Trow, 1904), A. poly- andra (Miicke, 1908) and Plectospira myriandra (Drechsler, 1927) agree essentially with Saprolegnia monoica in reproductive processes, as far as they have been studied. In A. americana, Trow first observed meiosis in the germination of the oospores, finding four chromosomes in the nuclear figures and eight in the first division of the zygote nucleus. In Aphanomyces laevis (Dangeard, 1891; Kasanovski, 1911), there is a notable reduction which is reminiscent of the relationships in Myzo- cytium and in the Peronosporaceae. After mitosis all the oogonial nuclei degenerate except one, the future egg nucleus. The single egg results from the protoplasm rounding up gradually in the interior and consuming all the protoplasm contiguous to the wall. In the center of the egg is a thick, deeply staining bit of protoplasm which probably corresponds to the coenocentrum (coenosphere) of the Peronosporaceae. In the antheri- dium, also, all nuclei but one degenerate; this, together with the proto- plasm, penetrates the oogonium through a copulation tube and fuses OOMYCETES 69 with the female nucleus. The mature oospore is uninucleate. After a resting period of 6 months, it develops a germ tube. If we consider the life cycle of the Saprolegniaceae from the point of view of nuclear phase, we get the following picture: T1 y^oospores /Zoosporangia^ PC R / Antheridia— >-Male nuclei Mycelium s^^ [-^Oospores— >Zoosporangia — ^Zoospores \)ogonia— >egg cells J Diagram VII. This scheme corresponds essentially with that of Polyphagia Euglenae (p. 44) if one ignores the complication caused by heterothallism in the latter. The differentiations caused by the development of the mycelium in form and function of the haplont, have been discussed in the intro- duction to the Oomycetes (p. 51). Saprolegnia is saprophytic on animal cadavers in all sorts of water, occasionally, parasitic on living fish, whose eggs it may infect and thus cause extensive epidemics. As far as is known, the infection is preceded by a weakening or injury of the individuals infected. The genus includes about 30 species which are chiefly distinguished by the structure and arrangement of the sexual organs; the value of these specific characters should be more thoroughly studied as its habit is extensively influenced by nutritive conditions. The same species occur in Europe and North America, as S. dioica, S. monoica, S. mixta and S. ferax (S. Thureti) (Humphrey, 1892; Coker, 1923). Some of them appear in the Alps and in Lapland beyond the borders of the snow (Tiesenhausen, 1912; Gau- mann, 1918). S. anisospora forms two kinds of zoospores like Gonapodya, a smaller typical form and a larger, more than double the size of the smaller, with dark-brown protoplasm. There are transitional types; but one sporangium contains spores of one type only. Whether this phenomenon has a special significance is still unknown. Achlya polyandra of Europe and A. racemosa of North America behave like Saprolegnia. In Protoachlya we have a transition from Saprolegnia to Achlya, as in P. paradoxa whose form and sporangial arrangement agree with Achlya and whose diplanetism resembles that in Saprolegnia (Coker, 1914; 1923). Isoachlya is similar but all the zoospores are motile, the oogonia are often in chains and the antheridia are rare (Kauffman, 1921; Coker, 1923). In Aphanomyces, which differs from Achlya in its long fusiform sporangia, A. laevis causes a root blight of sugar beets and A. euteiches (Jones and Drechsler, 1925) a root rot of peas. Plectospira myriandra produces injury of tomato rootlets. 70 COMPARATIVE MORPHOLOGY OF FUNGI Leptomitaceae. — In the structure of their thallus, this family probably forms a considerably modified series parallel to the Saprolegnieae, and to the uniflagellate Blastocladiaceae. All species so far known are aquatic. One of the simpler species is Leptomitus lacteus, saprophytic in sewage rich in nitrogen. It covers everything with a dirty white, slimy coat, and in luxuriant development the mycelial masses become loosened in clumps, move away and collect in quiet spots where their mass and rapid decomposition cause trouble. The mycelium is ramose, the main axes are at times better developed. As in Gonapodya of the Blastocladiaceae (Fig. 35, 1), the main axis and branches are generally divided into seg- ments by constrictions. Each segment contains one or more granules Fig. 41.- — Rhipidium europaeum. 1. Plant with zoosporangia. 2. Zoosporangium during exit of spores. (After Minden, 1916.) of cellulin, a carbohydrate probably closely allied to cellulose: it is still unknown whether these granules serve as reserve materials or as plugs, because if they reach a stricture, they swell and fuse with the membrane so that a septum-like valve is formed. In this manner, a septation of the mycelium may be simulated. The sporangia correspond to segments and are sometimes formed in short chains. The zoospores are ovoid and, as in Pythiopsis of the Saprolegniaceae, possess two apical flagella. They often escape through a lateral pore. Sexual organs have not yet been found; under unfavorable conditions, however, gemmae are formed. The species of Apodachlya as A. pyrifera, on rotting plant substrates, agree in habit with Leptomitus, and like Achlya can renew sporangia by lateral sprouting. In the germination of their sporangia they are also OOMYCETES 71 reminiscent of the Achlya type; the zoospore initials pass out through an emission collar, collect before its opening in the form of a hollow sphere and surround themselves with a membrane. After a short time they slip out and, leaving behind the empty sheath, swarm away as reniform, laterally flagellate zoospores. Occasionally they do not shed the mem- brane so that the zoospores of the second swarm stage arise directly in the sporangium. Sexual organs have not yet been determined with certainty. Fig. 42. — Araiospora spinosa. Plant with simple and echinate sporangia. (After Minden, 1916.) In Rhiphidium and Araiospora both of which (like Apodachlya) possess laterally flagellate zoospores, the main axis is shortened and becomes a voluminous broad cylinder which bears a tuft of auxiliary axes. These axes may terminate in a sporangium or branch terminally like the main axis. The species of Rhiphidium, as R. europaeum, live on rotting fruits and fallen twigs in water. Their mycelium is reminiscent of allo- myces (Fig. 35, 2); it consists of a very large thick-walled basal cell 72 COMPARATIVE MORPHOLOGY OF FUNGI whose much-branched rhizoids are rooted in the substrate and bear on apical lobate processes, numerous thin, generally unbranched, hyphae which usually end with a sporangium (Fig. 41, 1). The zoospores arise, as in the Saprolegnieae, from peripheral protoplasm, shortly before evacuation the inner layer of the sporangial walls swells. The outer cuticular membrane is separated as a small lid at the top of the sporan- Fig. 43. — Araiospora -pulchra. Development of oogonia. 1. Young oogonium with peripheral nuclei. 2. Fundament of central egg cell. 3. Mature egg cell whose copulation papilla is in contact with the antheridium. 4. Young oospore with peripheral, faveolate cells. ( X 860; after King, 1904.) gium, and the swollen portion forms a tube into which the swarm spores migrate (Fig. 41, 2) and from which they are liberated. This species possesses antheridia and oogonia whose development is still unknown. Araiospora is similar in structure and mode of life. It differs from Rhiphidium by the presence of two kinds of sporangia, simple and echinate types (Fig. 42). The latter possess a solid membrane and may pass through a resting period; they are formed under unfavorable growth conditions, such as poor nutrition, low temperature and in places where, OOMYCETES 73 on account of their surroundings, zoospore emission cannot take place, such as in aerial mycelium in gelatin cultures (Minden, 1916). Appar- ently they have a biological significance similar to that of gemmae : they germinate like ordinary sporangia. King (1904) investigated the cytological development of A. pulchra. As in the Saprolegniaceae, zoospores arise by cleavage. At the time the oogonium is cut off, its protoplasm forms a homogeneous network with 35 to 50 nuclei, but whether this large number is caused by division is still unknown. They migrate to the periphery, thus causing a vacuola- tion of the interior of the oogonium (Fig. 43, 1). Thereupon most of the protoplasm migrates back to the middle without the nuclei, causing large vacuoles at the edge. The central mass of protoplasm becomes the egg (Fig. 43, 2). In the middle is differentiated a reticulate, strongly staining mass of protoplasm which apparently corresponds to the coeno- centrum of the Peronosporeae. Meanwhile the nuclei at the edge have divided once. One of them migrates back into the egg and lies in the neighborhood of the coenocentrum (Fig. 43, 3); the others remain in the peripheral layer of protoplasm, the periplasm. In the antheridium also, the nuclei divide. Only one of them is functional and at fertilization passes over into the oogonium. Indi- vidual peculiarities, such as the absence of a conjugation tube and the formation of a receptive spot, are reminiscent of the Peronosporaceae. The egg surrounds itself with a thick wall and becomes an oospore (Fig. 43, 4). The fusion of the two nuclei takes place only at germination. The periplasm changes into a peculiar faveolate sheath. The further fate and germination of the oospore is unknown. Peronosporaceae. — A few primitive forms are saprophytic on earth or fresh water; the higher ones are exclusively parasitic on land plants. The mycelium is ramose and consists of hyaline, generally compara- tively thick hyphae which are coenocytic when young or when well nourished, but which become septate in age. In some species of Pythium and Phytophthora, they may unite into growths apparently adapted to resist to external influences (Fig. 44, 1). Several species form thick- walled gemmae. In saprophytic forms, the mycelium is both intra- and extramatrical and in the latter case forms (particularly in Water) Sapro- legniaceous clumps; in the other cases, there is no differentiation into extramatrical hyphae and rhizoids. The parasitic forms develop exclu- sively within the substrate and only liberate conidiophores. In the simple representatives of this group, as in Pythium and Phytophthora, the mycelium is both intercellular and intracellular and generally forms no special haustoria penetrating the host. In the other genera it is exclusively intercellular and penetrates the host cells by characteristic haustoria, which in Albugo, Plasmopara, Bremia, etc., are like short sacs and in some species of Peronospora branch digitately and occasion- 74 COMPARATIVE MORPHOLOGY OF FUNGI ally fill up the whole host cell like a knot. Biologically, from the simpler to the higher forms, there is an increased adaptation to parasitism. Pythium and Phytophthora kill the infected tissue, Albugo and Perono- spora only stimulate it to hypertrophy or to storage of food. Some species of both these genera winter over in the rhizomes of the host and penetrate the whole shoot. Some species of Peronospora in flowers seem to grow up the stem as intercellular parasites and only develop their conidiophores on the corolla. Furthermore, most species of Pythium and Phytophthora are plurivorous and may be cultivated on artificial media; Albugo and Peronospora are much more specialized and will not grow saprophytically. Asexual reproduction takes place by sporangia which, even in the most highly metamorphosed form, are cut off as multinucleate structures nit 7< Fig. 44. — Phytophthora Syringae. 1. Mycelium. Phytophthora Arecae 2 to 7. tion of zoosporangia. (X 215; after Rosenbaum, 1917.) Germina- at the ends of hyphae or hyphal branches; nuclear divisions do not occur in them as in members of the Saprolegniaceae (Ruhland, 1904, disputed by Istvanffi and Palinkas, 1913). Within the family they undergo notable changes which were first recognized by Bary (1863). There are three stages of development corresponding to the tribes Pythieae, Albugineae and Peronosporeae. Pythieae. — In this tribe Pythium and Phytophthora take the lowest position. In the simpler species of Pythium (Subgenus Aphragmium) , true zoosporangia do not occur. Occasional hyphae emit their proto- plasm into a germ sac (remains of a first swarm stage with terminal flagella) where it changes to zoospores without being ab jointed from the rest of the mycelium (Fig. 45, 2 to 5). For this lower degree of develop- ment, it is further characteristic (as in the holocarpic Chytridiaceae) that, in proportion to their thallus, they can produce a very large number of spores; e.g., in Pythium gracile, almost the whole content of the hypha OOMYCETES 75 is discharged as zoospores. Most of the forms belonging here are aquatic. The only parasite of land plants is P. Indigoferae which rarely forms zoospores and reproduces almost exclusively by oospores, wasteful of material. In the subgenus Nematosporangium, the sporangia are filamentous, but separated from the rest of the mycelium by a septum. In the sub- -if *i 10 .••y-rjt^-. m 11 Fig. 45. — Pythium. Forms of sporangium. Pythium gracile. 1. Filament of Vau- cheria with parasite. 2, 3. Vegetative hyphae which have swollen terminally. 4. The protoplasm has passed into a germ sac. 5. Zoospore formation. Pythium proliferum. 6. Zoosporangia. 7. Proliferating zoosporangiferous hyphae. 8 to 11. Germination of zoosporangia. Pythium diacarpum. 12. Habit of fungus on decaying wood. Pythium intermedium. 13, 14. Formation of zoosporangia. Pythium palmivorum. 15. Germinat- ing oospores. (1 X 565; 2 to 5 X 330; 6, 12 X 67; 7 X 100 8 to 11, 13, 14 X 200; 15 X 270; after Butler, 1907.) genus Sphaerosporangium, the characteristic spherical sporangia lead to true conidia; in the section Orthosporangium, e.g., P. proliferum., they always remain attached to the mycelium and germinate in situ (Fig. 45, 6 and 7) ; here they behave as ordinary sporangia. In the section M eta- sporangium, e.g., P. debaryanum and P. intermedium (Fig. 45, 13 and 14), they may fall off and be disseminated by wind or water as true conidia. In their manner of renewal, also, these two sections may be distinguished. 76 COMPARATIVE MORPHOLOGY OF FUNGI In P. proliferum the sporangia are, as in many Saprolegniaceae, renewed by proliferation, which may be repeated until almost all the protoplasm has been used up in the formation of zoospores (Fig. 45, 7). In the conidia formation of P. intermedium, the sporiferous hypha continues in its growth under the terminal conidium, pushes it aside and terminally cuts off a new conidium : this process may be repeated, resulting in race- mose groups of conidia (Fig. 45, 13). Also the conidia may be cut off successively in moniliform chains (Fig. 45, 14). In Phytophthora, only conidial forms are known. These conidia are renewed like those of Pyihium. There is cut off terminally on each of the extramatrical hyphae, a conidium which is pushed aside by the developing hyphae, and falls off, as described for Pyihium intermedium (Fig. 45, 13). In the higher Peronosporaceae, differentiation has extended to the sporiferous hyphae. Just as the sporangia, which are firmly attached to the mycelia and hardly to be distinguished from them, result in morpho- logically and biologically differentiated conidia which break loose from the mother plant and fulfil a new function — that of dissemination — their sporiferous hyphae develop to differentiated conidiophores. The extramatrical hyphae no longer cut off conidia and when brought to any nutritive substrate, themselves develop to mycelia, but they represent characteristically formed sporophores which perform this function exclusively. They no longer develop indefinitely as typical hyphae, but limit their growth and only when the conidiophore is mature, does the terminal abstriction of conidia occur. Because this limited growth permits only one conidium to be cut off from a hypha, only those forms have been retained in which this loss is compensated by other adapta- tions. In this respect, two types are known, that of the Albugineae and that of the Peronosporeae. Albugineae. — The sporiferous hyphae of Albugo, as those of the Pythieae, are simple. They differ from them in the limitation of growth, in their thicker membrane at the base (Fig. 46, 5) and in the peculiarity that several conidia are cut off at a hyphal tip in basipetal sequence, as in Pyihium intermedium. From the hyphae which grow luxuriantly through a substrate, a few nuclei enter the young sporiferous hypha and, sur- rounded by thick protoplasm, migrate to the tip. When five to seven nuclei have collected, the tip is abjointed and rounds off as a conidium. The septum is laid down as a ring from the hyphal wall to the middle (Fig. 46, 1 and 2) ; it is differentiated subsequently into three layers, two outer, deeply staining with haematoxylin, and a central one which takes up a small amount of dye (Fig. 46, 3 and 4). After the conidium has rounded off, the original hyphal wall dissolves at the constriction; a conidium and hypha are only connected by the plate. The distal outer layer of the plate is let into the conidial wall, the proximal outer layer OOMYCETES 11 into the hyphal wall. The middle layer elongates, thus becoming narrower and is finally dissolved, serving as a disjunctor. Meanwhile new nuclei have entered the sporiferous hypha and are used in the forma- tion of another conidium. Apparently, nuclear divisions do not occur in conidiophores and conidia. Peronosporeae. — Here only one conidium arises at each hyphal tip; between it and the hypha, there is formed a single short sterigma of a water-soluble substance which facilitates the abscission (Rostowzew, 1903). The disadvantage of this single abscission is compensated in various forms in a definite manner; thus the conidiophores of Basidio- phora are still unbranched, as in Albugo; at their tips they are slightly Fig. 46. — Albugo Candida. 1 to 4. Formation of conidia. Albugo Portulacae. 5. Catenu- late conidia. (1 to 4 X 900; after Bary and Rosen.) clavate and closely covered with numerous small processes, each of which cuts off a conidium (Fig. 47, a) ; in this manner, there arises on a single conidiophore a large number of spores. Also in Bremia the tips of the branches are swollen and covered with short processes. In the other genera there appears a tendency to repeated branching. In some species of Plasmopara (Fig. 48, A) and in part in Sclerospora, there is present a typical monopodial principal axis from which radiate shorter, often trichotomous branches. In most species of Peronospora the conidiophores form regular trees with a high trunk and a definitely differentiated crown whose branches are forked dichotomously up to twelve times. How effective this forking of the conidiophores is may be seen from a calculation of Weston, where for S. philippinensis the 78 COMPARATIVE MORPHOLOGY OF FUNGI number of conidia formed per square centimeter of infected leaf surface is about three million. In contrast to variability of the conidiophores, the conidia appear approximately the same. They are spherical, ellipsoidal or ovoid, hyaline with a smooth, hyaline, brownish or dirty violet membrane. In most genera a short germ papilla is present at the top. Under certain conditions, the conidia of Pythium may thicken their wall and remain Fig. 47. — Basidiophora entospora. a, two conidiophores emerging from a stoma; st, short sterigma which forms a conidium ; b, conidium with apical papilla and remains of stalk; c, zoospore from germinating conidium; d, oogonium with mature oospore, whose exospore is ridged. Empty antheridium at the right, (a X 230; b X 540; c, d X 550; after Roze and Cornu.) capable of germination up to 11 months. In some species of Albugo, the wall is thickened equatorially, forming a ring (annulus). Furthermore, in Albugo the first conidium of a chain is generally larger than the others and has a membrane of even thickness. When such a conidiophore, by raising the epidermis from the tissue, breaks out of the host and the spore chains break up, these first conidia remain clinging to the epi- dermis of the host. Possibly these serve exclusively to raise the epi- dermis and are not capable of germination. Therefore they are called ''buffer cells." OOMYCETES 79 The conidia and sporangia of the Peronosporaceae behave very differently on germination. In Pythiomorpha gonapodioides the zoo- spores are formed in the zoosporangium and are discharged by the solution of the papilla and the rupture of the inner membrane. They come to rest, encyst, and germinate either by hyphae or swarming. The second swarm stage is non-motile. Secondary sporangia are some- times formed by proliferation of the primary sporangia as in Saprolegnia (Kanouse, 1925). In Pythiogeton at the evacuation of the sporangium the whole content passes out into a sac in 20 to 60 seconds (Fig. 49, 1); Fig. 48. — Plasmopara viticola. A, conidiophores with oogonia and oospores at the left; B, haustoria; C, germinating conidia. (After Millardet.) this ruptures and discharges the naked masses of protoplasm into the air (Fig. 49, 2). Shortly there appear indentations which penetrate deeper so that after 15 to 20 minutes the outlines of the zoospores are visible (Fig. 49, 3). These round off and swim away. Also in Pythium, the sporangia or conidia discharge their undivided contents into a sac where it then falls apart into swarm spores which are liberated by the bursting of the sac (Fig. 44, 4 and 5, 9 to 11). Under certain conditions P. debaryanum may germinate by a germ tube. In P. ultimum zoospore formation is entirely suppressed and only tube germination is known. After Pythium, the process of germination becomes continually simpler; thus in Pythiomorpha the zoospores are formed already in the sporangium. 80 COMPARATIVE MORPHOLOGY OF FUNGI In Phytophthora (Fig. 45, 2 to 7), Albugo, Basidiophora, Sclerospora and, in part, Plasmopora (Fig. 48, C), the stage of the germ sac has almost entirely disappeared. Here the mature zoospores swarm directly out of the conidium. In other forms, the formation of swarm spores is suppressed and replaced by the direct development of conidia to a myce- lium. Thus in Plasmopara pygmaea, the undivided content of the conid- ium swells out of the top, rounds off and puts out a germ tube. In Bremia, the conidium germinates directly by a germ tube which has grown out of a papilla at the tip; in Peronospora the papilla is lacking and the germ tubes come from any portion of the conidium. Wherever zoospores are formed in the Peronosporaceae they are reni- form and possess two lateral fiagella (Fig. 49, 4; 44, 5); thus they are $*- " -'riVV; ^ ^€p -''S>. •■>■-,. *->% fs -•;; y.'V'-.-.Vv '" -l'\ .•'■>:■> ► -;m i Fig. 49. — Pythiogeton transversum. 1. Hyphae with three zoosporangia, one of which is discharging. 2. Protoplast has formed an elongate mass on emerging. 3. Zoospore formation. 4. Single swarming zoospore. {After Minden, 1916.) connected directly to the Saprolegnieae of the Achlya type. Those of Pythiogeton swim about for a while (up to two days) then come to rest, surround themselves with a membrane and germinate to a mycelium. Butler (1907) has observed in Pythium diacarpum and Murphy (1922) in Phytophthora infestans the shedding of the membrane, as in Dictyuchus; the zoospores which have found no suitable substrate come to rest and surround themselves with a membrane. After a certain time they again slip out with the same reniform appearance and swarm further. The phenomenon has further been described by Bary for Pythium proliferum and by Atkinson for P. intermedium; ocasionally the bifiagel- late zoospores may split into two uniflagellate ones; this appears to be only a morbid specimen, however, since Butler could not find in his material the process described by Atkinson. In addition to this asexual reproduction, sexual organs, antheridia and oogonia are known in most of the Peronosporaceae. With the OOMYCETES 81 exception of Pythium, they arise only in the tissue of the host as clavate, terminal or intercalary cells of hyphae or hyphal branches; their develop- ment shows ascending differentiation proceeding parallel to the lines of development of conidiophores and conidia. In Pythium 10 to 15 nuclei enter the young oogonium, and three to six the young antheridium; thereupon the swelling is abjointed from the rest of the hypha. About simultaneously in both organs, the nuclei undergo division (Fig. 50, 2), in which there have been counted in P. ultimum (Trow, 1901) at least six chromosomes and in P. debaryanum (Miyake, 1901) approximately eight. Meanwhile the protoplasm of the oogonium has been differentiated more or less definitely into a thicker, denser, central ooplasm and spongy periplasm. In P. ultimum, all nuclei Fig. 50. — Pythium debaryanum. Gametangial copulation. 1. Young oogonium and antheridium. 2. Mitoses. 3. Degeneration of all but one male nuclei. 4. All but one female nuclei migrate to the periphery and degenerate. 5, 6. Plasmogamy. 7. Mature oospore. {After Miyake, 1901.) but one migrate to the periplasm and degenerate there. In P. debary- anum, all migrate into the periplasm, then one returns while the others degenerate (Fig. 50, 4). Meanwhile in the antheridium, at least in P. debaryanum, all nuclei but one disintegrate (Fig. 50, 3); in P. ultimum they all appear to remain intact. The antheridium puts forth a conju- gation tube into the oogonium and allows the male nucleus (in P. ultimum one of the many), together with a part of the male protoplasm, to pass over into the egg cell; there it lies in the vicinity of the female nucleus but only fuses with it after a long time. Shortly before nuclear migra- tion, the central ooplasm of the oosphere surrounds itself with a membrane, during which the greater part of the periplasm is resorbed; later a thick- walled endospore is formed on its inner side; but a true epi- spore, laid down by the periplasm, is not present. In both species the oospore germinates by a germ tube which develops to a hypha. In P. ultimum it can take place after 24 hours. In other species of Pythium different germination forms have been described, as in P. vexans, zoospore 82 COMPARATIVE MORPHOLOGY OF FUNGI germination and in P. proiiferum and P. paimivorum, germination with a hypha which ends in a sporangium (Fig. 45, 15). In Phytophthora two groups may be distinguished in the structure of the sexual organs. The P. cactorum group, including P. Nicotianae, agrees entirely with Pythium debaryanum, i.e., an antheridium is placed at the side of an oogonium into which it forces a fertilization tube. These forms are called paragynous. The P. infestans group, including P. erythroseptica, P. Phaseoli, P. parasitica and P. Arecae, shows a new structure, unique in the oomycetes; in it the oogonium grows through the antheridium so that the latter sits like a collar on the oogonial stipe. These forms are called amphigynous. Both types, however, are not so fundamentally different that they may be separated generically; thus in P. Syringae and P. Fagi occasionally amphigynous antheridia appear among the paragynous (Himmelbaur, 1911; Lafferty and Pethybridge, 1922). The life cycle may be discussed for a representative of the amphi- gynous group, P. erythroseptica (Pethybridge, 1913; Murphy, 1918). Its antheridium always arises earlier than its oogonium, and generally as a lateral outgrowth of a hypha from which later, as the material is used up, they are abjointed. In youth they contain 8 to 10 nuclei. Although the species is homothallic the oogonia arise on another hyphal branch and generally laterally. When an oogonium fundament comes in contact with an antheridium, in a short time, probably within a few hours, it grows through it. The fundaments which find no antheridia, cease their growth, except in P. infestans which develops partheno- genetically (Pethybridge and Murphy, 1913). Outside the antheridium, the oogonial fundament swells up to an oogonium (Fig. 51, 6). The strong stream of protoplasm flows out of the sporiferous hyphae into the oogonium until the hypha is almost empty; thus during this time the oogonium contains 90 to 100 nuclei. Generally it is not separated from the sporiferous hypha by a wall; but later the connecting passage is closed by a plug of highly refractive material. Two-thirds of the nuclei degenerate both in oogonia and antheridia. Thereupon they arrange themselves peripherally, with one in the center of the oogonium and undergo a single simultaneous division. All peripheral nuclei and one daughter of the central nucleus degenerate (Fig. 51, 7). Meanwhile there has collected around the central nucleus the somewhat denser ooplasm, while the periplasm remains almost structureless. It is entirely resorbed by the ooplasm, so that shortly after fertilization only the remains of the degenerated nuclei are present. Meanwhile in the antheridium the nuclei have also undergone division and all but one disintegrate. Then the oogonial wall is dissolved gradu- ally in one spot (receptive spot). Because of its higher osmotic pressure, the antheridium pushes a short fertilization tube into the oogonium (Fig. OOMYCETES 83 51, 7, lower left) and allows its nucleus with most of the protoplasm to pass over. Fusion of the two nuclei takes place very late during the maturation of the oospore. The wall of the mature oospore consists of three layers, the original membrane, a thin hyaline primary endospore and a thick secondary endospore which consists of reserve material which is dissolved at germination. This takes place through a hypha Fig. 51. — Phytophthora erythroseptica. Development of oospores. 1. Oogonium beginning to penetrate antheridium. 2. 2 hr. 20 min. later, the oogonium begins to swell beyond the antheridium. 3. Same as 1. 4. Older stage. 5,6. Development of oogonium after it has grown through the antheridium. 7, 8. Fertilization. 9. Immature oospore. (1, 2 X 420; 3 to 9 X 800; after Pethybridge, 1913, and Murphy, 1918.) which, according to circumstances, may develop to a mycelium or cut off a conidium. The species of the Peronosporeae, e.g., Plasmopara alpina (Rosenberg, 1903), P. densa, Sclerospora graminicola, Peronospora vernalis (Ruhland, 1904), P. Alsinearum, P. effusa (Berlese, 1898), P. Ficariae (Berlese, 1898; Kruger, 1910) and P. parasitica (Wager, 1900; Kruger 1910) show essentially the same steps in development as Phytophthora erythroseptica; only their antheridia are paragynous and at the time of fertilization contain all the nuclei of which only one enters the oogonium. In regard 84 COMPARATIVE MORPHOLOGY OF FUNGI to protoplasm and the length of life, however, their oogonia show a con- tinuous development, due to retardation of the degeneration of the superfluous nuclei in the periplasm. While in the Saprolegniacae and in Phytophthora this begins before mitosis (i.e., before the gametangial nuclei are activated as sexual nuclei) and continues after it; in the Perono- sporeae and in the Albugineae, as far as is known, it begins after mitosis; thus at fertilization the superfluous nuclei are still intact and, in con- junction with the periplasm, are adapted to creative activity. The transition from Phytophthora takes place gradually; thus in Plasmopara and Sclerospora the periplasm, as in Phytophthora, has only a slight struc- ture and even during mitosis is not sharply separated from the ooplasm. Especially in the last named genus the periplasm is always in several layers around the oogonial wall which persists and surrounds the oospore for a considerable time. In some species of Peronospora it behaves similarly; in others it increases in importance and becomes much denser and more homogeneous than the ooplasm; instead of the oogonial wall becoming strengthened, however, it deposits on the oospore itself a strong epispore with verrucose or reticulate sculptures; thus the oogonial wall remains thin and transitory and collapses after spore maturity. Only here the oospores have become true independent resting spores. Furthermore, in Peronospora there collects in the center of the oosphere, a deeply staining dense mass of protoplasm (the coenocentrum) in the vicinity of which the female nucleus is placed; this will be discussed in detail under the Albugineae. The germination of the oospores in Plasmopara takes place through zoospores, in P. viticola under certain conditions also with a germ tube ending in a large conidium (Ravaz and Verge, 1913), in Sclerospora and Peronospora through a germ tube which develops in the host to a mycelium. Opinions differ regarding the position of meiosis in each of these three genera. According to Wager, Rosenberg and Ruhland it takes place just before fertilization; according to Kriiger it takes place just after fertilization in the first division of the zygote nucleus. In rare cases (e.g., Peronospora Ficariae) it is connected directly with nuclear fusion, but ordinarily takes place much later in the germination in the oospores. According to present conceptions, and according to what is known con- cerning change of nuclear phase in other fungi, Kriiger's theory might easily be the correct one. In any case, further investigation of the question would be desirable. The Albugineae, because of their special position in regard to conidio- phores and fertilization, afford unique types, which are the most primitive known in the Peronosporaceae. They are further noteworthy in that in the same genus (Albugo) they go through fundamental changes while the form of the conidiphore remains entirely constant. OMYOCETES 85 In their youngest fundaments, the antheridia and oogonia agree with those of other Peronosporacese. They arise as terminal swellings of hyphal branches, whereby the antheridia acquire about 35 nuclei, the oogonia up to 300. At the spot where the antheridium is attached to the oogonium, the oogonial and antheridial walls are digested by an enzyme; as possibly the osmotic pressure of the oogonium is higher than that of the antheridium, the oogonial content, surrounded by a membrane, bulges like a papilla into the antheridium. This papilla is unfortunately named a receptive papilla. Later this is turned back and is followed by the fertilization tube which penetrates the pore. In the oogonia the nuclei are regularly scattered throughout the protoplasm. During their simultaneous division a fundamental Fig. 52. — Albugo Bliti. Development of oospores. 1. Antheridium and oogonium. 2. Mitoses at the periphery of oosphere. 3, 4. Penetration of copulation tube. 5, 6. Copulation figures of male and female nuclei. 7. Mature oospore. {After Stevens, 1899.) rearrangement occurs in the whole oogonium. Most of the protoplasm draws together into the dense oosphere, while the periplasm remains spongy and much vacuolate; then the nuclei are extruded from the oosphere and deposited in the periplasm. The details of development in the various species of Albugo differ considerably from each other. In Albugo Bliti (Stevens, 1899) and A. Portulacce (Stevens, 1901), a marked border layerae forms between the periplasm and oosphere. A part of the nuclear spindles are so placed (Fig. 52, 2) that only one daughter nucleus lies in the periplasm the other in the oosphere; in this manner 40 to 50 nuclei return to the oosphere. Here they soon divide for a second time (Fig. 52, 4), while those of the periplasm remain resting. Meanwhile the protoplasm in the center of the oosphere has become condensed into a small deeply staining coenocentrum, which appears to attract the nucleus. Its signifi- 86 COMPARATIVE MORPHOLOGY OF FUNGI cance is still obscure; possibly it is the dynamic center of the poly- energid egg or an organ of nourishment for the nucleus. In the antheridium also the nuclei go through two mitoses (Fig. 52, 4) ; the conjugation tube penetrates to the vicinity of the coenocentrum, dissolves at the tip and about 100 nuclei enter the egg; they approach the female nuclei and slowly fuse with them (Fig. 52, 5 and 6). Here- upon the fertilization tube and the coenocentrum are dissolved, the egg is surrounded with an exospore near which a primary and a secondary endospore are laid down. Fig. 53. — Albugo Tragopogonis. 1. Antheridium and oogonium with mitoses. 2. Nuclei near the coenocentrum dividing while the peripherial nuclei of the egg degenerate. 3. The rest of the egg nuclei except one, degenerating. 4. A male nucleus enters as the female approaches the coenocentrum. Albugo Candida. 5. Penetration of copulation tube. One nucleus remains in egg cell while the others migrate to the periplasm. 6. Fusion of male and female nuclei. (After Stevens, 1901.) Two species, A. Tragopogonis (Stevens, 1901) and A. Ipomoeae- Pa?iduranae (Stevens, 1904), correspond, as far as the maturation of the coenocytic egg, with A . Bliti. Of the 100 potential sexual nuclei only one is functional; it lies next the coenocentrum, develops to four times its original size when in A. Tragopogonis, the other nuclei dissolve (Fig. 53, 3 and 4) or, in A. Ipomoeae-Panduranae, migrate to the periplasm. From the equally multinucleate antheridium, one or more nuclei enter the egg (Fig. 53, 4) ;. one of them fuses with the female nucleus while the others are dissolved. The diploid nucleus soon divides repeatedly so that the oospore winters over with 30 to 40 nuclei. OOMYCETES 87 In still other species, as A. Candida (Davis, 1900; Stevens, 1901; Kriiger, 1910) and A. Lepigoni (Ruhland, 1904), reduction has pro- ceeded a step further. Here already at the differentiation of the protoplasm, a nucleus remains behind in the egg cell (Fig. 53, 5) and then divides, at least in A. Candida, simultaneously with that of the periplasm. One daughter nucleus becomes an egg nucleus, the other degenerates. Ooplasm and periplasm are no longer so distinct as in A . Bliti ; although the coenocentrum is much more highly developed and has become a sharply defined granular mass, rich in food, which can attain fourfold the cross-section of the nucleus; frequently it is also surrounded by a halo of less deeply staining, radial protoplasm. As in the other species of Albugo with only one functional egg nucleus, here also the zygote nucleus divides repeatedly after fertilization, so that the oospore winters over with a large number of nuclei. Except for this peculiarity and the formation of the coenocentrum, the Albuginaceae in A. Candida have attained the stage of Phytophthora. As far as is known, in all species, at germination, the oospores swell until the exospore bursts; the content of the endospore bulges out like a sac, bursts and liberates the biflagellate zoospores. If the developmental forms of the gametangia of the Peronosporaceae are compared with those of the Leptomitaceae, there appears a continua- tion of the tendency to limit fertilization to only a certain number of nuclei, i.e., to favor some nuclei as sexual nuclei. Thereby, the female gametangia from selection become more strongly developed than the male; as in Araiospora of the Leptomitaceae, the number of functional nuclei falls to one. In the male gametangia, however, again like the Saproleg- niaceae all nuclei remain equivalent; as many of them are used as there are present functional nuclei in the corresponding female gametangia. The female gametangia of the Peronosporaceae develop still further. While in the Saprolegniaceae there is a certain natural selection of the (virtual) female gametes, since only a part of the nuclei is used in egg formation, in the Peronosporaceae this differentiation between functional and supernumerary parts extends to the protoplasm and divides it into the gonoplasm (which takes part in egg formation) and periplasm (which has only vegetative duties). This distinction must have arisen so that differentiation ceases after the energids (as in Albugo Bliti) have been differentiated into functional and supernumerary. Thus a differentiation does not extend to the individualization of single functional energids, as in the Saprolegniaceae, but it leaves these unchanged in the center of the female gametangium in the form of a multinucleate egg. For this reason the coenocytic egg of the Peronosporaceae does not correspond to a single egg of the Saprolegniaceae but to the majority of eggs con- tained in an oogonium, just as an egg of the Saprolegniaceae corresponds to several gametes of Olpidium. Caryologically, the difference is not 88 COMPARATIVE MORPHOLOGY OF FUNGI very significant, as all functional nuclei are fertilized by male nuclei; only as it is a question of a simultaneous process in the same organ, this multiple fertilization, in contrast to the Saprolegniaceae, is consummated by a single sexual act. Selection goes still further and removes all but one nucleus from the coenocytic egg into the periplasm. Thus in every oogonium a single uninucleate egg is formed secondarily; this should not be considered homologous to a true gamete as its phylogeny shows it to be a coeno- gamete which has become uninucleate. Thus in the highest Oomycetes, the number of functional female energids sometimes is reduced to one. Similarly also in the antheridia of some, only one nucleus is functional and all the others degenerate. Thus between the contents of two game- tangia only one sexual act and one fertilization occurs and its product is only a single uninucleate zygote, which in Olpidium was the product of two daughter cells of the gametangium but is here the product of two gametangia themselves: as in the development of the zoosporangium to conidium, here the whole organ has assumed the function of a part. The Pythieae form the transition from the Leptomitaceae and are marked by the possession of true zoosporangia. Four genera should be mentioned here, Pythium, Phytophthora, Pythiomorpha and Pythiogeton. Pythium, as has already been indicated on page 75, is divided into three subgenera according to the structure of their sporangia: Aphragmium, Nematosporangium and Spkaerosporangium. To Aphragmium belong P. gracile which has been found in the north temperate zone, parasitic on Chlorophyceae and saprophytic in soil, and P. Indigoferae which in British India is epiphytic (?) on leaves of Indigofera arrecia. To Nema- tosporangium belong P. monospermum which appears in water on decaying insects and Lepidium seedlings, and P. aphanidermatum which in the United States is parasitic on sugar-beet seedlings, in Hawaii on sugar cane and in India on ginger, tobacco and Papaya. The subgenus Sphaerosporangiiwi finally is divided into two sections ; Orthosporangium, in which the sporangia remain attached to the mycelium; and M eta- sporangium, in which the conidia fall off. The species of Orthosporangium are mostly aquatic on plant and animal remains and renew their sporangia by proliferation as P. proliferum and P. diacarpum. The species of Metasporangium have passed over to terrestrial habitats and renew their conidia by lateral sprouting of sporiferous hyphae, as P. debaryanum which causes the destruction of young seedlings of crucifers, sugar beets, etc., P. palmivorum which in India causes a heart rot of coconuts, and P. intermedium which in Europe and North America is saprophytic on garden soil and parasitic on fern prothallia. These forms are so closely allied to Phytophthora that a border line may not be drawn. In some of its species the conidiophores do not possess an entirely mycelial character, as Phytophthora eryihroseptica OOMYCETES 89 in which they do not project above the substrate but cut off conidia under water (Pethy bridge, 1914). Also as regards the germination of conidia, transitions are very gradual; thus P. Arecae germinates generally with a sac as Pythium palmivorum (Rosenbaum, 1917). In contrast to Pythium, however, all species of Phytophthora so far known are parasitic. P. infestans causes the late blight of potatoes; it goes over to various other Solanaceae and Scrophulariaceae; in damp earth, the conidia remain capable of germination up to 4 weeks (Murphy, 1922.) P. erythroseplica causes a similar disease of potatoes in which the infected tissue of the tubers becomes salmon color after a half-hour and in a few hours assumes a deep purple brown color. The group of P. omnivora occurs in several strains, rather obscure in choice of host but morphologi- cally distinct in pure culture, which have earlier been given special names, as P. Syringae, P. Cactorum and P. Fagi (Himmelbaur, 1911). It appears on all kinds of hosts and causes particularly rots, in cacti, pear, buds of lilac, beech seedlings, etc. P. Faberi causes a bast rot of cacao, Hevea, etc., P. Phaesoli, an abscission of the pods of Phaseolus lunatus, and Phytophthora Arecae a heart rot of Areca palms. Both Pythiomorpha gonapodioides and Pythiogeton utriforme have been found exclusively on rotting fruits and other plant parts in water. The Albugineae are characterized by short sterigma-like conidiophores which cut off successively chains of conidia; they are generally laid down in a thick sorus under the epidermis of the host and are liberated by its rupture. Up to the present only one parasitic genus is known, Albugo, whose species cause hypertrophies and malformations; thus A. Candida on crucifers (Melhus, 1911), A. Tragopogonis on composites, A. Ipo- moae-Panduranae on sweet potatoes A. Bliti on Amarantaceae and A. Portulacce on Portulaca. The Peronosporeae, finally, are distinguished by the develop- ment of the sporiferous hyphae into true conidiophores; this takes place so gradually that systematic classification, which here rests only on the sporiferous hyphae, can only be certain of the most marked types and must rely on subjective measurements on many transitional forms (Wil- son, 1914). The only species of Basidiophora, B. entospora, lives on leaves of composites. Some species of Sclerospora are dreaded in India, the Dutch East Indies and the Philippines, as a cause of leaf disease of maize. Another species, S. graminicola, appears on various grasses in Europe and North America. Plasmopara is economically important as a cause of plant disease. Its conidiophores and conidia vary markedly in form and size from one host genus to another and sometimes even in the same genus (Wartenweiler 1918). In P. nivea and P. viticola, the downy mildew of grapes, the conidia germinate generally with zoospores; in P. pygmaea, on various Ranunculaceae, in P. alpina on Thalictrum alpinum and P. densa on Scrophulariaceae, generally with 90 COMPARATIVE MORPHOLOGY OF FUNGI germ tubes, whereby their contents pass out of the papilla as a ball. Bremia Lactucce causes a rot of various composites, especially lettuce and artichokes. It is divided into several biological forms which may be partially separated biometrically (J. Schweizer. 1919). Peronospora is divided into a large number of smaller morphological and biological species, which are usually specialized on single host genera and often on single host species (Gaumann, 1918a, 1923). P. cannabina causes a disease of hemp, P. Brassicae of cabbage, P. Schleideni of onions, P. Schachtii of sugar beets, P. Spinaciae of spinach. Having reached the end of the Oomycetes we will now return to the question of their source. We face the same dilemma as in the Archi- mycetes and the Chytridiales. According to one concept, the Oomycetes are derived from the Algae; thus Bary (1884) considers the Chloro- phyceae, especially Vaucheria; also Tavel (1892) names Vaucheria and related genera as ancestors but connects the Monoblepharidaceae with Oedogonium; Davis (1903) considers them derived from isogamous or slightly heterogamous Chlorophyceae at the stage of development which approximately corresponds with Cladophora and the isogamous Sipho- nales. According to the other concept, held by A. Fischer (1892), Dangeard (1906), Atkinson (1909a) and Scherffel (1925), the roots must be sought in the Chytridiales. The fundamental question is whether the structure of the zoospores is of phylogenetic significance or not. Most authors have answered this question negatively; and yet one must admit that in the fungi where the number and insertion of the fiagella have been accurately observed, they afford a systematic character with which other morphological facts entirely agree. Numerous ideas of this type have been recently upset by the fact that they have been based upon incorrect observations; thus Vuillemin (1907, contradicted in 1912) and Lotsy (1907) consider incorrect the observations of Hesse that Pyihium is uniflagellate. Since then, it has been substantiated that he made his observations on abnormal material. Similarly Thaxter has described biflagellate Monoblephari- daceous zoospores which, according to Woronin (1904), belong to a parasite. Even the justification for Myrioblepharis (Thaxter, 1895) has been questioned by Minden (1915). Further the observation of Atkinson that Pythium intermedium may form two uniflagellate zoospores is inconclusive, because the fate of the halved zoospores is unknown and because Butler (1907) could not find this in the same (?) species; further- more Dastur (1913) is inclined to consider abnormal similar phenomena which he observed in Phytophthora parasitica. It may easily be (and fungi offer several examples) that because of mode of life, parasitism etc., there appears a hereditary loss of fiagella, but there is no suggestion that only one of two fiagella is lost, and it is equally improbable that from two lateral fiagella a terminal flagellum could arise, or vice versa. Hence it appears OOMYCETES 91 justifiable to separate the uniflagellate forms (Monoblepharidaceae and Blastocladiaceae) from the biflagellate (Ancylistaceae, Saprolegniaceae Leptomitaceae and Peronosporaceae), the more so as other characters go parallel with the number of flagella. The uniflagellate zoospores are chiefly amoeboid, the biflagellate not; the uniflagellate families during growth give no cellulose reaction, the biflagellate always; the protoplasm in the former is often reticulate, in the latter homogeneous and periplastic. The Oedogoniaceae or the Chytridiales are possible sources of the uniflagellate forms. The type of fertilization suggests the Oedogoniaceae but this family is much more highly organized and has multiflagellate zoospores and sperms. The uniflagellate condition of the zoospores and the habitual agreement of the Blastocladiaceae with Macrochytrium sug- gest the Chytridiales, only in this case, the sperm fertilization in Mono- blepharis would be a new process. On account of the lack of intermediate forms, this difficulty seems greater than that which would arise in the derivation from Oedogoniaceous uniflagellate algae. Derivation of the biflagellate forms is still more difficult. The Chytridiales, so far as known, can hardly be considered, as biflagellate forms have not been observed in them. Atkinson (1909) attaches Lagenidium to Polyphagus, and considers the Oomycetes and Zygomycetes have developed in parallel lines from the Ancylistaceae and those in turn from the Rhizideae; it is difficult, however, to support this connection between Lagenidium and Polyphagus. Similarly Scherffel (1925) con- siders an ascending series, from the Monadineae (Pseudosporeae) through the Archimycetes, Chytridiales and Ancylistaceae (Ectrogella) to the Saprolegniaceae, which has developed parallel with the algae under discussion. Direct derivation, however, from the Vaucheriaceae accord- ing to Bary and Tavel, or lower biflagellate Siphonocladiales and Siphon- ales according to Davis, is more satisfactory. The structure of the zoospores might be explained by the assumption of a new diplanetism and oogamous fertilization by the development of a conjugation tube. Besides, certain Leptomitaceae, Rhiphidium and Araiospora, show in habit and position of sexual organs, a striking similarity to the Vaucheriaceous Dichotomo siphon. As Atkinson has already emphasized, however, it is questionable whether much significance may be attached to this agree- ment; for there is a great possibility of convergence phenomena, e.g. in the Chlorophyceae, the Codiaceae have developed independently forms very similar to the Vaucheriaceae. It seems to be the best solution to connect the Oomycetes with the Chlorophyceae. This is pure conjecture, however; the true ancestors in which separation took place have mostly died out and it is only by acci- dent that analogies could be found on which to base conclusions. The finding of some new tropical species, however, might supply an entirely new point of view. CHAPTER IX ZYGOMYCETES The Zygomycetes form an isogamous series, parallel to the Oomycetes, which has become adapted to terrestrial habitats. The thallus in the simple forms is coenocytic like that of the Oomycetes, in the higher forms, secondarily divided into cells. In several families, under certain condi- tions, the hyphae may fragment into oidia, hyphal bodies, etc., which develop further as sprout mycelia. Under unfavorable conditions, small portions of hyphae are thickened to gemmae. The fructifications are aerial. The haploid portion produces sporan- gia, conidia and gametangia; the diploid, zygospores. The sporangia and conidia are each characteristic for a special developmental series. As in the higher Oomycetes, zoospore formation is absent. Instead the spo- rangia form non-motile, endogenous sporangiospores, while the conidia germinate by a single germ tube. While the conidia remain equivalent to each other, the sporangia, even within a single family, undergo funda- mental changes and in various ways are reduced to conidia. In both sporangia and gametangia, the individual daughter cells are no longer motile and the gametangia fuse, like those of the Oomycetes, in the coenocytic condition. The sexual act is essentially isogamous, in spite of heterothallism. The higher Zygomycetes tend more and more toward heterogamy. Within the gametangia in some Zygomycetes (as in the higher Oomycetes) there appears a tendency to privilege a few gamete nuclei; only in typical cases the division between functional and supernumerary nuclei occurs before the demarcation of the gametangia, so that the supernumerary nuclei may still migrate, while in the Oomy- cetes they are differentiated after the delimitation of the gametangia and then degenerate within them. The products of the sexual act, the zygospores, are essentially different from the oospores of the Oomycetes in that their wall is itself formed by the gametangial wall while the walls of the oospores are new structures. In the higher Zygomycetes, especially in the Endogonaceae, between plasmogamy and fertilization (as in the Peronosporaceae), a short dicaryophase is inserted. In the Zygomycetes the development pro- ceeds further and removes caryogamy both in time and place; for the first time in the fungi, caryogamy no longer occurs in the place designed for it (in the gametangia), but is retarded and shifted to an outgrowth of the female gametangium. 92 ZYGOMYCETES 93 The relationships of the Zygomycetes are wholly obscure. Vuillemin (1886, 1912) and Lotsy (1907) connect the Zygomycetes through Basidio- w < w o < o -a *— i O co £ C Q "a 8.2 W OcbW a < a o Mucor, Absidia and Zygorhyn- chns (Swingle, 1903; Moreau, 1913; Green, 1927) the protospore stage is omitted. The division of the nucleus in Phycomyces, probably also in the other genera, occurs simultaneously in the whole sporangium. Hereby the sporogenous protoplasm splits directly into multi-, rarely uninucleate portions which round off, sur- round themselves by a membrane and develop directly to spores without further nuclear division (Fig. 59). The sporangiospores are unicellular, generally ellipsoidal or spherical, hyaline or dully colored; they lie either free in the sporangium or are embedded in a finely granular intermediate substance, swelling gel-like in water, which is probably developed within themselves (Fig. 5, 2). At germination they swell considerably and develop into a mycelium through one or more germ tubes. Their morphological characters are not yet clear. One can either regard them as analogous to the zoospores of the Oomycetes, i.e., as akinetes which because of incomplete cleavage have remained large and multinucleate; or one can, probably with more reason on the basis of the parallelism in protospore formation between Pilobolus- Sporodinia and the Synchytrium decipiens-S. Taraxaci series, regard the sporangiospores as reduced sporangia and the Mucor sporangia are reduced sori. As in Synchytrium and Urophlyctis alfalfae the contents ZYGOMYCETES 101 of the sori, are differentiated into individual sporangia which, because of the transition to terrestrial habitats, germinate with germ tubes instead of zoospores. According to this explanation the import of columella formation remains obscure. The original sporangial type discussed above, represented by Mucor, Sporodinia, etc., in the higher forms is modified in two directions, either the individualization of oospores is retarded without being entirely suppressed as in the Oomycetes, or the sporangia decrease successively in differentiation, size and spore number and finally sink to conidia in appearance and function. In the direction of retardation of spore formation, undoubtedly the Choanephora-Piptocephalis series must be indicated. In poorly nourished Choanephora cucurbitarum sporangiophores and sporangia similar to those of Mucor are formed. The ends of the brown, smooth sporangiospores Fig. 60. — Cunninghamella echinulata. Development of sporangiophores. (X740; after Moreau, 1914.) have two to three hyaline processes from each of which up to 20 hairs arise. With liberal food, on swollen tips of vertical hyphae or eventually on the short secondary branches, the spores arise, not endogenously by cleavage, but exogenously by budding. Spore formation is ontogeneti- cally retarded and is transferred from the interior of the sporangium to its upper surfaces. These exogenous spores, in contrast to the endogenous, are longitudinally striate and not ciliate (Wolf, 1917). This exogenous spore formation may be seen in Cunninghamella cytologically investigated by Moreau (1913). In C. echinulata and C. Bertholletiae, the ends of the sporophores swell, like sporangia, into sacs (Fig. 60, 1), whose content is differentiated into a watery inner and a rich outer zone. The peripheral layer splits, not into spore initials, as Sporodinia, but allows the protoplasm to pass out into small spherical sacs, sessile on short sterigmata, with three to eight nuclei each. These sacs are cut off and transformed to spores (Fig. 60, 2) corresponding in size and form to the typical Mucoraceous spores but borne on the outer surface of the sporangia instead of within them. 102 COMPARATIVE MORPHOLOGY OF FUNGI This developmental series finds its continuation in Blakeslea irispora (Thaxter, 1914a). This species, also as Choanephora, forms under certain conditions of growth, e.g., in saturated atmosphere, typical multispored Mucor sporangia with large pyriform columellas (Fig. 61, 1). These sporangia show a marked tendency toward degeneration: with slight alteration of cultural conditions, they decrease in cross section and spore number, the columella becomes smaller and disappears (Fig. 61, 2) and there result forms, which only distantly resemble the original sporangium. Fig. 61. — Blakeslea trispora. Modifications of sporangia. 1. Original form. 2. Reduced form without columella. 3, 4. Formation of exogenous sporangioles. 5. Spor- angiospore from sporangiole. 6. Mature sporangiole with broken sterigma. (1 to 4, 6 X 260; 5 X 720; after Thaxter, 1914.) Under normal conditions of growth, the spore protoplasm migrates from the sporangium into saccate protrusions, sessile on spherical sterigmata (Fig. 61, 3) and there, by meridianal splitting, divide into three spores each (Fig. 61, 4) which, as in Choanephora, bear little tufts of hairs at their tips (Fig. 61, 5). At maturity, the protuberance is separated from its sterigma or with its sterigma from the sporangium and is disseminated (Fig. 61, 6). In this species, spore formation (in contrast to Cunning- hamella) is again retarded; between the differentiation of sporangial con- tent into a sterile and a fertile zone and the individualization of the ZYGOMYCETES 103 single spores, the sporangium also continues its development and develops into numerous extrasporangial partial sporangia, each of which forms a small number of sporangiospores. In Syncephalastrum racemosum and S. cinereum (Thaxter, 1897; Moreau, 1913) the facultative formation of Mucor sporangia is entirely lost; the extramatrical partial sporangia have reached a higher stage of development. They develop several sterigmata, generally joined palm- ately into long cylindrical tubes which take up as many as 20 nuclei (Fig. 62, 1 and 2). When they have attained their full length, their content splits simultaneously into uni- or multinucleate portions which Fig. 62. — Syncephalastrum cinereum. Development of extrasporangial partial sporangia. ( X 740; after Moreau, 1914.) round off and are surrounded by membranes (Fig. 62, 3). These are liberated by disintegration of the sporangial membrane. In Syncephalis, development goes still further (Tieghem, 1875; Vuillemin, 1902). After the destruction of the partial sporangium, the spores always remain connected with the adjacent cuff -like part of the sporangial membrane; the spore wall itself remains thin and insignificant while the sporangial wall is thick and occasionally sculptured. In S. auraniiaca, the partial sporangia divide by septa into as many locules as there are spores. By splitting these septa, they divide into oidial members, each of which contains a spore ; thus the spores are completely surrounded by a sporangial wall, inseparable from their own wall. 104 COMPARATIVE MORPHOLOGY OF FUNGI In all these genera, the sporangium which has become functionless, remains in open connection with the sporiferous hyphae; it retains its more or less definitely capitate shape and collapses only after maturity of the partial sporangia. It has degenerated only in so far as the sterile inner part is no longer separated from the peripheral spore protoplasm by a columellar wall. In Piptocephalis it also takes part in the develop- ment ; it loses its typical capitate form, and shrinks to a verrucose basal cell (Fig. 63) bearing at its top the partial sporangium which is freed Fig. 63. — Piptocephalis Frescniana. in, mycelium with haustoria, h, which penetrate the hyphae, M, of Mucor Mucedo; Z, zygospore with its two suspensors, S. Conidiophore at the right. (After Brcfeld.) from the sporiferous hypha by its degeneration (Brefeld, 1872; Tieghem, 1875). The partial sporangia, as in Syncephalis aurantiaca, break up into monosporous members in which the sporangial membrane is fused with the spore membrane and is externally almost indistinguishable from it. The sporangiophores, therefore, have been changed into conidio- phores which may be recognized as original sporangiophores only by their phylogeny. The catenulate spores of Piptocephalis, which correspond to the sporangiospores of Syncephalastrum plus the section of the surrounding ZYGOMYCETES 105 sporangial wall, and the monosporous members of the partial sporangia of Syncephalis, do not fall under the scholastically narrow concept of conidia and have been described by new terms. As none of these is very fortu- nate, and as the differences really possess no important principle, it seems preferable to employ here also the term conidia, which already includes structures very different phylogenetically ; it is essential to keep in mind that these parts have resulted by the fragmentation of extrasporangial partial sporangia. All these phenomena, especially in genera like Choanephora and Blakeslea, besides their actual interest, have a fundamental significance for the comprehension of the higher fungi; for they show that the change of nutritive conditions produce different types of fructifications which externally are so different from each other that the determination of their relationships can only be obtained in pure culture. The Thamnidium-Chaetocladium and the Mortierella-Haplosporan- gium series penetrate the nature of the Mucoraceous fructification more deeply than the Choanephora-Piptocephalis series. In the latter, the number of sporangiospores remains unaltered; only they no longer are endogenous in the sporangia, but are somewhat retarded and in a certain sense exogenous in the germination of the partial sporangia, so that in the highest forms they remain enclosed in these partial sporangia. In the Thamnidium-Chaetocladium series, however, the sporangiospores are numerically much reduced; their functions are assumed by the sporangia and these themselves successively degenerate to conidia. In Thamnidium elegans the main axis possesses an apical multispored sporangium which, like that of Mucor, has a columella (Fig. 64, 1 and 2, a). Under definite conditions dichotomous branches terminating in sporangia are formed from the main axis. These sporangia, however, are smaller than the terminal, have no columella, become loosened as a whole from the sporangiophores and contain only a few, generally four spores (Fig. 64, 2 and 4). These are liberated not by deliquescence but by disintegration of the sporangial membrane. These reduced sporangia are called sporangioles. The spores in both types of sporangia behave similarly in their germination and further development. Under favor- able conditions of nourishment, however, they are continued through several generations when the sporangioles become as large and multi- spored as the sporangia. Conversely, with poor nourishment the terminal sporangia change into sporangioles whose spore number is often reduced to one (Tavel, 1892). Since within the same species both well-developed and reduced sporangia appear, Thamnidium elegans corresponds to the genera Choanephora and Blakeslea in the Choanephora- Piptocephalis series; only in the latter both sporangial types arise sepa- rately on special sporangiophores while in T. elegans they are formed on the same sporangiferous hypha. 106 COMPARATIVE MORPHOLOGY OF FUNGI \^ Fig. 64. — Thamnidumelegans. 1. Habit, a, terminal sporangium ; c, the sporangioles. 2. Same, more enlarged. 3. Smaller sporangiophore bearing few-spored sporangioles, c; ra, portion of hypha. 4. Sporangioles. Chaetostylum Fresenii. 5. Sporangiophore with terminal sporangium, a, and sporangioles, c; borne on branches which either terminate in a sporangium, b, or are sterile. 6. Sporangiophore producing only sporangioles, c; tips of main axis and branches are sterile. 7. Germination of sporangiole, a; leaving the sporan- gium, b; formation of germ tube, c; empty spore wall, d. Chaetocladium Jonesii. 8. Germination of sporangia with single spores a to d. Chaetocladium Brefeldii. 9. Conidio- phore with conidia, the tips of the branches sterile. 10. Germination of conidia. (1 X 6; 2, 5, 6 X 120; 3, 4 X 200; 7, 8 X 300; 9, 10 X 450; after Brefeld.) ZYGOMYCETES 107 This line of development is continued through Chaetostylum Fresenii (Thamnidum chaetocladioides) . Here, under unfavorable conditions of nourishment, the terminal sporangia abort (Fig. 64, 6) and only with adequate nourishment again bear true apical sporangia (Fig. 64, 5). In these two species the terminal sporangia already have declined in number, as the sporangioles predominate, while in Chaetocladium they disappear entirely, never to reappear. In this genus, the sporangi- oles also degenerate. They become monosporous so that the spore walls coalesce with the sporangial wall. In Chaetocladium Jonesii, this double nature of the spore wall is evident in germination; here the sporangial wall is thrown off as exospore and the spore lies free at germination (Fig. 64, 8). In C. Brefeldii, however, this differentiation is suppressed and the monosporous sporangium puts forth its germ tubes directly (Fig. 64, 10). Thus the sporangium is here entirely transformed into a conidium (Brefeld, 1872; Tieghem and Lemonnier, 1873). Fig. 65. — Haplosporangium bisporale. 1. Sporangiferous hypha. 2. Monosporangium with a single sporangiospore. (X 720; after Thaxter.) Mortierella and Haplosporangium show a similar degeneration. In Mortierella the sporangium, like the sporangioles of Thamnidium, is separated by a basal septum from its sporangiophores; there is no dif- ferentiation of its content into sterile and fertile zones and the spores arise directly by cleavage of the whole protoplasm. Their number decreases notably and in some species is only two to four (Tieghem and Lemonnier, 1873). In Haplosporangium bisporale (Thaxter, 1914a) this condition has become the rule. Here the sporangia remain very small and retain only one or two spores (Fig. 65, 1). The spore wall is deli- cate, the sporangial wall thick and sculptured; unrelated to Thamnidium and Chaetocladium, here the same process has taken place and has led to one- or two-spored sporangioles, biologically regarded as conidia. In a biological sense, Thamnidium-Chaetocladium and Mortierella- Haplosporangium form a series parallel to Pythium-Peronospora under the Oomycetes. Only in the Oomycetes, reduction of the sporangia to a single spore has resulted from inhibition of zoospore formation, i.e., it has remained a purely internal process which has had no direct reaction on the form and size of the sporangia themselves; thus the conidia of 108 COMPARATIVE MORPHOLOGY OF FUNGI Peronospora are just as important as the sporangia of Plasmopara. In the Mucoraceous series, the primary import does not lie in an inhibition of formation of spores whose individuality is retained but in a degenera- tion of sporangia. A decrease in size of the sporangia leads to a decrease in the number of spores. Biologically, the result is the same in both cases: a single conidium replaces sporangia with many spores. Besides this asexual reproduction, in most Mucoraceae sexual organs are known. In the homothallic forms their appearance is mainly depend- Fig. 66. — Mucor Mucedo. Zygospore formation. 1. Two copulation branches approach. 2. Separation of gametangia, a, from suspensors, b. 3. Formation of azygo- spores instead of copulation. 4. Mature zygospore, b, between the suspensors, a. 5. Germination of zygospore. (1 to 4 X 225; 5 X 60 after Brcfeld.) Mucor erectus. 6, 7. Azygospore formation. Mucor tenuis. 8, 9. Azygospores. (After Bainier.) ent on conditions of nourishment; the heterothallic forms require the presence of both sexes. Mycelia of one sex may be cultivated alone for any number of "generations" without the appearance of normal sexual organs, which appear promptly whenever the opposite sex is brought into the vicinity. If two sexually mature (in heterothallic forms also dynamically opposite) hyphae come in contact with one another under favorable conditions, each forms an outgrowth toward the other (Fig. 66, 1). This is cut off from the sporiferous hyphae close behind the tip by a diaphragm- like wall laid down from the edge inwards (Fig. 66, 2). The tip cell is ZYGOMYCETES 109 the gametangium, the sporiferous hypha is the suspensor and the whole outgrowth is called copulation branch. As the homothallic forms are bisexual, there apparently takes place in their hyphae, at the formation of the copulation branches, a spatial separation of + and — energids. In some forms, the copulation branches may arise from ordinary hyphae; in others they are formed on special branches, the zygophores. The separating double wall between the gametangia is gradually dissolved from the middle toward the edge and the zygote becomes a hypnospore by the formation of a many-layered wall, the zygospore (Fig. 66, 4). If in the homothallic forms, the copulation branch finds no mate, in many species the gametangium is surrounded by a many- layered wall, and is called an azygospore (Fig. 66, 8 and 9) or chlamydo- spore. The same thing occurs if the cultures are removed to unfavorable conditions, such as high temperatures. In the heterothallic forms similar phenomena may occur if the copulation branches belong to two different species; in this case they cease growing and transform the gametangia (in case they have already been cut off as such) into azygo- spores. This incomplete hybridization, however, does not seem to occur between all species, for it occurs between Phycomyces nitens + and Mucor Mucedo — and conversely, but not between Phycomyces nitens and Rhizopus nigricans (Blakeslee, 1904, 1915, 1921, 1927). While both gametangia are usually of the same size and thus extern- ally suggest isogamy, in individual species their size relationships show a notable tendency to heterogamy. Thus in the homothallic Zijgorhynchus Moelleri, the copulation branches are unequally developed. In the heterothallic Absidia Orchidis, the gametangia are unequally broad, so that the zygospore is conical. In Piptocephalis, the zygospores grow upward from the point of fusion so that it is borne upon the top of the copulation branch (Fig. 63). In Syncephalis nodosa, one copulation branch coils around the other in a helix (Thaxter, 1897) ; the zygospore does not arise at the point of fusion but comparatively distant, on the outer wall of the helix near the septum separating the gametangium from the suspensor. Still more puzzling is Dispira americana (Thaxter, 1895a), parasitic on other Mucoraceae, where, at the tips of the vegetative hyphae, thicker fertile branches swell and approach the sporangiophores of the host, forming small sinkers. A septum divides the swollen part into two cells, both gametangia. After copulation the proximal cell swells and changes to a zygospore which is surrounded with digitate processes of the distal cell. All these phenomena may be referred to a unified basic form as soon as one considers the cytological relationships. As an example may serve the homothallic Sporodinia grandis (Leger, 1895; Dangeard, 1906; Lendner, 1908;Moreau, 1913;Keene, 1914). Its young gametangia contain more than a thousand nuclei (Fig. 67, 1). While the separating wall 110 COMPARATIVE MORPHOLOGY OF FUNGI •■• .-*■■»•; y*/jj3&4¥a ..V:.." > -W:. ..' .: •*-. ■ •.'.•:-r-c.-v,'-^X: .: ';'^«>V«V- . •••::■. S.'-t' -.*-.V- !•*•••■ ;.vN;Vv.".i> ^•/{•••^"■^'■v'.'-KC- ••'."■• VV^VVW:.--.. ••■ •i?»i?;Ai-'- >■•••••.;■•.•.•■ ••:.'-*i- ••;■• .•.•;•:•;•-:••. '.- •■'•■?«' i*, *•■'• . >"." v."-'- ••"•'^ >■'•''••'•'••,•.'•.■ -\ ?ssaafasss'.*?'a®g3S •^'•-W/iV. ,.•.'.'.'.'•'■ '.•"■•- .:'■ , '•i'S:»J :■ •', :.■ ■".r->;j<; .-.. * • .nit •••. ■•*;,• -, -V't^. ■•?•.-■•:.« '.v.- *m» ^■y rvivv :>?.-?:;i ■ :•£ ■iV-i &»* ti¥V : ^.'y. ll*j> -V' >'■ j K • •• :■//' J '.; ■'.:.. .•.';», V ." '/ . i:*;Jc- .-. .••-■'. ' • • ;-'A. .• '• '■..'';.'•'•.•.'.;•,. hv.;»- •■'*:.'•-.•■'■• •.•.•^.■•f: ■ * •'■ .;v ".• ; ;. ..-Via [&■'■■ ■• W" ■""*-■■■■ !si' ■••.-'•.••' £g5?Ml Fig. 67. — Sporodinia grandis. Development of zygospores. (X 124; after Keene, 1914.) ZYGOMYCETES 111 between the gametangia is dissolved, the nuclei undergo a division almost simultaneously; their cytoplasm intermingles (Fig. 67, 2) and their nuclei subsequently pair and fuse. Those without mates, especially those near the periphery, degenerate and disappear. Meanwhile at the surface, a wall of several layers has been formed, the suspensors collapse and the zygospores presently lie free upon their substrate (Fig. 67, 3 and 4.) It is characteristic of this process that no dynamic differentiation occurs between the + and — energids in spite of their separation in space. Thus both gametangia are cytologically equivalent, and fertili- zation is isogamous with reference to the nuclei. In Sporodinia, as in the higher Oomycetes, there is no individualization of gametes, so that two coenocytic gametangia copulate and accomplish, as in Albugo Bliti, a multiple nuclear fusion, i.e., several fertilizations. Thus the zygospore of Sporodinia is not a simple zygote like that of Olpidium but is the prod- uct of two coenogametes, a coenozygote or zygosporangium. All other Mucoraceae so far investigated conicide with Sporodinia grandis in their essential cytological relationships, e.g., Mucor (Dangeard, 1906; Moreau, 1914), Rhizopus, Absidia, Phycomyces and Zygorhynchus (Moreau, 1914, contradicted by Gruber, 1912). In Zygorhynchus Dan- geardi, all gamete nuclei but four degenerate in the young zygote. The surviving nuclei fuse in pairs very late, after the endospore has been formed. A similar retardation of caryogamy has been observed in Phyco- myces nitens (Burgeff, 1915), in which the nuclei in the zygospores, 5 months old and ready to germinate, still he arranged in pairs. Perhaps tendencies similar to those which cause a retardation of nuclear fusion in the oospores in the Peronosporeae are present in the Mucoraceae. In spite of external heterogamy, Absidia and Zygorhynchus copulate just as Sporodinia, and hence are dynamically isogamous and partially homothallic. The wall of the zygospores in the more carefully studied species of Mucor, Sporodinia and Zygorhynchus consists of five layers (Vuillemin, 1904). The innermost is thin and granular; it forms the transition from the protoplasm and, to a certain extent, is the mother layer. The next is thickest and called the cartilaginous layer on account of its elasticity. This is covered by a thin sheath, the middle cuticular layer. The fourth, or carbonaceous layer, is fragile and brown or black; the outermost cuti- cular layer is either pale and elastic, or dark and fragile, and often inter- rupted or fractured. The greatest modifications in the various genera are shown by the relief of the carboniferous layer, which is verrucose or reticulate. The two outer layers are grouped as exospore, the three inner as endospore. In Absidia and Phycomyces, the zygospores are loosely surrounded by echinulate branches of the suspensors. In Mortierella, these branches 112 COMPARATIVE MORPHOLOGY OF FUNGI intertwine with the neighboring hyphae into a solid felt whose outer sur- face is cuticularized and brown. Within this tissue lies the zygospore. Thus in Mortierella, for the first time in Phycomycetes, a true fructifica- tion is formed, in Brefeld's terminology, a carpospore. The zygospores germinate only after a long resting period. The exospore is ruptured, the endospore puts forth a germ tube which develops to a mycelium or, with insufficient nourishment, directly to a sporangium (Tig. 66, 5) or a conidiophore. During germination, meiosis of the diploid nuclei occurs. Where the germ tube becomes the fundament of a sporangium (e.g., Phycomyces nitens; Burgeff, 1915) meiosis only occurs in the latter which is called a germ sporangium and, as we shall see later, is the precursor of the ascus. The sexual relationships existing at meiosis have been more closely studied for three type (Sporodinia, Mucor Mucedo and Phycomyces nitens; Blakeslee, 1904, 1906). In Sporodinia the sporangiospores are homo- thallic and the separation of the + and — energids occurs only in the formation of the copulation branches. This life cycle may be represented in the following scheme which corresponds in its fundamental characters to that of Polyphagus and Saprolegnia: f± Sporangia — *■ ± Sporangiospores P C R +Spore— *± Mycelium^+Gametangia— *-(-Coenogamete Coeno— >Zygo— *± Mycelium v zygote spore — Gametangia— >— Coenogamete Diagram IX. In the heterothallic Mucor Mucedo, the separation of the + and — energids occurs probably in the formation of sporangia; i.e., the spores are all of one sex in one sporangium and are all + or all — : + Sporangium | y -(-sporangium — >■-(- p C R t + Mycelium ^+G^metangium-*+Coenogamete I Zvgo8pore_± Mycelium vcelium— >■— Gametangium— »— Coenogamete )•'=>*' i L- ^-Sporangium-*- -Sporangium Diagram X. In the equally heterothallic Phycomyces nitens, the separation of sexes occurs only in the formation of spores. Even so, it is incomplete: besides the + and — spores, there are also unstable, neutral, bisexual spores in ZYGOMYCETES . 113 whose sporangia the separation into + and — spores is continued (Bur- geff, 1912): + Spore — > + Sporangium PC R ._> + Spores + Mycelium — -> +Gametangia — Mycelium — » — Gametangia — Spore ^ —Sporangium T T Zygo — >±Spor — >±Spores— ►+ Mycelium—* + Sporangia spore angia~~*- —Spores I Diagram XI. The systematic classification of the Mucoraceae is based on the asexual organs of fructification; but since these merge into one another through numerous transitional forms, the dividing lines are drawn by various authors in entirely different places. Four tribes should be mentioned: the Mucoreae, Cephalideae, the Chaetocladieae and the Mortierelleae. The Mucoreae (including Piloboleae) are characterized by a com- pletely developed sporangium provided with a typical columella. They include Mucor, Rhizopus, Sporodinia, Absidia, Phy corny ces, Zygorhynchus and Parasitella. They are generally saprophytic on all possible sub- strates, but Sporodinia occurs mostly on pileate fungi; Parasitella alone is preponderantly parasitic on other Mucoraceae. The Cephalideae are distinguished from the Mucoreae by the retarda- tion of spore formation which generally occurs in the extrasporangial partial sporangia. They include Choanephora, Cunninghamella, Blakes- lea, Syncephalastrum, Syncephalis and Piptocephalis. Choanephora is a feeble parasite on wilted floral organs of many phanerogams, e.g., Cucu- mis, Hibiscus and Gossypium, and causes in part a rotting of the fruit; Piptocephalis is parasitic on other Mucoraceae, the other genera are saprophytic. The Chaetocladieae form a series parallel to the Cephalideae. They are characterized by the increasing degeneration of the sporangium. Of the genera here discussed, they include the saprophytic Thamnidium and Chaetocladium, which is generally parasitic on other Mucoraceae. The Mortierelleae, finally, are marked by the absence of a columella and by their ability to form fructifications. The only well-known genus, Mortierella, is generally saprophytic; M . Bainieri is parasitic on Basidio- mycetes. The genus Haplo sporangium, which perhaps also belongs here, is saprophytic. Endogonaceae. — On account of the structure of their sporangia and the formation of fructifications, this family is closely connected to the Mortierelleae; in contrast to the latter, however, the relationships of 114 COMPARATIVE MORPHOLOGY OF FUNGI the sporangia and zygospores have not been experimentally determined. Endogone is saprophytic and generally subterranean, while Sphaerocreas, Sclerocystis and Glaziella are lignicolous. The thallus consists of multinucleate hyphae often anastomosing and becoming septate in age. The sporangia, formed in special fructifications (sporangiocarps), are known only in Endogone reniformis and E. malleola. These consist of a thick, solid, whitish-yellow pseudoparenchyma (Fig. 68, 1) which may attain a considerable size, up to 2 cm., and at times possesses a definite form (e.g., reniform in E. reniformis). In the rind layer or in special sporiferous hyphae radiating in all directions, terminal or inter- calary Mucoraceous sporangia are formed. As in Mortierella, their contents split into regular portions and finally flatten polyhedrally from Fig. 68. — Endogone malleola. 1. Longitudinal section of a sporangial fructification. 2. Young sporangium. 3. Section of mature sporangium. 4. Mature sporangium. Endogone reniformis. 5. Mature sporangium. Endogone fasciculata. 6. Young chlamy- dospore. 7. Fascicle of chalmydospores. Glaziella aurantiaca. 8. Hollow chlamydo- sporic fructification. 9. Group of chlamydospores in ground tissue. (1 X 12; 2 to 6 X 370; 7 X 67; 8 reduced; 9 X 36; after Bucholtz, 1912, and Thaxter, 1922. lateral pressure (Fig. 68, 2 to 5). The spores germinate with one or several germ tubes (Bucholtz, 1912; Thaxter, 1922; Walker, 1923). The zygospores are also united into fructifications and arise mostly inside the whitish or yellowish tuberiform hyphal knots up to the size of a hazelnut (Fig. 69, 9), which in some species contain latex organs. At present the youngest known stage of these fructifications consists of a comparatively thick tissue of ramose hyphae which at the periphery are closely intertwined and form a sort of peridium. In the ground tissue, there appear a large number of pairs of copulation branches whose development proceeds approximately simultaneous throughout the fructification. In the only species whose sexual reproduction is well known at present, E. lactiflua (Bucholtz, 1911, 1912), the copulation branches arise mostly ZYGOMYCETES 115 at the ends of hyphae or of their branches (Fig. 69, 1-2). On their surfaces they form very thin, rapidly tapering processes which later, because of the enlargement of the copulation branch, are shoved aside or toward the base. These are probably the fundaments of the hyphae which surround the zygospores at maturity. Fig. 69. — Endogone lactiflua. 1. Young copulation branches in contact. 2. Single copulation branch. 3. Two gametangia with numerous peripheral nuclei. 4. Large central nucleus in the female copulation branch. 5. Formation of copulation opening. 6. Nuclear migration. 7. Formation of hyphal sheath around zygote. 8. Zygote still connected with gametangia. Endogone incrassata. 9. Section of sporocarp with peridium and gleba. 1,2 X 400; 3 to 5, 7 X 630; 8 X 370; 9 X 10; after Bucholtz, 1912, and Thaxter, 1922.) The female copulation branch is somewhat larger and bent at the base. The copulation branches press together and bend around so that the male is surrounded by the female. Their content is granular and multinucleate. The nuclei are arranged peripherally (Fig. 69, 3) and undergo a simultaneous division, after which, in the center of the game- 116 COMPARATIVE MORPHOLOGY OF FUNGI tangium, there is a large nucleus which probably has migrated in from the periphery (Fig. 69, 4). The remaining nuclei withdraw toward the base, and are separated from the upper part by a septum. The terminal uninucleate cell corresponds to the gametangium of the Mucoraceae, the basal multinucleate cell to the suspensor. The nuclei which do not withdraw into the suspensor at the right time, degenerate. In another less well-known species, E. pisiformis (E. sphagnophila) , copula- tion is isogamous (in contrast to E. lactiflua) and all gametangial nuclei participate in the sexual act, so that, as in the Mucoraceae, many fertili- zations occur between the two gametangia, rather than a single game- tangial nucleus serving as a sexual nucleus (Atkinson, 1918). Thus both the sporangia and gametangia of Endogone seem to be directly connected with the Mucoraceae. Almost simultaneously with or directly after the formation of the basal septa, the separating walls disappear at the tips of the game- tangia and the male nucleus passes over into the female game- tangium (Fig. 69, 5 and 6). Near the copulation opening, a thin walled sac grows out on the female gametangium. The contents of both gametangia migrate into this sac which enlarges and becomes a zygo- spore; its membrane thickens, plugs the basal pore and forms a thick cartilaginous endospore. This apparently corresponds to the cartilagi- nous layer of the zygospores of the Mucoraceae. Furthermore, numerous verticillate, multiseptate, adherent sheath hyphae surround it (Fig. 69, 7), thicken their walls considerably and form in cross section the so-called halo (Fig. 69, 8). Functionally, this is possibly a substitute for the carbonaceous layer of the Mucoraceous zygospore. In this species, apparently, the nuclei fuse only on germination; in other species, such as E. pisiformis (E. Ludwigii), fusion occurs shortly after copulation. The germination of the zygospores is unknown. Perhaps it takes place only after the spores have passed through the digestive tracts of animals. In eleven other mostly northern species, as E. microcarpa and E. macrocarpa, the zygospores are replaced by similar multinucleate azygo- spores or chlamydospores (Fig. 68, 6 and 7). In E. fasciculate, the chlamydospores arise from a plexus of clearly defined, thick-walled, interlacing hyphae, forming a core from which radiate short, irregular sporiferous branches. Thus the chlamydospores are at first associated in racemose clusters. In the same fructification, the zygospores are formed as a result of homothallic heterogamous conjugation, and are in a scattered group, not in racemose clusters. In the tropical genera, Sclerocystis (Xenomyces, Akermannia) and Glaziella (G. aurantiaca, Endogonella borneensis) the chlamydospores are arranged in special layers within the fructification (Fig. 68, 8 and 9). The Endogonaceae, especially E. lactiflua, show essentially the same characters which we have come to know in the Mucoraceae, only they ZYGOMYCETES 117 are more marked in several respects. In the higher Mucoraceae, Mortier- ella, each single zygospore is surrounded by a sheath; in Endogone, numerous sheathed zygospores come together into a fructification with a common ground tissue, thus forming a sporocarp, according to Brefeld's terminology. In Sclerocystis and Glaziella this fructification shows considerable differentiation. The Mucoraceae, however, are at least morphologically slightly heterogamous, e.g., Zygorhynchus, but dynami- cally still isogamous; some species of Endogone are both morphologically and dynamically heterogamous. Thus in the Mucoraceae which have been investigated, the sexual act and fertilization directly follow each other and the gametangia (except Sijncephalis and its relatives) themselves change to zygospores; in Endogone, fertilization is retarded and a dicaryo- phase, during which the fertilized female gametangium develops into a sac which subsequently becomes a zygospore, is inserted between plasmog- amy and caryogamy. This life cycle may be represented as follows: ^- : + Sporangium*— ± Mycelium 1 *± Sporangium — *• + Spores PC R ±Sporangiospore— ♦ ± Mycelium ^*+ Gametangium — ►-fCoenogamete j Zygospore— »• ^—Gametangium — »•— Coenogamete [ Diagram XII. This scheme corresponds entirely to that of Sporodinia grandis (p. 112), except the formation of the dicaryon, caryogamy and the development of the zygospore is removed one step. Entomophthoraceae. — This family is mostly parasitic on insects, higher fungi, fern prothalli, etc., rarely saprophytic on orchid seeds and amphibian dung. The thallus is variable, ranging from a well-developed mycelium of the Basidioboleae to the hyphal bodies of the parasitic Entomophthoreae. The sexual reproduction shows a progressive development from the stage represented by Basidiobolus where a sporan- gium, still capable of developing sporangiospores, is discharged, as in Pilobolus of the Mucoraceae, to the typical conidium of the higher Mucoraceae which germinates by a germ tube. The sexual act takes place, as in the Mucoraceae, between coenocytic gametangia, which tend strongly toward heterogamy. The family may be divided into two tribes on the structure of the sexual organs and mycelium : the Basidioboleae with usually uninucleate mycelium and the Entomophthoreae with multinucleate mycelium. In the former, the zygospore membrane is formed as a new structure such as we find in the Ancylistaceae, rather than the usual type of the Zygomycetes. Basidioboleae. — At present only two species are known in this group, Basidiobolus ranarum (B. lacertae), saprophytic on the intestinal content and excrement of amphibia (Eidam, 1887; Raciborski, 1896; Fairchild, 118 COMPARATIVE MORPHOLOGY OF FUNGI 1897; Lowenthal, 1903; Woycicki, 1904, 1907, 1927; Olive, 1907; Lakon, 1926; and Levisohn, 1927), and B. myxophilus on bacterial zoogloea on fallen pine needles (R. E. Fries, 1899). The mycelium of B. ranarum develops abundantly on the excrement of frogs in 2 to 3 days. It consists of ramose hyphae whose cells when young are uninucleate and sometimes, in age or poor nourishment, multi- nucleate. The hyphae are persistent in the excrement, but in artificial culture may break up into oidia, resembling the hyphal bodies of the Entomophthoraae. After a short time, asexual reproduction begins. Each cell grows into a thin, upright sporangiophore, which projects above the medium, swells clavately at its end and absorbs the nucleus and considerable cytoplasm Fig. 70. — Basidiobolus ranarum. 1. Young mycelium with conidiophores. 2. Conid- ium germinating as conidiophore. 3. Conidium. 4. Conidium which has divided once, each half germinating with germ tubes. 5 to 8. Development of conidium and its appara- tus of discharge. (1 X 40; 2 X 140; 3, 4 X 375; 5 to 8 X 335; after Eidam, 1887.) from the cell (Fig. 70, 5 to 8). The swelling is abjointed as a sporangium. Although only a thin protoplasmic peripheral layer remains in the sporangiophore, the absorption of water from the mycelium continues uninterruptedly. When the increasing turgidity exceeds the elasticity of the membrane, the sporangiophore splits, and its dome, together with the sporangium, flies off a few centimeters. While still in the air, the portion of the sporangiophore usually falls off the sporangium. The discharged sporangium is pyriform and papillate below (Fig. 70, 3). On the papilla there is a small hyaline peg with triangular base and a small tip with a fine point where the sporangium separated from the sporangiophore . The sporangia are eaten by beetles, principally Carabidae, Scarabaei- dae and Silphidae which prowl about the excrement. These in turn furnish food for the frogs. In the intestinal tract of the frog, the nucleus ZYGOMYCETES 119 of the sporangium divides about three times, forming eight thin-walled sporangiospores, which rupture the sporangial membrane and are liber- ated. If they are retained for a long time in the intestines of the frog, they may multiply further by ordinary cell division, not by sprouting. When they are excreted they develop the normal mycelium. In artificial cultures, this process may be followed under extremely favorable condi- tions, but ordinarily the sporangia germinate with one or more germ tubes which soon end in a small secondary sporangium. The sporangia also serve biologically as hypnospores, remaining alive for at least 9 months under laboratory conditions. Their ability to germinate either by sporangiospores or by hyphae is reminiscent of conditions in Pythium debaryanum of the Oomycetes. On the excrement, with failing nourishment, the mycelium begins to form zygospores. Two neighboring cells, or two daughter cells of one mother cell, put forth directly at their septa (in B. myophilus) one each Fig. 71. — Basidiobolus ranarum. Development of zygospores. 1. Nuclei resting in the beaks with a pore already formed between the latter. 2. Completed plasmogamy. 3. Mature zygospores. (X 990; after Fairchild, 1897.) above and below, rostrate processes which approach and develop approxi- mately to one-half the cross section of the sporiferous hyphae (Fig. 71, 1). Both nuclei migrate into the beak and divide. Each daughter nucleus, cut off at the tip by a more or less marked septum, degenerates. Both other nuclei migrate basipetally. Meanwhile a pore is formed at the base of the beak; the nucleus of one cell migrates into the other cell, which has swollen in the meantime, and there lies beside the other nucleus (Fig. 71, 2). Under certain conditions, yet insufficiently known, both nuclei of the young zygospore may again divide amitotically, producing four nuclei, of which two degenerate while the other two fuse. The young zygote withdraws considerable cytoplasm into itself, swells much and surrounds itself with a thin membrane on whose inner side is laid down a thick endospore of several layers (Fig. 71, 3). Gener- ally caryogamy occurs only after two weeks; it may be hastened, however, by desiccation and may then occur after three days; conversely it may be retarded by favorable nourishment. After a rest period, the zygote may 120 COMPARATIVE MORPHOLOGY OF FUNGI germinate with a germ tube (Fig. 72, 4) which may develop to a myce- lium or sporangiophore. Entomophthoreae. — In this tribe the sporangia have become conidia, as in the higher Mucoraceae. Conidiobolus utriculosus, parasitic on Tremellaceae, may be cultivated on artificial media (Brefeld, 1884). Its Fig. 72. — Basidiobolus ranarum. 1 to 3. A conidium has divided as in Fig. 70 into two halves which behave as gametangia and form a zygospore each. 4. Germinating zygospore. (1 to 3 X 335; 4 X 575; after Eidam, 1887.) conidia germinate with a single germ tube, which in insufficient nourish- ment, ends in a secondary conidium, but under favorable conditions develops to a mycelium with numerous sacs. This is coenocytic when young; after one or two days, however, it forms numerous septa. Finally Yiq. 73. — Conidiobolus utriculosus. 1. Mycelium with condiophores. 2. Single coni- diophore. 3. Conidiophore which has discharged its conidium. 4. Copulation of two gametangia. 5. Zygospores. 6. Germination of zygospore with a conidiophore. (1 X 80; 2, 3, 6 X 200; 4, 5 X 150; after Brefeld.) it breaks up and the sacs develop to tubes, each of which grows upward, swells apically and cuts off a conidium (Fig. 73, 1). The septum projects convexly into the conidium. With the further development of the conidium the septum is reversed into the conidiophore and is subsequently differentiated into two lamellae. The conidiophore swells turgidly and ZYGOMYCETES 121 suddenly shoots off the conidium by an arching back of the wall (Fig. 73, 2 and 3), which collapses, although uninjured. The conidiophores and zygospores are formed approximately at the same time. Certain protrusions develop to thick hyphae whose tips swell after contact (Fig. 73, 4). The smaller hypha discharges its content into the larger which is surrounded by a double wall and becomes the hypnospore (Fig. 73, 5). After a few days the zygospore may germinate with one or more hyphae which generally begin to cut off conidia after a short period (Fig. 73, 6). In Condiobolus mllosus, conidia and asexual hypnospores were produced but no zygospores (Martin, 1925). The cytological relations of this species have not yet been investigated, but in the closely related Delacroixia coronata, on agarics and orchid seed, the hyphal cells and conidia are multinucleate (Gallaud, 1905). The peculiar outgrowths of the mycelium of Conidiobolus also appear in Completoria complens, parasitic on prothallia and young leaves of several genera of ferns (Leitgeb, 1882). Because its parasitism is limited to a few host cells, its thallus has undergone considerable degeneration, so that in the Entomophthoraceae, Completoria occupies a place like that of Lagenidium in the Oomycetes. The conidium germinates by a tube which forms numerous protrusions within a host cell, and finally entirely fills this cell which meanwhile has swollen to twice its original volume. Where these protrusions touch the side wall, they penetrate the neigh- boring cells where they develop to similar knobs. At the end of the vegetative period, the protrusions develop to hyphae, each of which pierces the cell walls and cuts off a conidium. The conidia are discharged by the bursting of the conidiophore. With insufficient nourishment, e.g., in young prothallia, the fungus proceeds to the formation of hypnospores. The content of the group of tubes collects in one or more parts and is surrounded with a thick wall of several layers. Entomophthora, parasitic on insects, lacks the mycelial protrusions and, in contrast to Conidiobolus, increases by sprouting and division; here the sprout mycelium is the only thallus. Entomophthora Muscae (Empusa Muscae) causes epidemics among flies in the fall (Brefeld, 1884; Thaxter, 1888; Olive, 1906). The conidia cling between the hairs of the upper surface of the body. They form a germ tube which generally penetrates the interior through the breathing pores or through the thinner membrane at the junction of the appendages or the thinner parts of the integument on the lower side of the body. Inside it develops into irregular, thick multinucleate fragments of variable form and size, called hyphal bodies. These reproduce con- tinually by sprouting and division and are distributed over the whole body by the blood vessels. After 2 or 3 days, the flies are plugged by fungi; they cling somewhere, often on window panes, and die. The hyphal bodies germinate with one or more unbranched germ tubes which 122 COMPARATIVE MORPHOLOGY OF FUNGI pierce the body wall, especially on the back of the fly and cut off a conid- ium at each tip (Fig. 74, 1 and 2), into which as many as 18 nuclei enter. Because of considerable water absorption, the conidiophores rupture directly under the septum and discharge the spores with a part of the Fig. 74. — Entomophthora Muscae. 1, 2. Development of conidiophore. 3. Catenu- late gemmae (azygospores?) within old conidiophore. (1, 2 X 720; 3 X 800; after Olive, 1906, Goldstein, 1923.) protoplasm so that the flies are surrounded by a ring of spores. In old, dried-up flies, the hypnospores arise in masses as thick- walled, multinu- cleate, intercalary swellings of the hyphae (Fig. 71, 3). Whether they should be regarded as gemmae or azygospores is still obscure (Goldstein, 1923). Fig. 75. — Entomophthora Grylli. 1 to 3. Development of zygospore from hyphal body. Entomophthora Fresenii. 4 to 7. Development of zygospore from two hyphal bodies. (1 to 3 X 145; 4 to 7 X 290; after Thaxter, 1888.) The other species of Entomphthora show essentially the same charac- ters as E. Muscae. For hypnospores they form both zygospores and azygospores. In E. Fresenii, two hyphal bodies change into gametangia and copulate (Fig. 75, 4 and 7), whereby the junction swells to a zygospore ZYGOMYCETES 123 (Thaxter, 1888). In E. Grylli, the hyphal bodies divide by a septum into two daughter cells; hereupon the content of one passes over into the content of the other (Fig. 75, 1 to 3) and this becomes a zygospore (Thaxter, 1888). In this species azygospores may be formed instead of zygospores; under favorable conditions the hyphal bodies put forth a process which takes up the protoplasm together with the nuclei, is abjointed and surrounded with a thick wall. The nuclei neither divide nor fuse. Accordingly the azygospores develop entirely parthenogene- tically (Riddle, 1907). The remaining species are distinguished by uninucleate conidia and branching conidiophores, as E. sphaerosperma (E. radicans) on the caterpillars of cabbage butterflies (Brefeld, 1881), E. Sciarae on the larvae and imago of Sciara, a small species of fly (Olive, 1906), E. geometralis on a moth (Riddle, 1907), E. americana on certain flies (Riddle, 1907), E. Delpiniana (Cavara, 1899) on Polyete lardaria, etc. The germ tube rapidly penetrates the host, especially the fat bodies, branches, and forms a coenocytic mycelium with only a few septa (Fig. 76, 1). When the fat body is consumed and the hyphae have reached the blood vessels, they divide (in some species, e.g. E. sphaerosperma) into hyphal bodies which increase by sprouting and division. Under cer- tain conditions these may be changed to gemmae by the thickening of their walls. After approximately a week, the infected insects die. The whole content, even to the tracheae and stomach contents, is used up and the insects are changed into mummies (fungus pseudomorphs). Toward the end of this time, in the species with undivided mycelium, e.g.,E. Delpiniana, the number of septa increases considerably, and the hyphae are eventually divided into cells with few nuclei. These (in other species corresponding to the hyphal bodies) develop almost simultaneously to long tubes which pierce the body wall on all sides. On the lower side of the insect they change to rhizoids and attach the dead body to the substrate. On the distal side they develop conidiophores and fork so much that the branches form a palisade and surround the insect with a thick felt. Some of these threads remain sterile and become setaceous, like the paraphyses of the hymenium in the higher fungi. The others form at each end a young conidium into which a nucleus (in E. Culicis 2) slips and which is finally cut off by constriction. They swell by continual water absorption and discharge the conidia for a considerable distance as the Piloboleae do their sporangia. The thin- walled conidia retain their ability to ger- minate for about 8 days; under unfavorable conditions each germ tube ends with a secondary conidium. At the appearance of unsuitable growth conditions, hypnospores, zygospores and azygospores are formed. In E. sphaerosperma, only azygospores are known. As the season progresses the hyphal cells no longer develop conidiophores but their content migrates into a pro- 124 COMPARATIVE MORPHOLOGY OF FUNGI tuberance which is abjointed. The empty hyphal cells break up so that the mummy seems to be filled only by resting spores. In E. Culicis and E. Delpiniana, the azygospores, like the conidia, arise as terminal swellings of the hyphae (Fig. 76, 3 and 4) and then surround themselves with double walls. In other species true zygospores are formed. In E. americana and E. geometralis, two species with hyphal bodies arise in two different ways 1 8 10 Fig. 76. — Entomophthora Sciarae. 1. Young hypha. Entomophthora americana. 2. Two gametangia fused at the tip, forming a lateral zygospore. Entomophthora Culicis. 3, 4. Development of an azygospore. Entomophthora cchinospora. 5. Copulation. Entomophthora sepulchralis. 6, 7. Development of a zygote. Entomophthora occidentalis. 8, 9. Copulation; the zygote develops from one gametangium at a distance from the point of copulation. Entomophthora sphaerosperma. 10. Development of an azygospore. (1 X 180; 2 X 500; 3, 4 X 720; 5, 8 to 10 X 290; 6, 7 X 145; after Olive, 1906; Riddle, 1907, and Thaxter, 1888.) (Riddle, 1907). In one case, hyphal bodies fuse near their tip and the zygospore buds, as in Piptocephalis (Fig. 63), laterally from the point of fusion (Fig. 76, 2). In the other case, copulation takes place, as in E. Fresenii, through an H-formed piece, whereby the zygospores, as in Syncephalis, are far removed from the point of fusion out of which a gametangium grows. Caryogamy occurs only on germination. Similar relationships are shown by E. occidentalis and E. echinospora (Thaxter, 1888), which do not break up into hyphal bodies but in which copulation ZYGOMYCETES 125 (in the latter extramatrical) takes place between hyphal ends (Fig. 76, 5, 8, 9). In E. sepulcralis within or without the host, two hyphae form lateral outgrowths which often dissolve the separating wall without abjunction from the hyphae. The zygote does not arise at the point of fusion but on a copulation branch (Fig. 76, 6 and 7). E. rhizospora forms its zygospores extramatrically like E. echinospora; in it the remaining extramatrical hyphae become sclerotia and without being dissolved change into a horny, chocolate-colored tissue which holds the spores firmly together (Fig. 77). In many Entomophthoreae only hypnospores are known. These are provisionally placed in Tarichium (Lakon, 1915). The relation to the other Zygomycetes, especially the Mucoraceae, is still obscure. As regards their asexual fructification they appear Fig. 77. — Entomophthora rhizospora. 1. Group of extramatrical hyphae, forming zygospores. 2. Old hardened hyphae which surround the zygospores with rhizoidal processes. (X 290; after Thaxter, 1888.) below these as they possess no conidiophores but only conidial hyphae. As regards their sexual fructification, however, they are on the same level. Possibly we have to do with two parallel unrelated lines. Summary. — The thallus develops from a uninucleate, centrally organized thallus to a multinucleate, eventually septate, mycelium whose hyphae are adapted to independent existence. The organs of repro- duction, sporangia and gametangia, however, remain essentially the same in their gross characters. In comparison with the thallus, they require a continually smaller supply of material and hence one individual can form increasingly larger numbers. By a premature end of develop- ment, the individualization of the daughter cells is suppressed; the sporangia become conidia, and their daughter cells assume the task of propagation; the gametangia remain equally coenocytic, a continually decreasing; number of their nuclei function as sexual nuclei, and they 126 COMPARATIVE MORPHOLOGY OF FUNGI assume the function of sexual cells, instead of gametes. Thereby arises the possibility of the transition from hydrochory to anemochory, and from hydrophily to gametangial copulation, i.e., from aquatic to terres- trial habitats. Plasmogamy and caryogamy are separated in time and place, and the diplophase is lengthened by the insertion of a short dicaryophase beyond the true zygote. The zygotes become increasingly specialized as hypnospores and finally co lect in conspicuous fructifications. CHAPTER X ASCOMYCETES The Ascomycetes are those fungi in which meiosis takes place in characteristic sporangia with endogenous spore formation. These sporangia are called asci, their spores, ascospores. Their thallus is generally well developed and much branched; its hyphae (in contrast to those of the Phycomycetes) are regularly divided by septa into uni- or multinucleate cells. Under certain conditions of nourishment, they may continue growth by sprouting; in some forms, only sprout mycelium is known. The imperfect forms reach the culmination of development in this group. Besides oidia, gemmae, etc. the most varied conidia have been known which in part are joined into stromata, pycnidia, etc.; at times these fructifications approach the perfect forms in size and luxuriance of growth. In certain families, several of the imperfect forms may appear successively or simultaneously on the same species (polymor- phism). In case the corresponding perfect form is unknown, the imper- fect forms are classified as Fungi Imperfecti and given special names; for practical reasons these are occasionally retained in plant pathology, even when the corresponding ascus form has been discovered, as often only the imperfect forms are encountered. The sexual organs are inclined toward those of the Zygomycetes and, like them, are formed as simple isogamous or heterogamous copulation branches. In the higher forms, they undergo an extensive functional and morphological differentiation: the male copulation branch becomes an antheridium and the female an ascogonium. The antheridia gener- ally exceed only by little the original size of the copulation branch, and at most they coil helically. The ascogonia undergo specific further development and in addition retain (or initiate) trichogynes; this cor- responds functionally mutatis mutandis to the fertilization tubes of the Oomycetes. In the simplest case, the sexual organs are arranged as shown in Fig. 78: a unicellular antheridium approaches an also unicellu- lar ascogonium and is surrounded by a trichogyne; thereby ascogonium and trichogyne form the female copulation branch. Subsequently both the ascogonia and trichogynes may become multi- cellular and coil characteristically and furthermore the ascogonia may be borne on stipe cells; thereby arises a typical structure which earlier was designated as Woronin's hypha, or scolecite. 127 128 COMPARATIVE MORPHOLOGY OF FUNGI Because of a peculiar weakening of sexual tendencies in the Ascomy- cetes, plasmogamy early loses it obligatory character and becomes facultative. This functional disturbance first affects morphologically only the antheridia: these become superfluous and disappear, and instead of amphimictic fertilization, appear all sorts of deuterogamous processes which we shall later follow in detail under the individual orders. Gradu- Fig. 78. — Pyronema conflucns. Sexual organs. Antheridium, Anth, and ascogonium, arch, with trichogyne, t. (X 1,750; after Claussen, 1912.) ally, however, this functional degeneration extends to the female organs; they also degenerate and disappear. Eventually no organ is formed and the plasmogamy becomes pseudogamous. Hand in hand with this degeneration, there also appears a shifting of the significance of the sexual organs for the formation of fructifications. Originally the laying down of the fructifications was begun by the formation of sexual organs; hence the female organ was called archicarp. In many higher forms, the fructifications begin their development inde- ASCOMYCETES 129 pendent of the sexual organs, by the physiological stimulation of nourish- ment, and the sexual organs are later formed in them. As was the case in the Endogonaceae, so also in the Ascomycetes, plasmogamy is not followed directly by caryogamy but one or several dicaryons are formed (according to the number of gametangial nuclei). In the lower forms the dicaryon migrates directly into an ascus (as into the zygote of Endogone) which is formed as the product of the plasmogamy. In the higher forms, caryogamy is more and more retarded and the fertilized gametangium develops into one or more hyphae which take up the dicaryon and, by conjugate division, branch and proceed to the formation of asci. These dicaryotic hyphae are called ascogenous Fig. 79. — Pyronema confluens. Development of ascogenous hyphae. Claussen, 1912.) (X 1,165; after hyphae; biologically they offer the advantage that, in contrast to the lower forms, one gametangium can create a number of asci. In most of the higher Ascomycetes, the asci arise on the ascogenous hyphae according to the hook type. In this connection may be men- tioned Pyronema confluens. The ascogenous hyphae springing from the ascogonium are coenocytic, i.e., they contain a number of dicaryons (Fig. 221, 1), and develop by repeated forking, more or less vertically toward the top of the future fructification. Subsequently they divide by septa so that in the neighborhood of the ascogonium, the cells contain 2 to 8 dicaryons and farther away only one (Fig. 221, 2). A cell with only one dicaryon puts forth a lateral process whereby the nuclei become 130 COMPARATIVE MORPHOLOGY OF FUNGI rather far separated; shortly the process bends around into a hook (Fig. 79, 2) and the nuclei begin to divide conjugately and to draw into a layer (Fig. 79, 3). The spindles lie approximately parallel to each other. After the division, the crook is abjointed from both the tip and the stipe (Fig. 79, 4) ; thus the crook contains two nuclei, while the tip and stipe contain one nucleus each. In the simplest case, the nuclei of the crook fuse to a diploid nucleus, the primary ascus nucleus (Fig. 79, 5), and the crook develops to an ascus. In another case, the crook develops to a new hook, which again develops, etc., so that several lie transitorially behind one another (Fig. 79, 6 to 8) ; only the last terminal hooks proceed to ascus formation. In the third case, the dicaryon of the hook divides without a previous formation of a new hook. The crook develops a branch which only later returns to hook formation; on these hooks, asci may arise directly; or caryogamy may be again displaced, so that a tuft of hooks arises (Fig. 79, 8). By the combination of these various possi- Fig. 80. — Geopyxis catinus. Development of ascogenous hyphae. 1905.) (After Guillermond, bilities there have arisen those manifold pictures which have so long delayed the morphological comprehension of ascogenous hyphae. Occa- sionally hook stipe and hook tip fuse, the stipe nucleus generally migrat- ing into the tip (Fig. 79, 5 and 6); the tip cell which has now become binucleate develops a branch which gradually forms a hook; this hook can, by fusion of its nuclei, develop directly to an ascus or again (Fig. 79, 8) grow into a transitory tuft of hooks. Besides the characteristic formation of hooks, the ascogenous hyphae of Pyronema confluens pass through two morphologically different phases of development. In the first phase (directly after development from ascogonia), they are coenocytic and longitudinally striate and develop with normal growth of the tip; in the second phase (after the growth from septate hyphae), they only develop further by hook formation and have only one dicaryon in each cell. The most striking development of pri- mary and secondary ascogenous hyphae, we meet in the Plectascales. In addition to the hook type, a whole series of other developmental forms of ascogenous hyphae is known in the higher Ascomycetes. In ASCOMYCETES 131 Geopyxis catinus (Peziza catinus), the terminal cell of the ascogenous hypha (like the hook cell of Pyronema confluens) is uninucleate, the sub- terminal is binucleate (Fig. 80) . This subterminal cell grows out laterally and develops to an ascus (Guillermond, 1905a). Somewhat further removed is the Plicaria (Galactinia) type, (Maire, 1905) which includes Plicaria succosa (Galactinia succosa) and Acetabula leucomelas (Peziza leucomelas). In these, the ends of the ascogenous hyphae include a series of cells with a dicaryon each, the terminal cell of which develops to an ascus by the fusion of its nuclei. This type, how- ever, in spite of its morphological picture, which is entirely at variance with the Pyronema type (as also the systematic relationships of all these forms would allow us to suppose), does not seem to be fundamentally different. As an anomaly in Pustularia vesiculosa (Peziza vesiculosa), the ascogenous hyphae may form a hook of the Pyronema type, whose crook cell, instead of developing to an ascus by repeated division of its dicaryon, grows into an elongate hypha whose terminal cell proceeds to the forma- tion of an ascus according to the Plicaria type. Still further removed from the hook type, is a fourth which has not yet been investigated cytologically. In it the cells of the ascogenous hypha, as in the Plicaria type, apparently each contain a dicaryon. A large number of them, however, develop asci (in contrast to the Plicaria type) so that the asci lie behind each other, as in a chain, and then divide. Possibly this type is the most primitive of the four, as it has only been definitely ascertained in the lower Plectascales. It has been named by Dangeard (1907) the rectascous type in contrast to the curvascous type of Pyronema. In a fifth type, finally, no true ascogenous hyphae are formed, but asci develop from a cell complex which arise directly from the fertilized cells of the ascogonium. We will discuss this type more fully in the Laboulbeniales. The further development of the asci, as far as is known, is the same in all Ascomycetes. The primary ascus nucleus, which has arisen from the fusion of the dicaryon, undergoes three steps in division with meiosis, whereupon the eight daughter nuclei cut out eight ascospores from the cytoplasm of the ascus by free cell formation. The cytoplasm remaining behind is called epiplasm; in addition to the nourishment of the ascospores growing in it, it provides for the formation of the sculpturing of the spore walls. In certain forms, the number of divisions may be limited to two or rise to sixteen, whereupon in the first case the number of nuclei is reduced to four, in the second rises to many thousand (64,936). In case the asco- spores are thick walled, they possess a typical terminal germ pore or a meridional slit; in the latter case the two halves of the ascospore wall separate in germination like the cover of a box. According to the Anglo-Saxon school (especially represented by Harper and Gwynne- 132 COMPARATIVE MORPHOLOGY OF FUNGI Fig. 81. — Phyllactinia corylea. 1. Young ascus with dicaryon. 2 to 4. Caryogamy. 5. Spireme. 6 to 9. Steps in division of primary ascus nucleus. Erysiphe cichoracearum. 10 to 12. Spore formation. 13. Immature ascus. (1 to 5 X 1,500; 6, 13 X 1,000; 7 to 12 X 670; after Harper, 1905.) ASCOMYCETES 133 Vaughan (nee Fraser) the nuclear fusion in the young ascus is not the first and only fusion, but is preceded by another fusion in the ascogonium directly after the sexual act. The ascogenous hyphae, according to this conception, do not contain haploid dicaryons but undivided diploid nuclei which only after the formation of the hooks, come together to dicaryons. Because of this double fertilization, this primary ascus nucleus is tetraploid, and, according to this school, contains 2x double chromo- somes. In the first step in division (heterotypic division or meiosis) each daughter nucleus contains 2x simple chromosomes. The second step is homoeotypic, the 2x simple chromosomes are halved so that every daughter nucleus still contains 2x simple chromosomes. In the third step (brachymeiosis) one-half the undivided chromosomes migrate to each pole, so that the daughter nuclei of the third generation contain x simple chromosomes. Although the cytological findings in part contradict each other (Guillermond, 1913) e.g. Claussen (1912) states the haploid number is 12 while his figures never show more than 6 (Tandy, 1927) — and in part may be interpreted to either conception, at present the author prefers the theory of simple fertilization as developed by Dangeard (1907) and Claussen (1912). According to this conception, the life cycle of the Ascomycetes in the ideal case proceeds according to the following scheme : Conidia I P C R ' \scoeonia -♦Ascogenous Hyphae— >Asci—>Ascospores Mycelium^Ascogonia ^Antheridia im\ Diagram XIII. There arise on the haplont, first imperfect forms, then sexual organs (antheridia and ascogonia). Between these sexual organs plasmogamy takes place, whereby each male and female nucleus pair as a dicaryon. These dicaryons migrate into the ascogenous hyphae and divide con- jugately. The ascogenous hypha, thus, caryologically represents a special phase of the diploid phase, the so-called dicaryophase ; to be sure, this is virtually diploid; cytologically it only produces dicaryons from two sexually different haploid nuclei. The dicaryophase, and with it the sexual process altogether, ends with nuclear fusion in the young asci (caryogamy). Caryogamy is followed directly by meiosis, usually producing eight haploid ascospores. In the higher Ascomycetes, this scheme of development is further complicated, since the haploid thallus proceeds to form fructifications on or in which the ascogenous hyphae complete their development. As in most Florideae and in the sporophyte of the mosses, the dicaryophyte is to a certain extent parasitic on the haplont and nourished by it. 134 COMPARATIVE MORPHOLOGY OF FUNGI In the simplest case, these fructifications form an undifferentiated mass of tissue, a stroma, on or in which the asci are formed. A fructifica- tion of this sort is called ascostroma or ascoma; it corresponds approxi- mately to the sporodochium and acervulus of the fructifications of the imperfect forms. In the higher forms, the hyphal tissue of the stroma undergoes many differentiations both in form and histological structure, and develops to fructifications which form the basis for the systematic classification of the Ascomycetes. All these higher fructifications are referred to two basic forms, perithecium and apothecium. The perithecia (Fig. 82) consist of a solid, often pseudoparenchyma- tous, wall and a cavity containing the asci. The more primitive types are usually spherical ; the asci lie irregularly in the interior and are only liberated at the decay of the perithecial wall; thus the lower forms are cleistocarpous. In the higher types, they are generally flask shaped; at their top, there is formed by the periclinal arrangement of the hyphal elements during the course of development, a special open- ing (ostiole) whose canal is often closely covered with hyphal ends, periphyses (Fig. 82, e). Between the asci (generally basal), there are arranged sterile, haploid, hyphal branches, the paraphyses, which serve chiefly to nourish the growing asci. While young they are rich in reserve materials; during development of the fructification they become vacuolate and in some forms finally disappear. The liberation of the ascospores from these flask-shaped perithecia takes place in various ways. In many forms, they are liberated into the interior of the perithe- cium by the disintegration of the asci and are then gradually pushed out. In other forms, they are actively shot out. A good example was described by Zopf (1883), for two relatives of Podospora fimiseda {PI cur age fimi- seda) shown here, P. minuta and P. curvula, which, because of their transparent perithecia, allow one to follow under the microscope the course of spore discharge in the unaltered living perithecium. The asci are cylindrical and at the beginning of the discharge period their upper third broadens. Hereupon one ascus after another elongates, penetrates the opening of the perithecium and projects above the ostiole. Then it bursts and shoots off its top, with ascospores firmly attached to it and to in> Fig. 82.- — Podospora fimiseda. Perithecium. e, periphyses ; o, asci ; s, ascospores; m, hyphae. (After Tavel, 1892.) ASCOMYCETES 135 each other by a gelatinous appendage. The rest of the ascus collapses, withdraws and makes place for the next. The height of projection of the ascospores occasionally attains a relatively enormous value if one considers that the perithecia are only about half a millimeter high in the middle. Thus in Podospora fimiseda, it reaches 15 cm. and in P. curvi- colla, as high as 45 cm. (Weimer, 1920). In other forms, as Leptosphaeria acuta (Hodgetts, 1917), Pleospora her- barum (Atanasoff, 1919) and P. scirpi- cola (Pringsheim, 1858), this discharge is favored by an anatomical differentia- tion of the ascus wall. This consists of two layers which are only recognizable at the moment of spore liberation, a rigid inelastic cuticular outer layer which does not swell in water, and a thicker gelatinous inner which absorbs water and swells. The paraphyses also swell in damp weather. By the pres- sure of the swollen inner layer, the outer ruptures at the tip, the inner together with the ascospores pushes out, tears open laterally with a jerk at the point of emergence or at the top and dis- charges the ascospores. In still other forms, as in Endothia parasitica and in many Gnomoniaceae, the length of the perithecial neck does not permit the asci, as in Podospora, to reach the opening and there to eject their spores. Hence they break loose from their point of formation and closely press together, more or less parallel, with the tip, directed toward the entrance canal and fill up the interior of the peri- thecium. Hereupon they are gradually pressed out through the canal by the periphyses. On the drying of the peri- thecial neck, the asci are pressed together until they rupture under the lateral pressure and discharge their spores. Thus the mechanism of discharge here rests in the perithecial opening; if this is cut off, at least in Endothia parasitica, spore discharge ceases (Heald and Walton, 1914). The apothecium, the second basic form mentioned above, differs from the perithecium mainly in the greater development of the fertile Fig. 83. — Humaria convexula. Above, cross section of apothecium. ( X 20.) Below, section of hymenium showing asci and paraphyses. (X 550; after Sachs.) 136 COMPARATIVE MORPHOLOGY OF FUNGI part (Fig. 83) ; consequently the asci are united into a broad continuous layer, a hymenium, which in certain forms, especially lichens, can occasionally continue its growth for years. By this lateral development of the fertile part, the top of the fructification is ruptured into shreds, so that at maturity the hymenium is exposed. As with the perithecia, the asci in the apothecia are generally imbedded between paraphyses (Fig. 83) ; at times, as in certain Geoglossaceae, these arise in special rich storage cells similar to the auxiliary cells of the Florideae and hence show their primary function as nutritive organs. Corresponding to the open position of the mature asci, the violence of ascospore discharge has undergone a considerable increase. In several groups, the top of the ascus opens like a cover whereupon the ascospores are shot out with great force (in Ascobolus immersus up to 35 cm. high), and, as in the perithecia, are given over to an anemochoric dissemination. As in the discharging perithecia, so also in the discharging apothecia, all spores of one ascus remain clinging together by gelatinous shreds or sheaths, so that an enlargement of the discharged mass is attained; thus the volume of one of these spore balls of Ascobolus immersus is about 2,000 times larger than that of a basidiospore (Buller, 1909); thus may easily be explained the greater momentum with which these fungus "cannons" shoot off their projectiles. As in many discharging perithecia, e.g., those of Endothia, so also in many discharging apothecia, the activity of the asci is largely dependent on external influences (Falck, 1916); still others react chiefly to mechanical stimuli, as those which are liberated by cur- rents of air or wind (Falck, 1923). Systematic classification of the Ascomycetes rests upon the degree of development of the dicaryophase. Those forms in which the dicaryo- phase is lacking and in which the sexual cells and ascus arises directly as the product of a sexual act are called Hemiascomycetes; those forms in which the sexual organs (Thelebolus and the Laboulbeniales excepted) developed to ascogenous hyphae which in turn are adapted to the formation of numerous asci are called the Euascomycetes or typical ascomycetes. We will discuss briefly, in the review at the close of the Ascomycetes, the probable phylogeny of these two subclasses and the phylogenetic derivation of the Ascomycetes as a whole, when the reader will have oriented himself in the various forms. CHAPTER XI HEMIASCOMYCETES The Hemiascomycetes form the link between the Ascomycetes and the Phycomycetes. According to the classification followed here they fall into two orders, Endomycetales (Saccharomycetales) and Taphrinales (Exoascales). The Endomycetales include those forms in which an ascus arises directly as product of the sexual act (wherever this takes place). They resemble the Zygomycetes, as will appear in the following discus- sion, only, instead of the zygospore, an ascus develops as a hypnospore. The Taphrinales include two isolated, incompletely investigated families which have some primitive characters in the development of their asci, without any closely related forms in the Ascomycetes known at present. ENDOMYCETALES The Endomycetales are divided into three f amilies : the Dipodascaceae, the Endomycetaceae and the Saccharomycetaceae. In the Dipodas- caceae, a multispored ascus arises from the copulation of coenocytic gametangia. In the Endomycetaceae, the gametangia (wherever they are formed) are uninucleate at the time of copulation ; each zygote devel- ops to a typical ascus of eight or fewer spores. In the Saccharomyce- taceae, gametangial copulation is replaced by a pseudogamy whose product (if it really is completed) is a typical ascus of not more than eight spores, as in the Endomycetaceae. Both the Endomycetaceae and Saccharomycetaceae develop rapidly to apomictic forms. Dipodascaceae. — The only known representative of the family, Dipodascus albidus, was originally found in the slime-flux of a bromeliad in Ecuador, later in the same habitat on birch in Sweden. The hyphae are branched, septate, divided into multinucleate cells of variable length. In nutritive solution, they break up into oidia. Under unfavorable conditions, they form gemmae: their content rounds off and surrounds itself with a thick membrane. After a few days, two neighboring cells put forth young copulation branches directly beside the septum separating them (Fig. 84, 1). At first both copulation branches are of the same size and it is impossible to determine which will later be the male and which the female. Frequently the female branch appears somewhat earlier and survives through the whole development of the male. Occasionally both copulation branches may arise from different hyphae (Lagerheim, 1892; Juel, 1902; 1921; 137 138 COMPARATIVE MORPHOLOGY OF FUNGI Dangeard, 1907). When the copulation branches have attained a certain length, their tips come in contact, whereupon they abjoint from Fig. 84. — Dipodascus albidus. 1. Young copulation branches not yet abjointed. 2. Diploid nucleus in female copulation branch. 3. First step in division of diploid nucleus. 4. Telophase of 3. 5, 6. Later stages of young ascus. 7. Nearly mature ascus, the dark points indicating degenerate nuclei. (1, 2, 5 to 7 X 900; 3 X 800; 4 X 600; after Juel, 1902 and 1921; Dangeard, 1907.) the sporiferous hypha, an apical gametangium of 10 to 12 nuclei; generally the septum lies near the hypha, but it may be shifted rather far toward the top, in which case the gametangia rest on suspensor-like stipes. HEMIASCOMYCETES 139 When the septum between two gametangia is dissolved, a sexual difference between the copulation branches begins to appear. Nuclei of the male gametangium migrate into the female, whereby a male and a female nucleus fuse in the gametangium near the copulation canal (Fig. 84, 2). The female gametangium develops an elongate tapering ascus at the tip, while the male ceases development. The fusion nucleus which was originally very large, undergoes several successive divisions whereby the daughter nuclei gradually approach in size and appearance the super- numerary original gametangial nuclei and finally may not be distinguished from them (Fig. 84, 3 to 6). Each cuts out of the cytoplasm a large, thick-walled ascospore while the non-functional gametangial nuclei gradually degenerate (Fig. 84, 7). At maturity, the ascus opens at the tip. The spores, with the rest of the protoplasm, are forced out and col- lect before the opening as a slimy, sticky ball. They are capable of immediate germination. As an exception, this development may take place parthenogenetically where the gametangia develop asci without fusion. The fertilization of Dipodascus is strikingly reminiscent of that of Endogone. As in the latter, only one gametangial nucleus is activated as a sexual nucleus; only, at least in Endogone pisiformis, the supernu- merary unprivileged nuclei are pushed out of the gametangium, while in Dipodascus they remain in the gametangium and only are resorbed in the development of the ascus. Furthermore, the product of the sexual act is a thick-walled hypnospore in Endogone while it is a sporangium in Dipo- dascus. These differences may be explained, however, by the different biological conditions of the two genera. Even the free cell formation of Dipodascus can cause no difficulty in the conception. If the content of the asci were divided by cleavage, as is always the case in the sporangium of Endogone and other Zygomycetes, the unactivated gametangial nuclei would survive in the spore. That can only be avoided if each daughter nucleus of the fusion nucleus forms a membrane within its sphere and leaves the unused protoplasm with the original vegetative nuclei as peri- plasm. Hence it appears justifiable to seek the roots of the Dipodas- caceae in the Zygomycetes with a life cycle of the type of Endogone. Endomycetaceae. — This family is often saprophytic on sugar con- taining substrates, in the slime-flux of trees, the ambrosia fungi in the borings of Coleoptera, more rarely parasitic in fructifications of Agari- caceae and on man. Some of the species are used in Asia and Africa by the natives as yeasts for fermentation. The best-known representatives are Eremascus and Endomyces. In the former were originally placed the sexual, in the latter the asexual forms; more recent investigations have entirely destroyed these differences. As a starting point Eremascus fertilis on fruit juices (Stoppel, 1907; Guillermond, 1909) should be mentioned. The hyphae are often branched 140 COMPARATIVE MORPHOLOGY OF FUNGI and consist of long, narrow cells which are multinucleate (up to 15) in the neighborhood of the growing tip (Fig. 85, 1). In the older part, however, they are uninucleate by septation. Approximately 5 days after sowing in artificial culture, two cells form copulation branches in the region of their septa (Fig. 85, 2). The copulation branches do not always arise simul- taneously, however, and their length is often unequal; also, both proc- esses may not arise from neighboring cells but from cells separated by a small, intermediate sterile cell. If they are not too short, they make a half to complete turn about each other. In Eremascus albus (Eidam, 1883a), they coil helically (Fig. 86). Their tips touch, the walls at the point of contact are dissolved, and the two copulation branches come into open communication. The M Fig. 85. — Eremascus fertilis. Development of asci. (X500; after Guillermond, 1909.) nucleus of the hyphal cell divides; one daughter nucleus remains behind in the hyphal cell, the other wanders out into the copulation branch, and fuses there with the nucleus of the other branch (Fig. 85, 4 to 8), The zygote (the bend of the copulation bridge) swells up to an ascus, which is ab jointed from the copulation branches; its nucleus divides thrice and the eight spores are surrounded by a double membrane (Fig. 85, 9 and 10); occasionally some spores remain behind in development and degenerate. The spores are liberated by disintegration of the asci. At germina- tion the spores swell to twice the size, rupture the exospore to form one or more germ tubes which, after repeated nuclear division, develop to hyphae. In addition to this normal development, cases of parthenogenesis occur occasionally; two copulation branches may swell to asci without copulation; similarly, a copulation branch which finds no partner may develop independently (Fig. 85, 11); besides, especially in old cultures, HEMIASCOMYCETES 141 even the hyphal cells, though they earlier may have formed a copulation branch, swell up themselves parthenogenetically to asci (Fig. 85, 12 to 14), which are generally smaller than the diploid, but like the latter, may have eight spores or some spores may abort. From the type of Eremascus fertilis, there are two developmental series, one includes isogamous forms like E. fertilis, the other heterog- amous forms. Both, however, may develop parthenogenetically. In the isogamous series there may be directly connected to E. fertilis, the Endomyces fibuliger, originally isolated from spoiled bread. Its hyphae are always uninucleate, and show (in contrast to Eremascus fertilis a tendency to disintegrate into oidia which develop to a sprout mycelium. Furthermore, the hyphal cells also may proceed to sprouting (Fig. 87, 8). This development from sprout mycelium is apparently connected with an extensive adaptation of the fungus to starch and sugar-containing media: thus Endomyces fibuliger, in contrast to Eremascus fertilis, is able to ferment sucrose and some monosaccharides. Wherever the Fig. 86. — Eremascus albus. Development of copulation branches and ascus. ( X 600 ; after Eidam, 1883.) budding cells arise on aerial mycelium, the diameter is smaller and the wall somewhat thicker than in the submersed sprout cells. They are then very resistant and survive a long period in temperatures up to 55° ( !. Biologically, they apparently possess the significance of gemmae and, because of the exogenous formation, may be designated as conidia. As in Eremascus fertilis, every two cells form copulation branches which may approach each other; only very rarely however, after the dissolution of the wall, are the two nuclei joined into a fusion nucleus (Fig. 87, 1). Generally the copulation branches develop parthenogenet- ically, even when the separating walls are temporarily dissolved (Fig. 87, 5). As an exception, a pseudogamous anastomosis of two sprout cells may occur in which one changes to an ascus (Fig. 87, 2 to 4). In a large number of cases, no copulation branches are formed but the asci, like the sprout cells, arise as lateral outgrowths of the hyphal cells (Fig. 87, 6 and 7) ; then, however, they are three to four times larger than the ordinary sprout cells. Occasionally they arise from ordinary hyphal cells by swelling, or from swelling sprout cells. When they begin to appear the formation of sprout cells slows up, but does not 142 COMPARATIVE MORPHOLOGY OF FUNGI cease, and thus hyphae may form sprout cells and asci simultaneously. One finds even young asci which continue to cut off sprout cells until they begin spore formation. Periods of vegetative growth and fructification are thus not sharply separated from each other. The asci contain four spores of a peculiar hat shape, such as we shall meet later in Endomyces decipiens and in Willia of the Saccharomyceta- cese. At germination they throw off the exospore and germinate with either germ tube or sprout mycelium (Dombrowski, 1902; Guillermond, 1909, 19106, 1913a). Ylo. s7— Endomyces fibuliger. Development of asci. (X 500; after Guillermond, 1909.) In contrast to Eremascus fertitis, in Endomyces fibuliger sexuality is so completely weakened that the sexual organs may only be explained as vestiges. In a large number of cases, no copulation tubes are formed and the asci arise directly from vegetative hyphae or sprout cells. In the following forms, the copulation branches no longer fuse, they are formed less frequently and the asci arise parthenogenetically throughout. The growth of mycelium through sprouting increases proportionally. In two Chinese species, E. Lindneri and E. Hordei, the copulation branches no longer change directly to asci but develop to a short, occasionally branched mycelium (Fig. 88, 1 and 2), on which the asci arise by swelling of the hyphal cells. In the majority of cases the asci HEMIASCOM YCETES 143 are formed directly from the sprout cells, without this detour (Mangenot, 1922). Both species ferment sucrose and a series of monosaccharides. In two other species which terminate the isogamous development, Endomyces javanensis and E. capsularis (Saccharomycopsis capsularis), the copulation branches have entirely disappeared (Fig. 88, 3 to 5). According to cultural conditions, either the hyphal or sprouting condition preponderates. At the end of the hyphae, there arise by swelling of cells or by lateral sprouting, at times also intercalary, four-spored asci whose spores are divided into two unequal halves by annular thickenings (Guillermond, 1909). Both species have been isolated from earth, the former in Java, the latter in the Swiss Alps. In both, the fermenta- tive ability is small. Fig. 88. — Endomyces Lindneri. 1, 2. E. capsularis 3 to 5. Development of asci. (1, 2 X 470; 3 to 5 X 500; after Mangenot, 1922, and Guillermond, 1909.) The second, heterogamous series is connected to the Eremascus fertilis type through Endomyces Magnusii, found in the slime-flux of trees. Its hyphae are generally multinucleate (2 to 8); in the growing hyphal tips the number of nuclei may mount to 50 (Fig. 89, 1), in weak hyphae it may sink to one. In contrast to Eremascus fertilis, and like Endomyces fibuliger, the hyphae divide easily into oidia; naturally these are generally multinucleate, rarely uninucleate, with a tendency toward the uninu- cleate condition. Often they thicken the wall and become gemmae (Fig. 89, 14); hence under certain conditions, e.g., in Raulin's solution, the whole culture may disintegrate after two weeks into oidia which change into gemmae. Under favorable conditions the oidia, as in E. fibuliger, may develop to sprout mycelia. This, however, does not take place by the inde- pendent development of the small outgrowths of the mother cell to sprout 144 COMPARATIVE MORPHOLOGY OF FUNGI cells, but by the fission of the mother cell so that both daughter cells round off and develop to the size of the mother cell (cell division, in contrast to sprouting) . When the mycelium is ready to form asci, it assumes a characteristic habit: it branches into numerous, short, slender branches with short cells which contain only a small number of nuclei, often only one (Fig. 89, 3 and 4). The branches end either in a very large cell full of reserves, the female copulation branch, or in a narrow, often twisted branch with hyaline content, the male copulation branch. The upper third of the female copulation branch swells considerably and collects the cytoplasm Fig. 89. — Endomyces Magnusii. 1. Young multinucleate hypha. 2. Older hypha. 3 to 13. Development of asci. 14. Gemmae. (1, 2, 14 X 1,500; 3 to 13 X 500; after Guillermond, 1909.) with two or three nuclei. At the beginning of copulation, it bends over somewhat to meet the male copulation branch. In this stage, the swollen part contains only one nucleus, the others have migrated down- ward (Fig. 89, 5). The narrow male copulation branches contain one to three nuclei when young, of which only one remains at the tip. In approximately three-fourths of the cases, copulation occurs between the male and the female copulation branches. The male copulation branch approaches the female, swells slightly and ab joints the apical uninucleate gametangium from the stipe cell. Meanwhile the uninucleate tip of the female copulation branch is ab jointed from the stipe cell. Hereupon the walls separating the gametangia are dissolved and the zygote develops to a 4-spored ascus (Fig. 89, 6 to 8). HEMIASCOM YCETES 145 In addition to this usual course of development, there occur also numerous variants; thus, the male copulation branch may approach the female at the side instead of the tip (Fig. 89, 8); or the copulation branches may contain only a single nucleus with no ab junction of the stipe cell; or the female gametangium may develop parthenogenetically without copulation (Guillermond, 1909). In Endomyces decipiens, which is also characterized by the type of cell multiplication but contains uninucleate cells, sexual organs are almost entirely absent (Brefeld, 1891; Dangeard, 1907; Juel, 1921). It is parasitic on fructifications of Armillaria mellea and fruits in the lamellae. The asci arise on the hyphae as small branches which swell into sacs and Fig. 90. — Endomyces decipiens. Development of asci. ( X 800; after Juel, 1921.) are abjointed from the hypha. As a rare exception, a sexual act takes place (isogamously!). Although occasionally three nuclear divisions occur in the asci, they always contain only four spores which, as in E. fibuliger, cucullate. In cultures, the hyphae break up into uninucleate oidia. On branches they form thick-walled, yellowish gemmae the size of asci which, under suitable conditions, germinate with one or more germ tubes. E. decipiens has reached the same height as E. javanensis and E. capsidaris in the isogamous series. Let us review the course of presentation. The Endomycetaceae contain some forms with completely developed sexuality, such as Eremas- cus fertilis and the heterogamous Endomyces Magnusii. Their life cycle may be illustrated as follows: I PC. R Mycelium— »Gametangia-+Ascus— >Ascospores Diagram XIV. Thus the gametangia which copulate without further differentiation arise on a hermaphrodite mycelium. The zygote develops to an ascus in which 4 to 8 ascospores are formed by meiosis. This life cycle is essentially the same as Dipodascus, Basidiobolus, Entomophthora, etc. 146 COMPARATIVE MORPHOLOGY OF FUNGI In Eremascus fertilis, the division of the hyphal nucleus before copulation is strongly reminiscent of Basidiobolns, in Endomyces Magnusii the extrusion of the supernumerary nuclei is reminiscent of Endogone. Only the zygote in Basidiobolus and Endogone develops to a hypnospore, while in Eremascus fertilis and Endomyces Magnusii to a sporangium in which are formed the ascospores which function as hypnospores. From these sexually well-developed forms, there may be observed a gradual decline of sexuality. Thus in a second stage, Endomyces fibuliger, the copulation branches can still copulate; however, they usually develop parthenogenetically, so that the life cycle almost disappears in the haploid phase; Mycelium— >-Gametangia— >Ascus— * Ascospores Diagram XV. Nevertheless, in E. fibuliger sexuality is not entirely suppressed; it is possible for two sprout cells to copulate; no special sexual organs are used, but the sexual act is shifted into the thallus and takes place pseudogamously : PC R Mycelium— >Sprout cells— ^Ascus— > Ascospores Diagram XVI. Finally, in the third and last stage, E. javanensis and E. capsularis, the functionless gametangia are no longer formed; similarly, the sexual act no longer takes place between two vegetative cells, and the thallus mostly disappears in a sprout mycelium. Thus the life cycle is as follows : I 1 Sprout mycelium— >Ascus— ► Ascospores Diagram XVII. Herewith morphologically we arrive at the stage of the yeasts. Before we proceed to the discussion of this family, two more genera, Pericystis and Ascoidea, should be briefly mentioned, which, although insufficiently known, certainly belong in the vicinity of the Endomycetaceae. Peri- cystis apis, the cause of chalk brood of bees, is a heterothallic form in which the sexual dimorphism marks even the habit of the mycelium. A multispored ascus is formed by copulation of two gametangia of unequal size (Claussen, 1921). P. alvei (A.D. Betts, 1912) occurs on stored pollen in beehives. Ascoidea rubescens forms a thick reddish-brown mass in the slime-flux of beech. It is composed of felt-like tissue of ramose, septate hyphae, HEMIASCOM YCETES 147 whose membrane is hyaline in youth, but appears brownish in age. Hyphal ends swell to conidia. Lateral outgrowths of hyphae form new conidia which push aside the previous ones so that finally a tuft of as many as 30 conidia is formed (Fig. 91, 1). The conidia are quite variable in size ; in general the earlier ones are larger than the later. They germi- nate with germ tubes which, with liberal nourishment, grow into mycelia or, with poor nourishment, form new conidia (Fig. 91, 2.). After a time, the conidia are gradually replaced by asci (?). The hyphal ends swell as in conidial formation, abjoint, and change into Fig. 91. — Ascoidea rubescens. 1. Conidiophore and conidia, o. 2. Conidium, a, germinating under unfavorable conditions, cutting off conidium, b. 3, 4. Conidial and ascigerous hyphae, a, conidia; b, ascus discharging spore mass, /, while the second ascus, c, forms within the wall of the first; d, e, ascus fundaments. 5. Ascigerous hyphal tip; ac, evacuated ascus walls; d, youngest ascus fundament, e, spore in the gelatinous sheath, /. (1, 3, 4 X 80; 2 X 120; 5 X 540; after Brefeld, 1891, and Tavel, 1892.) multinucleate asci. After many nuclear divisions, its contents divide into numerous small, uninucleate, cucullate spores which at first are joined in pairs. Corresponding to the variable size of the ascus, they are also indefinite in number; however, they are distinguished by a remarkably regular form, similar to that of Endomijces decipiens. Like the Mucor spores, they are embedded in a finely granular, strongly swelling inter- mediate substance. At maturity this expands greatly with water absorp- tion, pushing from the strongly swelling sporangial tip like a screw, and, together with the imbedded spores, is liberated as a vermiform mass 148 COMPARATIVE MORPHOLOGY OF FUNGI (Fig. 91, 3 to 5). After repeated nuclear division, the spores germinate within the intermediate substance by germ tubes which usually proceed again to conidial formation. The complete evacuation of the ascus is only effected by the stipe cell beneath developing to a new ascus; in proportion as this new structure bulges upward, the remainder of the spore mass is pushed out. This sporangial proliferation may be repeated up to twelve times; it is very reminiscent of the relationships of the Saprolegniaceae where it is placed by Lohwag (1926). Unfortunately, the cytological details of the life cycle of this interesting species are still insufficiently known; possibly it develops parthenogenetically (Brefeld, 1891; Popta, 1899; Lohwag, 1926). Saccharomycetaceae. — The yeasts may be regarded as direct deriva- tive of the Endomycetaceae in which the growth of the thallus by sprout- ing has become entirely prevalent. Some forms, as Saccharomy codes Ludwigii, Debaryomyces Kloeckeri, Ztjgosaccharomyces Priorianus and Pichia membranifaciens, under certain conditions of nourishment, e.g., on gelatin substrates, can still form true hyphae; these are unstable, however, and with a slight alteration of the substrate break up into sprout mycelia. The sprout cells are generally spherical or ellipsoidal, and hyaline, the size varying according to substrate and age. Under unfavorable condi- tions they can store fat and glycogen and surround themselves with a double membrane. These resting cells are very resistent to environment and can carry over unfavorable periods; probably they correspond to the gemmae in Endomyces. At germination, the outer fragile wall is rup- tured and the cells grow into a sprout mycelium. We may distinguish two tribes of the Saccharomycetaceae according to the type of cell multiplication. In the Schizosaccharomyceteae, it takes place as in Endomyces Magnusii: the cells elongate; when they have attained a certain size they divide by septa into two daughter cells each, which round off, separate, grow and divide similarly. These types are chiefly of southern origin and at present only a few are known. In the other group, the Saccharomyceteae, the sprout cells are formed, as in Endomyces fibuliger, as small lateral protrusions of the mother cell; they are abjointed, increase in size and finally attain the appearance of the mother cell. This second tribe includes the greater part of the known yeasts technically used as ferments. These two tribes are not as sharply separated as would seem at first sight, thus Saccharomycodes Ludwigii generally follows the first tribe but it may also increase by sprouting. The sprouts are only formed at the poles, not at any spot as is usually the case in yeasts. If the sprouting proceeds rapidly, the daughter cells may sprout fur- ther (and in Schizosaccharomyces divide) before they are separated from the mother cells. Thus there are formed small colonies and, in old cul- HEMIASCOMYCETES 149 tures, long filaments. As far as is known, in all these cell multiplications nuclear divisions are amitotic (Fig. 95, 1 to 4). Under certain conditions of nourishment, especially in age, with the exhaustion of nutrient, or on solid substrates like gypsum blocks, asci with ascospores appear in the cultures, as in the Endomycetaceae. This character distinguishes the family from numerous other families dis- cussed in this book, belonging to other groups which also may form a sprout mycelium, and especially also from the imperfect yeasts, as Torula, Mycoderma, il Dematium," Cryptococcus and Monilia. In the wild yeasts, the number of ascospores varies from one to twelve ; in many industrial yeasts, certain numbers predominate, thus in Schizo- saccharomyces octosporus 4 or 8, in Saccharomyces cerevisiae and the yeast Johannisberg II 4 and in Saccharomyces Pastorianus 2. They are very resistant and, in the wine yeasts, may winter over in the soil of the vine- yard. Generally they are spherical or oval; in Willia anomala, as in Ascoidea and Endomyces fibuliger, they are hemispherical, with the flat wall projecting over the edge like a hat brim. In Willia Saturnus they are citriform and (like Endomyces capsularis) provided with an equatorial projecting ring; in Pichia membranifaciens, they are irregular, spherical, hemispherical to tetrahedral; in Nematospora, they are fusiform and pro- vided with a slender appendage at each end. They are generally smooth, but rough in Debaryomyces and Nadsonia. In contrast to the majority of the Endomycetaceae, the wall is usually one layered; in rarer cases, two layered, as in the Endomycetaceae, in which case the outer layer ruptures on germination. The processes in the formation of ascospores may be next discussed in connection with Schizosaccharomyces octosporus, on figs and grapes in the Mediterranean region (Guillermond, 1903, 1905, 1910, 1917; Coker and Wilson, 191 1). About three days after the culture is made the cells copulate in pairs by short tubes (Fig. 92, 1 to 6). In cell chains, it occasionally happens that the separating wall between two sister cells is dissolved (adelphogamy). Two nuclei migrate into the copulation canal and fuse; the copulation canal broadens and the two individuals develop into a barrel-shaped structure in which, within approximately a half-hour, after three or more, rarely two, nuclear divisions, eight — rarely four — spores appear (Fig. 92, 7 to 22). Often the copulation canal does not attain the breadth of the mother cell, and the young ascus is shaped like a dumbbell between whose ends the eight spores are divided. At germination the spores in the ascus swell, the ascus wall ruptures, the spores are freed, and each is divided by a septum into two daughter cells which later divide in a similar manner. Under unfavorable conditions, copulation may occur earlier, so that already in the ascus the ascospores copulate with spores of the same or neighboring ascus. Other cultures have a tendency to become aspor- 150 COMPARATIVE MORPHOLOGY OF FUNGI ogenous; these may still form processes; since many cells no longer take part in copulation, however, these are forced to grow long distances; or they grow past each other and no longer copulate. Exceptionally in some cells, four spores may arise parthenogenetically, the other cells may develop purely vegetatively. This life cycle of Schizomaccharomyces odosporus may be connected directly to that of Endomyces fibuliger. In this species, two sprout cells may copulate with each other; only in E. fibuliger one sprout cell becomes an ascus, while in S. odosporus the sexual act is isogamous. Gametangial copulation, which in Eremascus fertilis was the only form of sexuality and in Endomyces fibuliger was partially replaced by pseudogamy (copulation of two vegetative cells), in S. odosporus is entirely suppressed 1 8 /^% ffc Fig. 92. — Schizosaccharomyces odosporus. Copulation and development of asci. (X 750; after Guillermond, 1903, 1905, 1917.) and replaced by pseudogamy. This also disappears, and the cells, after unfruitful attempts at copulation, may change parthenogenetically to asci or, without this attempted copulation, may develop asci directly and vegetatively. In the other Schizosaccharomyceteae, sexuality and spore formation degenerate still further. Thus in S. Pombe, the yeast of a negro beer, and in S. Mellacei, a yeast occurring in the rum factories of Jamaica, numerous asporogenous strains are known and in S. asporus, the yeast of arak manufacture in Java, no spores are known. While in the Schizosaccharomyceteae, the fertilization has become chiefly isogamous, in the Saccharomyceteae there appears a tendency to heterogamy and pedogamy. The simpler forms, as Zygosaccharo- myces Barkeri (Barker, 1901), Z. Priorianus and Willia anomala (Guiller- mond, 1911a), like Schizosaccharomyces odosporus, may be connected HEMIASCOM YCE TES 151 directly with the pseudogamous development of Endomyces fibuliger (Fig. 87, 2 to 4). Two cells form a copulation process toward each other (Fig. 93, 1 to 5) the nuclei migrate into the bridge and fuse, the diploid nucleus divides, both daughter nuclei migrate back into copulation cells, there divide a second time, and in each fusion cell two spores arise. The dumbbell structure corresponds to an ascus. In some cases, at least in Z. Priorianus, copulation is absent and the individual sprout cells develop parthenogenetically to asci. Exceptionally, especially in small colonies, if the cultures are transplanted into conditions of nourishment which stimulate them to copulation and spore formation, 15 16 17 10 11 19 zo m ii zi 1* Fig. 93. — Zygosaccharomyces Barkeri. 1 to 5 (X650). Dcbaryomyces ghbosus. 6 to 14 (X 1,000). Zygosaccharomyces Chevalieri. 15 to 22. (X670). Debaryomyces Kloeckeri. 23 (X 1,000). Copulation and development of asci. (After Barker, 1901; Guillermond, 1912; Guillermond and Peju, 1920.) the mother cell, for lack of other cells, will copulate with a daughter cell. Thus, exceptionally, the sexual act may be pedogamous. That which was an anomaly in Zygosaccharomyces Priorianus, how- ever, becomes increasingly common in the following forms; simultaneously, copulation, because of the weakening of the sexual tendencies, becomes more and more difficult. Thus, in Debaryomyces globosus from the Antilles, approximately 75 per cent of the asci are parthenogenetic. Occasionally copulation branches are still formed, which for lack of sexual attraction, grow by each other. In about 25 per cent of the cases, a sexual act occurs. This may take place between two mature individuals in which the diploid nucleus either divides in the bridge and returns a daughter nucleus to each fusion cell or withdraws undivided 152 COMPARATIVE MORPHOLOGY OF FUNGI into a fusion cell and there forms a spore (Fig. 93, 6 to 11); it may just as often occur, however, between a still sprouting mother cell and a young daughter cell (Fig. 93, 12 to 14) where the content of a daughter cell migrates back into a mother cell (Guillermond, 1912a). This pedogamous form of the copulation becomes the normal in the following species. The West African Zygosaccharomyces Chevalieri and the west European Z. Pastori and Z. Nadsonii, in the Russian Debaryomyces tyrocola, in the French D. Kloeckeri and in the Russian Nadsonia fulvescens and N. elongata (Nadson and Konokotina, 1911, Konokotina, 1913; Guillermond, 1918, 1919, 1920; Guillermond and Peju, 1919, 1920 and 1921). Exceptionally there is no difference between the fusion cells, and the daughter cells have already developed to the size of the mother cell (Fig. 93, 15 and 16). In most cases, copu- lation takes place (in case it is still necessary and is successful) between a mother cell and a daughter cell which has just been formed (Fig. 93, 17 to 23); generally the content of smaller cells returns to that of the larger, which is abjointed and develops to a 1 to 4 spored ascus, while the smaller fusion cell disappears. Besides, especially in Zygosaccharo- myces Chevalieri, with insufficient nourishment the two ascospores may copulate after they have swollen and ruptured the ascus wall or an asco- spore may copulate with a sprout cell and change into a one-spored ascus, or the ascospore, without any copulation, may function as an ascus and form ascospores within. In Nadsonia (Guilliermondia) , spore formation does not generally occur inside the larger fusion cell; on the side opposite the copulation canal, a sprout cell receives the united contents of both fusion cells and changes into 1 to 2 brown-walled spores. It is still obscure whether this relationship has a deeper significance and whether one may ascribe to it in principle the same significance as to the development of the ascogenous hypha of the typical Ascomycetes. From this paedogamous group, the lines diverge to entire partheno- genesis and to diploid sprout mycelium. The starting point of the first series is Zygosaccharomyces Pastorii and its relatives. In this group, as earlier in Debaryomyces globosus, although many cells form copulation processes, only a few are able to copulate because of increasing weakening of sexuality. This character continues in Torulaspora Delbrueckii, in English beer, and in T. Rosei, in slime flux of oak. On favorable media the sprout cells form numerous copulation tubes and seem to attempt to anastomose with each other. (Fig. 94, 1 to 3). Often they lie so close that the pressure of the cover glass no longer suffices to isolate them. Exceptionally, the cell content migrates to the copulation bridge and there, after a sexual act, the ascospores arise. Generally the separating wall is no longer dissolved, but each cell forms 1 to 4 spores parthenogenetically (Guillermond, 1912a). HEM1 ASCOMYCETES 153 In Schwanniomyces occidentalis, on earth in the Virgin Islands, dynamic sexuality is lost and morphologically only a few traces remain. At sporu- lation the cells which will develop to asci form longer or shorter copulation processes. Their sexual attraction is so small that they are only seldom Fig. 94. — Torulaspora Rosei. Development of asci. (X 1,000; after Guillermond, 1912.) able to join and, even when this happens, they no longer come into open communication but change parthenogenetically to asci. From this species, it is only a short step to purely parthenogenetic forms in which no traces of sexuality are retained either dynamically or morphologically and in which the ascospores under suitable conditions Fig. 95. — Saccharomyces cerevisiae. 1 to 4. Formation of sprout cell with amitosis of nucleus. (X 1,500.) 5 to 11. Development of sprout cell to ascus and germination of ascospore. ( X 750.) (After Guillermond, 1902, 1904.) are formed directly as endospores in any vegetative cells (Fig. 95, 5 to 9). This parthenogenetic group contains many technically important species discussed in detail in Lafar, Handbuch der iechnischen Mykologie, as Saccharomyces cerevisiae, the group of beer yeasts; S. Pastorianus, cause of a beer disease; S. ellipsoideus, the collective type of the more important wine yeasts; S. minor, a yeast of bread making; and Pichia membranifa- 154 COMPARATIVE MORPHOLOGY OF FUNGI ciens, a wild yeast. With the disappearance of sexuality in many of these forms, spore formation also disappears, and in them there are known numerous asporogenous strains, hereditarily fixed. The starting point of the second series, which leads to the diploid character of sprout mycelium, is formed by Zygosaccharomyces and its relatives. In this form, as in Schizosaccharomyces octosporus, the asco- spores, immediately after their liberation from the ascus, may copulate with one another or with vegetative cells or they may change partheno- genetically to new asci. This has been observed only as an exception in Zygosaccharomyces Chevalieri, but is the rule in the following groups: the west African Saccharomyces Chevalieri, S. Mangini, in Willia Saturnus, on earth in the Himalayas and in the yeast Johannisberg II (Guillermond, 1910, 1914). At germination the spores swell and rupture the ascus wall. AM m m •piQ. 96. — Yeast Johannisberg II. Copulation and developnent of asci. (X750; after Guillermond, 1905.) Some of them grow normally to a sprout mycelium. Some, before, dur- ing or after the rupture of the ascus wall, copulate in pairs (Fig. 96, 1 to 6). In contrast to Zygosaccharomyces Chevalieri, the zygote does not change into an ascus but sprout cells, which develop to an apparently diploid sprout mycelium, appear in the copulation canals, occasionally also on the whole upper surface of the copulating cells (Fig. 96, 7 to 9). Later, without further sexual processes, as in S. cerevisiae, the ascospores arise in the vegetative cells. The end of this second series is formed by Saccharomy codes Ludwigii in slime flux of oak (Guillermond, 1903, 1905). Its asci almost always contain four spores which lie in pairs at the two poles (Fig. 97, 1 and 2). The spores at one pole result from the division of one nucleus; thus they are sister cells and remain connected by a protoplasmic layer remaining from the periplasm. At germination they swell much in the ascus and form small beaks toward each other which broaden to copulation canals (Fig. 97, 1 to 4). At times several spores fuse. Two cells of the same IIEMIASCOM YCETES 155 tendency often attract a third of different tendency. Occasionally copulation may be retarded and the tubes attain a considerable length or, as the ascus is torn by them, they may grow into the open. Further- more, the copulation processes may go in a meridianal direction and fuse with the spores of the other pole ; or the spores may develop unsimultane- ously or abort, in which case fusion with spores of another ascus may occur (Fig. 97, 9). Finally, as an exception, the spores may germinate parthe- nogenetically, especially in old cultures, in which case there results a special strain which only germinates parthenogenetically; it does not differ morphologically from the original strain, and forms a germ tube which ruptures the ascus wall. After the copulation processes have come into open communication, the nuclei migrate into the bridge and fuse (Fig. 97, 6 and 7) ; occasionally the fusion may occur in one of the spores instead of in the canal or may Fig. 97. — Saccharomyces Ludwigii. Copulation and development of asci. (X 750; after Guillcrmond, 1905.) be retarded and take place only in the germ tube which grows out of the copulation canal, breaks through the ascus wall and germinates to a sprout mycelium. If one imagines this copulation entirely suppressed (as occurs in cer- tain strains), one arrives, as in the Torulaspora-Schwanniomyces series, to asexual forms of Saccharomyces cerevisiae. Only these forms, in contrast to the former, would be regarded as apogamous since their thallus belongs to the diplonts. The forms of the S. cerevisiae type thus may be considered biphyletic, where it is not easy to distinguish which belong to the partheno- genetic and which to the apogamous groups. It need hardly be said that in reality the roots of these asexual forms are much more numerous and that the Saccharomycetaceae form a polyphyletic family since Endo- myces capsularis and its relatives could have led directly to such forms. In order to demonstrate more clearly the present conception formu- lated by Guillermond, the different forms have been connected according to the similarity which they show in the point of view given in our treat- ment on page 156. 156 COMPARATIVE MORPHOLOGY OF FUNGI SACCHAROMYCETACEAE Pichia membranifaciens Saccharomyces minor Saccharomyces ellipsoideus Saccharomyces pastorianus Saccharomyces cerevisiae Saccharomycodes Ludwigii t Johannisberg II Willia saturnus Saccharomyces Mangini Saccharomyces Chevalieri Schwanniomyces occidentalis Torulospora Rosei Torulospora Delbrueckii Nadsonia elongata Nadsonia fulvescens Debaryomyces Kloeckerii Debaryomyces tyrocola Zygosaccharomyces Nadsoaii Zygosaccharomyces Pastorii Zygosaccharomyces Chevalieri f . Debaryomyces globosus Schizosaccharomyces asporus Schizosaccharomyces mellacaei Willia anomala Schizosaccharomyces pombe Zygosaccharomyces prioranus Schizosaccharomyces octosporus Zygosaccharomyces Barkeri ENDOMYCETACEAEI Endomyces capsularis Endomyces javanensis Endomyces decipiens EndomycesMagnusii Endomyces Hordei Endomyces Lindneri Endomyces fibuliger L Eremascus albus Eremascus fertilis Diagram XVIII. The isogamous Eremascus forms the beginning from which two branches separate, an isogamous (with sprout cells) and a heterogamous (with cell division) ; both end with chiefly parthenogenetic forms {Endo- myces decipiens and E. capsularis). As the Saccharomycetaceae still possess true sexuality they cannot result from these end forms but they must branch off earlier, e.g., at the level of E. Magnusii and E. fibuliger. The family of the Saccharomycetaceae is divided into two lines, according to whether the development of their sprout cells agrees with HEMIASCOMYCETES 157 one or the other of the Endomycetaceae lines: the Schizosaccharomyce- teae are connected with Endomyces Magnusii and the Saccharomyceteae with E. fibuliger. The justification of this separation is uncertain, as there are transitional forms between the two lines, e.g., Saccharomy codes Ludwigii. In both lines a reduction of the thallus has arisen as a result of their mode of life : in general, they form only sprout mycelium. This degenera- tion of the thallus is followed by a degeneration of the sexual organs; whereas the thallus is habitually altered until unrecognizable, they have been able to retain traces of the form of the sexual act; gametangial copulation of Eremascus has been lost but the pseudogamous substitute, which has already appeared in Endomyces fibuliger, is retained unaltered in the primitive Saccharomycetaceae. Both in the Schizosaccharomyceteae and the Saccharomyceteae, the pseudogamous sexual act still is isogamous. While the former rapidly develop apospory, the latter undergo a peculiar development toward heterogamy. They are heterogamous as regards their products while the sexual act is still isogamous (no longer the copulation canal, but one of the copulation cells becomes the ascus) ; then they become heterogamous as regards the sexual act (larger and older or better nourished cells copulate with smaller, younger or poorer cells). From this dynamic heterogamy, pedogamy and adelphogamy result. Thus paedogamy, at least in the Saccharomycetaceae, may be considered a sign of retrogression. Hand in hand with these morphological and dynamic changes, goes a weakening of the sexual act. The forms develop increasingly asexually and the sexual act is completed in a smaller per cent of individuals. Also the sexual act becomes more labile in this relation. It can occur earlier and take place between two spores in an ascus. But it appears to be completed with difficulty because of a lessening sexual power; copulation tubes may still be formed, but they grow by, for they are no longer attracted to, each other. Finally, the sexual act may be wholly suppressed and the forms develop apomictically, which brings us to the same stage reached in the Endomycetaceae by Endomyces decipiens and E. capsularis. In the scheme on page 156, sexual act and sexuality have changed in form, place, time and content between the stages of Eremascus fertilis and Saccharomyces cerevisiae. In form, it develops from gametangial copula- tion to pseudogamy which becomes paedogamy, either of a parthenoge- netic or an apogamous type. In place, the sexual act occurs normally in the thallus, then in the gonotoconts, the asci. At first it normally closes the vegetative period, while later it begins it. In content, the sexual act is first a copulation of the principal fruit form, the asci, later this becomes unnecessary and disappears. If this concept is correct, then Saccharomycodes Ludwigii cannot be, as some authors (e.g., Nadson, 1911) have assumed, a primitive form, but 158 COMPARATIVE MORPHOLOGY OF FUNGI must be considered a degeneration stage in our scheme of relationships, like its analogue in the Ustilaginales. This is much simpler as diplontic Endomycetaceae, which might be considered ancestors of S. Ludwigii, are unknown. Atichiaceae. — Before we leave the yeasts, we should mention a group which has long puzzled mycologists. It has been placed in the Floridieae, Fucaceae, Lichenes, Saccharomycetaceae, Perisporiaceae, Capnodiaceae, Myriangiaceae, Ascocorticiaceae and Bulgariaceae. Atichia forms Fig. 98. — Atichia glomcrulosa. 1. Thallus. 2 to 4. Propagula. after Neger, 1918.) (1 X 80; 2 to 4 X 400; gelatinous cushions on leaves and needles, apparently as epiphytes (Fig. 98, 1). These cushions are formed of sprout cells which develop ascospores in the superficial layers. Under favorable conditions these cells develop into a multitude of three-rayed reproductive bodies, called propagula (Fig. 98, 2 to 4), which are disseminated by wind and rain. They develop again to cushions (Hoehnel, 1910; Cotton, 1914; Neger, 1918). Perhaps they are highly developed yeasts, adapted to an epi- phytic existence, but one may not entirely discard the concept of a degen- eration of simple Discomycetes. CHAPTER XII TAPHRINALES In the Taphrinales, some hyphal cells may swell to more or less thick- walled chlamydospores (gemmae) which immediately after formation or after a winter's rest, germinate to an ascus. Ascospores do not arise, as in the typical Ascomycetes, in the free space of the ascus, but are cut out of a protoplasmic layer, adjacent to the wall. At present only parasitic forms of the Taphrinales are known. Accord- ing to the number and method of formation of the ascospores, they fall into two families, the Protomycetaceae and the Taphrinaceae. In the Protomycetaceae, each of the spore mother cells, present in an indefinite number along the walls, divides into four ascospores, endo- spores. In the Taphrinaceae, they arise in fours or eights by free cell formation, as in the typical ascus, from the protoplasmic layer at the wall. Protomycetaceae. — The life cycle of this family will be discussed for two of the best known representatives, Protomyces pachydermus and P. macrosporus; the former is found on Taraxacum officinale; the latter, in various biological strains, is more or less sharply specialized on various Umbellif erae ; both cause callosities on the stems and leaves of the host (Popta, 1899; Biiren, 1915, 1922). Their hyphae are intercellular, the cells are multinucleate. They swell to intercalary or terminal chlamydospores (Fig. 99, 15). From youth these are multinucleate and the nuclei are often paired. Each possesses a three-layered membrane, a thick, brownish, smooth exospore, thin meso- and endospores (Fig. 99, 1). After a complete winter's rest, they germinate. They are finely granular, somewhat turbid, with a faveolate structure. The exospore ruptures and the endospore comes out, in P. pachydermus as a cylindrical, in P. macrosporus as a spherical sac (Fig. 99, 2). The vacuoles fuse to a large central vacuole and the proto- plasm lines the wall as a homogeneous layer (Fig. 99, 3) ; probably nuclear divisions take place in it. By radial fissures, the wall layer is divided into uninucleate portions (spore mother cells) which, after two simultaneous nuclear divisions, separate into four spores each (Fig. 99, 4 to 7). At the top of the sporangium these gradually form a ball which, at the rupture of the sporangium, is shot off a short distance (Fig. 99, 8 to 10). The spores are ellipsoidal, hyaline and uninucleate. Directly after they are ejected from the sporangium, they are connected by a small process and copulate (Fig. 99, 11 and 12). The nuclei enter the bridge 159 160 COMPARATIVE MORPHOLOGY OF FUNGI and whether they join in pairs or fuse has not been determined on account of technical difficulties. Hereupon they grow in nutrient solutions to a large sprout mycelium whose cells cling together (Fig. 99, 13 and 14). When they reach the host they put forth germ tubes between the epi- dermal cells into the interior. The other species correspond to P. macrosporus, only in P. inundatus on Apium graveolens, the chlamydospores are differentiated into summer Fig. 99. — Protomyces pachydermus. 1 to 3, 8, 9. P. macrosporus. 4 to 7, 10 to 15. 1 to 10. Germination of hypnospores. 11 to 14. Copulation and development of endo- spores. 15. Young hypha with hypnospores. (1 X 540; 2, 3, 11, 12 X 670; 4 to 7 X 1,500; 8 X 520; 9, 10 X 300; 15 X 170; after Meyer, 1888, and Bilren, 1915, 1922.) and hypnospores. The summer spores germinate immediately after formation; in them the endospore does not come out, however, but degenerates in the interior of the chlamydospores into single endospores. In the hypnospores, which only germinate after a winter's rest, germina- tion proceeds as in P. macrosporus (Dangeard, 1906; Biiren, 1918). A second genus, Taphridium (Volkartia), differs from Protomyces in that the chlamydospores are not formed irregularly in the deeper tissues of the host but as a continuous layer under the epidermis. In the forms TAPHRINALES 161 with exogenous germination, as T. umbelliferarum on Heracleum and Peucedanum and T. Rhaeticum on Crepis, the germ tubes (like the asci of Taphrina) stand beside each other like a hymenium. The endospores develop in a still unknown manner and fill the mature sporangium. In both species, the chlamydospores are capable of immediate germination; in the former, the mycelium winters over in the rhizome (Buren, 1917; Juel, 1921). An explanation of the life cycle of the Protomycetaceae from the point of view of change of nuclear phase is impossible at present, as the nuclear behavior is not clear. From an analogy to the Taphrinaceae and Ustilaginales, one might suppose that the dicaryon results from the copulation of the spores and the mycelium in the host belongs to the dicaryophase. Caryogamy would then occur in the chlamydospores before germination. The position of meiosis is still uncertain in this scheme. Biiren (1915) seeks it in the "tetrad-formation!" of the spore mother cells; hence he is forced to consider the spore mother cells as naked asci and the resulting endospore tube as a complex structure, a synascus, which is an entirely isolated structure in the fungi. If one wishes to avoid this explanation, one must assume that the quartering of the spore mother cells does not have the significance of a meiosis and that the spore mother cells, like the protospores of the Mucoraceae and Synchtriaceae, represent only an intermediate stage not connected with change of nuclear phase. Meiosis then, as in the Dipodascaceae and Endomycetaceae, would be sought in connection with the nuclear fusion in the beginning of nuclear divisions (not clearly demonstrated for Protomyces pachydermia and P. macro- sporus but very probable from the observation of Fig. 99, 2 and 3) at the emergence of the endospore. Like the ascus of Dipodascus, the endospore would correspond to an ordinary ascus with still definite sporangial character, but encysted like the zeugites of many parasitic Basidiomy- cetes. Because of these uncertainties, the' systematic position of this family is doubtful. Taphrinaceae. — As a representative of this family may be cited Taphrina deformans, which causes serious damage to peach trees in Europe and North America. (Dangeard, 1894; 1896; Eftimiu 1927.) Its hyphae consist of binucleate cells which winter over in the bark, in the pith and in the medullary rays of the year-old twigs. In the spring, they penetrate the leaves emerging from the buds, spread rapidly and stimulate these to the formation of wrinkles by unequal growth. Even- tually they force their way between the epidermal cells of the upper sur- face and form a reticulate tissue between epidermis and cuticle. The individual cells swell during nuclear fusion (Fig. 100, 1), round off, thicken their walls slightly, forming between epidermis and cuticle a compact layer of chlamydospores (Fig. 100, 2) capable of immediate germination. The exospore is ruptured and the endospore with the 162 COMPARATIVE MORPHOLOGY OF FUNGI protoplasm bulges out as a papilla, rupturing the cuticle. When the chlamydospores become entirely empty, the protoplasmic portion is abjointed from the vacuolate portion (Fig. 101, 1). This apical cell forms the young ascus; the vacuolate chlamydospore is called the stipe cell (in systematic literature). The young ascus (Fig. 102, 5) contains a large diploid nucleus formed by the fusion of two hyphal nuclei during the formation of the chlamydo- spore. This nucleus divides thrice. In the first division, the spindle is generally transverse and here meiosis occurs. The protoplasm is in a peripheral wall layer, which is denser near the nucleus (Fig. 102, 8). The developing spores lie imbedded in a meager periplasm. In water, or sugar solutions, they develop sprout mycelia like yeasts; occasionally sprouting begins in the ascus, which then becomes filled by a dense sprout mycelium (Fig. 101, 4). In certain forms, young, still sporeless asci may develop vegetatively either to hyphae or sprout mycelia (Fig. 101, 2). These sprout mycelia are apparently biological substitutes for conidia since they fulfil the functions of propagation. 1 Fig. 100. — Taphrina deformans. 1. Subcuticular, binucleate ascogenous hyphae before caryogamy. 2. Young chlamydospores. (After Dangeard, 1894.) Thus the chlamydospores may be interpreted as zeugites, organs in which at the close of the dicaryophase, caryogamy occurs. In this sense they would be considered homologous to the probasidia and sclerobasidia of the Auriculariales, to the teliospores of the Uredinales and the smut spores of the Ustilaginales, and thus the conceptions to be discussed under the Basidiomycetes, concerning the differentiation of zeugite and the sporophores and the encysting of zeugites, would also be important for the Ascomycetes. Although the validity of this interpretation is not yet certain, with these reservations it may be useful. The position of plasmogamy in this life cycle is unknown. In analogy to the Protomy- cetaceae and Ustilaginales one would expect it in the sprout mycelium although copulation has not yet been observed there. The other Taphrinaceae follow, as far as known, the development of Taphrina deformans. In Taphrina bullata on pears and quinces, however, several dicaryons instead of one are present in the hyphae, but the myce- lium becomes binucleate before spore formation. TAPHRINALES 163 The position and germination of the chlamydospores in the leaves of the host vary. In T. epiphylla on Alnus incana, (Juel 1921), T. bullata and T. Betulae (Exoascus Betulae) on Betula alba (Eftimiu 1927), the mycelium grows subcuticularly on the leaves and consequently the chlamydospores are formed between the epidermis and cuticle. In T. aurea on poplar, T. Alni-incanae and T. Crataegi, the mycelium appears just below the epidermis. In the majority of the Taphrinales, as in T. deformans, T. institiae and T. Pruni, the vegetative mycelium grows in the parenchyma while the ascogenous mycelium which forms the chlamy- dospores develops only under the cuticle. In T. (Magnusiella) Potentillae O^ooSH aads Fig. 101. — Taphrina deformans. 1. Hymenium (X670). Taphrina Carpini. 2. Germination of asci in distilled water (X400). Taphrina aurea. 3, 4. Hymenium (X 330). (After Gwynne-Vaughan, 1922, and Sadebeck, 1884.) on Potentilla, the mycelium lives only in the interior of the leaves and the asci, as in Taphridium of the Protomycetaceae, are formed in a mycelial layer under the epidermis. In T. aurea on Populus and T. epiphylla on Alnus, the whole outer wall of the chlamydospores continues in the wall of the young ascus. There is no septum between ascus and chlamydospore, i.e., no abjunction of a stipe cell (Fig. 101, 3 and 4; 102, 4). The types of germination of these forms are occasionally strikingly reminiscent of the Protomycetaceae. In T. Coryli on Conjlus americana, the diploid nucleus divides into two daughter nuclei in the chlamydospore. One remains in the basal cell and degenerates; the other migrates into the young ascus and divides there into the 8 spore nuclei (Martin, 1924). 164 COMPARATIVE MORPHOLOGY OF FUNGI Because of this variation in the subordinate characters and the similarity of the more important characters, the systematic classification of the Taphrinales is confused. For a time, the forms with 4- or 8- spored asci were placed in Exoascus, the forms in which the germination of ascospores to sprout mycelium occurs in the asci in Taphrina (Sade- beck, 1884). This distinction has been shown untenable however, and consequently both genera must be united; for this the name Taphrina possesses priority. The forms in which the asci are not catenulate and intercalary, but single and terminal on branches which penetrate between the epidermal cells, are occasionally placed in Magnusiella: thus the Fig. 102. : — Taphrina Potcntillae. 1 to 3. Development of ascus. Taphrina epiphylla. 4. Ascus before spore formation. Taphrina Pruni. 5 to 8. Development of ascus. (1, 2, 5, 6 X 1,000; 3, 7, 8 X 1,265; 4 X 670; after Juel, 1921.) mycelium of T. {Magnusiella) Potentillae forms a continuous layer under the epidermis; from these there rise to the surface, between the epidermal cells, hyphal branches which grow toward the cuticle, each changing its end to an ascus (Fig. 102, 1 to 3). True chlamydospores are not formed in this case; this genus, however, is connected directly with Taphrina by transitional forms. At present the Taphrinales include only parasitic forms which only recently have been demonstrated cultivatable in artificial media (Martin 1925), and which mainly occur in temperate zones, rarely in the tropics. They are specialized on three groups of cormophytes in three lines which are more or less sharply distinguished by the form of their asci (Giesen- TAPHRINALES 165 hagen, 1895). The first line, with clavate asci on ferns, has not been carefully studied. The second line with blunt, cylindrical asci more or less flattened at the top, on Amentiferae, includes T. Tosquineti on the leaves and female catkins of Alnus, T. aurea which causes saccate pro- trusions on leaves of Populus and forms yellow hymenia on their concave lower surfaces, and T. Carpini which stimulates the twigs of Carpinus betulus to the formation of witches' brooms. A third line with clavate to narrow cylindrical asci more or less rounded at the top, on Rosaceae, includes numerous species important in phytopathology, as T. Pruni, T. institiae and T. Cerasi on Prunus. The hyphae of T. Pruni live in the branches of plums and at flowering grow into the young fruits which undergo an abnormal development, Instead of forming a stone and outer fleshy layer, the fruit wall assumes a waxy, coriaceous character, and the whole fruit is a deformed, unpalatable structure. In these, the hyphae come out between the epidermal cells and branch between epidermis and cuticle to such a degree that the whole fruit is covered by ramose short-celled hyphae which subsequently become chlamydospores. T. institiae on plum and T. Cerasi on cherry stimulate the host to the formation of witches' brooms; T. deformans causes leaf curl of the peach. The Taphrinales show relationships to the Protomycetaceae. As in the latter, intercalary chlamydospores are formed on the mycelium, singly in the Protomycetaceae, serially in the Taphrinaceae. As in the Proto- mycetaceae, these chlamydospores germinate with an ascus; only in most Protomycetaceae the endospore separates from the exospore, while their connection continues in the Taphrinales. The separation of the ascus from the stipe cell, regarded in this light, might be considered as a subsequent device to prevent the retreat of the protoplasm. In both families the ascospores arise in a protoplasmic peripheral layer; in Taphrina the chlamydospore generally shows a simple zygote, in Pro- tomyces (if this interpretation is permissible) a coenozygote, and, as in the Protomycetaceae, the ascospores germinate to a sprout mycelium. Which of these families may be considered as primitive and which derived, and whence their derivation, is still obscure. The simplest form so far investigated is T. (Magnusiella) Potentillae which lacks true chlamydospores; whether it is next the ancestral form, may not be determined at present. In any case, the Taphrinaceae form a very old family, as may be concluded from their biological relationships, especially from their adaptation to hosts. CHAPTER XIII EUASCOMYCETES The Euascomycetes differ from the Hemiascomycetes in that the zygotes develop first to ascogenous hyphae which then proceed to the formation of asci. Parellel with this formation of ascogenous hyphae, there generally develops ascigerous fructifications whose morphological relationships form the basis of the systematic classification of this subclass. Originally the Euascomycetes were divided into four orders which may be regarded as the four historical orders, the Pyrenomycetes with perithecia, the Discomycetes with apothecia, the Tuberales with hypo- gaeous tuberiform fructifications and the entomophilous Laboulbeniales with a modification of the perithecia. Recently the Pyrenomycetes, and Discomycetes have been extensively subdivided on the basis of the manner of opening of the fructifications and the arrangement of the asci. The cleistocarpous Pyrenomycetes, in which the ascospores are only liberated by a decay of the perithecia, are assembled in the Plectascales Perisporiales and Myriangiales. The higher Pyrenomycetes, however, in which generally the liberation or discharge of ascospores is facilitated or made possible by the formation of a special opening, are grouped in the Hypocreales, Sphaeriales, Dothideales, Hysteriales and Hemisphaeriales. The Discomycetes are divided into the Phacidiales, in which the apothe- cial covering is only ruptured at maturity, and the Pezizales, in which it is generally reduced to threads during the development of the apothecia. Thus in the classification followed here the Euascomycetes include 12 orders whose characters will appear in the course of the discussion and whose probable morphological relations are graphically represented in the collective scheme at the close of the book (p. 618). PLECTASCALES Among the typical Ascomycetes the Plectascales are characterized by the possession of angiocarpous perithecia without ostioles, whose interior is irregularly penetrated by ascogenous hyphae, consequently the asci (generally spherical) lie scattered irregularly in the ground tissue of the fructification. The peripheral layers of the fructifications may thicken to a pseudoparenchymatous rind which, in the lower forms, gradu- ally degenerates at maturity. 166 EUASCOMYCETES 167 The forms of the Plectascales to be discussed here fall into six families: the Gymnoascaceae, Aspergillaceae, Onygenaceae, Trichocomaceae, Terfeziaceae and Elaphomycetaceae. The Gymnoascaceae and Asper- gillaceae have simple perithecia, without or with a loose pseudoparenchy- Fig. 103. — Amauroascus verrucosus. 1, 2. Fundaments of copulation branches. 3, 4. Ascogonium develops parthenogenetically, while nuclei degenerate in antheridium. 5. Knot of ascogenous hyphae being surrounded by sterile hyphae. 6. Young perithecium with ascogenous hyphae. 7. Older stage with young asci. ( X 600; after Dangeard, 1907.) matous peridium. In the highest representatives of the second family, the perithecia develop to complicated structures which are divided by sterile veins into ascogenous nests. The third to sixth family include high forms with complicated and much differentiated fructifications. In the Onygenaceae and Trichoco- 168 COMPARATIVE MORPHOLOGY OF FUNGI maceae, they are divided into sterile stipes and fertile heads. In the Trichocomaceae, the sterile veins have intertwined to faveolate structures open at the top. In the Terfeziaceae and Elaphomycetaceae, they have developed to truffle-like, hypogaeous structures which in the former are soft and degenerate as a whole, in the latter surrounded by hard, resistent peridium, the gleba breaking down into a dusty spore mass with capillitium. The diagrammatic representation of the morphological relationships between these families is given in the summary at the close of the order. Gymnoascaceae. — The simplest member of this group to be studied cytologically, Amauroascus verrucosus (Dangeard, 1907), is generally closely connected to Eremascus. On its substrate, garbage and dung, it forms a white arachnoid covering which thickens in places to small white knobs, 'the fundaments of fructifications. From any two hyphae multi- nucleate copulation branches are formed and basally abjointed (Fig. 103, Fig. 104. — Gymnoascus Rcessii. 1. Small fructification; a, vegetative hyphae. b, loose peridium which surrounds the ascigerous tissue. 2. Group of asci. 3. Mature ascus. After Brefeld, 1891 and Baranetzky, 1872.) 1 and 2). One branch, the antheridium, is vertical and somewhat the stronger; the other, the ascogonium, is somewhat slenderer and is coiled around the antheridium in a helix. A solution of the separating wall at the tip of both organs and nuclear migration has not yet been observed. The ascogonium continues its growth and branches often (Fig. 103, 3 and 4). The branches coil spirally (Fig. 103, 5) and after a certain time divide into binucleate cells which swell to eight-spored asci (Fig. 103, 6 and 7). Meanwhile this knob of ascogenous nyphae is surrounded by a compact, sterile, hyphal tissue, so that the asci are imbedded in a loose brownish hyphal cushion, which is the simplest form of a fructification (perithecium). In Gymnoascus the hyphal sheath possesses a more marked peridial character. Gymnoascus is saprophytic on earth, on offal, dung, cadavers, etc., and forms a fluffy, occasionally brightly colored, covering on the EUASCOMYCETES 169 substrate. The hyphae are slender and divided into short multinucleate cells; in some species, as G. setosus, they laterally abjoint hyaline conidia which may grow further by sprouting; in other species, as G. uncinatus, they may break up into oidia. In G. Reessii imperfect forms are unknown and reproduction takes place only sexually by perithecial formation. Fig. 105. — Ctenomyces serratus. A. Feather covered with fungus. B. Hum with pectinate organs. C. Vegetative hyphae with conidia. Resting myce- D. Copulation branches. E. Section of mature fructification. (A X %; B to D X 400; E X 200; after Eidam, 1883.) As in Amaurascus verrucosus, each of two neighboring cells of a hypha (as in G. Reessii) or two different hyphae (as usually in G. candidus) forms a copulation process which is abjointed. Generally both branches appear simultaneously; occasionally the antheridium appears somewhat earlier. 170 COMPARATIVE MORPHOLOGY OF FUNGI As in Amauroascus, the ascogonium winds helically around the anther- idium; in contrast to Amauroascus, the separating wall at the tip is dis- solved and the male nucleus migrates into the ascogonium. This is divided by septa into binucleate (?) cells which develop to ascogenous hyphae on which arise, terminally or laterally, the eight-spored asci. Meanwhile the sexual organs have become surrounded by a loose hyphal tissue (Fig. 104, 1) whose peripheral hyphae form peculiar lateral spines and whose membranes thicken and turn brown at maturity (Eidam, 1883; Dale, 1903). The most compactly built rind is found in Ctenomyces. Its only well- known species, C. serratus, found on decaying feathers in henyards, forms hyphal tissue, hyaline when young, whose hyphae abjoint laterally numer- ous oval hyaline conidia. The cells of the hyphae are 1 to 4 nucleate, the conidia (Fig. 105, C) are generally uninucleate. The conidiophore hyphae may branch in fascicles and may finally come together to pycnidia-like masses in which the conidiophore hyphae later swell, filling the cavity with a slimy conidial mass. The young copulation branches are 1 to 3 nucleate, the male branch develops to a vertical clavate structure which finally contains 10 to 12 nuclei (Fig. 105, D) . The ascogonium winds 6 to 7 times about the anther- idium and finally contains about 20 nuclei. A solution of the separating wall and nuclear migration has not been observed. Without further proc- esses the ascogonium divides into binucleate almost isodiametric cells; these develop to ascogenous hyphae which again coil helically and sur- round the original helix. From this confusion, the eight-spored asci arise in an unknown manner. Meanwhile the whole knob is closely sur- rounded by sterile hyphae which, with considerable thickening of their walls, become moniliform and partly develop on one side to peculiar short processes. Besides these perithecia, light brown sclerotia are also formed on the feathers. The cells in the vicinity of the septa are nodose (Fig. 105, B). From these there arise unusual pectinate, falcate or setiform hyphae, whose unguiform processes are turned in the same direction. Possibly they serve to disseminate the sclerotia by clinging to foreign bodies (Eidam, 1883; Matruchot and Dassonville, 1899; Dangeard, 1907). These falcate and other structures of Ctenomyces are strikingly reminis- cent of certain imperfect genera, as Trichophyton, Microsporum and Achorion, which cause ringworm, favus and other skin and hair diseases in men and animals. It has become probable through the investigations of Matruchot and Dassonville (1899a, 1901 ; Grigoraki, 1925) and others that these imperfect genera belong to the Gymnoascaceae, i.e., to Ctenomyces and the closely related Eidamella. Aspergillaceae — The simplest member of the Aspergillaceae, Aphan- oascus cinnabarinus, is directly connected to the Gymnoascaceae. Like EUASCOMYCETES 171 most Gymnoascaceae, it is found on decaying feathers and dung. The cells are multinucleate. As in Gymnoascus setosus and Ctenomyces serratus, they abjoint lateral or terminal, hyaline, oval, multinucleate conidia. The formation of the perithecium takes place as in the Gymnoas- caceae. The copulation branches arise from neighboring cells of the same hyphae or two separate hyphae. From the first, they are multi- nucleate and subsequently undergo several nuclear divisions. The ascogonium is slender and lies as a helix around the spherical antheridium (Fig. 106, 1). Fertilization is absent; the male nuclei degenerate; the ascogonium develops parthenogenetically. As in Ctenomyces serratus, Fig. 106. — Aphanoascus cinnabarinus. 1. Small ascogonium coils about spherical antheridium. 2. Ascogenous hyphae coil about antheridium whose contents are degener- ating. 3. Section of periphery of an immature perithecium. The cells of the ascogenous hyphae are about to develop laterally to asci. 4. Mature fructification. (1 to 3 X 600; 4 X 10; after Dangeard, 1907.) it divides into binucleate cells; some of these grow to ascogenous hyphae which coil helically and form lateral secondary branches which again coil helically. The whole system is abjointed into binucleate cells which apparently form the asci as lateral outgrowths (Fig. 106, 3). Meanwhile the knot is closely surrounded by sheath hyphae intertwining at the periphery into a pseudoparenchymatous wall of several layers. The perithecia are up to 2 mm. in diameter, hyaline at first, becoming yellow- ish brown and finally cinnabar red (Dangeard, 1907). In Aphanoascus the peripheral layers of the rind form a definite pseudoparenchymatous peridium, while in the Gymnoascaceae they form a plectenchymatous tissue; Aphanoascus, thus, has been considered by 172 COMPARATIVE MORPHOLOGY OF FUNGI many authors a member of the Gymnoascaceae. The other genera of the Asperigillaceae may be divided into three radiating lines whose represent- atives will be discussed as the Monascus- Magnusia, the Thielavia, and the Aspergillus-Penicillium groups. Monascus has been well investigated in two species, M. purpureus and M. Barkeri. Both were originally isolated from red Chinese rice but have since been found in silage and preserves (Buchanan, 1910; C. E. Lewis, 1910). As far as may be culled from conflicting accounts, (e.g., Barker, 1903; Ikeno, 1903; Kuyper, 1905; Olive, 1905; Dangeard, 1907; Schikorra, 1909) the development is probably as follows: the mycelium consists of regularly branched hyphae which cut off singly, or basipetally in chains, spherical or pyriform conidia (Fig. 107, 1 C). Both the hyphal cells and conidia are multinucleate. When the fructification develops, a four- to eight-nucleate terminal cell is abjointed and remains stationary in its development, becoming the antheridium. Directly under the septum, the ascogonial mother cell is Fig. 107. — Monascus purpureus. Development of copulation branches. C. conidium. CI, 2 X 420; 3 X 725; 4, 5 X 835; after Schikorra, 1909.) abjointed and coils helically about the antheridium. It is further divided into a three- to four-nucleate terminal cell, the trichogyne, and a four- to six-nucleate subterminal cell, the ascogonium. The nuclei of the tricho- gyne subsequently degenerate. Usually the antheridium forms a papilla toward the trichogyne, open communication results, and the male nuclei migrate into the trichogyne. Thereupon the wall between trichogyne and ascogonium is temporarily dissolved, the male nuclei migrate into the ascogonium, pair with the female nuclei, and migrate into the ascog- enous hyphae. The antheridium collapses and disintegrates (Fig. 107, 3 to 5). Meanwhile the cell group has become closely surrounded by sterile sheath hyphae which apparently nourish the swollen, spherical ascogo- nium and hence are gradually dissolved in the core of the fructification. The peripheral layers are brown and pseudoparenchymatous, forming the perithecial wall. The ascogenous hyphae divide (according to Dan- geard) ; as in previous forms, into binucleate cells which swell into eight- spored asci. According to Schikorra, the development of the asci takes place according to the Pyronema type. EUASCOMYCETES 173 In Monascus, in contrast to Aphanoascus and the Gymnoascaceae, the female copulation branch no longer fulfils its original sexual function as a whole, but is divided into a receptive cell, the trichogyne, and the true female gametangium, the ascogonium. This development continues characteristically in Magnusia, which extends much beyond Monascus both in the imperfect forms and the structure of sexual organs and perithecia. The only representative so far investigated, Magnusia nitida, in contrast to Monascus, has uninu- cleate cells (Satina, 1923). Its imperfect forms are reminiscent of tufts of Penicillium and under favorable nutritive conditions form coremia. The sexual apparatus consists of a unicellular antheridium, a helical ascogonium and a multicellular trichogyne; the latter grows toward the antheridium, embraces it, twines around it, comes into open connection and its content flows into the ascogonium. The latter develops ascoge- nous hyphae according to the hook type. The perithecia are shining black, ellipsoidal or irregularly angular; they have long spiral appendages decep- tively like the appendages of the Erysiphaceae ; only, in contrast to the latter, they do not arise from peripheral but from deeper cells and hence, in a certain sense, are formed endogenously. As regards the morphology of the sexual organs, Magnusia is distin- guished from Monascus by the spiral ascogonium, by the septation of the trichogyne and by the length of the latter which varies with the distance from the antheridium. This relationship offers an approach to the com- prehension of several higher orders of Ascomycetes. A second line is formed by Thielavia whose best-known representative, T. basicola, appears in damp weather on the roots of numerous phanero- gams and in Europe and North America causes a serious root rot of tobacco. The mycelium penetrates the infected roots in all directions, and on their surfaces cuts off such a great mass of conidia that they seem to be covered by a mildew. Because of their peculiar manner of libera- tion, these conidia are called "endoconidia" by the phytopathologists (Brierly, 1915). A hypha forms a lateral outgrowth and the nucleus divides so that a daughter nucleus migrates into the daughter cell. The daughter cell is abjointed and elongates into a flask-shaped conidiophore (Fig. 108, 1) whose nucleus divides again. One daughter nucleus remains at the base, the other migrates toward the tip which is abjointed. Now the membrane of the terminal cell separates into an outer and inner layer; the outer ruptures at the top and the conidium gradually emerges (Fig. 108, 2). Meanwhile the nucleus of the basal cell divides and repeats the ab junction of the conidium. With every conidium, the sheath increases in length and finally a long row of conidia are enclosed in the sheath and slowly press outward. Thus these conidia are not endoconidia in the strict sense of the word, but ordinary acrogenous conidia which, however, have been freed from the mother plant by a peculiar mechanism of libera- 174 COMPARATIVE MORPHOLOGY OF FUNGI tion. This same manner of formation of conidia we will meet again in the following order in the Erysiphaceae, only there the spore membrane does not rupture. With the progress of the disease, the conidia disappear and there appears on infected roots, a dark covering of brown, thick-walled gemmae (chlamydospores) which arise catenulately and are liberated as the hyphae disintegrate (Fig. 108, 3). Later, when the roots are dead, there appear shining black perithecia whose ontogeny and whose connection with both imperfect forms has not been experimentally investigated. While the Thielavia group shows a strong development of conidial apparatus, this reaches its maximum in the third line, the Aspergillus- Penicillium group. The representatives of this group are cosmopolitan and the most common of all fungi. In them, also, various groups of Fig. 108. — Thielavia basicola. 1. Young conidiophore before the formation of the first conidium. 2. Older stage. The left branch has formed the wall of the first conidium; the basal cell is again binucleate. The right branch shows the first conidium leaving the sheath. 3. Chlamydospores. ( X 500; after Brierly, 1915.) species vary in their ecological characters. Thus the true species of Penicillium occur in forest floors, more rarely on cultivated, manured ground as mesosaprobes on which bacteria preponderate. In forests they are more important than the Mucoraceae, and by the digestion of hemi- celluloses play an important role. In addition, they occur in temperate climates on garbage and offal. In the tropics, the species of Aspergillus predominate and there colonize everything possible. Many species of this group are technically important on account of their hydrolytic powers on starch, sugars and tannins and cause fermenta- tions to oxalic, citric, and gallic acids, more rarely to alcohol, as Asper- gillus Oryzae which is used in Japan in the preparation of sake (rice wine) and soy bean sauces by the hydrolysis of starch. In America, the diastase from this organism is widely used instead of malt diastase in industry; Aspergillus Wentii, by the loosening of the hard tissue of the EUASCOMYCETES 175 bean, assists in the preparation of the soy bean as used in Java; several species of Citromyces are used in citric acid fermentation; Penicillium roqueforti and P. camemberti lend to the corresponding cheeses their characteristic aroma and consistency. Some species whose optimal temperature is about 37° are pathogenic to animals and cause mycoses; Aspergillus fumigatus and A. flavus grow in the human ear and the former causes most of the cases diagnosed as tuberculosis, in which Myco- bacterium tuberculosis is not found. Still other species are plant path- ogens, thus P. italicum and P. digitatum (P. olivaceum) cause decay of ripe southern fruits, and A. niger is said to be parasitic in dates and make them unpalatable by fermentation of the starch. The thallus is formed as in the previous groups. It is generally color- less; in some species the hyphae may form in the interior of the cells Fig. 109. — Aspergillus herbariorum. Development of conidiophore. (X600; after Dangeard, 1907.) a yellow to red, rarely green, color which later diffuses through the cell membrane and passes out into the nutritive solution. Exceptionally, as in P. camemberti and some Acaulium sp., the hyphae may break up into oidia or, again in Acaulium sp., form gemmae or, as in Aspergillus niger or A. Oryzae (Schramm, 1914; Zikes, 1922), develop sprout mycelia. The hyphae form an arachnoid cover over the substrate and interwine rapidly into a dense mat or crust. This is generally white at first and after a few days attains its characteristic color from its conidia. As imperfect forms, in addition to the above-mentioned oidia, only conidiophores and conidia have been known. The conidiophores arise only on the mycelium of the upper surface as vertical, projecting, aerial hyphae. In the simplest case, as in Aspergillus, they are unbranched; as in Sy?icephalastrum among the Mucoraceae, their ends swell capitately and allow the majority of the nuclei to come out into short flask-shaped phialides (sterigmata) which cut off successively a chain of multinu- cleate conidia (Fig. 109). While in the typical species of Aspergillus, the phialides are unbranched (Fig. 114, A), in the subgenus Sterigmato- 176 COMPARATIVE MORPHOLOGY OF FUNGI cystis, they branch repeatedly (Fig. 116, 1 and 2). In the only cytologi- cally studied species belonging to this subgenus, the phialides, and hence the conidia, are uninucleate. From Aspergillus, Aspergillopsis and Citromyces form an unnotice- able transition to the second important genus whose conidiophores are much branched and lack the capitate swellings at the junction of phia- Fig. 110. — Pcnicillium claviforme. Coremia on malt agar, with snowy aerial mycelium. (After Wehmer, 1914.) lides (Fig. 117, B). The outermost branches from which the phialides radiate have a certain systematic value and are called metulae (Westling, 1911). While in the majority of forms the metulae and phialides (like the hyphal cells) have several nuclei, in some strains of the Penicillium crustaceum group, as in Aspergillus (Sterigmatocystis) nidulans, they are uninucleate; in these forms on a thallus with multinucleate cells there arise uninucleate conidia which only at germination again become multinucleate. EUASCOMYCETES 111 In many species, the conidia are bound together in chains by short disjunctors (connectives). Brefeld (1874) regards this in his Penicil- lium " crustaceum" as a section of the "sterigma." Thorn (1914; Thorn and Church, 1926) considers that in Aspergillus the true, thick, round spore wall has only arisen in the cells cut off from the phialides; in case these original cells are not entirely filled out, the collapsed residue remains hanging as a connective between the spores. According to some observa- tions of the author on Penicilliopsis clavariaefonnis it is a question of papil- liform arching at the base of the conidia whose function is still unknown. Fig. 111. — Penicilliopsis clavariaeformis. 1 to 3. Development of the eonidiophore. Sp, germinated conidium. Penicilliopsis brasilie?isis. 4. Conidiophore with dimorphic conidia. ( X 330; 1 to 3 original; 4 after Moller, 1901.) Under certain cultural conditions, as on substrates which contain nitrogen in the form of nitrates, also by increased transpiration, by lowering the oxygen tension of the air, in the presence of glycerol as a carbon source, or in definite physical state of the substrate, the conidio- phores of many species of Penicillium form coremia (Munk, 1912; Wehmer, 1914; Boas, 1915, 1916). While these conidia (Fig. 110) in true species of Penicillium form only as abnormalities, in some other genera (by some authors regarded as subgenera of Penicillium), as in Acaulium (Fig. 7, 2) and Stysanus (Fig. 7, 1), they have become the rule and thus arise normally. In these genera there are beginnings of conidial fructifications which we shall meet later in Isaria (imperfect forms of Cordyceps) under the Hypocreaceae; thus a series of species 178 COMPARATIVE MORPHOLOGY OF FUNGI fundamentally belonging in Aspergillaceae are placed in Isaria until their natural position has been determined on the basis of their perithecia. These imperfect forms attain the highest development in the tropical genus Penicilliopsis of which two representatives, the Javan P. clavariaeformis (Solms-Laubach, 1886) and the Brazilian P. brasiliensis have been carefully investigated. If P. clavariaeformis is allowed to grow on a synthetic substrate, many undifferentiated hyphae after two days begin to cut off a long chain of hyaline oval conidia (Fig. Ill, 1). In this respect they seem entirely like the conidial hyphae of Monascus. Later there appear on the mycelia true conidiophores (Fig. Ill, 3) whose form is intermediate between Penicillium and Aspergillus and is Fig. 112. — Penicilliopsis clavariaeformis. Coremia on fruita of Diospyros macrophylla. reminiscent of Citromyces caeruleus and C. purpurescens. Their myce- lium is an intense yellow. Later they collect into massive, plecten- chymatous, antler-like coremia whose peripheral hyphae radiate perpendicularly to the outer surfaces and again degenerate to short stipitate conidiophores. They often swell capitately to a greater degree than is shown in Fig. Ill, 3 for the free conidiophores and then seem deceptively like Aspergillus. The appearance of these coremia on the natural substrate (Diospyros macrophylla) is shown in Fig. 112; in artificial culture they may grow to 20 cm. In P. brasiliensis they are verticillately branched and generally reminiscent of Araucaria. Conidia of the Aspergillus-Penicillium group are spherical or ovoid, smooth, rough or echinulate, hyaline or slightly colored. It is their EUASCOMYCETES 179 masses which give the hyphal mats their characteristic tint. This tint, however, as well as the size of the conidia, varies considerably according to the nourishment, temperature and physical character of the substrate. Thus P. candidum forms on paper and on acid substrates a white strain with white conidia just as almost all Penicilia form a white or light red color on paper. If the same species grows on alkaline or protein sub- strates, the mycelium is dark, almost black and forms no perithecia. On carbohydrate substrates, it forms, if we may anticipate our discussion, carbonaceous perithecia which together form a hard shining mass. When the perithecia are emptied, the ascospores give these carbonaceous masses a mealy, flabby, lustreless appearance and a coffee-brown color. That variations of this sort, especially if they are caused by the presence of toxic agents or experimental interference, can remain constant through a long series of generations has been shown by Haenicke (1916) and others. At germination, the conidia swell to three times their original size and put forth several germ tubes which develop multi septate, and branched mycelium. An exception to all these forms is Penicilliopsis brasiliensis in which on the same conidiophores there are formed ellipsoid smooth and spherical verrucose conidia (Fig. Ill, 4). The physiological nutritive conditions and biological significance of this dimorphism is still unknown. As the imperfect forms of the Aspergillaceae are the forms ordinarily seen and since the physiological nutritive characters of the mycelium offer very important diagnostic characters in their relation to citric acid, tannins and arsenic compounds, they have been repeatedly monographed (Wehmer, 1901; Westling, 1911; Sopp, 1912; Thorn and Church, 1921, 1926; Biourge, 1923). As has been already mentioned, many forms are considerably modified by the substrate and a single description to enable later identification is often almost impossible; thus in forms described as Penicillium glaucum and P. crustaceum, extensive physiolog- ical investigations do not determine what the various authors really had in hand. The perithecia correspond with the perithecia of other Aspergillaceae. They are generally formed on the mycelial mats, with rapid transpiration, and begin to appear about 1 to 2 weeks after the inoculation of the cul- tures. The laws governing their appearance are still unknown. Brefeld (1874) assumes for Penicillium "crustaceum" an absence of oxygen as a fundamental condition; Bezsonov (1919) shows for P. "crustaceum," Aspergillus Oryzae and A. Wentii that a high sucrose content favors their formation. With the exception of Penicilliopsis, in all species so far studied, their formation is preceded by the formation of sexual organs. The process taking place may be briefly discussed in five groups. In the first group, as in Penicillium "crustaceum" (Brefeld, 1874) and occasionally also 180 COMPARATIVE MORPHOLOGY OF FUNGI in Aspergillus nidulans (Eidam, 1883; Dangeard, 1907), as in Eremascus, two equal copulation branches are formed; they coil around each other helically (Fig. 117, C) and apparently come into open communication at the tip. The content of one branch migrates into the other. Both copula- tion branches are then surrounded by a dense hyphal knot (Fig. 117 D), which subsequently assumes a plectenchymatous character. Thus in these forms antheridium and ascogonium are still equivalent and may be directly ranked with the equally isogamous copulation branches of many Endomycetaceae and Gymnoascaceae. £0 Fig. 113.- — Penicillium vermiculatum. 1. The multinucleate ascogonium and young antheridium. 2. The antheridium is in open communication with the antheridium but the male nucleus remains in the antheridium. 3. The ascogonium surrounded by sterile hyphae is divided into binucleate cells which are beginning to develop ascogenous hyphae. (X 600; after Dangeard, 1907.) In a second group, which at present includes only Penicillium vermic- ulatum (Dangeard, 1907), the copulation branches, as in P. "crustaceum," are arranged regularly; however, they show a characteristic differentia- tion in their behavior. In this species the hyphae are always uninucleate. On the formation of the perithecium there appears, as a branch of any hypha, a unicellular ascogonium rich in protoplasm, which, like the other cells of the hypha, contains a single nucleus. It elongates rapidly and by repeated nuclear division becomes as much as 16-nucleate. Meanwhile there has appeared a second slender branch, the young antheridium. Generally it arises from a different hypha than that which bears the EUASCOMYCETES 181 ascogonium. It winds several times around the ascogonium and cuts off a uninucleate apical cell which swells slightly (Fig. 113, 1). Meanwhile the number of nuclei in the ascogonium have reached about 64. The apical cell comes into open communication with the ascogonium (Fig. 113, 2). Dangeard could not see nuclear migration, however, and concluded that the male nucleus remains in the antheridium Fig. 114. — Aspergillus herbariorum. A. Conidiophore. B to F. Development of peri- thecium. G. Group of young asei. H. Mature ascus. (After Kny and Bary.) and degenerates. The ascogonium divides into numerous binucleate cells, however, each of which may develop ascogenous hyphae (Fig. 113, 3). Thus P. vermiculatum differs from P. crustaceum in two respects. Both copulation branches are differentiated morphologically as well as dynamically into antheridium and ascogonium ; secondly, the appearance of the antheridium is retarded. It appears a long time after the formation of the ascogonium, when the latter has already become multinucleate, 182 COMPARATIVE MORPHOLOGY OF FUNGI and, if Dangeard observed the normal development, its single nucleus is functionless. The behavior of the third stage will be described for the best-known Aspergillus herbariorum-repens group. (For A. herbariorum, by investi- gations of Fraser and Chambers, 1907, and Dangeard, 1907, and for A. repens, a small variety of A. herbariorum, by the investigations of Dale, 1909 and Moreau, 1913). As a branch of a hypha, there arises an ascogonium, which coils in a helix with a continually shortening radius. It is divided by one or more septa in two or more multinucleate cells of which the terminal is generally the longest and contains up to 20 nuclei. Shortly before or after septation of the ascogonium, the antheridium appears and climbs along the ascogonial helix (Fig. 114, B, C). Many times it is formed independently of the ascogonium, on another hypha, often it grows from two or three slender branches on the basal, more rarely from a higher coil of the ascogonium; occasionally it may arise from the interior of the helix and thereby attain the same aspect as in A phanoascus and Ctenomyces. An open communication between antherid- ium and ascogonium was not demonstrated in any case. The antherid- ium appears to be rudimentary; the nuclei often degenerate before it has reached its full length, or it ceases its growth half way and does not reach the tip of the ascogonial spiral; or it may be entirely absent. In all these cases, with or without the antheridium, the ascogonium develops parthenogenetically; it divides into binucleate cells some of which grow to ramose ascogenous hyphae. Thus the third stage is characterized by the functional degeneration of the antheridium, which may be formed only when the ascogonium has completed the portion of the cycle in which fertilization would be possible and has already entered upon a stage of septation. In the fourth group, as in Aspergillus flavus, A. fumigatus and A. Fischeri (Dangeard, 1907; Domaradsky, 1908), the antheridium is no longer formed. Only one helical ascogonium is formed which divides into binucleate cells and develops ascogenous hyphae in the usual way. In a fifth group, as in Penicilliopsis clavariaeformis, as far as previous observations of the author extend, the formation of the fructification is no longer introduced by the formation of an ascogonium. Conidiophoric coremia radiate laterally or teminally without apparent reason (Fig. 115, 2, outer right) and change into perithecia in a still unknown manner. Apparently there has taken place in the Aspergillaceae a gradual degeneration of sexuality, because of the retardation in the formation of the antheridium. The Penicillium "crustaceum" group is apparently still potent sexually; it may be directly connected to Gymnoascus Reesii. In other forms, as P. vermiculatum, the antheridium is formed when the ascogonium has already become multinucleate and hence may no longer be fertilized by the uninucleate antheridium. In still other forms, as in EUASCOMYCETES 183 the A. herbariorum-repens group, the antheridium is still more retarded and may only function when the ascogonium is already septate. Occa- sionally it may be entirely absent. In other forms, as A. flavus and A. fumigatus, the antheridium is entirely suppressed and the formation of fructifications proceeds only from the ascogonial helix. In a fourth stage, in Penicilliopsis clavariaeformis, the ascogonia are probably no longer formed and the development of the ascogenous hyphae takes place pseudogamously. These two important facts, that all these types occur so close together and that the different forms are often variable in behav- ior, allow one to conclude that the reduction of sexuality is still recent and has not yet become stabilized. s ■ Lj . J. „j r£ ftk Fig. 115. — Penicilliopsis clavariwformis. Left, coremia; right, young fundament of fructi- fication; center, half-mature fructification. (Natural size.) According to the further fate of the fructification fundaments in the Aspergillaceae group, two types may be distinguished. In the first type, to which belong the majority of the above forms, as A. herbariorum, A. fumigatus, Penicillium vermiculatum and Acauliumalbonigrescens, the asco- genous hyphae divide without resting periods into binucleate cells which, with fusion of their nuclei, swell to asci. They gradually dissolve the inner layers of the fructification parenchyma and thus provide the mate- rial for the nourishment of the maturing ascospores. At maturity the perithecia consist of a more or less solid pseudoparenchymatous sheath which is filled with a brownish spore powder and generally opens at the top by the decay of the cover. In Aspergillus nidulans, the fructifications do not arise free on the mycelial mat but are embedded in peculiar bladder- like sheaths (Fig. 116, 3). These are formed because the neighboring hyphae next the mycelial cover do not branch further, and the end cells 184 COMPARATIVE MORPHOLOGY OF FUNGI of the ultimate branches swell and thicken their membranes (Fig. 116, 5). To this first type also belongs Penicilliopsis, whose fructifications are divided into several ascigerous chambers by additional sterile veins differentiated from the ground tissue. In the second type, which is only investigated in a representative of the Penicillium "crustaceum" group, the sterile ground tissue first goes through a resting period. About a week after its formation, it thickens its membrane and changes in a stony sclerotium. In its interior lie inconspicuous, aseptate, ascogenous hyphae, recognizable by their more refractive content. Fig. 116. — Aspergillus nidulans. 1, 2. Conidiophores with branched phialides. 3. Perithecium, s, surrounded by conidial mycelium. 4. Conidia. 5. Vesicle. 6. Peri- thecium. 7. Section of perithecium; as, ascus; r, rind. 8. Young asci. 9. Germinating ascospore. (1, 2 X 230; 3 X 120; 4 X 1,000; 5, 8 X 400; 6 X 85; 7 X 170; after Eidam, 1883.) In this condition the sclerotia seem very like the sterile vegetative sclerotia of the other orders and, even in the Aspergillus-Penicillium group, several forms are known whose sclerotia are really sterile and form- ing only a resting condition of vegetative mycelia. Under favorable conditions, they develop directly to a mycelium. If, however, one sows the sclerotia of the above mentioned member of the Penicillium "crus- taceum" group investigated by Brefeld, one observes that only the asep- tate ascogenous hyphae possess life while the sterile ground tissue is passive and gradually consumed by the ascogenous hyphae. About 7 to 8 weeks after the sowing of the perithecia, the ascogenous hyphae which extend from the center of the fructification (Fig. 117, F) are divided into short, cylindrical, apparently binucleate cells. Out of many of them EUASCOMYCETES 185 Fig. 117. — Penicillium " crustaceum." A. Mycelium with conidiophores. B. Single condiophore. C. Young copulation branches. D. Growth of ascogenous hyphae in the knot of peridial hyphae. E. Young perithecium before hardening of the walls. F. Sclerotic perithecium. G to K. Development of asci. L. Ascospores. (A X 60; B X 315; C, D, G to J X 630; E, F X 150; L X 800; after Brefeld, 1874.) 186 COMPARATIVE MORPHOLOGY OF FUNGI there grow thicker buds whose tips coil spirally (Fig. 117, G). On their curved outer surface there arises a branch which curves upward, coils and forms a new branch, etc., so that the different branches together form a serpiform main axis on whose convex sides there appear small branches (Fig. 117, 1). The cells of the branches become spherical asci. Besides these thick buds, thinner branches coiling like tendrils grow out of the ascogenous hyphae (Fig. 117, G). They elongate rapidly and penetrate the sterile ground tissue, thereby making room for the develop- ment of the asci. They seem to be nurse-hyphae and in this sense are analogous to the haustoria of the parasitic forms and the ooblastema filaments of the Florideae. The animation of the sclerotia proceeds gradually from the center to the surface. Four to six weeks after germination, the first ascospores capable of germination are found in the sclerotia while the last asci still form mature spores 5 months later. The ascus walls gradually degener- ate and the spores lie free inside the brown perithecial rind, which consists of two or three layers of periclinal cells. By rupture or decay of this rind, the ascospores are liberated. They possess a double membrane and a meridional furrow like most members of the Aspergillaceae (Fig. 117, L); the exospore is ruptured at germination and the endospore develops one or more germ tubes. Onygenaceae. — This family has so far been found on animal sub- strates, hoofs, horns, hides, claws, feathers, teeth, etc., and in this sense forms a group sharply limited biologically. In the well-known Onygena equina the fructifications (Fig. 118, 1) are up to 1 cm. in height. They consist of solid homogeneous hyphal knobs which abjoint on their upper surfaces so many thick-walled gemmae (Fig. 118, 2) that they seem to be covered by a brownish powder. Later they are differentiated into a solid stipe, composed of parallel hyphae, and a somewhat looser head, consisting of radiating hyphae. Around the latter, on its outer surface and toward the stipe, the hyphae intertwine to a firm pseudoparenchyma- tous peridium. Their connection with the central ground tissue, however, lemains to maturity when they have become capillitium. The processes which occur in spore formation have been too little investigated. In numerous places inside the head there are formed from the hyphae, two short septate branches which coil spirally into a solid knot and in an unknown manner give rise to the spores. In these relation- ships, they are superficially like Penicillium, but they have not been studied cytologically. At maturity the cavity of the head is filled by a dark spore mass between which run the capillitium threads, generally starting at the base (Fig. 118, 4). The peridium is ruptured irregularly or around the base of the head and the spores scattered. They germinate directly after a resting period; this may be shortened if one places the spores in a mixture EUASCOMYCETES 187 of HC1 and pepsin corresponding to the gastric juice. Immature asco- spores and gemmae germinate without this stimulation (Ward, 1899; Brierley, 1917). Trichocomaceae. — The Trichocomaceae are a poorly known family of the warmer regions. Trichocoma paradoxa (E. Fischer, 1890) grows on dead wood and forms fructifications up 1 cm. in diameter and 2 cm. high. Out of a woody-brown, patelliform, basal sheath, resting on the substrate, there arises a more or less columnar tissue. It consists of a system of faveolate tubular chambers which run up from the base of the fructification and are filled by the spore mass. The maturing of the fructification apparently takes place basipetally. The asci arise by a swelling of the binucleate members of the ascogenous hyphae. The development of this peculiar family is still entirely unknown. Fig. 118. — Onygena equina. 1. Fructifications on a piece of horn. 2. Section through the periphery of a young fructification. The terminal portions of the hyphae are forming gemmae. 3. Branches of a hypha whose cells will become asci. 4. Median section of an immature fructification. (1 X 2.3 ; after Ward, 1899.) Terfeziaceae. — This and the following family are only known in the mature condition, and in the structure of their fructifications are next to Penicilliopsis; they are hypogaeous, however; furthermore, no conidia have been detected. Terfezia Leonis is found in the Mediterranean region under Cistus and Helianthemum bushes with which they apparently form mycorrhizas. The fructifications reach the size of a fist and are divided by sterile veins into ascigerous portions which gradually run outward into a soft peridium. They are edible and appear in the markets in the near East as "Karnes" and in North Africa as "Terfez." The Romans and Greeks also knew them. Probably the Terfeziaceae do not belong to this order. As rapidly as the genera formerly placed in this family have been investigated cytologically and ontogenetically, they have been transferred to the Tuberales. So far Terfezia, the only remaining genus, has not been investigated. 188 COMPARATIVE MORPHOLOGY OF FUNGI Elaphomycetaceae. — This family may be divided into two tribes each with a single genus, the Elaphomyceteae and the Mesophellieae, the former widely distributed in Europe and America with many species confined to Italy, the latter confined to Australia. The fructification in Elaphomyces cervinus (E. granulatus) and E. muricatus develops from a complex hyphal knot which is first differenti- ated into an outer layer, the fundament of the crust and cortex, then the inner layer is separated into peridium and core. The peridium becomes more or less pseucloparenchymatous traversed by aeriferous SVsf*--^^ Fig. 119. — Elaphomyces cervinus. A, B. Mature fructifications attached to pine roots. C. Mature fructification. D. Section of nearly mature fructification. E. Ascus. {A X l^i; C natural size; after Reess and Fisch, 1887.) veins, while the core remains a loose hyphal tissue. The sexual proc- esses have not been observed, but the ascogenous hyphae grow out from the inner wall of the peridium into the core and by repeated branch- ing form groups of asci, (Fig. 119, E) which early disappear. In some species these spore masses form small balls resembling those of Polysac- cum, while in others they completely fill the central cavity (Reess and Fisch, 1887). The ontogeny of the fructifications of the Mesophellieae have not yet been studied, but observations on the morphology of the mature fructifications suggest that it may be similar to that of the Elaphomy- ceteae. In Mesophellia castanea the sexual organs appear in little loculi near the aeriferous veins of the peridium. Two large septate EUASCOMYCETES 189 hyphae grow side by side, and coil once or twice. The terminal cells elongate and fuse near their tips. Ascogenous hyphae grow from the basal cell of one of these hyphae, suggesting that there is a differentiation into trichogyne and ascognonium, although the nuclear history could not be followed in the material available. The ascogenous hyphae produce asci in most of their cells, as in the Onygenaceae and Trichoco- maceae (C. W. Dodge, 1928). In M . castanea, the hard central core has comparatively few trabec- ule connecting it to the peridium which at maturity consists of a single layer, suggesting the peridium of Elaphomyces muricatus in its mottled appearance. In M. sabulosa, the peridium is cut off from the gleba by a well marked zone of fission and quickly gelifies so that at maturity it consists largely of a shell of sand held together by a gel. In M. arenaria, the rind is differentiated into a peridium and cortex having the texture of strawboard as seen in section. Elaphomyces forms mycorrhizas with the roots of conifers, (Fig. 119, A-B) especially E. muricatus, E. variegatus and E. cervinus. The latter has been used since the Middle Ages as an aphrodisiac in folk medicine. All three species are often infected with Cordyceps ophioglossoides and C. capitata of the Hypocreales. Summary. — The Plectascales hold an important position in the Ascomycetes as below they have their morphological relations with the Endomycetales and Zygomycetes, and have the beginnings of a varied upward development. Their imperfect forms, conidia, are basically the same as in these groups, but they have developed in three directions. One is represented by the Aspergillaceae ; morphologically it inclines toward the Syncephalastrum-Syncephalis group and in this sense forms a branch of the Choanephora-Piptocephalis series. While in Mucor, Sporodinia, etc., spore formation is still normally endogenous, in Choanephora, with liberal food, it is retarded and becomes exogenous, and in Syncephalastrum and Syncephalis it is fixed in an exclusively exogenous type. The Aspergillus group has proceeded a step beyond the Syncephalis type, however, and on its sporangia forms purely exogenous conidia. Just as in the further development of the Synce- phalis type, the sporangia which have become functionless collapse into gibbous basal cells (as in Piptocephalis) ; in the Aspergillus group the sporangia degenerate and through a series of intermediate forms the Penicillium type is reached, where long spore chains on flask-shaped phialides are cut off at the top of undifferentiated conidiophores. The second direction is represented by Thielavia. Its origin is still unknown; its morphological significance lies in endogenous conidial formation by the splitting of the conidial membrane. The third direc- tion is represented by Ctenomyces. Here for the first time the condio- phores intertwine into special pycnia with lysigenous cavities. 190 COMPARATIVE MORPHOLOGY OF FUNGI Like the imperfect forms, the sexual organs are directly connected to the Endomycetales and Zygomycetes, only the dynamic differentiation between the male and female copulation branches becomes morphologi- cal and, in the majority of forms, has led to special antheridia and asco- gonia which are characteristic both in form and function. As the imperfect form, so the sexual organs show development in three direc- tions. A first direction (Monascus-Magnusia) is distinguished by the functional development of the female copulation branch. This no longer participates as a whole in fertilization but is differentiated into a trichogyne and a female gametangium, the ascogonium. Herein lies the root of the relationships in many higher Ascomycetes. A second series (Gymnoascus-Aspergillus-Penicillium group) develops in the reverse direction, with the gradual disappearance of sexuality. Already in the simpler forms the sexual act has become facultative. In the higher forms, the formation of the antheridium is more and more delayed and can only function when the ascogonium has already passed the stage of maturity for fertilization and has become multinucleate or is already septate. Hence the ascogonia probably develop parthenoge- netically. When the antheridia are still formed, perhaps they only fulfil a physiological function of nourishment, and hence are called "tropho- gones" by Dangeard (1907). They are soon no longer formed and the ascogonia develop alone. In the third series (Penicilliopsis-Elaphomycetaceae) the sexual organs no longer initiate the formation of fructifications but function within them. While the imperfect forms and sexual organs of the Plectascales corre- spond with the Endomycetales and Zygomycetes in the further develop- ment of the zygotes, there appears a new factor, the dicaryophase and the development of the ascogonial cells to ascogenous hyphae. Thereby the developmental scheme of the Plectascales is lengthened by one mem- ber from that of the Endomycetales (p. 146) : I jt Secondary spore forms 11 ^^ P C R Mycelium— ^Sexual organs— ^Ascogenous hyphae— >Asci— *Ascospores Diagram XIX. In several forms the ascogenous hyphae show a peculiar separation into two phases; thus in Aphanoascus they first grow spirally ("primary" ascogenous hyphae), the branches again coil ("secondary" ascogenous hyphae); only the second generation forms the asci. More sharply distinct is the division in Penicillium "crustaceam;" where the ascogenous hyphae are developed into a resting and a spore-forming period. At present no interpretation of this change of ascogenous hyphae is evident; we meet it, however, in the Erysiphaceae. EUASCOMYCETES 191 Along with this development of the ascogenous hyphae, there takes place in the Plectascales a gradual development of fructification which in the highest hypogaeous forms rises to the level of Glaziella, Tuberales and Hysterangiaceae. If one attempts to divide the Plectascales from this point of view, one arrives at a scheme such as is represented below. It is obvious that the groups in this scheme may be disproportionately evaluated. Thus from Amauroascus, through Gymnoascus, Aphanoascus and Aspergillus, there is a gradual transition toward Penicillium, while on the other hand, Tkielavia and Monascus form sharply defined types and hence are often regarded as representatives of separate families. Similarly the four highest families of the Plectascales may be regarded as natural. PLECTASCALES TRICHOCOMACEAE Triehoeoma TERFEZIACEAE? Terfezia ELAPHOMYCETACEAE Mesophellia Elaphomyces ONYGENACEAE Onygena ASPERGILLACEAE Penicilliopsis Magnusia Penicillium f Thielavia Aspergillus Monascus Aphanoascus t GYMNOASCACEAE Ctenomyces Gymnoascus Amauroascus Diagram XX. As may be observed in the scheme at the close of the book (p. 618), there may be derived not less than five orders entirely or partly hypo- thetically from Plectascales-like types, of which the present known genera form only a small remainder. If one imagines the ascogenous hyphae short, so that the asci are joined into a tuft, one obtains the Perisporiales from the Thielavia-like forms. If one imagines that at maturity the perithecium is opened by an ostiole, one proceeds from the simpler Gymnoascaceae and Aspergillaceae to the simpler saprophytic Hypocreales and Sphaeriales. If one imagines that the mycelial mat develops stromatically in the Gymnoascus and A phanoasc ws-like forms, and that the hyphal covers are intertwined to a plectenchyma not only around the sexual organs, but throughout the whole extent, one comes to the Myriangiales and Pezizales. CHAPTER XIV PERISPORIALES The Perisporiales differ from the Plectascales in that their asci are not irregularly formed in the interior of the perithecia but in a fascicle (or umbel), free at maturity, attached at the base and generally still without paraphyses; thus the asci all stand at the same height. Externally, many Perisporiales may not be distinguished from the Aspergillaceae (e.g., Thielavia group) and only an investigation of the manner of forma- tion and arrangement of the asci offers a solution of the systematic posi- tion of the fungi in question. In contrast to the Plectascales, the Perisporiales are obligate parasites in which the perithecia, generally still cleistocarpous, as in the parasitic Plectascales, are extramatrical, in a position to take an active part in dissemination. Biologically they form a peculiar developmental series from the endoparasitic to the ectoparasitic method of life, whose end forms are distinguished by a special asterinoid habit (Arnaud, 1918); this type includes ectoparasitic forms, chiefly in damp climates, which spread radially over the surface of the host by aerial mycelia and derive their nourishment by the formation of haustoria or sinkers. In this sense the Perisporiales are circumscribed, half morphologically, half biologically. They form a transitional order from the Plectascales to the Pyrenomycetes and hence to a high degree their limits are determined by the subjective measurements of individual investigators. In the following discussion, we will recognize three families: the Erysiphaceae, the Perisporiaceae and the Englerulaceae. The Erysiphaceae include the forms with white aerial mycelium ; they are cosmopolitan but are best developed in the temperate zone. In addition to their hyaline extrama- trical mycelium, they are distinguished by the development of imperfect forms and by their unicellular ascospores. The Perisporiaceae and Englerulaceae include those forms with more or less dark-colored aerial mycelium. They are mostly tropical and subtropical. Imperfect forms have been found with certainty only in a single genus. Their ascospores are generally septate. The Englerulaceae differ from the Perisporiaceae by a peculiar histolysis of their perithecial wall, whereby their mature fructifications attain a half-open Discomycetous structure. Erysiphaceae. — The powdery mildews show most markedly the character of the Perisporiales. They form a very homogeneous, sharply denned group and are parasitic on Angiosperms. Together with the 192 PERISPORIALES 193 rusts they belong to the few groups of obligate parasites which up to the present have resisted all attempts at culture on artificial substrates; as in the rusts, they do not kill the affected host tissue but may stimulate it to slight hypertrophies. The hyphae are strongly septate; their cells are uninucleate; the haustoria alone are sometimes multinucleate. Their walls are hyaline, except in Sphaerotheca mors-uvae where they become dark in age. As regards their behavior toward the host, they may be arranged in a noteworthy series from endoparasitic, through hemiendophytic, to ecto- parasitic forms. Their lowest endoparasitic stage is represented by Fig. 120. — Erysiphe Polygoni on Geranium maculatum. Development of haustoria. ( X 1,200; after G. Smith, 1900.) Leveillula taurica (Oidiopsis taurica). In it the mycelium lies, as in many parasites, in the intercellular spaces of the host leaves; only in the later stages of conidial formation do the hyphae emerge on the surface of the leaf and then form, like the other Erysiphaceae, an arachnoid or felty mat. These extramatrical hyphae cling by appressoria to the sur- face of the leaf; on this surface, however, they form no haustoria but nourish themselves, as do the hemiendophytic forms, by branches which penetrate the interior of the leaf through the stomata. In the hemiendophytic stage, as in Phyllactinia, the mycelium lives in the manner characteristic of mildews, extramatrically on the 194 COMPARATIVE MORPHOLOGY OF FUNGI surface of the leaves. This external mycelium does not penetrate the epidermal cells by haustoria, but puts forth special branches of limited length through the stomata into the mesophyll (Fig. 121, 2) where they secure nourishment. The ectoparasitic stage includes all the other Erysiphaceae. These are entirely extramatrical and form a loose white covering on the surface of the host, so that it seems dusted with flour. The hyphae creep about the epidermis and from time to time form short branches. Where these come into contact with the wall of the epidermis, they spread out into a simple or lobate appressorium. The epidermal wall begins to swell and stains deeply (Fig. 120, 1). The very slender hyphal tip bores through Fig. 121. — 1. Uncinula Salicis on Salix discolor. Haustoria which have penetrated the hypodermal cell layers. 2. Phyllactinia corylea on Cornuss tolonifera. Hyphal branch penetrating the mesophyll. 3. Erysiphe graminis on Poa pratensis. Haustoria. (1, 2 X 600; 3 X 1,200; after G. Smith, 1900.) the cuticle and the cell wall into the interior of the epidermal cell (Fig. 120, 2 to 4) and expands there into a saccate haustorium (Fig. 120, 5 and 6). This simple tuberiform or saccate knot is the usual type of haustorium in this group. Only in Erysiphe graminis, the haustoria grow laterally to long filiform lobes (Fig. 121, 3). Generally the haus- toria remain limited to the epidermal cells; only in Uncinula Salicis they may penetrate to the subepidermal cells but never further (Fig. 121, 1). In spite of this extreme ectophytism which only differs from pure epiphytism in the formation of haustoria, and in spite of their hyaline walls, the Erysiphaceae are very resistent to external influences; e.g., they can thrive on parts of plants which are in full sunlight the whole day. They are found from the polar regions to the tropics but PERISPORIALES 195 prefer damp climates. The only endophytic species, Leveillula taurica, belongs to dry subtropical regions whose phanerogams are generally xerophytes with a very thick epidermis. Further it appears that the Erysiphaceae in the tropics generally only propagate by imperfect forms and that the perithecia degenerate. They are also sharply specialized even in their ectophytism (Salmon, 1900, 1903; Steiner, 1908; Blumer, 1922; etc.). From the numerous forms so far studied, except for Erysiphe dehor acearum, none is able to go beyond a single host genus, and is often limited to a single species Fig. 122. — Leveillula taurica. Conidiophores. ( X 830; after Foex, 1913.) or group of species within the genus. Salmon (1904, 1905) has shown, however, that here our observations on the fundamental relationships need clarification. If one wounds old leaves whose cuticle normally resist infection (e.g., if one cuts away a piece of epidermis), the fungus may then infect the mesophyll. In this manner, transitions between various biological strains might be possible. As imperfect forms, only conidiophores and conidia are known; earlier pyenia were ascribed to the Erysiphaceae but they have since been demonstrated to be the fructifications of a parasitic imperfect, Cicinnobolus Cesatii. The conidiophores are at first formed on both sides 196 COMPARATIVE MORPHOLOGY OF FUNGI of the leaf, but later, in proportion as perithecia are formed on the upper side of the leaf, they become limited to the lower side. According to the manner of cutting off the spores, they are divided into two types; in the first type, which includes the endo- and hemiendophytic forms, the CI f^ ktfuj '•'■■'/■■"" »;,*;.. -\ f'* *.. ■■"■ Mi &$j i&-:^ ■m .*»••■ -V ivS- \ :£>;;: v&\ *w*. • / fi ift i! ?4; ■M | ft :.;-^ J" ■ .'****.: '■ i':**',' :■ " i t -■ : *" r*-*' •' Y ■ -l r<^-... W- Fig. 123. — Sphacrotheca Humuli. Development of conidiophore. (X830; after Foex, 1913.) conidia are cut off singly, in the ectoparasitic forms they arise in chains (Foex, 1912, 1913; Bezsonov, 1913). In the first type, Leveillula taurica (Fig. 122), the hyphae collect in the substomatal cavity to dense, almost pseudoparenchymatous knots, whence radiate the mostly unbranched, aerial hyphae (conidiophores) PERI SPORI ALES 197 whose upper cells form conidia. When this falls off, the subterminal cell (or conidial mother cell) divides again into two daughter cells, the upper of which develops to a new conidium. The development of Phyllactinia proceeds similarly, except the conidiophores are formed only on the superficial mycelium. In the second type, e.g., Sphaerotheca Humuli (S. Castagnei) a protru- sion forms on a hypha above a nucleus (Fig. 123, 1); this elongates and divides into two cells of which one remains connected with the sporiferous hypha while the other projects over it (Fig. 123, 2). The latter is the mother cell of all future conidia; it cuts off successively a series of daughter cells which round off to conidia, or first divided into two and the resulting daughter cells change to conidia (Fig. 123, 3 to 6). Thus the mother cells in this group, which includes Erysiphe graminis, E. dehor acearum, Sphaerothecca pannosa and S. mors-uvae, lie directly on the sporiferous hypha. In another group, as Erysiphe Polygoni and Uncinula Salicis, it is separated from the sporiferous hyphae by a longer or shorter stipe cell. The conidia are hyaline, uninucleate and generally only capable of germination for a short time. As they are formed in enormous numbers, they facilitate a very rapid dissemination. In damp air or water, they develop one or more germ tubes on their narrow side. As they often appear months before the perithecia and as on many hosts the perithecia are unknown, many Erysiphaceae have been described as imperfects; thus the conidial forms of Leveillula taurica type were placed in the imperfect genus Oidiopsis, the conidial forms of the Phyllactinia type were in Ovulariopsis and the conidial forms of the ecto- phytic type in Oidium. Occasionally (although the expression has nothing to do with oidial formation) this designation is still used in plant pathology. The perithecia generally begin to appear in the course of the summer. From two neighboring hyphae there arises a thick, slightly ovoid asco- gonium and a slender, somewhat curved antheridium; often they coil about each other. Like the hyphal cells, they are both originally uni- nucleate, and separated from the sporiferous hypha by a septum. The male nucleus divides, and a basal stipe cell is cut off from the apical antheridium (Figs. 124, 2; 126, 1 and 2), exceptionally the ascogonium may also undergo a division. The further development of both copulation branches has been the object of considerable controversy. In a first group, as in Erysiphe Polygoni (E. communis) on Trifolium and Mellilotus (Harper, 1896), in Sphaerotheca Humuli on Humulus (Harper, 1895; Blackman and Fraser, 1905, denied by Dangeard, 1907), in Phyllactinia corylea on Fraxinus americana, Corylus americana, Celastrus scandens and Betula lutea (Harper, 1905) and in Sphaerotheca mors-uvae on Ribes sp. (Bezsonov, 198 COMPARATIVE MORPHOLOGY OF FUNGI 1914), the antheridium comes into open connection with the ascogonium and the male nucleus migrates into the ascogonium and fuses with the female (Figs. 123, 3; 126, 3). In S. mors-uvae, it goes through another division before migration, so that one daughter nucleus migrates into the Fiq. 124. — Sphaerotheca Humuli. Development of perithecia. 1. Young antheridium and ascogonium. 2. The antheridium divided into antheridial cell and stalk cell. 3. Plasmogamy. 4 to 6. Development of fertilized ascogonium. ( X 500 ; after Harper, 1896.) ascogonium while the other remains behind in the antheridium and degenerates. In a second group, as in Erysiphe Polygoni (E. Martii) on Pisum sativum and Ranunculus acris, E. cichoracearum on Sonchus oler- aceus, Phyllactinia corylea on Corylus Avellana, in Uncinula Salicis on Fig. 125. — Erysiphe Polygoni. 1. Primary ascogenous hypha with five nuclei. 2. Longitudinal section through a young perithecium with three asci; the perithecial wall is already differentiated. (X 470; after Harper, 1896.) Populus (all according to Dangeard, 1907) and in Sphaerotheca Humuli var. fuliginea on Melampyrum (Winge, 1911), fertilization is absent and the male nucleus degenerates in the antheridium. Thus in the Erysiphaceae the relationships are apparently the same as in the Plec- tascales. Although the sexual organs are normal morphologically, sexual- PERISPORIALES 199 ity is degenerating; in some species the sexual act still occurs, in others it is absent and the ascogonia develop parthenogenetically; in still others, as in Sphaerotheca Humuli, the behavior varies according to circumstances Fig. 126. — Phyllactinia corylea. 1. Coiled copulation branches. The male nucleus has divided to form a stalk cell and antheridial cell. 2. Antheridium completely divided into stalk cell and antheridial cell. 3. Plasmogamy. 4. Caryogamy. 5. Outgrowth of primary ascogenous hyphae. 6, 7. The binucleate penultimate cell of the primary ascogen- ous hypha (the ultimate cell is in the next section). 8, 9. The penultimate cell develops secondary ascogenous hyphae. (These figures represent successive, serial sections of the same hypha.) 10, 11. Young fructifications, the former .showing ascogenous hyphae, the second young asci. (1 to 4, 8, 9 X 670; 5, 6 X 250; 4, 7, 10 X 330; 11 X 200; after Harper, 1905.) and the ascogonia may continue their development with or without fertilization. According to the type of the further development, the fertilized or the unfertilized ascogonium grows while the antheridium collapses to a 200 COMPARATIVE MORPHOLOGY OF FUNGI thick hypha which in P. corylea, and in the forms of Erysiphe Polygoni (E. communis) on Ranunculus acris investigated by Dangeard includes, in a manner still unexplained, several bi- and several uninucleate cells; in the form of E. Polygoni on Leguminosae investigated by Harper, septation is first absent apparently because of very rapid elongation (Fig. 125,1), so that the hyphae have five to eight nuclei and only subsequently divide into single cells; thereby the subterminal cell is binucleate (Fig. 126, 6 and 7). The relationships are difficult to follow cytologically, as the copula- tion branches are already surrounded by a thick hyphal knot into which the primary ascogenous hyphae, growing out from the ascogonium, penetrate with irregular twistings. In a manner still to be studied, one or more of the binucleate cells grow out of this primary ascogenous hypha to secondary ascogenous hyphae (Fig. 126, 8 and 9) which branch many times, and change the terminal cells to asci with nuclear fusion. In Sphaerotheca, alone of all the forms so far studied, the primary ascogenous hypha, itself growing from the ascogonium, proceeds directly to the formation of a single ascus. Thus, as in Erysiphe Polygoni the ascogonium develops to a multinucleate tube which divides simul- taneously into several uninucleate cells and a subterminal binucleate cell (Fig. 124, 6). This subterminal cell develops directly to an ascus, with the fusion of its dicaryon. While each of the perithecia in the first type includes several (up to 20) asci, in the Sphaerotheca type it contains only one. In both, the primary ascus nucleus undergoes three steps in divi- sion, whereupon the daughter nuclei cut out of the protoplasm eight (or, on account of abortion, only four or two) unicellular, later brown ascospores. These, probably the largest unicellular spores in the fungi, in Phyllactiniar corylea attain a length of over 50 ju. They are liberated by irregular rupture or by crumbling of the peridium. An interpretation of the relationships of the first and second types of development seems to be possible only on the basis of relationships described in the Plectascales. The first type (Phyllactinia-Erysiphe) may be directly referred to the Aphanoascus-Penicillium type, in which the ascogenous hyphae divide into two phases of which only the second is sporogenous. Only in the Phyllactinia-Erysiphe type, and this seems to be a new character for the group, the first phase undergoes a gradual degeneration, while in Phyllactinia corylea and in Erysiphe Polygoni (E. Martii), as in the Plectascales, several binucleate cells are formed in the first phase so that several ascogenous hyphae result. There is only one binucleate cell in the form of Erysiphe Polygoni (E. communis) studied by Harper, consequently the number of ascogenous hyphae is limited to a single one which, by branching considerably, gives rise to a few asci. This limited elongation in the first phase of the ascogenous hyphae may undoubtedly be called the new characteristic point of the Erysipha- PERISPORIALES 201 ceae (and of the Perisporiales altogether) ; for only by this limitation does there result that tufted arrangement of asci which forms the character- istic feature of the Perisporiales. This degeneration goes still further in the Sphaerotheca type, for here the development of the subterminal cell to a secondary ascogenous hypha is also suppressed and the subterminal cell itself develops directly to an ascus. If the interpretation is correct, the Erysiphaceae may be regarded as a branch of the Plectascales in which the first and then the second phase of development of the ascogenous hypha gradually disappears reaching an end stage in Sphaerotheca. It is, however, not permissible (as repeat- edly occurs in the literature) to contrast the subterminal formation of asci in Sphaerotheca and their terminal formation in Erysiphe and Phyllac- tinia and to find fault with one or the other observation; for the sporo- genous ascogenous hypha belongs in the two groups to different stages of development. The second problem which arises in the consideration of the life cycle of the Erysiphaceae, is double fertilization. If the interpretation which Harper and others have given to their observations were correct, a first caryogamy occurs in the ascogonium and a second in the ascus. As was briefly discussed in the introduction to the Ascomycetes, it is at present impossible to clear up controversy over this point. As occasionally observations on material from different hosts have been combined, a source of error might lie here, as similar misinterpretations, resulting from mixing material of different biological strains, have occurred also in the Ustilaginales. In this case, one must assume that in the Erysipha- ceae (as in the Agaricales of the Hygrophorus conicus type in the Basidio- mycetes) the place of caryogamy varies, in one form, in the ascus, in the other in the ascogonium, and that, by a combination of these types, there is a deceptive picture of double fertilization. At maturity, the perithecia agree in the essential characters of their structure with those of the Plectascales. They consist of a homogeneous, brown, hard, brittle rind consisting of plates, regular polygonal cells and of a hyaline nurse tissue in which the asci are imbedded (Hein 1927). This collective tissue within the brown rind, together with the asci, is occasionally referred to in systematic literature as "nucleus," centrum, kernel or core. In contrast to the Plectascales, the perithecia in the Erysiphaceae have assumed a protective function by wintering over, as well as the task of propagation. Perhaps the limitation of the number of asci to one and consequent reduction of the dimensions of the perithecia is connected with this new function and hence in the Erysiphaceae there appear problems similar to those which we have met in the Oomycetes. This propagative function of the perithecia is facilitated by two impor- tant facts, by the development of special appendages and, in some forms, 202 COMPARATIVE MORPHOLOGY OF FUNGI by the special structure of the perithecial rind. Before the rind has completed its peridial structure, some of its cells develop to long append- ages; these are generally characteristic and offer one of the most conven- ient points for the separation of genera. In Erysiphe, Leveillula (Fig. 127) and Sphaerotheca, they are simple, hyphal-like and intertwined with the mycelium; in Podosphaera (Fig. 128, 4) and Microsphaera (Fig. 128, 1 to 3), they are repeatedly dichotomously branched at the tips; in Uncinula (Fig. 128, 5 to 7), they are coiled more or less spirally at the tips; in Typhulochaeta, they are clavate and arranged in a ring consisting of Fig. 127. — Leveillula taurica. Section through the lower surface of a leaf and the peridium of a perithecium, showing extra- and intramatrical mycelium and the hyphal appendages. (X 400; after Arnaud, 1921.) two or three rows around the top of the perithecium ; and in Phyllactinia, unbranched, but setiform and rigid, with a saccate base (Fig. 129, 1). As regards the structure of perithecial wall, there are two groups. In Sphaerotheca, Erysiphe (Fig. 125, 2) and Leveillula, the rind (as in the Plectascales) is spread approximately evenly over the whole fructifica- tion; in Microsphaera and Uncinula, it possesses a dorsi ventral structure consisting generally at the base of wide-lumened, thin-walled cells and at the top of narrow-lumened, thick- walled cells. Neger (1901, 1902) attempts to interpret these observations biologically as follows: in the first group, with the peridium symmetrical on all sides, the perithecia are generally sessile. Their appendages are interwoven with mycelium and PERISPORIALES 203 do not loosen even toward spring; if in the course of the winter, the peri- thecia dry, they shrink evenly so that the spherical form is not altered. The perithecia remain clinging to the substrate and only later, together with the mycelium, are washed away. Thus the appendages here serve for gripping the mycelium and indirectly, the substrate. Fig. 128. — Types of appendages. Microsphaera Alni. 1. On Syringa. 2. On Cornus alternifolia. 3. Var. Lonicerae. 4. Podosphaera Oxyacanthae. 5. Uncinula Aceris. 6, 7. Uncinula Sengokui. (X 270; after Salmon, 1900.) Fig. 129. — Phyllactinia corylea. 1. Perithecium with penicillate cells above, a turgid spherical cell on the right, a collapsed spherical cell on the left. 2. Erect perithecium with an apical drop of gel. (1 X 200; 2 X 100; after Neger, 1901.) In the second group, with dorsiventral rind, the perithecia are mobile ; they gradually break loose from the substrate, fall off more or less spon- taneously and are carried away by external agents. This active loosen- ing from the substrate is caused either by the action of the rind or of the appendages. The cooperation of the rind in the liberation of the perithecia is credible for Uncinula and Microsphaera. Upon drying, the whole rind does not shrink evenly, but only its thin- walled, lower surface; this becomes more or less concave inwards and thereby (especially with 204 COMPARATIVE MORPHOLOGY OF FUNGI repeated drying and wetting) tears the hyphae with which it was attached to the substrate. Apparently, in these two genera, the appendages serve for passive dissemination; possibly they also favor clinging to a new substrate, as in some species of Uncinula they are also sticky. The cooperation of the appendages in the liberation of the perithecia has only been demonstrated in Phyllactinia. The sac at the base of the appendage is thick walled on the upper side and thin walled on the lower side (Fig. 129, 1). In drought, the lower side wrinkles and bends down like a joint, thereby the perithecium is raised from the surrounding mycelium as upon stilts (Fig. 129, 2). Experiments in a desiccator have shown that the force developed is comparatively large: Four perithecia easily raise a cover glass of medium thickness. The clinging of the perithecia to the new substrate is not accomplished in Phyllactinia by the appendages but by peculiar tufts of hyphae at the top of the perithecia which swell to a hygroscopic, foamy drop of slime (Fig. 129, 2) and apparently, upon drying, attach the perithecia firmly. A review of the more important genera here discussed (taken in part from Arnaud, 1921) is presented in the following scheme: Sphaerotheca Podosphaera | Microsphaera Phyllactinia Erysiphe Uncinula Aspergillaceae Diagram XXI. The polyascous Leveillida-Erysiphe group is regarded as primitive and the monascous Sphaerotheca-Podosphaera group, as derived. With this development, a decrease of intramatrical and increase of extra- matrical mycelium occurs, i.e., a transition from endoparasitism to ecto- parasitism, and a consequent increase in the ability of the conidiophores to form spores. The Erysiphe- Sphaerotheca series is distinguished by undifferentiated, the Uncinula-Podosphaera series by characteristic appendages. Several representatives of these genera cause plant disease, as Erysiphe graminis on cereals, Uncinula necator (Oidium Tuckeri) on grapes, Sphaerotheca mors-uvae on gooseberries, S. pannosa on roses, S. Humuli on hops, cucumbers, etc., Podosphaera leucotricha on apples and Micro- sphaera alphitoides (Oidium quercinum) on oaks. Perisporiaceae. — In contrast to the Erysiphaceae, this family lacks sharp limits. It begins with forms with Perisporial characters, develops toward the Sphaeriales type and merges into this order in the Amphi- sphaericaceae and its relatives. This will be briefly discussed in four genera, Lanomyces, Balladyna, Meliola and Parodiopsis. PERISPORIALES 205 In Lanomyces tjibodensis (Gaumann, 1922c), parasitic on the leaves of Castanopsis argentea in the mountain forests of West Java, the hyphae are generally 2 to 3 nucleate; as those of Leveillula taurica they are pri- Fig. 130. — Lanomyces tjibodensis. 1. Extramatrical mycelium with three loosened peri- thecia. 2. Sinker penetrating between epidermal cells. 3, 4. Young copulation branches. 5, 6. Copulation branches which failed to mate and have hypertrophied. 7, 8. Fertiliza- tion. 9 to 13. Development of the young perithecium. 14. Section through a perithe- cium, showing both peridial layers. 15. Section through an immature perithecium; the outer peridial layer is left off, the ascospores are compressed. (1 X 55; 2 X 550; 3 to 15 X 335; after Gaumann, 1922.) marily endophytic, penetrate large areas of mesophyll, form knob-like haustoria of medium size and stimulate the leaves to form small galls. In time they push out between the epidermal cells, branch much there, 206 COMPARATIVE MORPHOLOGY OF FUNGI spread over the leaf surface and intertwine, forming chocolate brown to black, wooly coverings. These cling fast to the surface of the leaf by haustoria which, as in the Erysiphaceae, penetrate the epidermal cells, occasionally also by sinkers which bore between the epidermal cells (Fig. 130, 2). Besides the usual vegetative hyphae, larger, more deeply staining hyphae, the sexual organs, also extend to the surface. The terminal cells are uninucleate (Fig. 130, 3 and 4). Originally they are both of equal size but later are differentiated into a slender male and a clavate female. They come into open communication with each other when the male nucleus migrates into the female copulation branch and fuses with the female nucleus. The unmated copulation branches develop again to vegetative mycelia (Fig. 130, 5 and 6). The zygote develops, as in the Erysiphaceae, to a short filament whose cells are all uninucleate, as far as known. The terminal cell is the largest and is very rich in proto- plasm (Fig. 130, 9 to 11). The stipe cells are vacuolate and frequently undergo subsequent longitudinal division. When a filament has reached a certain length, it is surrounded by sterile cells from the stipe cell to the tip, and changes into a multispored ascus. The stipe cells collapse and the monascous perithecia finally lie free in the hyphal tissue (Fig. 130, 13). The peripheral cells of the sheath develop to long hyphae which (in con- nection with the mycelial hyphae?) surround the fructification like a wreath and finally intertwine in a hard crust (Fig. 130, 14). The spores mature only after the fall of the leaves; both this and the germination have not been investigated. Lanomyces differs from Sphaerotheca in that the hypha growing from the ascogonium remains uninucleate throughout, goes through a compli- cated septation, changes its terminal cell to an ascus and causes the perithecial ground tissue to arise, not from the sporiferous hypha of the archicarp, but from the ascogenous hypha itself. Besides, within the Perisporiaceae Lanomyces forms a noteworthy transition from endophytic to asterinoid growth. In the younger stages, the hyphae are entirely endophytic; later they develop predominantly on the surface of the leaf; similarly the copulation branches arise in the interior of the leaves but complete their development on the epidermis. This transition from endophytic to asterinoid growth attains its complete development in the two following genera, Balladyna and Meliola. Balladyna Gardeniae forms sooty coverings on the leaves of Gardenia sp. in Java and stimulates them to manifold wrinkling and galls. The brown, epiphyllous, aerial mycelium grows radially and clings to the surface of the leaf by short, generally unicellar branches (hyphopodia) (Fig. 131, 1). Other multicellular branches with equally limited elonga- tion are perpendicular to the surface of the leaf and project as rigid, vertical, pointed spines. A third kind of branch penetrates the mesophyll PERISPORIALES 207 through the stomata, and there forms numerous haustoria; these are reminiscent of the sinkers of Phyllactinia and are called stomatopodia ; their development corresponds to that shown in Fig. 134 for Parodiopsis; only in Balladyna the haustoria are coralloid and almost fill the host cell, somewhat as depicted in Fig. 203, 3 for Asterina Usterii (Raciborski, 1900; Arnaud, 1918). The perithecia arise from the clavate terminal cells of the branches of the aerial mycelium. In youth they are light brown, spherical; in age, brown, or black and ovoid. Their rind consists of a single layer of brownish, polygonal cells which at maturity become a greenish, almost hyaline slimy mass (Fig. 131, 2). The interior of the perithecium con- tains one, rarely two asci, each with eight dark, two-celled spores. Bal- ladyna appears to hold a place among its relatives similar to that of Fig. 131. — Balladyna Gardeniae. 1. Fungus mat showing hyphopodia, H, on the lower surface of a leaf, with setae, B, and young fundaments of fructifications, P. 2. Mature fructification. (X 250; after Arnaud, 1918.) Sphaerotheca among the Erysiphaceae, in that neighboring forms, e.g., the Javan Alina J asmini, possess polyascous perithecia. Meliola (Gaillard, 1892; Beeli, 1920; Doidge, 1920a, 1921; Ryan, 1926; Stevens, 1927) includes at present mostly tropical species (about 300), which form brown radiating mats on the under sides of leaves and fruits, rarely on young twigs. The asterinoid habit is already so marked that they are often considered epiphytes; in the more carefully investigated species, however, as Balladyna and the Erysiphaceae, they are ectopara- sitic, sending knob-like haustoria into the epidermal cells and the tissue beneath (Maire, 1908; Doidge, 1921). As plant parasites they do not cause serious injury; however, some of them, as Meliola Camelliae and M. Penzigii on oranges and other citrus species, considerably diminish the value of the wares. The hyphae are brownish black to brownish red; the growing parts and the parts which lie next the substrate are finer, lighter and thinner 208 COMPARATIVE MORPHOLOGY OF FUNGI walled, the more exposed superficial hyphae are more solid, thicker walled and darker. They form numerous sterile, rigid, very dark- colored spines (up to 1 mm. in length) which may be upright or bent over, simple, branched or forked, with a form often reminiscent of the appendages of Uncinula and Microsphaera in the Erysiphaceae. Accord- ~^r Fig. 132. — Meliola corallina. 1. Perithecium with hyphopodia and perithecial spines. 2. Median section of a mature perithecium which has discharged all ascospores but one. Meliola evodiae. 3. Mycelial branch with stigmopodia which develop perithecia. Irenina obesa (Meliola obesa). 4. Germ tube with hyphopodia. (1 X 100; 2 X 290; 3, 4 X 330; after Gaillard, 1892; Bucholtz. 1897.) ing to the more or less frequent appearance of these mycelial spines, the mats are now thin and crustose, now thick and wooly; occasionally both aspects may occur side by side on the same leaf. Besides these spines, the hyphae which tend to form perithecia in older mycelia, form hyphopodia. According to Gaillard, they may be divided into two types, the mucronate and the capitate types. The PERISPORIALES 209 mucronate hyphopodium (Fig. 132, 4) corresponds to the simple hypho- podia of Balladyna; they are mostly formed as two single, opposed cells which may be regarded as short, unicellular branches. Possibly they form the appressoria; their ontogeny is still unknown. The capitate hyphopodia or stigmatopodia (Fig. 132, 3) are generally darker than the mucronate hyphopodia and alternately branched; thus one cell forms one of these branches to the right, the next cell forms one to the left, the next to the right, etc. Generally the stigmatopodia are inclined obliquely forward toward the growing tip. They generally consist of two cells, a stipe cell and a spherical terminal cell, the stigmatocyst. Fig. 133. — Parodiopsis Perae. 1. Hyphae with setae and young conidia, C. Parodi- opsis melioloides. 2. Section through the lower surface of a leaf with setaceous mat and immature perithecium. (1 X 250; 2 X 100; after Arnaud, 1918, 1923.) They are slightly reminiscent of the appressoria of the Erysiphaceae and possibly are related to haustoria. The stigmatocyst may develop the perithecia; it swells and divides into two cells, the terminal cell developing slowly to form the core of ascogenous tissue while the basal cell produces the perithecium in a manner suggestive of that in the Laboulbeniales (Ryan, 1926). Thus the perithecia, as in Balladyna, arise from a single branch of a hypha. At maturity they are spherical and resemble the Erysiphaceae; they consist of a dark, often carbonaceous rind, and a hyaline ground tissue, the rosette of asci. The brown rind is generally homogeneous, as in Balladyna and the Erysiphaceae; occasionally, as a step in the 210 COMPARATIVE MORPHOLOGY OF FUNGI direction of the Sphaeriales, it may become many layered. In many species, as in Erysiphe and Leveillula of the Erysiphaceae, it is symmetri- cal throughout the fructification; in others, as in Microsphaera and Uncinula, it is dorsiventral and is drawn out to a small wart or papilla at the tip; in other species, as in Meliola corallina (Fig. 132, 2), as a definite step in the direction of the Sphaeriales, a true opening, an ostiole, is formed at the top of the perithecium (Bucholtz, 1897). At times the perithecia, as in the Erysiphaceae, are provided with appendages, or peri- thecial spines, which, however, are only simple, unbranched and generally Fig. 134. — Parodiopsis Stevensii. Development of stomatopodia. 1. Seen from above. 2. In section (X670). Parodiopsis megalospora. 3. Section showing intra- matrical mycelium (X 530). {After Arnaud 1921, 1923.) not numerous. Where complicated structures are described, there seems to have been a confusion with mycelial spines which rise below the perithecium. The asci (another transition from the Plectascales to the Sphaeriales type) are generally spherical, rarely clavate. They usually contain only 2 to 4 brown, multiseptate spores. From Balladyna and Meliola, the development proceeds in two directions, one blindly from Balladyna to the Englerulaceae, the other progressively from Meliola to the Sphaeriales. As we shall briefly discuss the Englerulaceae as a third family of the Perisporiales, the step to the Sphaeriales will be described here ; it is completed by Parodiopsis. In this genus, the transitional character of the Perisporiales appears with PERI SPORI ALES 211 surprising clearness. In the arrangement of asci, Parodiopsis shows marked Perisporial characters; by the brown color and the behavior of the mycelium and by the possession of an ostiole it suggests the Amphisphaeriaceae of the Sphaeriales (Fig. 133, 2) ; and by the form and color of its perithecial wall, it would belong in the Hypocreales. As in both previous genera, the aerial mycelium emerges as a brown covering on the under side of a leaf and forms a liberal intramatrical mycelium through well-developed stomatopodia (Fig. 134). The perithecia are ochraceous, solid and generally rise above the stomata. If one imagines them entirely ingrown, so that the hyphal tissue in the stoma thickens into a prosenchymatous tangle, one has the Mycosphaerellaceae which we will discuss under the Sphaeriales. Fig. 135. — Englerula Macarangae. Immature perithecium. ( X 130; after Hoehnel, 1909.) Englerulaceae. — The only well-known representative of this family, Englerula Macarangae in East Africa, forms light brown coverings on Macaranga leaves (Hoehnel, 1909). In the young stage, the perithecia are spherical, without opening, and surrounded by a single-layered, brown rind formed of polyhedral cells. During the development of the three to five asci, the perithecial ground tissue gelifies. The gel is tough and swells much in water without dissolving. The outside of the perithe- cial wall differentiates a sharply defined, often nearly cuticular, slime layer. The separation of the rind cells begins in the upper half of the peri- thecia so that, singly or in small groups, they are loosely imbedded in the slime or float upon it (Fig. 135). This process gradually continues, toward the bottom. At the bases this histolysis does not occur. Hence the mature perithecia are open above and surrounded by a hyaline, structureless gel into which the asci project. The remaining representatives are less known than this species (Theissen, 19166), hence an opinion as to their morphological relationships is not possible. Possibly they are connected to forms like Balladijna. CHAPTER XV MYRIANGIALES The Myriangiales, like the Perisporiales, lead directly from the Plectascales, but their origin undoubtedly is more remote than that of the Perisporiales, perhaps at the stage of the Gymnoascaceae. If one imagines that the ascogenous hyphae of the Gymnoascaceae are longer so that they penetrate the whole hyphal mat which becomes compacted into a pseudoparenchymatous stroma, one has forms like primitive Myriangiales. These form pulvinate, irregular stromata in whose inte- rior the asci are irregularly arranged in one or more layers; the ascospores are liberated only by the disintegration of the stromatal layers above them. Fig. 136. — Kusanoopsis guianensis. Diagrammatic section through a leaf showing two stromata. (Stevens and Wecdon, 1923.) Thus the Myriangiales (like the Perisporiales) are angiocarpous but at maturity every ascus lies embedded singly in the stromatal core, not tufted. The ascus chambers or cavities are called loculi. As none of the forms have been studied cytologically, our morphologi- cal discussions in regard to the Myriangiales still lack ontogenetic bases. According to the differentiation of the stromata and the number of ascogenous layers, they may be divided into a series of families, five of which we will discuss here: the Myriangiaceae, Plectodiscellaceae, Saccardiaceae, Dothioraceae and Pseudosphaeriaceae. Their mor- phological relationships are given in the summary at the close of this order. Myriangiaceae. — These are parasitic, more rarely saprophytic on leaves, bark and insects. Their distribution is chiefly tropical or sub- tropical. The consistency of their stromata is often suggestive of that of the Hypocreales, although in Myriangiam itself they are more cartilagi- nous-gelatinous and generally brittle. According to the formation of the asci, they may be divided into two types. In one type, the asci are scattered irregularly over the whole stroma. In the other type they are 212 MYRIANGIALES 213 localized in definite regions of the stromata, i.e., they are differentiated into sterile and fertile parts. The first type may be illustrated by Kusanoopsis guianensis in British Guiana, which on dicotyledonous leaves forms dark-colored pulvinate stromata, up to 1 mm. in diameter, erumpent from the interior of the host at maturity (Fig. 136). They lack a definite rind, although the pseudo- Fig. 137. — Myriangium Diiriaei. A. Habit (natural size). B. Same (X5). C. Section through an immature fructification (X 30). D. Section of conceptacle (X 100). E. Ruptured ascus and mature ascospores (X 250). {After Millardet.) parenchymatous structure is always more marked in the sterile periphery than in the fertile core. The asci are spread in several layers over the whole interior, except the basal intramatrical portion, of the stroma, which projects like a foot into the mesophyll. The asci are spherical, the ascospores are hyaline and dictyosporic. The second type is shown by Myriangium (Phymatosphaeria) . The majority of its species are parasitic on insects, especially plant lice. Like 214 COMPARATIVE MORPHOLOGY OF FUNGI the foot in Kusanoopsis, this second type spreads over the substrate in a sterile stromatic plectenchyma, which, in the forms on animals, as M. Duriaei maybe pulvinate, thestromatal hyphae being sclerotic and narrow lumened (Fig. 137, C) ; those on plants, as in M . Pritzelianum, form only a thin membrane of hyphae with unthickened walls. The cells on the surface of the stroma become brown and change to a dark, otherwise undifferentiated, rind. From this sterile basal stroma arises a tuft of numerous vertical processes like a small pezizoid group (Fig. 137, A and B). They consist of the same plectenchymatous ground tissue as the basal stroma. They form the spherical asci in an apical, sharply defined, patelliform zone. nn r^r^TT^rj^^r^ Fig. 138. — Plectodiscella Pyri. 1. Section through fundament of a stroma. 2. Stroma which has already ruptured the cuticle. 3. Section through a mature stroma. (1, 3 X 500; 2 X 82; after Woronikhin, 1914.) As in Kusanoopsis, these are arranged in several layers (except in the Singhalese M. Thwaitesii) and contain hyaline dictyospores, liberated by the crumbling of the peripheral stromatal layers. As this crumbling proceeds more rapidly in the middle than at the edges, the mature ascigerous parts seem more like an apothecium. Occasionally, when the vertical portions are absent, the flat basal stromata form the asci in their own apical portions (Petch, 1924). Myriangium forms only one branch of the Myriangiales and as such ends blindly, hence the ontogenetic connections of the higher families should be sought in the simpler Myriangiaceae, with undifferentiated stromata similar to Kusanoopsis. From this point, development has probably proceeded in two directions, one to the formation of special coverings of the stromata, the other to the reduction of the number of asci and their arrangement in a single layer. MYRIANGIALES 215 Plectodiscellaceae. — The first type is realized in Plectodiscella Pyri (Woronikhin, 1914) causing a leaf spot of apple and pear in the Caucasus. The young fructifications arise between epidermis and cuticle as a ball of closely intertwined hyphae colored light at the base, but brown on the upper side and at the edges. By the further development of this ball into a pulvinate stroma, the cuticle is ruptured and the young fructification is more or less exposed. In contrast to Kusanoopsis, there are special rind layers (Fig. 138, 3). The underside remains a hyaline, compacter, more-marked pseudoparenchyma than the core of the stroma. The upper side is brown, and develops to a strong, sclerotic, outer layer consisting of polyhedral cells and uniting at the base of the stroma with the basal rind layer. At maturity the outer layer breaks off and after it the stromatic ground tissue, liberating the hyaline 4-celled ascospores. A second species, Plectodiscella veneta (Burkholder, 1917), which causes anthracnose of Rubus in the United States, is noteworthy in that the asco- spores under definite conditions of nourishment germinate first to a sprout mycelium. As an imperfect form, the Melanconiaceous Gloeosporium venetum occurs. Fig. 139. — Bagnisiella australis. 1. Section through the stroma from the bark of the host, 2. Same, further enlarged. {After Theissen and Sydow, 1915.) Saccardiaceae. — In this family, in contrast to the lower Myriangiaceae, is realized the second possibility, the reduction of the number of asci which are no longer formed irregularly in several layers but in a single layer generally lying directly beneath the surface of the stroma and parallel with it (mutatis mutandis as in Myriangium Thwaitesii) . The Saccardiaceae include a whole series of chiefly monotypic genera, as Eurytheca, Saccardia and Anhellia; these are incompletely known and generally have been studied only in herbarium material. One may easily acquire an idea of their structure, however, if one imagines the asci of Kusanoopsis in Fig. 136 to be arranged in a single layer. Dothioraceae. — Among the simpler genera, as in Bagnisiella (asco- spores unicellular) and Dothiora (ascospores reticulately septate), we may consider Bagnisiella australis which forms its stromata in rows in the bark of dead branches of Acacia bonariensis in the Argentine; like those of the previous families, they are still indefinite in form, pulvinate, always surrounded with a special, dull black, crust-like rind (Fig. 139, 1). Their new covering behaves like the asci and ascigerous layer. In contrast to most Saccardiaceae, the asci are no longer spherical as in the 216 COMPARATIVE MORPHOLOGY OF FUNGI Plectascales, but elongate-clavate ; they are pressed together in a palisade and force the stromatic ground tissue, the so-called interthecial stroma (Fig. 139, 2) together to paraphysoid filaments, the pseudoparaphyses or paraphysoids (terminology of Petrak, 1923). The paraphysoids differ from paraphyses in that, as the remains of the interthecial stroma, they have a cellular structure and do not terminate freely but continue further into the pseudoparenchymatous cover tissue. In the higher Dothioraceae, as in Bagnisiopsis, there appears, as in the Myriangiaceae, a tendency to limit the asci to definite, narrowly limited conceptacles which are differentiated out of the interior of the stroma (Fig. 140). The dull black, pulvinate stroma of the Brazilian Bagnisiop- sis peribebuyensis is erumpent from the leaves of various Melastomataceae dotting their surface with small papillae. In contrast to Bagnisiella, the asci do not form a continuous layer but are localized in sharply defined nests which, like the fertile parts of Myriangium, are generally surrounded by a darker tissue. They lie singly (as in Bagnisiella and the other Myriangiales) in special loculi and are separated from each other Fig. 140. — Bagnisiopsis peribebuyensis. Section of mature stroma with two ascigerous conceptacles. (X 33; Arnaud, 1921.) by thin stromatal layers. With this spatial limitation of the asci, the whole stromatal cover does not degenerate at maturity but small parts, which have lain directly over the conceptacles, crumble and form an irregular pore through which the ascospores escape (Fig. 140, left). During further development of the Dothioraceous line the single conceptacle is gradually individualized. Like the fertile branches of Myriangium, they sprout from the sterile stroma, thereby acquiring their own wall while sterile stroma becomes more and more limited to the intramatrical part. This development may be followed in Botryosphaeria (Theissen and Sydow, 1915; Theissen, 1916; Hoehnel, 1920). The simpler species, as B. inflata (Fig. 141, 1) appear entirely like Bag?iiopsis but occupy a partly lower stage, for their conceptacles are scattered irregularly over the stroma and are still entirely imbedded in the plectenchyma; at maturity their tips project only a little beyond the stroma and hence hardly raise the bark of the host. In other species, as B. Viburni (Fig. 141, 2 and 3), they gradually collect and arch toward the surface of the stroma; but still, according to the luxuriance of the stromata, they may be surrounded by the plectenchyma entirely or only to half their height. MYRIANGIALES 217 In B. mascarensis (Fig. 141, 4) they develop entirely above the surface of the stroma upon which they rest at maturity; hence these are true, sterile, basal stromata, as in Bagnisiopsis peribebuyensis. Along with this development, there has been a fundamental alteration in the course of the stromatal hyphae. While in the lower forms, as in B. inflata, they still run entirely irregularly, in the higher forms they have become increasingly vertical and finally run parallel from the base to the top of the stroma. In the highest stage, as in B. Bakeriana, B. Quercuum and B. Ribis, the stromata begin to buckle and split between the conceptacles which are left standing on shorter or longer stipes and have their own walls, i.e., they become perithecia. 1 Fig. 141. — Development of stroma in Botryosphaeria. 1. B. inflata. 2, 3. B. Viburni. 4. B. mascarensis. 5. B. Bakeriana. (After Theissen, 1916.) B. Quercuum (Melanops Quercuum) forms its brown stromata on oak bark between the periderm and the bark parenchyma beneath and pushes out the periderm which it ruptures with radial splits, so that the perider- mal lobes remain like steep walls. Meanwhile it has grown higher, but seldom to such a degree that it projects over the peridermal lobes. As in Myriangium, there develop columnar outgrowths which broaden spheri- cally above and end at the top with a conical papilla. This conceptacle tissue is, as in the other Dothioraceae, entirely like the basal stroma in structure and is continuous with it. The spherical head portion is also a pseudoparenchymatous mass. In it, a hyaline spherical conceptacle, containing a palisade of monascous loculi, is differentiated. The para- physoids are occasionally not only pressed together into threads but also dissolved so that the asci are embedded in a gel. In this condition, the conceptacle appears entirely like the true perithecium and only its onto- geny shows its Myriangial character. 218 COMPARATIVE MORPHOLOGY OF FUNGI At maturity the papillae break off and the conceptacle parenchyma, possibly still present over the asci, is dissolved so that the tips of the asci are free. As Meliola and Parodinopsis of the Perisporiaceae, so also Botryosphaeria of the Dothioraceae has perithecia whose place of opening is typical. They do not, however, open by pores but by histologically differentiated parts of the stroma which, because of the formation of dehiscence zones, are more easily crumbled away. B. Ribis causes the currant cane blight (Grossenbacher and Duggar, 1911; Shear, Stevens and Wilcox, 1925). In July the first conidial forms (in the imperfect genus Macrophoma) appear on the withering young shoots; in the following spring there break forth from the dead branch Fig. 142. — Parodiellina manaosensis. Section through lower surface of leaf with concep- tacle and setaceous conidial stroma. (X 110; Arnaud, 1921.) numerous black stromata which first bear the pycnidia of the second imperfect form, Dothiorella, and later swell with the perithecia. This type of the highest species of Botryosphaeria appears again in the Dothioraceae with many modifications. In Parodiellina manaos- ensis on the under side of leaves of Brazilian Solanaceae, two stromata break out, one of which cuts off dark brown, uni- or multicellular con- idia, while the other bears perithecioid conceptacles (Fig. 142). The stroma surrounding these conceptacles consists of solid cells and is an intense reddish brown. When young, it is entirely closed, but at maturity gradually crumbles at the top. The ascigerous stromatal parts seem extraordinarily like the fertile branches of Myriangium, especially if one imagines the basal stroma in Fig. 137 less well developed, as is actually the case in many species, except they are more individualized with consequent reduction in number of asci. MYRIANGI ALES 219 This individualization of conceptacles is greater in the West African Chevalieropsis ctenotricha (Chevalieria ctenotricha) (Fig. 143); here the poorly developed echinate stroma forms several conceptacles which are only attached to the stroma by a narrow base. In several adjacent loculi, they contain a few, narrow, clavate asci, each of which normally forms 8 two-celled ascospores. At maturity, the pseudoparenchyma at the top of the conceptacle becomes slimy and the ascospores are liberated through this slime, apparently as in the Englerulaceae. Fig. 143. -Chevalieropsis ctenotricha. Section through a dicotyledonous leaf with several conceptacles. (X 33; after Arnaud, 1921.) With Chevalier opsis, Parodiellina and Botryosphaeria, we have tempo- rarily finished with a special branch of the Myriangiales, which we shall meet later in the families of the Dothideales and Sphaeriales. Pseudosphaeriaceae. — As the starting point of the last family of the Myriangiales to be discussed here, we must go back a few steps in the Dothioraceae to the stage of Bagnisiella and Dothiora. While the true Dothioraceae branching off from these two genera retain their broad pulvinate stromata, and only differ in that the conceptacles grad- c>5 o c s , u o o o »■» ^ — '/' //// /"///"• ////// ///////// Fig. 144. — Pyrenophora trichostoma. Section of young stroma. (After Theissen, 1916.) ually lie on the upper surface of these cushions, the Pseudosphaeriaceae develop in the direction of reducing the basal stromata to one concep- tacle. In both families there is a tendency toward the individualization of the conceptacle; in the Dothioraceae it is shown by the raising of the conceptacles over the stroma and by a gradual degeneration of the remaining stroma, while in the Pseudosphaeriaceae it is realized by the degeneration of the whole stroma. By this degeneration and spatial limitation of all the stromata, they attain in the Pseudosphaeriaceae a characteristic form and become as a whole true independent fructifications, 220 COMPARATIVE MORPHOLOGY OF FUNGI while in the higher Dothioraceae, one would rather consider the single conceptacle-bearing branches which grow out of the stroma as fructifications. From the perithecia of the Perisporiales (and of the Sphaeriales), these fructifications of the Pseudosphaeriaceae, except for the special question of opening, are distinguished by the fact that in the former the pore tissue of the perithecium is entirely resorbed during development while in the latter, as in all the other Myriangi ales, it remains as interthecial pseudoparaphyses (Hoehnel, 1909; Theissen, 1916; Theissen and Sydow, 1918; Petrak, 1923). An illustration of the fructification of this family is shown in Pyre- nophora (Fig. 144) and Pleospora (Fig. 145, 1). The fructifications are small and like perithecia; they are immersed in the host and liberated by Fig. 145. — Pleospora herbarum. 1. Section through an immature peri', hecium ( X 250). 2. Conidiophore (Altemaria type) (X 135). 3. Germinating conidium ( X 2.35). (After Arnaud, 1918, and Brefeld, 1881.) the rupture of the epidermis. They consist of a pseudoparenchyma which is thick walled and dark colored in the two or three outer layers of cells (outer crust) but on the inside has a more delicate structure. In the middle of the stroma, each of the elongate asci develops in its own core cavity. By the increase of asci in the course of development, the intermediate hyphal bundles are compressed as far as possible and finally remain only as thin, flabby paraphysoids merging into the stromatic cover. The top of the perithecium eventually becomes more or less markedly papilliform. It opens by the crumbling and falling away of the papillae, giving the appearance of opening by a round pore. While in Pyrenophora at present only saprophytes are known, Pleospora (numbering about 300 sp.) includes several plant pathogens, as P. herbarum on many stems and fruits, P. Hyacinthi, the cause of the MYRIANGIALES 221 black disease of hyacinths, and P. gramineum which causes the stripe disease of barley; their imperfect forms belong to Cladosporium, Alter- naria and Macrosporium (Fig. 145, 2), and in P. gramineum to Helmintho- sporium. In a special form of P. herbarum causing a leaf spot of Sivistonia australis (Corypha australis) Cavara and Mollica (1907) have demon- strated that the hyphae are uninucleate. From two hyphae, two unicel- lular branches are formed which, as in Penicillium "crustaceum" and Sphaeroiheca Humuli, approach, embrace and copulate. Meanwhile they have become surrounded by sheath hyphae and later develop ascogenous hyphae in an unknown manner. As sparse as this evidence is, it may be assumed that the Myriangiales have still retained the Plectascales type in the form and function of sexual organs. Pleospora and Pyrenophora have until recently been assigned to the Sphaeriales and only a special investigation of their young perithecia has demonstrated their undoubted Pseudosphaeriaceous character. Besides these, however, a series of genera, as Meliola and Parodiopsis in the Perisporiaceae and as Parodiellina, Chevalieropsis and Botryosphaeria in the Dothioraceae, show marked transitional forms which might be with equal justice classified in the family in which they root, in this case the Pseudosphaeriaceae, as in the group to which they lead, in this case the Sphaeriales. Didymella and Leptosphaeria will be discussed here. Didymella has 200 species parasitic or saprophytic on the roots and dry leaves of cormophytes. In structure of fructifications they develop from the simpler forms similar to the Pleospora-Pyrenophora type, through numerous transitions, to another extreme which extends into the Sphaeriales. In the simpler forms, as in D. moravica and D. proximella, the perithecia, as in Pleospora and Pyrenophora, are still entirely enclosed and open only at maturity by the crumbling of the more or less sharply defined tip. In this form, the interthecial plectenchyma is generally still present at maturity in the form of distinctly recognizable paraphy- soids. In the higher forms, as in D. Rehmii, D. cladophila and D. applanata, the cause of a " brush'"' disease of raspberries, the perithecia attain a more or less characteristically formed opening, an ostiole, which we meet again in the majority of the Sphaeriales. Besides, in them the perithecial stroma is only weakly developed and generally only present at maturity as a scant hyaline mass which easily swells in water. While D. moravica and its relatives belong to the Pseudosphaericaceae, the D. Rehmii group considered by itself would be placed in the true Sphaeriales. This transitional character is still more marked in Leptosphaeria, whose species show the characters of not less than three orders, the Myriangiales, Dothideales and Sphaeriales, and hence has been divided by most authors into different genera, which in practice are difficult to distinguish. 222 COMPARATIVE MORPHOLOGY OF FUNGI The simple species of Leptosphaeria correspond in structure of con- ceptacles and perithecia to Pleospora, and since Pleospora still is counted in the Sphaeriales, they were placed in the same family with it. In a few of them, as in L. doliolum, on the roots of the larger weeds, especially Urtica and Angelica, the conceptacles, as in Pleospora, are still closed in youth. They do not open by the crumbling of the papilla, however, but by partial slimy resorption of the lid tissue whereby at maturity a typical pore results. In both Pleospora and the L. doliolum group, the paraphysoids are long-celled filaments and, when mature, almost indistinguishable from typical paraphyses. In Leptosphaeria acuta on Urtica dioica and L. herpotrichoides causing the increased fragility of stalk in young shoots of rye, a typical ostiole pierced by a canal is formed organically in the course of development, as in the true Sphaeriales; fur- thermore, the species of this group, like the true Sphaeriales, have true par- aphyses formed by subsequent growth of the hyphae of the ground tissue. While Leptosphaeria doliolum and L. acuta mark the beginning and end of a series which leads from true Pseudosphaeriaceae to true Sphaeri- ales (i.e., the forms among these with discreet perithecia) a special branch of the Leptosphaeria group connects directly to Botryosphaeria and leads thence to the stromatic Sphaeriales and Dothideales. Not only do these genera merge in the vertical direction, but also horizontally and laterally. Hence it is difficult to decide whether this stromatic branch of the Leptosphaeria group (in the developmental scheme on p. 223 imagined as the left wing of Leptosphaeria) should be joined with forms having discrete fructifications which appear to be perithecia and show no traces of stromata, or whether they would not be better placed in a special genus of the Dothioraceae beside Botryosphaeria or, as Hoehnel (1918) wishes, shifted to the Dothideales. This left wing connects directly to the solitary species, through forms whose perithecia are gregarious only under favorable conditions of nourishment. In the higher forms as in Leptosphaeria caespitosa on the dry roots of Artemisia campestris, or L. salebrosa on decaying cabbage stumps, the perithecia appear evenly on a basal stroma which is often only weakly developed. If the basal stroma is more strongly developed and the conceptacles are caespitose, the mat ruptures during the epidermal development, i.e., before the conceptacles are externally visible, and the fungus attains instantaneously an entirely different appearance, sugges- tive of the higher species of Botryosphaeria and Chevalier opsis. If one imagines this basal stroma more strongly developed, one has Rosenscheldia which, according to present systematic classification, is placed in the Dothideales. Thus L. doliolum and L. acuta form the beginning and end members of the Pseudosphaeriaceae-Sphaeriales series and L. caespitosa and Rosenscheldia two stages in the line of development from the Pseudo- sphaeriaceae to the Dothideales. MYRIANGIALES 223 Unfortunately the species of Leptosphaeria, as all other Myriangiales, have been only incompletely investigated ontogenetically. Only for L. Lemaneae, on the fresh water red alga Lemanea, has Brierley (1913) observed that, as in Pleospora and Penicillium " crustaceum," at the for- mation of the perithecia, two hyphal branches embrace each other and come into open communication at the tips; it seems, however, that copulation may also occur without this helix formation between two extended hyphal branches. Many species of Leptosphaeria are important as causes of plant disease. The L. avenaria group, on numerous species of grasses, are related to each other but differ in their conidial dimensions and biologically according to their choice of host; their imperfect forms belong to Septoria (Weber, 1922, 1923). Septoria secalis, for example, is specialized on Secale cereale, S. Passerinii on Hordeum sp., S. Agropyri on Agropyron repens, S. Bromi on Bromus inermis, Leptosphaeria avenaria on Avena. Two other species have somewhat less specialized hosts, as Septoria tritici and S. nodorum which both infect Secale cereale, Triticum sp. and Poa pratensis. Summary. — The special distinction of the Myriangiales is that every author circumscribes and divides them differently; they are an order of transitional forms showing connections in all directions, but the further we go into their ontogeny the more they seem to be the key group to the higher Ascomycetes. As far as an interpretation may be based on the morphological relationships of mature fructifications, there are presented in the following diagram the relationships between the individual Myriangeles as the author conceives them; it is obvious here, as in all diagrams of this type, that we deal with types, not genera or species. The Myriangiales form the starting point with a massive, homo- geneous, often highly colored stroma, in which the spherical asci lie MYRIANGIALES PLECTODISCELLACEAE Plectodiscella DOTHIORACEAE Parodiellina Chevalieropsis Botryosphaeria Bagnisiopsis Dothiora BagnTsiella PSEUDOSPHAERIACEAE Leptosphaeria Didymella Pleospora Pyrenophora SACCARDIACEAE Anhellia Sacoardia Eurytheca MYRIANGIACEAE rMyriangium Kusanoopsis" PLECTASCALES Diagram XXII. 224 COMPARATIVE MORPHOLOGY OF FUNGI irregularly scattered. In them are the germs of two characteristic groups which are significant for the later development of the whole order. On the one hand, there is the differentiation of the stroma into a fertile and sterile part (Kusanoopsis-Myriangium series), on the other the localization of the asci into a single layer (Myriangium Duriaei-M. Thwaitesii) . The further development of the Myriangiales takes place in the two directions marked by the families of the Plectodiscellaceae and Saccardi- aceae. In the Plectodiscellaceae the irregular arrangement of the asci is retained; the stromata, however, form a special rind crust which develops on the upper side to a true cover plate. In the Saccardiaceae, however, the original irregular arrangement of the asci is lost and is replaced by a single palisade-like ascigerous layer; the homogeneous structure of the stromata, characteristic of the Myriangiaceae, is retained in them; the formation of a rind crust or cover plate is notably absent. By an increase in number and elongation of asci (transition from spherical to clavate form) the Saccardiaceae may have given rise to the lower Dothioraceae, whose stromata, indefinite in form, as in the Saccar- diaceae, are pulvinate. but whose interthecial stroma has become com- pressed to thread-like pseudoparaphyses by the maturing asci. Besides this degeneration of the interthecial core, there appears a tendency in the lower Dothioraceae, as in the Kusanoopsis-Myriangium series of the Myriangiaceae, to differentiate the stromata into sterile and fertile parts, i.e., to restrict ascus formation to definite fertile parts, the conceptacles, which become increasingly independent. This individualization of conceptacles has proceeded in two direc- tions. Each stroma of the higher Dothioraceae develops several concep- tacles which gradually emerge from the stromatal surface, finally dividing it into a sterile basal stroma and a sessile, external fructification, the perithecium. In the Pseudosphaeriaceae only one conceptacle is formed in each stroma, which is reduced to a single perithecium. In both the higher Dothioraceae and the Pseudosphaeriaceae the individualization of the conceptacles and formation of a special perithecial wall is accom- panied by a gradual differentiation of an ostiole, also by an entire gelifica- tion of the interthecial ground tissue and the formation of true paraphyses. As a result of these two developmental processes, the forms entirely lose their Myriangial character and join the higher orders. In these varied developmental forms lie the roots of a whole series of higher Ascomycetes. Hence in no less than five different orders, the Sphaeriales, the Dothideales, the Hemisphaeriales, the Phacidiales and the Pezizales, we will have to refer to the relationships of the Myriangiales. CHAPTER XVI HYPOCREALES The Hypocreales are generally denned as Pyrenomycetes with a soft (not hard and carbonaceous and hence not brittle), brightly colored (white, yellow, red, violet or light brown) perithecial wall. Where systematic relationships are firmly established, occasionally we include dark-colored or hard-walled forms, such as Ophiodotis, Entonaema and Xylocrea, which according to the definition would belong to the Dothide- ales or Sphaeriales. There are so many Hypocreales that it seems impossible to give a satisfactory systematic classification. Lindau (1897) and Seaver (1910) use as the fundamental principle, the behavior of the perithecia, whether they are solitary or united in slightly or highly differentiated stromata; they realize, however, that the consistent following of this principle separates parts of the same natural genus among entirely different families. In order to lessen this difficulty, which would be very serious in the present work, we have used the septation of ascospores as the only principle of division, as advocated by Saccardo in the Sylloge Fungorum and by Moller (1901). Thus we have divided the genera selected for discussion here into three groups : the first contains the Amerosporeae (ascospores unicellular) ; the second includes the Didymos- porae (ascospores bicellular), the Phragmosporae (ascospores tri- and multicellular) and the Dictyosporae (ascospores reticulately septate); the third contains the Scolecosporae (ascospores filamentous, unicellu- lar at first, becoming multicellular). It is obvious that this classification is entirely artificial; it has the advantage, however, that there is rarely any doubt as to where one should seek a genus. Further, it seems that the Scolecosporae, at least, form a more natural group because of the behaviour of their ascospores; their asci are always long, slender and fine and, as far as known, always have a characteristic cap with a thread-like canal. It is possible that this peculiar structure of the ascus is older and more important for a natural systematic classification than the morphology of the spores. The Amerosporae may be divided into three stages, the first, in which the perithecia generally stand singly on the substrate, the second, in which they are united in undifferentiated cushions and the third, in which these pulvinate stromata develop into specially formed fructifica- tions. Of the first group, we will cite here four genera, Melanospora, 225 226 COMPARATIVE MORPHOLOGY OF FUNGI Neurospora, Peckiella and Neocosmospora. Melanospora and Neurospora are saprophytic on all possible decaying substrates of animal and plant origin, and parasitic on other fungi. On their substrate they form a brownish or whitish, often felty tissue; occasionally the hyphae intertwine to form an enormous mass of small bulbils which, where the perfect form is unknown, are assigned to the imperfect genus Papulaspora (Hotson, 1912). Vincens (1917) regards these bulbils in part as undeveloped perithecia. Melanospora Mangini, M. globosa and Sphaeroderma bulbillifera have unicellular, hyaline conidia borne in chains on small phialides (Oospora or Spicaria type). M. marchica, M. globosa and Sphaeroderma bulbillifera also form dark-colored gemmae or bulbils, whose forms are reminiscent of the smut spores of Tuburcinia. As in the Aspergillaceae, M. parasitica (Kihlman, 1883) and M. Zobelii (Nichols, 1896), parasitic on other fungi, and the saprophytic M. marchica (Neger, 1914) form two copulation branches which, as in Peni- cillium " crustaceum," intertwine helically. The saprophytic M. globosa and Sphaeroderma bulbillifera, as in Aspergillus herbariorum, form a helical ascogonium up whose side the antheridium climbs. The cytological relationships are unknown; apparently the asci, at least in M. parasitica, M. Zobelii and M . Mangini, do not arise from ascogenous hyphae but a cell of the ascogonium divides in all three dimensions and the asci develop from cells of this complex. The hyphal cells are multinucleate. The mature perithecia generally have a one-layered wall and a very long neck, through which the brownish spore mass is pressed, following the degeneration of the asci. The hyphal felt under the perithecia thickens to a subiculum, then to a loose and finally to a fleshy stroma, on which rest the perithecia singly or in groups. Neurospora, which differs from Melanospora by black perithecia, absence of the long, fimbriate beak and its persistent asci, shows some resemblance to the Sordariaceae. Melanospora Mangini and related species show many characters in common with this genus and perhaps should be considered here rather than in Melanospora, where they form a very aberrant type. Melanospora destruens (Shear, 1917), on cranberries, also shows many characters similar to those of this genus. The conidial stages of Neurospora sitophila have usually been referred to Monilia sitophila or related species which appear as cushions of orange to pale salmon, oidia occasionally causing severe damage to the baking industry. The development and cytology of this group has been little studied except for the reports of Moller (1901), although an extensive investi- gation is in progress by B. 0. Dodge. Melanspora Mangini (Vincens, 1917) and Neurospora erythraea form only one copulation branch, origin- ally three to five celled (as in Aspergillus flavus and A. fumigatus), which coils helically or in an irregular tangle and is surrounded by sheath HYPOCREALES 227 hyphae in the usual manner. The perithecia are gregarious or scattered, smooth or with loose hairs, the cavity lysigenic, rilled at first with parallel septate hyphae which disappear as the young asci expand ; the ascospores become black or greenish black and longitudinally ribbed. N. erythraea is apparently homothallic, while N. sitophila and N. crassa are hetero- thallic (Shear and B. 0. Dodge, 1927). In N. tetrasperma, the spores vary much in size depending upon the number produced in an ascus. Ordinarily there are four spores, but occasionally five to six or two to three are produced. Cultures from the large spores are homothallic, while those from the small spores are heterothallic. The spindle of the first division in the ascus lies along the long axis, hence the daughter nuclei migrate toward the ends of the ascus. In the second division, the spindles are longitudinal or in about half the cases, oblique and appear to be dividing conjugately, hence the nuclei finally appearing at the ends of the ascus are non-sister nuclei. In the third division, the spindles are transverse and the adjacent non-sister nuclei unite in cutting out a large homothallic spore. This is followed by subsequent slipping and turning of the spores, since at maturity they lie in a single row. In the uninucle- ate heterothallic spores, the relations of the spore nuclei are not clear, but in N. crassa and N. sitophila, the adjacent, uninucleate spores are always developed from sister nuclei (B. 0. Dodge, 1927). In these species, where there is little chance for shifting, further studies by B. O. Dodge and Wilcox will probably locate conclusively in which division of the ascus the segregation of sex occurs. Peckiella is parasitic on pileate fungi and morphologically corre- sponds to Hypomyces of the Didymosporae; only their ascospores are unicellular. On the under side of caps of Lactarius deliciosus, P. lateritia forms a stroma thick enough to cover the lamellae. As in P. Thiryana (Maire, 1905), which has also been investigated in this respect, the hyphal cells are uninucleate. As in Melanospora Mangini and Neurospora erythraea, only the ascogonium is formed. It curls twice at the most. Its cells undergo repeated divisions but always remain uninucleate. Later, by nuclear divisions which are not followed by septum formation, they become binucleate and develop to ascogenous hyphae which form asci according to the hook type (Moreau, 1914). Neocosmospora vasinfecta will only be mentioned here because it is erroneously considered the cause of a wilt of cotton and of watermelons and is occasionally described as such in the literature of plant pathology. Its perithecia, like those of the simpler species of Melanospora, arise singly on the substrate and are colored a brilliant red (Butler, 1910). The second stage, in which the perithecia are united on undiffer- entiated pulvinate stromata, is shown by Entonaema and Polystigma. As Polystigma is known cytologically and hence affords opportunity for a special discussion, we will return to it at the end of the Amerosporae 22S COMPARATIVE MORPHOLOGY OF FUNGI after finishing the third group. Entonaema liquescens (Fig. 146) in the primeval forests of Brazil, forms light-colored, soft gelatinous, vesicular fructifications, suggesting Tremella, attaining a diameter up to 40 cm. and a height above the substrate up to 15 cm. Under this light-colored outer layer lies a deep black plectenchyma in which, over the entire fructification, are embedded the perithecia. Because of this dark color of the deeper tissues, which in another species, E. mesentrica, extends to the outer layers, and because of the dark color of the ascospores, the author of this genus assigned them to the Xylaria- ceae under the Sphaeriales. There, however, its position is entirely isolated while it easily fits in the Hypocreales. The dark color of the Fig. 146. — Entonaema liquescens. Habit of perithecial stroma ( X \i>; after Mollcr, 1901.) tissue does not necessarily argue against its classification in the Hypo- creales, as many unquestioned representatives of Hypocraea and Hypo- crella show an equally dark color of the rind or the deeper plectenchyma of the perithecial walls. The dark color of the ascospores is common to Entonaema and Melanospora. The third stage is represented by Xylocraea, in which the perithecial stromata develop elaborate fructifications. X. piriformis, on wood in Brazil, forms fructifications like those shown for Mycomalus in Fig. 159, except that it is pyriform instead of maliform. Furthermore, their perithecia are not formed over the whole surface but only in a limited region at its thicker end, corresponding to the blossom end of the pear. HYPOCREALES 229 In contrast to all these genera, Poly stigma is parasitic on angiosperms. Its best-known representative, P. rubrum, causes a red spot disease of Prunus domestica, P. insititia and P. spinosa (Blackman and Welsford, 1912; Nienburg, 1914). The ascospores germinating in the spring infect the young leaves bursting from the buds and grow to a large intercellular mycelia. The hyphal cells are uni- to trinucleate and contain an orange-yellow, alcohol-soluble pigment; their walls are at first thin, later becoming thick and gelatinous. In 5 or 6 weeks they fill the whole space between the epidermal layers and during the summer form shining, red- dish yellow or scarlet sclerotic stromata. Before this development has proceeded far, flask-shaped pycnidia are formed from knots of unthickened hyphae under the stromata. Fig. 147. — Polystigma rubrum. 1. Section through portion of leaf with young pyc- nium. 2. Section through young perithecial fundament showing helical ascogonium. 3. Pycnospores. (1 X 200; 2 X 600; 3 X 1,200; after Blackman and Welsford, 1912.) The pyenidial wall consists of a plectenchyma from which the sporiferous hyphal branches radiate (Fig. 147, 1). The pycnospores are terminal, uninucleate, tapering upward and falcate at their tips (Fig. 147, 3). They are embedded in a slimy substance and in damp weather are forced out of the mouth of the pyenia upon the leaf. Later, in July or August, the perithecium is formed, as a small hyphal tangle in which is embedded a helical ascogonium (Fig. 147, 2). Its development is incompletely known; a half schematic cross section of an older stage is shown in Fig. 148, 1. The basal cell of the ascogonium bordering on the ascogonial hypha is short and has few nuclei. Adjacent to it is an elongated cell with many small nuclei. The next cell has only a single, rather large nucleus but is much shorter than both the previous ones. There follow two cells with two small nuclei each; then the helix continues with cells with an irregular number of nuclei and finally is lost 230 COMPARATIVE MORPHOLOGY OF FUNGI in vegetative tissue. There regularly appear, however, always in the same order, the long cell with many small nuclei, the long cell with one large, and the short cell with one large nucleus. At this time the trichogyne is not present. Later, however, some ascogonial cells develop to longer, occasionally branched, hyphae which, like the remaining Fig. 148. — Polystigmarubrum. 1. Young ascogonium showing all essential parts except the trichogyne. 2. Wall between two ascogonial cells partially resorbed. 3. Completed plasmogamy. 4. Beginning of perithecial formation. Only the dicaryotic cell of the ascogonium remains. ( X 860; after Nienburg, 1914.) hyphae, stretch toward the stomata but seldom reach the surface (Figs. 147, 2; 149, 1 to 3). They are called trichogynes by the authors cited here. The development of the ascogonium at first proceeds very slowly and fertilization takes place only in December in the dead leaves lying on the HYPOCREALES 231 ground. Between the long, multinucleate, male and the long, uninucleate, female cell, there is formed a pore (Fig, 148, 2) and one of the many male nuclei migrates into the female cell. Then the pore is closed (Fig. 148, 3) and the nuclei remaining in the male cell gradually degenerate. Not only the ascogonium but also the surrounding vegetative cells show an increased vitality, probably because of stimulation of the sexual act. They begin to change to rafter-like, super-imposed paraphyses, while the ascogonium dies, except for the single cell with its dicaryon. m Fig. 149. — Poly stigma rubrum. 1. Part of mature ascogonium from which trichogynes extend to the left above and below. 2. Continuation of lower left trichogyne of 1. 3. Further continuation of the trichogyne of 2. (Note the renewed branching.) (X 860; after Nienburg, 1914.) By forcing aside these paraphyses, the perithecial cavity, filled by para- physes, is formed. During January the ascogenous hyphae grow into the cavity and change to asci. In March the development of the ascospores is completed. This life cycle of Poly stigma rubrum is generally interpreted according to the relations of the lichens to be discussed later in the Discomycetes, that the pycnia are spermogonia, and the structures here designated as pycniospores (and they are certainly very difficult to germinate) as functionless spermatia which earlier may have fertilized the ascogonia. 232 COMPARATIVE MORPHOLOGY OF FUNGI Thus also, the ascogonium would be designated as a rudimentary tricho- gyne. P. rubrum, thus, would be considered a form in which spermatial fertilization was lost and replaced by a parthenogamous sexual act. It must be emphasized, however, that among these proposed ideas there is no place for spermatial fertilization. The numerous examples of development of Hypocraeales and Sphaeriales are adapted without exception and with astonishing uniformity to the scheme of the Plecta- scales, hence the Pyrenomycetes undoubtedly have arisen from the Plectascales type. Thus there is no phylogenetic necessity for assuming prehistoric spermatial fertilization and, besides, such a fertilization would be practically impossible, for the pycnia (spermatogonia) develop in spring or early summer and then disappear. The ascogonia which they should fertilize arise months later on the same stroma; spermatial fertilization, as we shall see in the Uredinales, is quite improbable. The fact that we know insufficiently the conditions for the germination of these pycniospores is not proof that they are functionless spermatia. Brefeld, Tavel and Moller (not using single spore cultures or probably even pure cultures!) have reported germination of microconidia with mycelial development. It seems much more important for the explanation of relationships of Polystigma, to refer to its saprophytic, more easily investigated relatives such as Melanospora and the Aspergillaceae, whose imperfect forms do not resemble these and germinate easily, hence scarcely have the signifi- cance of disguised spermatia. In Melanospora parasitica, M. Zobelii, etc., as in the typical Aspergillaceae, are still formed two copulation branches which, at least in M. Zobelii, occasionally come into open communication at the tip. In other forms, only the helical ascogonium is formed, from which alone, development proceeds. Gaumann prefers to consider Polystigma rubrum as a reduced form of this type in which (and here is the fundamental significance) in spite of the degeneration and disappearance of the antheridium, caryogamy is still necessary, but leads to parthenogamy within the ascogonium. Thus the loss of the original cross fertilization is compensated. Unfortunately the reduced species of the Aspergillaceae and Melanospora corresponding to the Polystigma type have been insufficiently investigated, hence we are too uncertain whether the binucleate condition which leads to the formation of ascogenous hyphae, is caused by a usual nuclear pairing in any cells, or by a parthenogamy as in Polystigma. If forms which belong to the last type are discovered, the interpretation of Polystigma given here would be much reinforced. Concerning the nature of the ascogonial processes called rudimentary trichogynes, we can only offer conjectures. It is possible that these structures correspond to true trichogynes; but it must be emphasized that this in no way involves a spermatial fertilization, for the simplest HYPOCREALES 233 trichogyne fertilization known at present, that of Monascus, is easily connected to the relations predominating in gametangial copulation. The second group of the Hypocreales, that of the Didymosporae (ascospores two celled), Phragmosporae (ascospores three or more celled) and Dictyosporae (ascospores muriform) is the largest in species and most important for plant pathology. The representatives here discussed, as those of the Amerosporeae, may be divided roughly into three stages : a first in which generally a stroma is lacking and the perithecia, as in Neocosmospora and the simpler species of Melanospora, rest singly on the substrate; a second stage, in which they are joined into pulvinate undiffer- entiated stromata; and a third in which the stromata are differentiated in an unknown manner and change into characteristic fructifications. In order better to survey these (ideal) stages and their representatives, they are presented in the following table (after Moller) ; for comparison, the genera of the Amersporeae have been included. AMERO- SPOREAE DIDYMO- SPOREAE PHRAGMO- SPOREAE DICTYO- SPOREAE Stroma larking or poorly developed Melanospora Peckiella Neocosmospora Nectria Hypomyces Pyxidiophora Calonectria Pleonectria Stroma regularly pulvinate Entonaema Polystigma Sphaerostilbe Stilbonectria Megalonectria Stroma more or less erect Xylocrea Hypocrea Corallomyces Mycocitrus Peloronectria Shiraia Diagram XXIII. We will discuss as representatives of the first stage, four hemisapro- phytic, hemiparasitic (often weak, or wound parasites and thus important for plant pathology) genera : Nectria of the Didymosporae, Calonectria and Gibberella for the Phragmosporeae and Pleonectria of the Dictyosporeae. As in the Aspergillaceae of the Plectascales, the color of the mycelium is largely dependent on the nutrition, especially on the reaction of the substrate. Thus the olive green to brown mycelium of Nectria Ipomoeae on alkaline media becomes red on acid media; the red mycelium of Gibberella Saubinetii on alkaline media becomes yellow on acid, and the blue mycelium of Fusarium orthoceras on alkaline media, becomes red on acid. As the hyphae in a few Plectascales, the germinating ascospores of a few forms of this group, as Nectria sinopica, may develop by sprout- ing under certain nutritive conditions. In some other forms, as N. inaurata on the dry branches of Ilex aquifolium and N. Coryli on Corylus, Salix and Populus, this sprouting of the ascospores may begin in the ascus (Fig. 150, J), whereby the asci may be entirely filled with a sprout mycelium, as in Taphrina (Brefeld, 1891). 234 COMPARATIVE MORPHOLOGY OF FUNGI Gemmae and conidia are known as imperfect forms. The gemmae are mostly hyaline or brownish and occasionally verrucose; they develop (especially in drying cultures) on hyphae, singly or catenulately, and Fig. 150. — Nectria cinnabarina. A. Conidial stromata (shown light) perithecial stromata (dark) erumpent from bark of host, B. Section through a stroma which is still cutting off conidia at the top while it has formed perithecia on the sides. C. Ascus. D. Hypha with microconidia. Nectria ditissima. E. Perithecial layer breaking from the bark. F. Longitudinal section of conidial fructification. Nectria sinopica. G. Ascus. H. Part of pycnium. Nectria inaurata. J. Ascus without and with sprout cells. Nectria oropensoides. K. Coremium. (A X 10; B X 20; C, D, G, J X 350; E X 3; F, H X 380- K X 60 ; after Tidasne, Brefeld and Lindau.) show little individuality. The conidia, also in exhausted nutrient solutions, may thicken their walls and change into a sort of gemmae. The conidia are hyaline or yellowish, brownish, orange red, etc., and are cut off, either terminally or laterally, from hyphae which are HYPOCREALES 235 differentiated to special, more or less developed conidiophores. Often they are embedded in slimy masses which are called pionotes. In Nectria oropensoides and N. Peziza, the conidia adhere to the conidio- phores in small slimy heads; in luxuriant cultures, the conidiophores unite to coremia surrounded by capitate spore masses (Fig. 150, K). Under certain cultural conditions, the conidiophores change to flat, pulvinate stromata, or sporodochia (Fig. 150, F) ; these suggest, morpholo- gically, horizontally broadened coremia and often consist of thick- walled, plectenchymatic stromata and conidiophores radiating from them. Fig. 151. — Conidial types of the Fusarium group. 1. F. Solani. 2. F. subalatum.. 3. F. discolor. 4. F. gibbosum. 5. F. didymum. 6. F. Willkomii. (X 070; after Appel and Wollcnweber, 1913.) In Nectria and Pleonectria, these sporodochia develop to pulvinate or gibbous fructifications often of characteristic form (Fig. 150, A and B); these imperfect forms were formerly classified in the genus Tubercularia of the Fungi Imperfecta Exceptionally, the conidiophores are formed in the interior of irregular winding cavities (Fig. 150, H) instead of superfi- cially; thus, in Nectria sinopica on hard stems of ivy, the orange- red mycelium, with suitable food, collects in knots which in about two months are differentiated to pycnia and at maturity forces white coils of very small, hyaline conidia from the ostioles. For practical purposes, the conidia may be divided into macro- and microconidia; both types are only the two extremes of the same 236 COMPARATIVE MORPHOLOGY OF FUNGI spore form and connected with each other by transitional forms; still, often depending on conditions, one or the other type predominates. The microconidia are small, spherical or elongate and 1 to 2 celled (Fig. 150, D); they were earlier placed in the Imperfect genus Cephalosporium, as they are collected into small heads. The macroconidia are larger and often falcate; on account of this shape they were placed in the Imper- fect genus Fusarium along with the conidia of many other Hypocreales. They are mostly multiseptate, but under unfavorable conditions of growth the septa may be subsequently dissolved or they may never be formed. For the purpose of easier survey, these Fusaria important in plant pathology have been grouped, according to form, size and septation, into several types, as F. Solani, F. subulatum, F. discolor, F. gibbosum, F. Willkommii and F. didymum (Fig. 151). The fructifications of the perfect form, the perithecia, arise generally singly or in loose groups and rest loosely on the substrate or on a more or less strongly developed subiculum (Fig. 151, B). In the forms with Tubercularia stromata, they are laid down on or in these stromata (Fig. 152, B) and are then generally united in groups; they may often be found singly, however, also on the same piece of bark, without stromatal development. Their formation is preceded by the formation of a helical ascogonium whose cells are multinucleate in the species so far studied, Nectria Ribis, N. galligena and possibly N. Ipomoeae (Vincens, 1917; Cayley, 1921; Cook, 1923); unfortunately more details of cytological development are unknown. The perithecial rind is generally deeply colored : in Nectria, Calonectria and Pleonectria, yellow, red or brown, in age often almost black; in Gibberella brown or violet. Here also as in the mycelial mats, however, the colors are frequently dependent on the reaction of the substrate; thus the perithecia of G. Saubinetii are blue on alkaline media, red to brown on acid. Systematically these four genera have, if possible, a larger variety of forms than the Aspergillus- Penicillium group of the Plectascales, and hence, up to .the present, have defied satisfactory solution (Appel and Wollenweber, 1914). There is no doubt that in the principles of division employed at present (of the forms with yellow or red perithecia, the Didymosporae to Nectria, the Phragmosporae to Calonectria, the Dictyosporae to Pleonectria, and of the forms with violet or blue peri- thecia, the Phragmosporae to Gibberella), species from entirely different developmental series, on the basis of these two chosen characters, are placed together in artificial heterogenous genera; up to the present, how- ever, these principles cannot be replaced by a better artificial or phylo- genetic system. Theissen (1911) attempts for Nectria to utilize the condition of the ascospore membrane (smooth spores to the Leiosporae, longitudinally striate spores to the Rhabdosporae and verrucose spores to the Cosmosporae). Wollenweber (1924) attempts to utilize the imperfect HYPOCREALES 237 forms. Weese (1914, et seq.) attempts to create developmental series according to the structure of the perithecial wall. Consequently the different genera are differently defined by different authors; all these attempts, however, have not yet afforded a complete system. The most important plant pathogens in the genus are: Nectria cinnabarina, a wound parasite in most of our frondose trees and shrubs, causing canker and dieback of the twigs and forming on the dead twigs striking red conidial fructifications, Tubercularia vulgaris (Fig. 152, A, D); N. cucurbitula, a wound parasite of conifers; and N. galligena, the Euro- pean canker of apple (imperfect form, Cylindrocarpon [Fusarium] mali). Often the harmless saprophytic N. ditissima (imperfect form Cylindro- carpon (Fusarium) candidum), which is only pathogenic for beeches, on account of its association with JV. galligena, is often considered as the cause of the canker. In Calonectria, C. graminicola (C. nivalis, Fusarium Fig. 152. — Calonectria erubescens. A. Ascospores ( X 750) . B. Mature perithecium with subiculum (X 140). C. Mature asci (X 400). (After Weese, 1914.) nivale), the "snow mould" chiefly on rye, causes a wad-like covering and death of seedlings; furthermore in damp summers it appears at the base of the stems and causes a foot rot of grain (Schaffnit, 1912, 1913). Gibber- ella Saubinetii (Botryosphaeria Saubinelii according to the nomenclature of Weese 1919) causes foot disease and scab of small grains; Pleonectria berolinensis causes the death of Ribes. Hypomyces differs from the four previous genera in the extensive development of gemmae. It is chiefly parasitic on agarics and forms a stroma on the underside. The infection is generally visible by the appearance of a fine, arachnoid mycelium whose hyphae cut off acroge- nously fine, hyaline, generally unicellular conidia; in this stage, the fungi in question have been assigned to various imperfect genera, as Verticillium, Botrytis and Sporotrichum. Later there appear on the same hyphae, thick-walled, often sulptured gemmae. These two forms were earlier regarded as independent species and assigned to Sepedonium, Mycogone, 238 COMPARATIVE MORPHOLOGY OF FUNGI etc. Hypomyces ochraceus on Russula has hyaline conidia, called Verti- cillium agaricinum, its ochraceous gemmae being Mycogone puccinioides. H. chrysospermus lives mainly on Boletus; its golden-yellow gemmae were called Sepedonium chrysospermum. The imperfect Mycogone rosea, which also may belong to Hypomyces, along with others lays waste the mushroom cellars. Hypomyces species, whose conidia are of the Thie- lavia type, are placed in Pyxidiophora. As far as the cytological develop- ment is known for Hypomyces, it follows the Melanospora type. In H. rosellus (Dangeard, 1907) and H. aurantius (Vincens, 1917), the hyphal cells are multinucleate, in H. ochraceus (Dangeard, 1907) uninucleate. The representative of the second stage in which the perithecia are united on or in undifferentiated stromata, as Sphaerostilbe in the Didymo- Fig. 153. — Hypocrea delicatula. Habit. (Natural size; after Tulasne.) sporeae, Stilbonectria in the Phragmosporae, and Megalonectria in the Dictyosporae, arise directly from the stromatic forms of the first stage and frequently may not be easily distinguished from them. Their conidio- phores, in contrast to the stromatic Nectriaceae, are joined into clavate coremia at whose base the perithecia develop. In the Brazilian Megalo- nectria verrucosa, the ascospores germinate to a sprout mycelium in the interior of the ascus, as in some Nectriaceae. Sphaerostilbe repens causes a root disease of Hevea in Ceylon. In the representatives of the third stage, the stromata gradually develop to definitely formed fructifications; they have been studied in five genera: Hypocrea, Corallomyces, Mycocitrus, Peloronectria and Shiraia. The species of Hypocrea are distinguished in that their bicellular asco- spores at maturity separate into single cells, so that the asci apparently HYPOCREALES 239 contain sixteen spores. Their lowest representative connects directly to the Melanospora-Nectria type. Thus in H. delicatula, the perithecia stand comparatively irregularly on or in a slightly developed stroma (Fig. 153). In other forms, the stromata have an even greater develop- ment; thus, in the cosmopolitan H. citrina, they appear in the form of irregularly formed, yellow or ochraceous, thin mats on earth, leaves or tree trunks, often flat, up to one-half meter in cross-section. In the higher species, the stromata no longer form irregular crusts growing indefinitely in all directions, but begin to be individualized: they attain definite outlines and become fructifications. A first stage is represented by H. rufa, whose stromata are still rather indefinitely formed and spread over the substrate as flesh-colored, later red-brown, Fig. 154. — Hypocrea rufa. 1, 2. Sections through poorly and well-developed specimens. 3. Habit. (Natural size; after Tulasne.) often confluent cushions (Fig. 154, 3). Under favorable conditions of nourishment they are raised from the substrate by slight stipes and then become differentiated into sterile portions directed toward the substrate, and fertile portions directed away (Fig. 154, 2). The conidia of this species cover the cultures with a greenish powder (Trichoderma viride). They show a change in color similar to that of the conidia of numerous other Hypocreales changing from greenish on acid to yellow on alkaline media (Milburn, 1904). In a closely related segregate, Hypocreopsis lichenoides (Hypocrea par- melioides, Hypocreopsis riccioidea) and H. Rhododendri, the stroma devel- ops centrifugally into thick, subdichotomous lobes, resembling Parmelia physodes. The perithecia are confined to the upper, outer surface and are progressively developed as the lobes extend outward (Thaxter, 1922). 240 COMPARATIVE MORPHOLOGY OF FUNGI Somewhat higher stands the Brazilian, H. pezizoidea forming cup- shaped pezizoid fructifications in whose interior are embedded the perthecia. Higher still is H. poronioidea in which the stromata, as in the agarics, are differentiated into a stipe and pileus and on whose upper surface are embedded the perithecia. Highest of all are Podostroma alutacea and P. comu-damae. P. alutacea grows through the whole north temperate zone, forming a vertical clavate fructification (up to 3 cm. high), which divides into a sterile stipe and a narow clavate head (Fig. 155, 1). Externally it appears like Xylaria of the Sphaeriales or Clavaria of the Basidiomycetes (Atkinson, 1905). In the Thibetan P. comu-damae, the 10-cm. high fructifications are branched like a staghorn and appear deceptively like the Clavariaceae. CB§ • — — ]^ j^ Fig. 185. — Diaporthe leiphaemia. 1. Section of old pycnium. Diaporihe syngenesia. 2. Section of old pycnium. Pi, original pycnium with large conidia; Pi, secondary pseudo- pycnium with smaller conidia. Melanconis stilbostoma. 3. Section of young ectostroma, bearing conidia. 4. Diagrammatic section of mature fructification. Kon, shows the remnants of conidial layer between periderm and stromatal surface. Ect, ectostroma; Ent, entostroma; Per, periderm; Rp, bark parenchyma. (After Ruhland, 1900.) opening of the periderm. Hereupon it is differentiated within to a large pycnium whose interior is entirely covered with conidiophores cutting off hyaline bacillif orm conidia. Subsequently at the middle of the base of the pycnium, conidial formation stops and the ectostroma which lies there develops to a comparatively high plectenchymatic cylinder which projects into the cavity of the pycnium and divides lengthwise into two special sinuses. Diaporthe oxyspora (Wehmeyer, 1928) agrees with this type of development, having a Phomopsis conidial stage. In Diaporthe syngenesia (D. Berlesiana), the conidial hymenium is more elaborate. The ectostromatal layer, which separates pycnium from periderm, is much more developed than in D. leiphaemia. After the periderm is ruptured, conidial formation overlaps to the face of the distal ectostromatic layer (Fig. 185, 2) and thereby forms on the outer SPHAERIALES 283 side of the opening of the original pycnium px a second external false pycnium p2. The pycniospores of the former are larger and thicker than those cut off on the upper surface. The stromata develop further as in Diatrype disciformis. First an entostroma is laid down which serves as the site of perithecial formation. In contrast to D. disciformis, however, the upper part of the entostroma is not differentiated into marked scleren- chymatic placodium, so that the connection of both stromatal layers is not so roughly interrupted. The perithecial necks gradually push out through the ectostroma and help to raise the dark brown layer which has meanwhile died. Finally all the stromatal substance blackens. Whether sexual acts occur in the perithecia is not yet determined histolo- gically; possibly they are present, as in certain strains of Diaporthe perniciosa there is a peculiar physiological sexual differentiation (Cayley, 1923). Apioporthe anomala has a strongly developed stroma, like that of Diatrype, and unequal two-celled spores. Apioporthe obscura has a well- developed stroma about the perithecia, although it is not as erumpent as in A. anomala. In A. phomospora, this entostromatic development shows a still greater reduction, with only a slight development of myce- lium about the perithecia and a slight blackening of the bark surfaces above them. Conidia are produced in stromata by the breaking up of the mycelium (Wehmeyer, 1928). Parallel to the Diaporthe group, we find a second sub-series which does not produce a dark marginal zone, at least not until late in the history of its development. In Melanconis the stromatic development is limited to an ectostromatic disc and the perithecia are imbedded in the unaltered cortex. The ascospores become colored and uniseriate in the ascus, but remain two-celled. The imperfect stage is a typical Melanconium with the conidia borne in the shallow cavities on the sides of a sterile disc, or over the entire surface of a hemispherical ectostroma. Melanconis stilbostoma is fairly common on the dry twigs and pieces of stem of Betula alba. Under the periderm, it forms a fibrous cell complex which arches out to a head (Fig. 185, 3) and cuts off over its whole surface, dark-walled conidia of Melanconium bicolor. On account of the formation of conidia on flat or pulvinate layers, Melanconis is usually regarded as the type of the Melanconideae and hence contrasted to the Valsaceae in the narrower sense, which form conidia in pycma. Frequently the fungus, especially in unfavorable weather, does not attain this conidial stage, but transforms its pseudoparenchyma into a sclerotic tissue. In contrast to the previous genera, the entostroma remains mycelial and does not develop to an independent stromatal layer. The necks of the perithecia grow through the whole ectostroma, whose outer layer changes into a rind-like placodium (Fig. 185, 4). While in Diatrype the 284 COMPARATIVE MORPHOLOGY OF FUNGI placodium belonged to the entostroma, here it is supplied by the ecto- stroma; hence the first genus is called entoplacodial, the latter ectoplacodial. In Pseudovalsa there is no definite ectostroma and where a stromatic mycelium is formed, it is within the bark about the perithecial necks. Where the entostroma develops, there is a faint, dark, marginal zone, but the entostromatic mycelium is usually dark colored, hence the stromatic areas are not light as in Diaporthe. The imperfect stage is ectostromatic, but is usually not connected with the perithecial stroma, or where it is, as in some species of Pseudovalsa, the ectostroma is reduced. Diaporthe Wibbei, var. Comptoniae on Myrica asplenifolia, forms a transition from Diaporthe to Pseudovalsa, showing no marginal zones in the substrate, and producing septate, appendiculate conidia. In the stromatic tissue, loose ends of hyphae appear at one or several points and cut off conidia until a central, spherical or irregular cavity with a peripheral hymenium of conidiophores results. The subhymenium acts as a nurse tissue to the conidiophores. The connection of conidium and conidiophore becomes constricted and elongate. The conidium is abjointed at the apex of this elongate tip. The next conidium is con- stricted somewhat back of the apex of the conidiophore. The growth of the portion of the conidiophore above this constriction gives rise to the spore while the elongation of the stalk of the previous conidium forms the apical appendage. This conidial stage was described as Pestalotia flagellifera (Barclay ella flagellifera, Neobarclaya flagellifera). The peri- thecial stroma lacks an ectostroma and the blackened zones, while the entostromatic hyphae develop about the perithecia, suggesting the simpler species of Pseudovalsa (Wehmeyer, 1928). In Pseudovalsa lanciformis on dead branches of Betula alba, the ento- stroma is entirely absent. The hyphae connect inside the bark into a tangled stroma which at first cuts off conidia on its surface (Coryneum disciforme) , then ruptures the periderm and forms ascogonia and perithecia. In the second series, the main line of development in Cryptosporella and Cryptospora shows a similar stromatic structure and similar imperfect stage. The relationships among the lower forms are still vague. Gno- moniella has no stromatic development and may be considered as an ancestral form. Sphaerognomonia shows the development of a stromatic "clypeus" about the ostiole while Mamianiella shows a well-developed stroma about the perithecium. These three genera are found on leaves. Mazzantia (Hoehnel, 1918) has a stromatic structure identical with that of a well-developed Diaporthe, but it has unicellular ascospores. M. Gallii has a well-developed, differentiated entostroma within the tissue of the substrate, bounded by a darkened zone. The cylindrical, hyaline conidia are borne in an enclosed locule within the stroma. SPHAERIALES 285 The species of Cryptosporella and Cryptospora are characterized by unicellular ascospores and by a conical ectostromatic disc about which the perithecia are arranged circinately with the unaltered bark cortex. There is no differentiated entostromatic area nor dark marginal zone. The imperfect stages have been placed in Fusicoccum and Disculina (Cryptosporium) . The fructifications consist of an ectostromatic cushion which contains open cavities or enclosed locules, usually on the marginal portions of the ectostroma. The conidia are unicellular, hyaline and more or less elongate. These characters show a relationship to Melanconis. The third series includes Valsa, Leucostoma, Valsella, Endothia and Valsaria. In Valsa the structure is quite simple and resembles that of Melanconis, but in the other genera there is a well-developed and strongly differentiated entostroma. Ascospores, except in some species of Endothia and Valsaria, are allantoid, hyaline and unicellular. The conidial chambers are numerous or labyrinthiform and produced both in ento- stroma and ectostroma. Glomerella, with its allantoid ascospores, presents a possible origin for this series among the simple Sphaeriales. There seems to be a wide gap between such forms and the species of Valsa. The species of Valsa have a definitely differentiated truncate conical ectostroma which forms the erumpent disc. The perithecia are buried in the bark cortex beneath this ectostroma. The entostroma is very slightly developed and visible only under a microscope, while the ecto- stroma is sharply defined. The imperfect stage belongs to the form genus Cytospora. The fructifications consist of an entostroma containing numerous locules which often coalesce into a labyrinthiform chamber. The conidia are small, allantoid, unicellular, hyaline and ejected in large numbers in the form of a spore horn. In Leucostoma, the differentiation between ectostroma and entostroma is vague. In some species, as Leucostoma subclypeata (Valsa subclypeata) , there is formed a differentiated cap of ectostromatic mycelium. In all species the stromatic area is delimited very early in its development by a dark marginal zone of tissue which limits the size of the stroma. In Leucostoma Persoonii (Valsa leucostoma), the dieback of stone fruits, this zone runs just beneath the periderm and the stroma develops between the periderm and the bark surface. In Leucostoma subclypeata, this blackened zone may penetrate into the bark, cutting off a spherical area within which the bark cells are absorbed and replaced by a stromatic fungous tissue. Where there is formed a differentiated cap of tissue which opens the periderm, the stromatic tissue, in which the perithecia are imbedded, should undoubtedly be considered as entostroma. In many cases this tissue develops entirely upon the bark surface. Valsella differs only in its polysporous asci. Endothia is also close to Leucostoma. In E. parasitica (Fig. 186) the stroma usually arises as a 286 COMPARATIVE MORPHOLOGY OF FUNGI hyaline ectostromatic cushion just beneath the periderm. The amount of this tissue formed varies widely. When a well-developed ectostroma is formed, pycnidia are formed within it. If this tissue is much reduced it remains sterile and, unless pycnia are formed in the entostroma, only perithecia are produced. At about the time the ectostroma ruptures the periderm, its tissues are colored yellow becoming a reddish orange. The perithecial initials are formed within the bark cortex beneath the ectostroma. Along with the development of the perithecia, there is production of entostromatic mycelium. This may be so vigorous that a large stromatic mass containing only the remnants of the bark cells is pushed up through the periderm. In these larger stromata the ecto- stroma can no longer be distinguished (P. J. Anderson, 1913). This species has done much damage to Castanea in the United States and Eastern Asia (Shear, Stevens and Tiller, 1917). Endothia gyrosa and E. singularis show a great growth of entostroma, resulting in a large crumbly mass of fungus tissue in which only the rem- nants of the bark cells may be found. This genus must have arisen as a divergent line from some ancestor of Valsa and Leucostoma rather than directly from the latter. Xylariaceae. — The haplostroma- tic type is most marked in the last family (Tavel, 1892; Theissen, 1909). 186.— Endothia parasitica, l. Sec- rp^e smipier genera, as Nummularia, tion of pycnium. 2. Section of perithecial ,. *^ t , x x1 t^:_j.__- stroma. (After Heald, 1913.) «*Sitt$x mmmlr Fig. are directly connected to the Diatry- paceae and Diaporthaceae. They form round, discoid, generally amorphous, crustose black stromata, as N. Bulliardi on beech branches. Their mycelia in cultures have branched, fibrous conidiophores with heads of colorless spores. In the interior of the young hypophloedal stroma, there arises in a simple cavity, a flat conidial hymenium which cuts off similar conidia. The outer layer of the stroma covering it is pushed off with the periderm of the twig, so that at maturity the stromata of the perithecia lie free on the surface. In the other genera, the stromata develop wholly on the surface of the substrate but as in Ustulina, are indefinite in form. U. vulgaris covers the surface of old trunks and stems of frondose woods with often gigantic, undulating black crusts which in youth are soft and covered by SPHAERIALES 287 a conidial hymenium but later become brittle, hard and carbonaceous. A related species, U. zonata, causes a root disease of Hevea and tea. In the higher genera these external stromata, as in the higher Hypo- creales, gradually attain characteristic limits and become true fructifi- cations. At first they arch in the middle and become hemispherical or (as in Mycocitrus and its relatives) tuberous, e.g., in Hypoxylon (Fig. 187) and Daldinia; but one may not draw a sharp line between these two genera and Ustulina as their stromata, especially in immature specimens, often still remain resupinate crusts. The mycelia of both these genera exhibit very beautiful, graceful, often characteristically branched conidio- phores whose spores in Hypoxylon unitum are lateral on the conidiophores and in H. fuscum and H. coccineum are terminal in a solid little head. ^^ Fig. 187. — Hypoxylon coccineum. Fructifications in various stages of development, the youngest still bearing conidia. {After Tulasne.) Coremia also occur. Usually the conidiophores are scattered over the whole mycelium; more rarely their appearance is limited to the sur- face of the young stroma. They are always present there, however, and by the mass of their spores give it a powdery appearance and a peculiar color often differing from that of the mature fructification. In all cases the perithecia develop after the disappearance of the conidial fructification. Both genera inhabit, mainly, rotting wood and dry branches. In Hypoxylon the stromata are homogeneous, in Daldinia in concentric layers; this distinction is rather quantitative, however, and only reliable in extreme forms; thus the tropical D. exsur- gens shows a slight zonation but is otherwise similar to Hypoxylon. In the highest genera, as Xylaria, Thamnomyces and Poronia, as in the highest Hypocreales, there begins the differentiation of the stromata into a sterile and fertile part. Xylaria is cosmopolitan, but especially well represented in the tropics. It generally inhabits dead wood, rarely dung 288 COMPARATIVE MORPHOLOGY OF FUNGI or dry fruits (as X. carpophila on beechnuts). From the ascospores develops an extended mycelium whose hyphae unite into thick strands; these grow tall and show an intense heliotropism so that even when under bark or tree trunks they easily come to the outer surface. They are first differentiated into a black pseudoparenchymatic rind and a light fibrous core and then gradually develop to the cylindrical, clavate or branched fruc- tifications. Many species (inconvenient forsystematists!) are inseparable ' Fig. 18S. — Xylaria Hypoxylon. Group of stromata on fallen wood. {After Tulasne. from Hypoxylon, thus X. obovata, X. anisopleura and X. allantoidea show in the same species all sorts of transitional forms from Hypoxyloid central attachments to Xylarioid stipes. In spite of its inconspicuous occurrence in nature, its formation in culture is dependent on conditions of nutrition; thus X. Hypoxylon requires asparagin as a nitrogen source in formation of fructifications, while X. arbuscula and X. polymorpha require ammonium nitrate. Similarly darkness, red, yellow or green light favor vegetative SPHAERIALES 289 growth, while daylight or blue light are favorable to stromatal formation (Freeman, 1910; Bronsart, 1919). The growing tip of the stromata remains white for a long time and is covered with a strikingly regular hymenium of palisade-like conidiophores which, if unicellular, cut off ovoid conidia; if they are multicellular, how- ever, at any position they cut off fusiform conidia at their tips. In cultures similar conidia are cut off directly on the mycelium. In two American species, X. tentaculata and X. trachelina, the conidia do not arise directly on the stroma itself but on special branches which grow like coremia from the tips of the stromatal branches and fall off after shedding their spores. Fig. 189. — Thamnomyces Chamissonis. (X %, after M oiler, 1901.) Long after the coremia have disappeared, as in the spring when X. Hypoxylon (Fig. 188) has borne conidia in the previous fall, the stromatal branches swell clavately in the upper part and proceed to form perithecia. As far as is known, e.g., in X. tentaculata and X. trachelina (as in Hypo- xylon coccineum; Lupo, 1922), this precedes the formation of an asco- gonium without trichogyne, whose cells are first uni- or binucleate, later multinucleate (Brown, 1913). Thamnomyces Chamissonis (Fig. 189), on hard, dry woods lying on the forest floor, forms numerous caespitose, black, erect stipes of 1 to 2 mm. diameter which grow to 7 cm. without branching. Then they branch five or six times dichotomously, the members becoming thinner and shorter with every subsequent division. The level of each division is nearly perpendicular to the previous; thus arise rigid trees up to 11 cm. 290 COMPARATIVE MORPHOLOGY OF FUNGI high. Each of the ultimate branches is slightly swollen and contains a single perithecium with a firm, carbonaceous wall (Moeller, 1901). The last genus of the Xylaria group, Poronia (Fig. 190), differs from Xylaria and Thamnomyces by the discoid expansion of its fertile part. Its best known species, Poronia punctata, is found in the northern hemi- sphere on old horse dung, from which often only its fertile disc protrudes. In youth it is covered with light gray conidia. Later, at different times, helical ascogonia which end in a trichogyne, as in Poly stigma, are formed in spots and develop in an unknown manner (Dawson, 1900). Summary. — Here we have finished our forced march through the steppe of the Sphaeriales. In this order, especially in their parasitic representatives, pleomorphism (richness of various imperfect forms) reaches its highest point. The perfect forms are developed during the winter in our climate, where they are hastened to maturity by alternate Fig. 190. — Poronia punctata. Longitudinal section of a stroma. (After Tulasne.) wetting and drying, and hindered by the cold of winter until spring begins. Their sexual organs incline toward the Plectascales type, as do the Hypocreales, and, as the latter, still possess active antheridia. Besides they show, e.g., in Sordaria macrospora type, wholly new pecul- iar forms whose significance is at present unknown. The form of fructi- fications vary as in the Hypocreales and, like them, attain to aggregate fructifications which begin with simpler Nectrioid cushions and ascend to highly individualized, possibly perennial stromata like Cordyceps. Many Sphaeriales live in consort with algae and form the Pyreno- mycetous lichens, whose fungus components are still of uncertain relationship, CHAPTER XVIII DOTHIDEALES It is still more impossible to give a discussion of natural groups cor- responding in any way to natural relationships in the Dothideales than it was in the Sphaeriales. Originally the classification was based upon the fact that the ascigerous locules arose without perithecial wall directly inside darker, harder stromata. Thus they were regarded in part as Xylariaceae without perithecial walls. When it was subsequently recognized that in the highest Scolecosporeae of the Hypocreales, forms without perithecial walls gradually arose from forms with solitary peri- thecia lacking stromata, it was necessary to reorganize the Dothideales. As a matter of fact, in the last decade numerous genera and several families have been removed to the Myriangiales, not to the Sphaeriales or even to the Hypocreales; thus the Dothioraceae are mainly composed of genera removed from the Dothideales. Even at present this process is incomplete and the classification is only provisional. At present one can best describe them as Myriangiales with polyascous loculi, thus expressing the Pseudosphaeriaceous character of the majority of their forms as, in the higher Myriangiales, the stroma consists of parallel compact hyphae rising vertically from the host. In the centrally attached forms they first spread out flabelliformly until they have attained the entire basal area of the fructification, and only then rise. In this compact mass, the loculi are formed by resorption. Since there is no perithecial wall, there is no ostiole; the top of a loculus is always formed by part of the stroma which may or may not be thick- ened and may or may not have a crumbling papilla, rounded bluntly or drawn out into a neck. The main families of the Dothideales, the Dothideaceae and Phyl- lachoraceae, differ in the topographic position of the mature stromata; in the former, these lie on the surface but in the latter they are at first covered by host tissue. Dothideaceae. — This family falls into three tribes: the Dothideae, the Leveillelleae and the Coccoideae. The Dothideae are the central group. Their ascus stromata arise subepidermally and are freed by the rupture of the epidermis. In Systremma Ulmi (Dothidella Uhni), para- sitic on elm leaves (Killian, 1920), the ascospores infect the young leaves during the spring rains and grow there between epidermis and cuticle to a flat, plectenchymatic crust whose elongate, palisade-like, terminal 291 292 COMPARATIVE MORPHOLOGY OF FUNGI cells cut off unicellular, uninucleate conidia. As the hyphae only pene- trate the deeper leaf tissues late, the injury to the leaf is slight and the disease is only recognized in late summer (the end of August) by discolored spots. After the end of conidial production this subcuticular conidial stroma is carried away; only the hyphae in the interior of the leaf remain and intertwine between epidermis and palisade tissues to a dense plectenchyma. The cells, which in the central and basal layers are uninucleate and especially poor in protoplasm, thicken their walls Fig. 191.— Systremma Ulmi. 1, 2. Sexual cells. 3. Plasmogamy. (After Killian, 1920.) and turn brown. At the top of the plectenchyma the cells are richer in protoplasm; here they divide rapidly, especially in the spaces between the epidermal cells, so that the walls are usually periclinal to the mass, forming over the plectenchyma numerous small tissue swellings consisting of rows of cells, regularly septate when young. In the middle of each of these new pads there appears a darkly stain- ing cell which elongates and abjoints into three to four daughter cells (Fig. 191, 1 and 2). These gradually become 2 to 3 nucleate. Two of the cells develop more strongly and push the others together. Subse- quently they come into open communication (Fig. 191, 3), the nuclei DOTHIDEALES 293 migrate from one cell to the other, unite there in pairs and enter the ascogenous hyphae. Meanwhile the cells of the top of this young meristem have flattened ; they gradually thicken their walls, as happened earlier in the basal plectenchyma, and change into a cover layer. An interpretation of this life cycle is at present impossible, as Sys- tremma Ulmi is the only ontogenetically investigated species. It may be mentioned, however, that similar relations have been found in Epi- chloe Bambusae (Gaumann, 1927). One must regard the ephemeral cell series as the remains of a solitary ascogonium in which, as in Poly stigma, parthenogamy occurs between two sexually activated cells. From the point of view of the morphology of fructifications, the differentiation of the stroma into a conidial ectostroma and ascigerous entostroma is characteristic for Systremma Ulmi; and furthermore the OOODQOOOD coaoac ^ooodbDOGoD do oc Fig. 192. — Dothidella Derridis. Section of stroma. (After Theissen, 1914.) entostroma is first laid down as a hypodermal sterile basal stroma which only later develops fertile pads at the top. This budding of the ento- stroma is undoubtedly the same process as that which in the Myriangiales has led to the budding of the loculi. If one imagines that the fertile hyphae budding from the entostroma no longer unite into pads under the epidermis but emerge from the stomata singly or fasciculately and there intertwine to form a fertile tissue, one has the second tribe, the Leveillelleae. These possess an extensive sterile subepidermal basal stroma, which is connected by numerous hyphae or mycelial strands with the fertile extramatrical ascus stroma. In systematic literature the subepidermal basal stroma is usually called the hypostroma. This removal of the fertile ascus stroma from the interior of the leaf to the surface may be regarded as an expression of the asterinoid direction of development which we have observed in many Perisporiales, 294 COMPARATIVE MORPHOLOGY OF FUNGI Hypocreales and Sphaeriales and which tends to pass from endoparasitism to ectoparasitism and to the asterinoid habit, i.e., to become free from the host and transfer the fructifications from the interior of the leaf to its surface. Thus we will observe how in many Leveillelleae the intramatrical hypostroma gradually degenerates; its cross section diminishes in propor- tion to that of the ascus stroma and the hypostroma finally shrinks to a spatially limited foot from which the fertile hyphae rise in a single column (Fig. 192) . The forms which belong to this new type are united in the sub- family Coccoideae. Under these conditions, a natural line between the Leveillelleae and Coccoideae cannot be drawn, but this line rests upon a more or less arbitrary relationship of breadth between fertile ectostroma and sterile entostroma. No representative of either of these tribes has been fully investigated. Phyllachoraceae. — While the ascus stromata of the Dothideaceae are independent of the place of their formation, and at maturity are always free, in this family they are always covered by the host tissues; in the tribe Trabutieae they lie between cuticle and epidermis, in the Scirrhieae between epidermis and palisade layer, and in the Phylac- choreae in the mesophyll. The artificiality of this division is shown by the fact that the ascus stroma of Phyllachora graminis (Phyllachoreae) is formed directly under the epidermis and later penetrates deeper. Morphologically the Phyllachoraceae may be derived from Dothi- diaceae which, on account of their exclusively intramatrical life, have undergone all sorts of modifications. Thus instead of the tuberous or pulvinate stromata of the true Dothideae, there appears a more flat- tened stroma. Further in most genera the cuticle or epidermis is pene- trated in all directions by stromatal hyphae bound inseparably with the stroma and incorporated with it. The cuticle in the Trabutieae, or the epidermis in the remaining genera, thereby becomes an organic component of the stromatal cover layer. This is called the clypeus. Beginnings of such clypeal formation are already present in the Pseudo- sphaeriaceae (in the Didymella Rehmii group), in the Sphaeriales, in the Mycosphaerellaceae and in the Clypeosphaeriaceae, not otherwise dis- cussed in this book. However, they never attain the typical structures of the Phyllachoraceae and can hardly be confused with these as the stroma forming them in the Sphaeriales contains true perithecia. How the limits of the Phyllachoraceae, as contrasted with the Dothideaceae and simpler Sphaeriales, may best be drawn will appear only with extensive ontogenetic investigation. As characteristic of the position, a single example will be cited: the common Phyllachora graminis, which causes elongate black wales on grasses, has no stroma (in spite of the specific character of the order), but true solitary perithecia which are, however, held together by a common clypeus. Futhermore, it possesses true paraphyses which grow into the cavity of the perithecia (C. R. DOTHIDEALES 295 Orton, 1924). If one wishes to regard it as derived, one must consider it as transitional to the Montagnellaceae. If one regards it as primitive it must be connected to the Mycosphaerellaceae. Which of these two concepts is more justified, is still uncertain. Montagnellaceae. — As an appendix, a third family is considered (Theissen and Sydow, 1915) whose content and limits subsequent dis- cussion must settle. Some of their representatives remind one of the simpler Phyllachoraceae without stromata and clypeus; others (as the higher species of Botryosphaeria) possess a well-developed stroma which encloses single asci (in contrast to the several asci of Botryosphaeria) in columnar outgrowths. The latter forms, as the Rosenscheldia group, are probably derived from the Dothideae or Pseudosphaeriaceae; the former, as the true Montagnelleae, probably by the loss of the clypeus from the Phyllachoraceae. As the majority of their forms are tropical, probably an ontogenetic study will not be made for a long time. CHAPTER XIX HYSTERIALES With the Hysteriales begins the group of hemiangiocarpous Ascomy- cetes; they are Pyrenomycetes with elongate perithecia, closed during development, opening at maturity by a long slit which follows an earlier dehiscence line and almost completely uncovering the hymenium (Fig. 193, y). This special form of perithecium is called a hysterothecium. They appear depressed or conchoidal and have a carbonaceous or 2 membranaceous wall; often they are irregularly bent. The longitudinal slit (a typical ostiole is lacking in the true forms) penetrates the upper surface as a deep groove. In damp weather, after complete maturity, the walls open like lips, more or less closing in dry weather. This process may be repeated many times. On the base of the perithecium, the asci form a broad, light-colored hymenium with paraphyses. The Hysteriales have the elongate opening in com- mon with the Lophiostomataceae of the Sphaeriales. According to the idea of Hoehnel (1918), these two families should be united in a new order, the Hystero- stomeae; but such a rearrangement should be deferred until more ontogenetic and morphological information is secured. At any rate, the present limits of the Fig. 193. — Lopho- Hysteriales include entirely heterogeneous forms, dermium pinastri. on i • 1 • ,i <• , --it 1 ^ , • i i pine needles, a, one- which in the future will be removed to neighboring year-old spots; b, two- orders. According to Lindau (1897), they may be year-old dead needles ...... _ .... with mature, x, and divided into five families: the Hypodermataceae, empty, y, hysterothe- whose hysterothecia are embedded in the substrate, overgrown by a layer of host tissue with which they form a clypeus; the Dichaenaceae, hysterothecia membranous — leathery; Ostropaceae, hysterothecia thick, almost corky, at first embedded, later erumpent and free; Hysteriaceae, hysterothecia carbonaceous, black; and Acrospermaceae, hysterothecia horny, brown, free at the top, but with the bottom somewhat embedded in a subiculum. Only a few Hypodermataceae are of economic significance, especially Hypodermetta (ascospores unicellular, lachrymiform) Hypoderma (asco- spores two-celled) and Lophodermium (ascospores unicellular, elongate) which cause a premature drying and abscission of coniferous needles : L. 296 HYSTERIALES 297 pinastri, Hypodermella sulcigena and Hypoderma deformans on pines, L. macrosporum on spruce, L. nervisequum on white fir, Hypodermella laricis and L. laricinum on larches, etc. (Tubeuf, 1901; Haack, 1911). The needles of the young plants are infected in the summer by the ascospores, and begin to turn yellow, browning in zones. In the first year, the fungus forms pycnia, in the second and third, when the needles have fallen, hysterothecia. In Lophodermium hysterioides on Crataegus Oxyacantha, the mycelium from the germinating spore penetrates the stoma and forms a small sclerotium in the substomatal cavity. This then gradually invades the mesophyll. The pycnia develop under the cuticle and form flat discs of the Leptostroma type. Likhite was unable to effect germination of conidia. About the end of January the apothecia develop, often in the vicinity of the pycnia. In the hysterothecial stroma large multinucleate cells give rise to uni- or binucleate spiral ascogonia, lying in the plane of the hysterothecium. Pores form in the cell walls and nuclear migration is probable, although not observed. Paraphyses develop from spherical mother cells with many small nuclei. In April and May ascogenous hyphae arise from some of the ascogonial cells, while the rest degenerate and develop, without the formation of hooks (Killian and Likhite, 1924; Likhite, 1926). Close relatives of the Hysteriaceae form with species of Trentepohlia, crustose lichens, which are common on tree trunks, especially in the tropics, e.g., Graphis scripta. CHAPTER XX HEMISPHAERIALES With the Hemisphaeriales, we have left the classic Pyrenomycetes and passed to the Discomycetes. As their name signifies, the Hemi- sphaeriales form a group of families which originally were included in the Sphaeriales (including Perisporiales and Hysteriales), but have been removed to a new order on account of their disciform, pseudosphaerial fructification whose scutellate cap, with a peculiar, generally radial structure but lacking an ostiole, ruptures irregularly. They are inter- mediate between the Pyrenomycetes and the Phacidiales. The Hemi- sphaeriales are a temporary, artificial order, containing a series of generally parasitic families. Stigmateaceae. — This family is distinguished by the subcuticular position of the fructification, as in the Trabutieae. Stigmatea Robertiani (Hormotheca Robertiani) on Geranium Robertianum (Theissen, 1916; Theissen and Sydow, 1917; Klebahn, 1918; Killian, 1922) appears on the leaves of the host, in damp weather in summer and fall, in the form of small spots up to 3 mm. across. It continues to develop through the winter. The mycelium lives only on the outer surface of the infected leaves, generally on the upper surface, occasionally on the lower surface, often on both. Between epidermis and cuticle, it forms a continuous membranous layer which neither penetrates the deeper tissues by hyphae nor the epidermal cells by haustoria (Fig. 194, 1). In the central part, it gradually thickens into a flat plectenchymatous cushion in whose interior there appear two deeply staining uninucleate cells, in one or several neighboring positions, without conidial production (Fig. 194, 2). Gen- erally only one develops while the other is resorbed. This one cell goes through several nuclear divisions, elongates and develops, by the forma- tion of several septa, into a slightly bent, fertile hypha (Fig. 194, 3). Its innermost cell, i.e., that which lies next the middle of the plecten- chyma, elongates again perpendicular to the leaf surface and develops to a binucleate ascogonium with a peculiar receptive process at its tip (Fig. 195, 1). Another cell of the fertile hypha develops to a binucleate antheridium. The two organs come in open communication with each other, the male nucleus migrates to the ascogonium (Fig. 195, 2), after repeated division unites with the female nucleus and migrates into the ascogenous hyphae which later proceeds to the formation of asci between true paraphyses. 298 HEMISPHAERIALES 299 Fig. 194. — Stigmatea Robertiani. Development of fructification. 1. Section through a sterile plectenchyma on the upper surface of a leaf. 2. Young fructification fundament. 3. Young fructification with a fertile hyphae. (X 1,000; after Killian, 1922.) Fig. 195. — Stigmatea Robertiani. 1. Young fructification with a mature ascogonium. 2. Plasmogamy. (X 1,000; after Killian, 1922.) 300 COMPARATIVE MORPHOLOGY OF FUNGI Meanwhile the surface of the plectenchymatic cushion has become brown and chitinized. At its tip is differentiated a small papilla which later breaks off and leaves a circular hole through which the ascospores escape (Fig. 196). At the periphery, the aliform surface layer extends over the edge of the narrow perithecium and ends blindly. Thus it Fig. 196. — Stigmatea Robertiani. Section through a fructification. (X 341 ; after Kle- bahn, 1918.) Fig. 197. Fig. 198. Fig. 197. — Stigmatea Robertiani. Surface view of the subcuticular mycelium which merges at its lower edge with the outer layer of the fructification. ( X 804 ; after Klcbahn, 1918.) Fig. 198. — Stigmatea Robertiani. Portion of the edge of the fructification. {After The- issen and Sydow, 1917.) forms only the central part of a scutellate cover which gradually con- tinues outward into the original mycelial membrane (Fig. 197). Seen from above, the elements radiate in waves and themselves often form secondary centers of radiation (Fig. 198). This life cycle of S. Robertiani is notable in three respects. First, its fructification no longer has a perithecial wall, but is an apothecia-like HEMISPHAERIALES 301 cushion which has only a covering and no specially differentiated basal layer. Seen from above, its development appears as if a round or elliptical portion of the thallus arches up and begins to thicken, while an ascigerous hymenium forms under the arch. This process is called pycnosis in systematic literature, and the fructifications thus formed pycnothecia. In the second place, the formation of ascogenous hyphae is preceded by a true sexual act, which on the whole takes place in organs of a structure like that of Claviceps purpurea of the Hypocreales. In the third place, under the same cover layer, several ascogonia may be active, so that under certain conditions the ascogenous hyphae radiate from several centers. This last peculiarity suggests a tribe of the Stig- mateaceae, the Munkielleae, ontogenetically still unknown, which, with a structure otherwise the same, has under the same cover several hollow, arched discs of asci. Polystomellaceae. — This family is characterized by its ascomata arising only on the surface while the mycelium is parasitic in the interior of the leaf. They show a great similarity to the Coccoideae and Leveillel- leae of the Dothideaceae. They may be briefly described as Coccoideae or Leveillelleae with radial cover layers. As in the Coccoideae, so also in certain Polystomellaceae, the fructifications are rooted in the host tissue by a central column; in other Polystomatellaceae, as in the Leveillelleae, several of these columns may be present. According to the outline of the loculi, the family may be divided into two tribes, the Polystomelleae with round, and the Parmulineae with linear loculi. This distinction, however, is only of value for mature perithecia; thus in many species of Hysterostomella the young loculi at the edge of the turf are round, developing their linear outline only at maturity. In this linear outline of the Parmulineae, people have tried to see a rela- tion to the linear opening of the Hysteriales, and hence have called the Parmulineae Hemihysteriaceae. It seems here to be a question of con- vergence phenomena, however, for from the irregularly tearing slit of the Parmulineae to the labiate opening of the typical Hysteriales, the step is just as great as from the opening of the Dothideales to the ostiole of the typical Sphaeriales. In any case the originally circular perithecium shows a further development. Hysterostomella discoidea (Parmularia discoidea, Schneepia discoidea) corresponds to the Leveillelleae type of the Dothideales. In West Java, it is parasitic on fronds of Polypodiwm longissimum and there forms more or less circular stromata up to 3 mm. in diameter. The infected leaf surface is slightly vesicular and the stroma arches over convexly. In the hypostomatal cavities, the hyphae collect in brown or violet tangles, and then push outward to the leaf surface in perpendicular prosenchymatic columns (Fig. 199). Here they expand horizontally. Generally the hyphal bundles are only present in the central portions of the stroma 302 COMPARATIVE MORPHOLOGY OF FUNGI while the outside of the flat stroma has no direct connection with the sub- strate. In contrast to the Stigmateaceae, the basal layer of the stroma is dark, and hence definitely recognizable as such. Again, differing from Stigmatea Robertiani and like the Munkielleae, the numerous radial Fig. 199. — Hysterostomella discoidea. Section of ascus stroma on lower surface of leaf. (X 250; after Arnaud, 1918.) 1 Fig. 200. — Cycloschizon Alyxiae. 1. Lower surface of Alyxia leaf with ascus stroma. 2. Part of surface of young ascus stroma. (1 X^;2,3 X 250; after Arnaud, 1918.) loculi, generally under the same covering layer, are irregularly sinuous, recurved and often forked acutely. Cycloschizon Alyxiae (Maurodothis Alyxiae, Dielsiella Alyxiae) in Australia and Tasmania is parasitic on the leaves of Alyxia buxifolia. HEMISPHAERIALES 303 The mycelium penetrates for short stretches, and hyphal columns emerge on the lower sides of the leaves in numerous places where each develops to a small flat fructification. Thus these small fructifications are close together and often form groups up to 7 mm. cross section (Fig. 200, 1). At times they are so close that they look like a single crust; the oldest lie in the center, the youngest at the periphery. At maturity, the single fructifications are circular, 0.5 mm. in diameter and divided in the middle by a hemispherical knob with radial furrows (Fig. 200, 2). In contrast to Hysterostomella, only one central column is present in each fructification (Fig. 200, 3), while in Hysterostomella as many as half a dozen are to be Fig. 201. — Asterinella Puiggarii. 1. Section of recently opened fructification. 2. Part of mycelium, showing young and mature fructifications. (1 X 250; 2 X 34; aftir Arnaud, 1918.) seen. As a substitute for this, the stromata of Cycloschizon put out from time to time peculiar sinkers which penetrate the interior of the leaf through stomata, serving to anchor and to nourish the stromata (Fig. 200, 3 right). In contrast to Hysterostomella, only one loculus, instead of several, is present in the fructification. While in Fig. 199 one must imagine, to right and left, cross and longitudinal loculi, for Cycloschizon all portions of the loculus are visible in Fig. 200, 3. These belong to a single loculus which circumscribes the hyphal knob under the radially striate cover, like a horseshoe or a ring. Hence at maturity the cover does not rupture radially, as in Hysterostomella, but perpendicular to the furrows of the cover with the sterile knob as the center; only subsequently may this circular split fray out by short radial slits. Microthyriaceae. — This family shows the purest type of asterinoid habit. It has given rise to the idea of asterinoid life forms (Theissen, 304 COMPARATIVE MORPHOLOGY OF FUNGI 1912, 1914; Theissen and Sydow, 1917; Hoehnel, 1917, 1918; Arnaud, 1918; Doidge, 1920). It is difficult to describe briefly the characters of the Microthyriaceae, as all their forms merge into each other and into related families. In any case, they are usually superficial ectoparasites. The ascus stromata are provided with radial covers. In the Microthyrieae there is no aerial mycelium at maturity; in the Asterineae, the mycelium is persistent, dark colored, squarrose, asterinoid, often like the sooty moulds, aerial (Figs. 201 and 202). As in the Perisporiaceae, so also in the Asterineae, there Q^SapQ oooooQQQP Fig. 202. — Lembosia Bromeliacearum. 1. Section of fructification (X250). 2. Central portion of mycelium bearing a fructification (X 34; after Arnaud, 1918.) are formed on the hyphae numerous specialized branches, hyphopodia and stigmopodia. As there, so also here the stigmocysts may develop to fructifications. Besides, the formation of fructifications may take place directly under any hypha so that the hypha lightly touches the young perithecium or it may — in the species without mycelia — take place directly on the transitory germ mycelium which develops from the ascospores. In all these cases, the mother cells first divided to small cell complexes which either remained discoid, flat and one layered or grew into knob-like papillae, which frequently persisted a long time (Fig. 203, 1). This layer grows centrifugally, so that the newly added cells have an elongate pris- matic outline. Thus there is formed under the main hypha close to the HEMISPHAERIALES 305 leaf, a thin, light-brown fruit disc, of radiating prosenchyma, in one layer at the periphery, with pseudoparenchyma in the middle. While this develops to its definite limits, as in Stigmatea, it begins to rise from the center outward, being pulled from the developing core, and to arch up like a flat spherical cap or hemisphere. Thus the generative hyphae are torn off, with increasing tension the cover is soon ruptured, forming an opening which may be widened by histolysis. The asci arise singly in the loculi and are generally eight spored. The development of the fructifications of the Microthyriaceae, often called thyriothecia has puzzled the systematist for a long time. As rrrrn-T-rri Fig. 203. — Dimcrosporium Veronicae. 1. Group of fructifications on lower side of a leaf. The older has ruptured at the top. 2. Section of fructifications. Asterina Usterii. 3. Hyphae and epidermal haustoria on lower surface of a leaf. (1 X 7, 2 X 250; 3 X 620; after Arnaud, 1918, and Maire, 1908.) the thyriothecia are not oriented by the mycelium but by the host, their generative hyphae hang downward. Hence they are inverted, i.e., their morphological base is at the top. Since the Microthyriaceae have been considered connected, through a series of intermediate forms, with Meliola of the Perisporiaceae, the thyriothecia must be regarded as halved perithecia, i.e., as perithecia in which the tip (lying beneath) has not developed further for lack of space. According to this conception, since the radial cover layer remained unexplained, the thyriothecia were considered complex structures, i.e., as upright perithecia, lying free from the substrate, protected by their radial shield and no longer needing a 306 COMPARATIVE MORPHOLOGY OF FUNGI special perithecial wall, gradually reduced to a naked core. It seems better to interpret the thyriothecia in the light of the pycnothecia and the ascomata of Plectodiscella and to defer further conclusions until ontogenetic Fig 204 —Trichothyrium fimbriatum on Meliola. A. Upper surface of leaf showing points of infection. B. The same enlarged. C. Periphery of mat. Some mycelium of Meliola still visible in the middle. D, E. Hyphal bands. F, H. Formation of fructifica- tions. I. Section of immature fructifications. J. Ascospores. (A X AA\ -» X 8; D to 1 X 285; J X 750; after Arnaud, 1918.) investigations of the Microthyriaceae are made. The actual striking correspondence between the habit of Meliola and of the Microthyriaceae would then be regarded as convergence phenomena. HEMISPHAERIALES 307 The Microthyriaceae include about 40 genera with about 400 species, chiefly of the tropics and subtropics. Just as in the Polystomelleae- Parmulineae series, a gradual transition occurs from round (Fig. 201) to linear (Fig. 202) fructifications, since in Hysterostomella even the linear fructifications in youth have a rounded outline. At present no species of economic importance is known. Trichothyriaceae. — The representatives of this family (Theissen, 1912; Hoehnel, 1917; Arnaud, 1918) may be regarded as Microthyriaceae which have become specialized for parasitism on other, especially asteri- noid, fungi. The originally independent hyphae cling together in brown bands (Fig. 204, D and E) which cover the mycelium of the host and occasionally are confused with it. As the members of this family do not themselves directly parasitize leaves, their fructifications lie on their own mycelium unprotected beneath by the cuticle of the host. Conse- quently the basal stromatal parts attain a more marked cover layer character: they become brown and pseudoparenchymatic (Fig. 204, 7). In some genera, as Loranthomyces, parasitic on the stromatic Sphaeriales, the fructifications appear entirely inverted and the asci hang down from the morphological base above. These inverted thyriothecia are called catothecia by Hoehnel (1917). Unfortunately their ontogeny is entirely unknown. CHAPTER XXI PHACIDIALES The Phacidiales are connected on one side to the Hysteriales, on the other side to the Dermateaceae and Bulgariaceae, in the Pezizales. In time they will probably be divided between these two groups. They are Discomycetes with ingrown or superficial perithecia, surrounded or only developed above, rupturing at maturity by several irregular slits above. According to one's definition and personal viewpoint, they may be divided in different ways. Lindau (1897) divides them into three families: the Stictidaceae, with slightly fleshy, bright-colored perithecia and Tryblidiaceae and Phacideaceae with black leathery or carbona- ceous, perithecia, which in the former possess a thick hypothecium and project above the substrate; the latter, having only a thin, poorly developed hypothecium, remain immersed in the substrate or in their stroma. Hoehnel (1917) divided the order in the narrower sense into six families based on the situation of the fructifications in the host tissue: the Schizothyriaceae with flat fructifications upon the cuticle, the Lepto- peltinaceae with subcuticular fructifications, the Dermopeltinaceae with intraepidermal fructifications, the Phacidiaceae with subepidermal or still deeper fructifications, the Phacidiostromataceae whose fructifica- tions include the whole tissue between the epidermal layers of leaves, coalesce with them or (in ramicolous forms) are sunk deep in the stem tissues and here coalesce with the stem epidermis, and the Cryptomycet- aceae with fructifications under the periderm of stems and twigs. The ontogeny of Cryytomyces Pteridis (Killian, 1918) and Rhytisma acerinum (Jones, 1925) is known. C. Pteridis, causing a leaf roll of the brake, belongs to the Phacidiaceae of Lindau's treatment, to the Crypto- mycetaceae of Hoehnel's. At the beginning of the warm spring rains, the ascospores of the over-wintered fructification infect the young fronds of Pteris. At first the hyphae grow intercellularly, then intracellularly in all directions and intertwine in the hypostomatal cavities to flat cushions whose apical cells cut off fusiform, uninucleate conidia (Figs. 205 and 206). Conidial formation continues until the beginning of cold weather. A protective layer is formed, changing the cushions to flat, irregular pycnia. During the summer the fundaments of the ascus fructification are formed as small plectenchymatic knots in the hypostomatal cavity. The cells of the plectenchyma lying between the guard cells have a 308 PHACIDIALES 309 denser content and deeper staining properties. They grow to fertile hyphae, which bore under the plectenchyma in a group and reach a length of six cells (Fig. 207, A). Meanwhile the knot thickens the cell walls on its outer surface, and becomes a flat, brown, sclerotic mass. The fertile hyphae stow themselves on the hard basal peridial layer, bend irregularly and fork. irffi Fig. 205.— Cry ptomyces Pteridis. Section of young hypertrophied fronds of the brake covered with acervuli. ( X 330; after Killian, 1918.) The further development proceeds from the three more strongly developed end cells (Fig. 207, A, cells a, b, c). Cell a later elongates so that only the subterminal cell b and the terminal cell c retain their characteristic cubical appearance. In late summer, the subterminal cells of two neighboring fertile hyphae develop copulation papillae toward each other and the nucleus migrates from one cell to the other while the rest of the fertile hypha collapses and disappears. 310 COMPARATIVE MORPHOLOGY OF FUNGI Fig. 206. — Cryptomyces Pteridis. Section of a young acervulus in the substomatal cavity. (X 550; after Killian, 1918.) PHACIDIALES 311 6 >• ' • , ■ - •. ' m : i - £'*$ v. I Fig. 207. — Cryptomyces Pteridis. A. Section of a young ascus fructification with immature fertile hyphae. Above, the apical layer, below, the basal (X 830). B. Older stage with young asci ( X 550). {After Killian, 1918.) 312 COMPARATIVE MORPHOLOGY OF FUNGI As in Venturia, there is now a rest period which lasts through the winter. In spring, the binucleate cell develops in an unknown manner ascogenous hyphae which form 8-spored asci (Fig. 207, B). This peculiar ontogeny may not be interpreted at present, since Cryptomyces is still too isolated morphologically. In certain relations it reminds one of Penicillium crustaceum as there the ascogenous hyphae, so here the fertile hyphae grow like foreign bodies in the plectenchyma of the fructification and parasitize it in a certain sense; this relation finds its explanation in the fact that at that time only the tissue of the fructification can furnish nourishment, since the leaf of the host is already exhausted. It is also suggestive of the relations of the ooblastema filaments to auxiliary cells in the red algae. In regard to the origin of the fertile hyphae, Cryptomyces Pteridis is reminiscent of Systremma JJlmi; as in the latter, they are the apical cells of the parenchyma of the fructification which, by renewed growth, change the sclerotoid tissue body to true ascomata. Only in S. JJlmi this growth takes place upward from the tissue body, while in C. Pteridis from above down into the tissue body. It is possible that this localization of the meristem at the top of the tissue body is connected with the acid require- ments of the fertile hyphae. In form of fertile hyphae, C. Pteridis is almost unique. While in the previously discussed forms, the ascogonia, with the exception of Sordaria macrospora in the Sordariaceae, generally are helical, in C. Pteridis the fertile hyphae (antheridia and ascogonia) are elongate. To use an expression of Killian, they form a parallel thread type. It is possible that they must be regarded as end forms in a sense which will be again met in the Pezizales, in the Leotia-Spathularia series of the Geoglossaceae and the Icmadophila-Baeomyces series of the discomycetous lichens, in which the ascogonia (which alone are formed in these species, since the antheridia are suppressed) gradually lose their specific form, finally becoming vege- tative hyphae filled with reserves. In this manner, the fertile hyphae of Cryptomyces may be regarded as an (ideal) step in the direction of the pseudogamy which takes place in the Uredinales (e.g., in the aecia between two specialized hyphae). The other forms so far studied give no answer to this question. In Coccomyces hiemalis (Higgins, 1914), the leaf spot of cherry, and Phaci- dium repandum on Galium rubioides (Satina, 1921), helical ascogonia with trichogynes of the Polystigma type were observed. In Rhytisma acerinum, one of the Dermopeltinaceae of Hoehnel, the ascogonia are elongate and no longer typical, while there are no antheridia. The hyphae penetrate maple leaves in all directions from the spot of infec- tion and fill the epidermal cells of the upper surface of the leaf, less often those of the lower side, with a dense tissue. The walls between the epidermal cells are broken and gradually dissolve so that the hyphal PHACIDIALES 313 tissue forms a long continuous plectenchymatic stroma. In the central parts of the stroma, numerous hyphal tips rise within the limited region from the plectenchyma, form a regular palisade and, after June, cut off an enormous number of uninucleate conidia. Their pressure ruptures the outer epidermal wall, pieces of which are occasionally raised by the conidial mass as upon a column, and the conidia are liberated in a milky drop. Morphologically, thus, R. acerinum does not form pycnia, as systematic literature often states, but acervuli like Cryptomyces Pteridis. Like the conidial layer, the apothecia are formed in the epidermis of the upper surface of the leaf, chiefly on the peripheral parts of the stroma. The majority of them are formed de novo, but a few are laid down in the exhausted acervuli. In the fall, the whole stroma changes to a sclerotic tissue which blackens on the upper surface, less often on the under surface (i.e., toward the palisade layer of the leaf). In the interior of the plec- tenchyma are differentiated numerous apothecial cavities filled with loose hyphal tissue and covered by a thick-walled, pitch-black epithecium (and the outer epidermal wall) and below rest on a somewhat broader, brighter hypothecium (with the inner epidermal wall). In each apothecial fundament are formed several ascogonia which consist of a uninucleate stipe cell, 2 to 3 multinucleate ascogonial cells and a uninucleate trichogyne cell. The septa between the ascogonial cells break down, as in Ascobolus citrinus of the Pezizales (Fig. 227); the nuclei pair parthenogamously and migrate into the ascogenous hyphae, which coil and grow out again, as we have already seen in Aphanoascus cinnabarinus of the Plectascales. Eight ellipsoidal ascospores are formed and elongate to filaments. They may be shot up for 1 mm., probably as a result of contraction of the stroma in dry weather. Thus the swollen paraphyses (which are formed from the loose hyphal tissue between the epi- and hypothecium) press the asci which in turn squeeze out the spores and secure their dispersal by air currents. While the asci are still in the uninucleate stage in early spring, a dehis- cence zone about 12 cells wide is formed in the middle of the apothecium in the lower fourth of the epithecium. The cells of this zone become dis- organized, causing a narrow slit which, by the degeneration of the bordering apical layers, expands somewhat at the top. In the lowest fourth of the epithecium, below the horizontal slit, lateral growth begins so that this lower fourth arches downward into the apothecial cavity. By this lateral growth the upper layer of the epithecium is ruptured. Finally the pressure of the ascospores ruptures the lower wall layer under the split, and the edges spring back, exposing the hymenium. Unfortunately these relationships cannot be figured in this book, as the work of Jones was only available to the author after the figures had been sent off for reproduction. 314 COMPARATIVE MORPHOLOGY OF FUNGI Rhijtisma acerinum causes the tar spot of maple ; the biological form platanoides (K. Muller, 1913) lives mainly on A. platanoides, less on A. platanus and A. campestris; while forms Pseudoplatani and campestris are specialized on A. Pseudoplatanus and A. campestris. Because of the obscure character of the Phacidiales, we will mention only that several forms, as the above Coccomyces hiemalis, C. lutescens and C. prunophorae on cherries and plums (Higgins, 1914) and Phacidiella discolor, the cause of a canker of the apple in the Caucasus (Potebnia, 1912) form both macro- and microconidia in acervuli. In the latter species, the hyphae may develop sprout mycelium under certain con- ditions of growth. CHAPTER XXII PEZIZALES In the Pezizales are grouped all fleshy Discomycetes. They are characterized by the special structure of the fructifications which, as briefly mentioned in the introduction to the Ascomycetes, are called apothecia. A diagrammatic cross-section of a lichen apothecium is given in Fig. 208. This discoid fertile layer (the ascus hymenium or thecium) is desig- nated as t. It generally lies free in the later stages of development, as — m Fig. 208. — Section of the apothecium of Physcia pulverulenta. (After Nienburg, 1913.) shown in Fig. 208 ; in the early stages it is arched over by a special cover layer which appears approximately in the direction of the dotted line in Fig. 208 and only later, with the expansion of the hymenium, is reduced to threads. Forms which, like these, begin their development angio- carpously and end gymnocarpously are called hemiangiocarpous. Histologically, the fertile layer is composed of asci which form the ascospores Sp and of the paraphyses p. The asci belong to the diplont, but the paraphyses and the rest of the fructification to thehaplont. The paraphyses show their haploid nature in teratological cases, e.g., Fabraea 315 316 COMPARATIVE MORPHOLOGY OF FUNGI Fragariae, where they may proceed to form conidia. In certain forms they do not arise directly from the ground tissue of the fructification but from large storage cells. Their fate varies in the different families. In one they swell, as in many Sphaeriales, into a structureless gel, in another they are persistent and partly intertwine over the tops of the asci to a thin, brightly colored layer, the epithecium e; it is this cover layer which, seen from above, gives the characteristic color to the apothecia. Besides the paraphyses in the hymenium of many forms there are peculiar paraphysoid setae, which also belong to the haplont (not shown in Fig. 208). While the true paraphyses are thin walled, hyaline and multiseptate, the setae are thick walled, brown and always unicellular. In the young stages they bend together (in the hemiangiocarpous forms, after the rupture of the layer covering the young fructification) and form a sort of sheath over the developing hymenium. Later they are pushed aside and at most surround the disc. In the purely gymnocarpous forms, whose hymenium is free and exogenous, they often remain scat- tered over the hymenium during its development. In this case they rise far below in the hypothecium and secrete a brown gluten at their tips. This gluten flows over the surface of the hymenium, which in this case is chiefly formed of the capitate ends of paraphyses, and there forms a struc- ture which, at first glance, might be confused with the epithecium. In this gel there often live a large number of bacteria which assist in the rapid decay of the fructification. Under the hymenium is the hypothecium h, which forms the para- physes directly and the asci indirectly. In some families the layer which bears the hymenium, the hymenophore, is marked by a denser structure or darker color; in systematic literature it is called the exciple. In the ideal case, the hypothecium projects beyond the edge of the ascus layer and forms the rim of the saucer or bowl pt; when this rim is distinguished from the other tissue by a darker color, it is called a parathecium. In certain forms the outer wall of the hypothecium is pseudoparenchymatic and often darker in color (r in Fig. 208). The previously named layers and organs are all an inheritance of the fungi; in the special case of the lichens mentioned here, they may be surrounded by a thalline margin (exciple) which forms the amphithecium ; this is usually similar in structure to that of the thallus of the lichen in question and is generally composed of a cortex r, the algal layer a and the medulla m, which is connected to the hypothecium either directly or by a second algal layer. It is clear that in nature no apothecium has simultaneously all the different layers here mentioned. In the lower forms, the apothecia are of simpler structure and consist of a stromatic cushion, with an ascigerous hymenium. In the higher forms they are much modified, so that the fructifications in their histological differentiation, formation of latex PEZIZALES 317 vessels, extensive formation of special tissues, etc., remind one of the structures of pileate fungi, or of the stems and leaves of cormophytes. An attempt has been made to use the structure of the apothecium for systematic classification of the Pezizales, especially to distinguish funda- mentally between gymnocarpous (exogenous) and angiocarpous (endo- genous) forms and to unite the gymnocarpous forms in the series with the Helvellales and the angiocarpous forms in the Pezizales. Ontogenetic investigations have not supported this conception. On the one hand, many earlier forms considered gymnocarpous, as Helvetia, have been shown hemiangiocarpous; on the other hand, in Ascobolus gymnocarpous and hemiangiocarpous species appear side by side. Besides the vari- ability of the terms gymnocarpous and angiocarpous lead to abstract difficulties; thus in Leotia the sheath is only transitory and disappears before the hymenium is formed. The hymenium is exogenous, as in typical gymnocarpous forms, although the young fructification was surrounded by a hyhal veil. Hence one is obliged to unite the earlier order of Helvellales and Pezizales, as is done here with the support of Boudier and Durand. The classification of this large new order is accomplished on the biological individuality of the asci. In one series, the Inoperculatae, the asci open, as in the other Ascomycetes, at their tips by an irregular rupture which may close after the exit of the ascospores and be no longer visible. In another series, the Operculatae, they open by the raising of a pre-formed lid (operculum). In addition to this anatomical feature of the asci, these two series differ in histological characters (Lagarde, 1906), which cannot yet be formulated in general terms. The further classification of the two series is based on the structure of the fructifications. Each series is split into a large number of families on characters of the fructification, of which seven will be discussed in the Inoperculatae, and five in the Operculatae. They are parallel in several respects and, in the higher forms, lead to striking convergence phenomena. As very few of the transitional types have been ontogenet- ically investigated, the construction of a family tree is not yet possible. The simpler groups of the Inoperculatae, as the Philipsielleae, the Agyrieae, the Celidiaceae and Patellariaceae, are mostly parasitic or saprophytic on wood, bark or lichens, etc. Morphologically they are very close to many lichen-forming Discomycetes and have therefore often been considered lichens. The fructifications are frequently small and transitory and hence generally known only from hebarium material. In any case, they are connected by numerous intermediate forms with the Plectascales, especially the Gymnoascaceae, and with the Myriangiales, especially the Saccardiaceae, so that they are classified variously by systematists. The Philipsielleae and Agyrieae, especially, have entirely atypical immarginate fructifications whose spherical or ovoid asci are 318 COMPARATIVE MORPHOLOGY OF FUNGI separated from each other by irregular paraphysoid hyphae intertwined above to a loose, lumpy epithecium (probably the remains of an inter- thecial stroma) as imperfect stages, free conidiophores, and pycnia are known. In the higher groups, as the Dermateaceae (apothecia horny or leathery) and Bulgariaceae (apothecia gelatinous), the fructifications are conspicuous and possess a typical apothecial structure. Their disc is covered by a membranous layer which is finally torn and disappears; by this character they are related to the Phacidiales, on one hand to the Stictidaceae whose fructifications, as in the Bulgariaceae, are gelatinous, and on the other hand to the Tryblidiaceae which usually seem decep- tively like many Dermateaceae, e.g., certain species of Cenangium. The if) v§$g@^ Fig. 209. — Dermatea Ccrasi. 1. Section of stroma, with apothecia, a; conidial cavities, c. 2. Macro- and microconidia. Dermatea carpinea. 3. Stroma showing apothecia, a; conidial fructification, c. 4. Portion of conidial fructification of Dermatella dissepta, showing bacilliform conidia, s; ellipsoidal conidia, r. (1 X 10; 2, 4 X 380; after Tulasne.) paraphyses intertwine to a firm epithecium above the tips of the asci in the Bulgariaceae and Dermateaceae (as in many Philipsiellaceae- Patellariaceae and Phacidiales). Dermateaceae. — Some species of Dermatea and Cenangium are important plant pathogens. Their several fructifications are erumpent from a poorly developed hypophloedal stroma ("Fig. 209() ; when dry, they form an invisible, usually dark-colored membrane; in moist weather they swell to conspicuous leathery structures. The same stroma bears first conidia, later apothecia. In many forms, as D. Cerasi, the conidiophores are united into Valsaceous pycnia (Fig. 209, 1), in others as Dermatella dissepta they are free on the substrate (Fig. 209, 4). Dermatea carpinea causes a dangerous stem and twig disease of the hornbeam, D. cinnamomea, a similar one of oak and Cenangium Abietis, one on pines. PEZIZALES 319 Bulgariaceae. — Bulgaria and Coryne are notable for the remarkable development of their imperfect forms. Bulgaria polymorpha (B. inquin- ans) forms circular brown fructifications on the wood or bark of fallen frondose trees. The nuclear divisions in their asci do not take place simultaneously, so that the early and late maturing nuclei compete for the epiplasm (Moreau, 1914). The first-formed spores are normally brown and have a meridianal germination slit; the younger remain hyaline and lack this split (anisospory). The species of Coryne are mostly saprophytic or hemiparasitic on wood and bark. Fig. 210. — Coryne prasinula. 1. Ascus whose spores are already forming sprout cells. 2. Discharged ascospores continuing sprouting. 3. Spherical sprout cells which are form- ing bacilliform cells. 4. Sprouting hyphae. 5. Beginning of conidial formation. Coryne Cylichnium. 6. Sprouting ascospores. Coryne sarcoides. 7. Germinating ascospore. 8. Conidiophores. (1 to 5, 7, 8 X 350; 6 X 300; after Brefeld and Tulasne.) In both genera the ascospores develop sprout cells in nutrient solu- tions or mycelium, which in turn may form sprout cells. In Coryne prasinula, a form with greenish apothecia on decaying wood, sprouting begins in the ascus (Fig. 210, 1); the several-celled hyaline ascospores develop tiny, spherical sprout cells, and continue to grow after ejacula- tion (Fig. 210, 2). Besides, they may just as frequently develop to luxuriant hyphal mycelia whose cells cut off on all sides large masses of bacilliform sprout cells. Similar bacilliform cells occasionally sprout from the spherical sprout cells (Fig. 210, 3) or their germ tubes. Both types multiply intensively and in solutions form opaque precipitates, but may at any time, with a change of cultural conditions, proceed to hyphal growth. Similar relationships have been determined for Coryne Cylichnium and C. sarcoides, whose large apothecia have a dark flesh-red color, in 320 COMPARATIVE MORPHOLOGY OF FUNGI which the formation of bacilliform cells on the mycelium is no longer indefinite but limited to the tips of the conidiophores; these arise only when the mycelium has attained a large expanse and by their general rich branching give rise to coremial formation (Fig. 210, 8). In nature these coremial formations have proceeded further to large, irregular, folded conidial layers of the color and consistency of apothecia, whose surface is occupied with conidiophores such as the mycelium produces. Cyttariaceae. — This monotypic family forms a special type of the stromatic Pezizales. Cyttaria is parasitic on species of Nothofagas in the Fig. 21 1. — Cyttaria Gunnii. a, twig of Arothofagus Cunninghami with fungus galls; b, group of stromata; c, section of a single stroma, (a X Ml after Berkeley.) southern hemisphere and stimulates them to abnormal woody growths. These knobby stromata, in some species brightly colored, generally break out in groups (Fig. 211, 6); they gelify at maturity and are used by the natives for food. Numerous apothecia arise over the entire stroma under the cover layer (Fig. 211, c), and are only liberated at maturity by gelification of this tissue. In C. Darwini, the pycnia are found on the stipe in young fructifications, in C. Harioti sparsely scattered on the lower side, and in C. Hookeri on the apical portion (E. Fischer, 1888). All these stromatic Pezizales, despite their varied forms and unknown ontogeny form a special side line of the order. In the next groups, with- out stroma or epithecium, we deal with portions of the order which have been very much investigated cytologically. We will discuss two para- PEZIZALES 321 sitic families, the Mollisiaceae and Helotiaceae, and the saprophytic Geoglossaceae. In the Mollisiaceae and Helotiaceae the peripheral layers are developed to a special peridium; in the Geoglossaceae the hypothe- cium is homogeneous but differentiated into pileus and stipe; in the Mollisiaceae the peridium is paraplectenchymatic and often built of dark, thick-walled cells; in the Helotiaceae it is prosenchymatic and formed of hyaline, thin-walled cells. Fig. 212. — Pseudopeziza Ribis, a, with its secondary spore form, Gloeosporium Ribis, b. (After Klebahn, 1906.) Mollisiaceae. — Pseudopeziza (Drepanopeziza) Ribis (Klebahn, 1906), causing anthracnose of Ribes rubrum and R. aureum, from early summer on, produces small brown conidial spots singly or in fused groups 1 or 2 mm. broad, which arise under the upper epidermis of leaves and subse- quently raise and rupture it (Fig. 212, 6). They were earlier described as Gloeosporium Ribis. Their spores are colorless, unicellular and sickle shaped, with the thickest spot toward one end rather than in the middle. In damp weather they swell out as light-brown, waxy columns and are generally scattered by rain or insects. They retain their ability to germi- nate, and possibly to infect, over the whole winter. During the winter, 322 COMPARATIVE MORPHOLOGY OF FUNGI the apothecia are formed in the interior of the leaves as brown hyphal tangles and break forth during early spring rains. They have a brown peridial layer, 2 to 3 cells thick, which elongates below like a stipe and opens above like a cup. A similar life cycle has been determined for Pseudopeziza Medicaginis, causing a leaf spot of alfalfa, for P. Trifolii on clover, forming apothecia even on the living leaves, for P. tracheiphila the cause of red burn of the vine and for Fabraea (differing from Pseudopeziza by multi- rather than unicellular ascospores), e.g., F. maculata (Entomopeziza Soraueri, E. Mespili), the cause of a disease of leaves and fruits of many fruit trees (conidial form Entomosporium Mespili), and F. Fragariae, the cause of strawberry leaf spot (conidial form Marssonina Fragariae). In other forms, in addition to free conidiophores, pycnia are known, as in Pezizella Lythri (Shear and B. 0. Dodge, 1921) which causes an early rot of strawberries and other fruits and exits in pathological litera- ture under 27 synonyms : the acervuli as Hainesia Lythri, Sphaeronema corneum and Patellinia Fragariae, etc., the pycnial form as Sclerotiopsis concava, Leptothyrium macrothecium, Sporonema quercicolum, etc. Only Fabraea Ranunculi, on Ranunculus cassubicus whose young apothecia form a group of ascogonia with long multicellular trichogynes, has been studied cytologically. Antheridia are lacking (Guseva, 1923). Here are relationships similar to those we shall follow in detail in the operculate forms. Helotiaceae. — This family, as that of the Epichloe-Claviceps series of the Hypocreales, includes two different groups of forms, one (probably simpler) without sclerotia and one (probably higher) with sclerotia. Unfortunately no intermediate forms are known between these two extremes. Of the stage without sclerotia, may be mentioned Dasycypha caly- cina (D. Willkommii), the cause of larch canker. The mycelium of the fungus grows through the bark as a wound parasite and stimulates the cambium to cankerous growths. After the death of the bark these erupt as small, yellowish-white pustules which, in tortuous cavities of their surfaces, form small unicellular hyaline conidia. On the same spot (and also on fallen branches) there later arise orange-colored apothecia. Sclerotinia is divided into two subgenera, Stromatinia, which develops sclerotia in mummified fruit, and Eusclerotinia which develops them in root stems or leaves. In the former, the shape of the sclerotia is deter- mined by that of the fruits, in the latter the sclerotia occur in regular weals or callosities. The more important representatives of the first subgenus are parasitic on fruits of Ericaceae and Rosaceae, e.g., Sclerotinia Urnula (S. Vaccinii) on Vaccinium Vitis-idaea, S. Ledi (S. heteroica) on Ledum palustre and V. uliginosum, S. baccarum on V. Myrtillus, S. Padi on Prunus Padus, PEZIZALES 323 S. Linhartiana on quinces, S. fructigena on apples and pears, S. laxa on apricots and S. cinerea on cherries, plums and peaches. In Sclerotinia Urnula, the young shoots, infected in the spring, become brown and dry. In their rind, appears a stromatic fungus tissue which sends through the cuticle simple or dichotomously branched conidiophores and cuts off on them moniliform, oidial, citriform, hyaline conidia, smell- ing like almonds; thus the diseased branches appear mouldy. The conidia were early placed in Monilia. At first they cling firmly together with their flat septa. Later these septa split into two lamellae each of which Fig. 213. — Sclerotinia Urnula. 1. Young conidial chain. 2. Older stage showing fundaments of disjunctors. 3. Mature conidial chain. 4. Germinating conidium with germ tube beginning to sprout. (X 345; after Woronin, 1889.) detaches in the middle (mutatis mutandis, somewhat as in Albugo) a small conidial plug (Fig. 213). Both plugs form a fusiform body, thedisjunctor. Hence the connection between the conidia has become very loose. When they are touched by insects they cling to them and thus reach the stigmas of their host. Here they germinate to mycelia which, like pollen tubes, penetrate the stylar canals and ovaries, even to the surface of the berries and change them to longitudinally ribbed, brownish, sclerotic mummies. These mummies fall to the ground and winter over. Directly after a thaw, the erupting ascigerous fructification bears an apothecium as broad as 1 to 1.5 cm. on a 2- to 10-cm. long brown stipe, hairy at the base. The ascospores are shot out with great force and, in case they reach the young shoots of the billberry, develop to the above described mycelium. We find a similar life cycle, especially a similar rhythmic change between moniliform spores provided with disjunctors and apothecial 324 COMPARATIVE MORPHOLOGY OF FUNGI forms maturing in the overwintering fruit, in the other representatives of the subgenus Stromatinia. In the forms on Rosaceae, the conidia are also formed on the fruits (often predominantly on these) so that an infec- tion from fruit may take place. In this manner the fungus may spread extremely rapidly, especially on stored fruit, causing the fruit industry enormous losses. The change, here described in detail for S. Urnula, of an imperfect form developing in spring on the young shoots of a host to a perfect form developing in the course of the summer on the host fruit, has the possi- bility of a special biological relationship, which has been investigated in S. Ledi and S. Rhododendri. When in the spring the ascospores of the Fig. 214. — Sclerotinia cincrea. Apothecia developed in the spring from peach mummies (Photograph by E. E. Honey.) former are mature, Ledum is not yet developed; V actinium is ready, how- ever, to unfold its young shoots. These are infected by the ascospores which develop mycelia in them and form moniliform conidia. Mean- while Ledum has bloomed, the conidia from V actinium uliginosum infect the ovaries of Ledum palustre and here develop the sclerotia with which the fungus overwinters. Similarly, in the spring, S. Rhododendri forms its Monilia stage on the twigs and branches of V actinium Myrtillus, while in summer it parasitizes fruits of Rhododendron (E. Fischer, 1926). S. Rhododendri and S. Ledi, as the Claviceps on Brachypodium silvaticum, in the Hypocreales, need two hosts for the completion of their life cycle; Vaccinium Myrtillus and V. uliginosum for the imperfect forms and Rhododendron ferrugineum and R. hirsutum and Ledum palustre, respec- tively, for the perfect forms. Thus they are heteroecious, even if not in PEZIZALES 325 the obligate manner we shall find in the Uredinales. While in the latter the host change is connected with a change of nuclear phase, is condi- tioned in its rhythm by plasmogamy and meiosis, and, besides, usually takes place between two hosts far removed systematically; in Sclerotinia and Claviceps we are dealing with plurivorous forms which have been specialized on seasonal hosts. The economically important representatives of the subgenus Eusclero- tinia, as S. Fuckeliana, S. Libertiana, S. Trifoliorum and the various Sclerotinias on monocotyledonous bulbs, in their choice of hosts are much less specialized than those of the subgenus Stromatinia. Thus, S. Fuckeliana is parasitic on the Vine, Ribes, turnips, etc., S. Libertiana on all sorts of cultivated garden vegetables and *S. Trifoliorum on alfalfa, Fig. 215. — Sclerotinia sclerotiorum. 1. Conidial stage. Botrytis cinerea. 2. Appressorium. 3. Diagrammatic cross section of apothecium. (After R. E. Smith, 1900.) Onobrychis sativa, clover, etc. During the summer, they kill the infected organs, developing in them the sclerotia in which they overwinter. Their conidia arise singly on characteristically formed conidiophores (Fig. 215, 1) and hence, in contrast to those of Stromatinia, are placed in Botrytis rather than in Monilia. As the cultural determination of the perfect form is rarely possible, one generally places them, especially those of the S. Fuckeliana and S. Libertiana groups, in the collective species Botrytis cinerea. Thus one provisionally names all entirely or hemiparasitic pathogens which probably belong in the life cycle of a Sclerotinia. Kharbush, (1927) reports the usual nuclear phenomena in the devel- opment of the ascogenous hyphae and asci in Sclerotinia Fuckeliana. Geoglossaceae. — While in the Mollisiaceae and Helotiaceae the fructifications have the typical apothecial structure, in the last family of the Inoperculatae, the Geoglossaceae, there appears a fundamental 326 COMPARATIVE MORPHOLOGY OF FUNGI change. The young stages of their lower forms connect directly to the higher forms of both these families, which lack sclerotia and generally are tough, fleshy or leathery, but gelatinous in some Cudonieae, as in the Bulgariaceae. Since there appears a strong epinastic growth of the top of the hypothecium, however, the ascus hymenia are not longer formed in the interior of patelliform or cyathiform fructifications but on the convex exterior of clavate fructifications. This may be best followed in a very simple example, Roesleria pallida (Calicium pallidum) on the roots of the Vine. Its fructification consists of a coremial hyphal tuft which is differentiated into a stipe and a flat Fig. 216. — Calicium pallidum (Roesleria pallida). Portion of hymenium showing asci and paraphyses. 1912.) 1. Section of fructifications. 2. (1 X 8; 2 X 320; after Arnaud, discoid head (Fig. 216, 1). If we imagine this disc curved like an urn, as it is in Caliciopsis, a related genus, we have before us a true apothecium of about the height of an Agyrieae-Pattelariaceae group. If we imagine the hypothecium more strongly developed, so that the subhymenial layer arches convexly, we have one of the simplest Geoglossaceous fructifications represented in Fig. 216. The extremely primitive position of Roesleria pallida is further shown by the fact that its asci mature at different times, so that while the old asci discharge first uni- then bicellu- lar ascospores, the hymenia continually form new asci. In the higher Geoglossaceae this arching of the hypothecial tip goes still further and leads to a clavate outline of the fructification as shown in Fig. 217 for Gloeoglosswn glutinosum; in it the whole club is fertile, i.e., covered by an ascus hymenium. At times, as in G. difforme, this hyme- nium may extend over the whole stipe. PEZIZALES 327 In the course of the further development, the fertile portion becomes increasingly separated from the sterile and changes to pileate head; this head is fertile only on its upper side, however, while the lower remains sterile. The forms with the originally clavate fructifications are united in the subfamily Geoglosseae, those with capitate fructifications in the Cudonieae. Their classification rests on the special differentiation of these fructifications and on the form of the ascospores and paraphyses. To the Geoglosseae belong Mitrula, Microglossum, Geoglossum, Gloeoglos- sum Trichoglossum and Spathularia; to the Cudonieae, Leotia and Cudonia (Dur- and, 1908). As far as the ontogeny of the Geo- glossaceae has been studied, about one- half the forms correspond to the normal hemiangiocarpous type, the other half to the purely gymnocarpous. To the former there belong Spathularia velutipes, Cudonia lutea, Microglossum viride (Duff, 1920, 1922) and Mitrula paludosa (M. phalloides) (Dittrich, 1902). To the second group belong Trichoglossum hirsutum, T. velutipes, Geoglossum glab- rum and Gloeoglossum difforme (Duff, 1920, 1922). While the hemiangiocar- pous type includes all possible forms, the gymnocarpous forms are closely related and grouped around Geoglossum. In youth, the fructifications of both groups seem identical. They arise as a tangle of closely twined hyphae which are elongate at the periphery and entirely surround the tangle. In the middle of the base, however, they are more rounded or polyhedral. The middle cells elongate upwards and thus cause the elongation of the whole fructification, while the basal cells remain irregularly angular with thickened walls. In the hemiangiocarpous group the peripheral hyphae, six to eight cell layers deep, gelify and surround the whole fructification in a gelatinous sheath which in systematic literature is called veil or volva; it corresponds to the velum universale of the Agaricales {mutatis mutandis). In most forms it remains one layered; in Spathularia velutipes it divides into a compact, thin-walled, inner and a loose, thick-walled, outer layer. In the gymnocarpous group, there is no differentiation of a special sheath layer and the fructification is open throughout its whole development. In the apical parts of the fructification, the hyphae underneath (or in the gymnocarpous forms, those directly under the surface) become Fig. 217. — Gloeoglossum glutinosum. (Natural size; after Falck, 1916.) 328 COMPARATIVE MORPHOLOGY OF FUNGI arranged in a palisade and develop to paraphyses. By the pressure of the growing paraphyses, the sheath is ruptured, allowing the apical por- tion to project. Finally the ascogenous hyphae push from the ground tissue and form asci. In certain species, e.g., Cudonia lutea, the tearing of the veil may come very late when many asci are already mature. The sexual organs of the Geoglossaeae undergo a peculiar degenera- tion, such as we shall meet again in the Lecanoraceae-Cladoniaceae (Icmadophila-Baeomyces) series. As in the latter, the ascogonia do not arise directly from vegetative hyphae but from a loose tangle of densely staining hyphae, the so-called generative or primordial hyphae. In the first stage, as in Leotia gelatinosa (L. lubrica), they form one (or several) ascogonia at the base of the fructification (Dittrich, 1902; Brown, 1910, Duff, 1922) very early, when the fructification is a small, undif- ferentiated tangle. Nothing is known of their form. It was observed, however, that from a single large cell, the ascogenous hyphae develop pari passu with the elongation of stipe and finally form asci between the paraphyses. In analogy to the Operculatae, one may assume that this one large cell is the privileged sexual cell of the ascogonium and that the sexual act is probably parthenogamous. In the second stage in Cudonia lutea, the formation of ascogonia is retarded. Here the generative hyphae are early differentiated before the volva is formed. They remain inactive, however, in the apical zone of the fructification several cell layers below the later paraphyses and are raised by the central hyphae, on the elongation of the fructification. At a given time, they grow out into the ground tissue of the head and form a large number of slightly curved or helical, at first uninucleate, later multi- nucleate ascogonia which open out into typical multicellular trichogynes; these penetrate the veil and project a distance into the open but degener- ate early. Antheridia are lacking ; the nuclei in the ascogonia are arranged in pairs and migrate into the ascogenous hyphae. Thus the sexual processes are autogamous. In Spathularia velutipes, not only the formation of ascogonia, but also that of generative hyphae is retarded, and they only appear when the fructification attains a considerable size; here also they lie directly under the tip and, as in Cudonia lutea, develop to ascogonia. These are morpho- logically quite degenerate, however, and no longer possess trichogynes (Fig. 218, 1); they differ from the usual vegetative hyphae of the hypo- thecia only in their greater cross section and deeper staining. Their nuclei also pair and migrate into the ascogenous hyphae. Finally, in the fourth stage, in Trichoglossum hirsutum, the sexual organs are no longer morphologically recognizable as such. Neither generative hyphae nor ascogonia are formed and the ascogenous hyphae develop in some unknown manner from any vegetative hyphae rich in protoplasm. PEZIZALES 329 In the Geoglossaceae so far known the antheridia have completely disappeared and, consequently, the ascogonia develop autogamously. They undergo a gradual degeneration : at first they possess a typical form and a well-developed trichogyne, then the typical form is lost, along with the trichogyne, and finally they are no longer formed and the develop- ment of the ascogenous hyphae takes place pseudogamously. In contrast to the previous families, imperfect forms are still unknown in the Geoglossaceae on account of their saprophytism on decaying wood, etc. ; in Spathularia and Cudonia it has been noted that the ascospores Fig. 218. — Spathularia velutipes. 1. Ascogonium with ascogenous hyphae. Rhizina undulata 2. Young ascogonium. 3. Development of ascogenous hyphae. (1 X 1,330; 2, 3 X 335; after Duff, 1922, and Fitzpatrick, 1918.) (as also in the Dermateaceae in Tympanis and in the Patellariaceae in Biatorella) may germinate to a sprout mycelium while still in the ascus. In summary, the Inoperculatae are an entirely indefinite mixture of various poorly known genera which will only be arranged in clearer lines after more detailed ontogenetic investigations. Apparently the lower forms connect directly to the Plectactascales and Myriangiales and perhaps properly belong there. As long as their ontogeny is unknown, however, an approach to the understanding of the Inopercu- latae and the Discomycetes in general is closed to us. On the other hand, we are comparatively well informed on the onto- genetic relationships of the Operculatae, in any case in the lower forms. They are here described for only the five more important families, the Rhizinaceae, Pyronemaceae, Ascobolaceae, Pezizaceae and Helvellaceae. 330 COMPARATIVE MORPHOLOGY OF FUNGI The Rhizinaceae and Pyrenemaceae form the gymnocarpous stage; the former ascend from simple, loose layers to tuberous, tortuous fructi- fications, the latter develop to typical apothecia of the Pezizales. Rhizinaceae. — The lowest stage is Ascocorticium whose representa- tives form thin membranes of whitish or reddish color on bark, etc., such as we shall meet in the Corticiaceae of the Basidiomycetes. On these coverings, there is laid an even hymenium of eight-spored asci without paraphyses. Perhaps the curious Medeolaria Farlowi on Medeola virginiana belongs here. The indeterminate hymenium spreads over the epidermis of the host, producing many fascicles of paraphyses but few asci with dark brown, striate spores (Thaxter, 1922). Unfortunately the ontogeny of these forms is not yet known. A higher stage is taken by Rhizina, whose original flat fructifications, later generally arched upward, have the consistency of fleshy crusts. R. undulata forms luxuriant white mycelia on the roots of many forest trees. Later these intertwine on the roots or on the earth to small hyphal tangles whose peripheral ends show a tendency to form a palisade, later a paraphyseal layer. When these knobs have attained a cross-section of about 1 mm., as many as eight ascogonia form in their interior. From the beginning, these are multinucleate and arise from ordinary vegetative hyphae. These wind loosely through the other hyphae and consist of ten to nineteen or more cells (Fig. 218, 2). The terminal cell is small and pointed; its content is early disorganized; possibly it is a functionless trichogyne. When the ascogonia have matured, large pores are formed in the septa so that the cells come into open communication with each other. About half of the cells, chiefly those which lie in the middle of the ascogonium, develop now into ascogenous hyphae (Fig. 218, 3) into which flows the protoplasm of the remaining basal cells (Fitzpatrick, 1917, 1918). The highest stage is shown by the Sphaerosoma group (Rouppert, 1909; Setchell, 1910) whose fructifications are generally hidden in the forest between dead leaves and, on account of their tuberous form and fleshy mass, are often considered truffles. Their earliest stage corre- sponds in structure to the simple apothecial scheme (Fig. 219, 1). Then, however, the hymenium develops very strongly towards the sides, conse- quently the edges of the cup arch downwards and often form an indented, folded, hollow sphere up to 3 cm. in diameter, which in S. fuscescens (S. Janczewskianum) and S. echinulatum show their origin from a stipe (Fig. 219, 2). The hymenium develops hemiangiocarpously on the exterior of this hollow sphere (while the interior remains a sterile hypo- thecium) and consists of asci and paraphyses, which latter often inter- twine over the tips of the asci. In the closely related Sphaerozone ostiolatum {Sphaerosoma fragile) , having verrucose instead of echinulate spores, development has been reported as gymnocarpous. In another PEZIZALES 331 closely related genus, with reticulate spores, Ruhlandiella berolinensis and R. hesperia, the paraphyses form a gelatinous epithecium which is persistent at maturity, while the hypothecium is poorly developed. The highest member of this series is Mycogalopsis retinospora (G jura- Sin, 1925) which superficially is very close to Ruhlandiella and perhaps should be referred to that genus. Here the hymenium is covered with a layer of plectenchyma until maturity, suggesting the conditions found in the Tuberales. The presence of a thin, more or less evanescent subic- ulum (also found in Ruhlandiella) and the well-developed stalk suggest their relationship to the Sphaerosoma group, while the breaking away of Fig. 219. — Sphaerosoma fuscescens. 1. Section through a very young fructification. 2. Diagrammatic section of an old fructification. (1 X 67, 2 X 4; after Rouppcrt, 1909.) the covering of the apothecium, leaving a dusty mass of yellow spores, suggests conditions seen in Myriangium. The ascus stroma develops rapidly on rabbit dung, maturing in about a week. Three to six, three- to four-nucleate ascogonia arise at a point on the subiculum, grow perpendicular to it and are abjointed. No antheridium was observed. The ascogonia are soon surrounded by a thin peridium developed from neighboring hyphae. Ascogenous hyphae develop from the ascogonia forming asci directly on the tips of the branches while the paraphyses develop from the cells immediately below the ascogonia. Nuclear fusion in the ascus and subsequent spore forma- tion is normal. ■ Thus in this family we have a transition from a simple hyphal subic- ulum of unlimited growth and a gymnocarpous formation of the hymenium to a highly developed, more or less tuberous ascocarp, with angiocarpous 332 COMPARATIVE MORPHOLOGY OF FUNGI development very suggestive of the Tuberales; hence in that order we shall return to this series. Pyronemaceae. — The significance of this family does not lie in its fructifications, but in the relationships of its sexual organs. They form an extremely primitive group and include forms which are lower than any of the previously discussed types of the Inoperculatae. Their fructifications rest on single hyphae or hyphal tissues, and are merely loose, open, immarginate, ascigerous discs, penetrated by paraphyses. Sometimes one consists of a tuft of asci resting upon a more or less well- developed hypothecium. Only two genera will be discussed here: Pyronema, morphologically higher with a well-developed hypothecium, and Ascodesmis, morphologically simpler with poorly developed or almost no hypothecium. An idea of Pyronema may be derived from the figure of Sphaerosoma fuscescens (Fig. 219, 1), if one imagines the apothecial margin absent so that the ascigerous hymenium, as in the Phillipsielleae and Agyrieae, covers the whole top of the hypothecium. Figure 223, 5 shows Ascodesmis; if one imagines this ascus tuft laid on or in a loose subiculum, one has a cross section through one of the Gymnoascaceae. Pyronema confluens, the best known representative (Harper, 1900; Dangeard, 1907; Kosaroff, 1907; Claussen, 1912), is gregarious on the bottom of damp piles of charcoal, occasionally on pots of sterilized earth, and forms there its lenticular, 1 to 3 mm. broad, flesh or rose-red fructifi- cations (apothecia) which are generally confluent in groups (hence the species name) resting upon fine hyphal tissues. The hyphal cells are multinucleate. At the formation of the fructifica- tion one, more rarely several, hyphae fork repeatedly and grow upwards so that small tufts of rosettes result. Originally this whole branching system is unicellular. Later the single multinucleate branches are abjointed. Such an abjointed uninucleate, cellular branch (the later ascogonium) attains a thick, clavate structure and, while at its base one or two stipe cells are formed, its tip elongates to a multinucleate papilla, the later trichogyne. Subsequently, its lower end is abjointed from the swollen ascogonium beneath (Fig. 220, 1). In the immediate vicinity of the ascogonial branch and on the same hypha there arises an antheridial branch (and this occurs very early) in which the first contact of the two organs stimulates branching, such as has just been described for the female organ. The female branches are always somewhat ahead of the male in development. Finally, in the latter, the multinucleate end cells and one or two stipe cells are abjointed from the hypha and develop to clavate antheridia (Fig. 78). During the further development, the nuclei in both antheridia and ascogonia increase much in size; those of the trichogynes, however, remain small and gradually degenerate (Fig. 220, 2). Both in anther- idium and ascogonium, a few nuclei degenerate before plasmogamy. The PEZIZALES 333 number of female nuclei in each ascogonium always reaches several hundred. The male nuclei group into a thick protoplasmic mass in the vicinity of the tip of the trichogyne; the separating membrane is dissolved and they migrate into the trichogyne (Fig. 220, 3). Mean- while, the female nuclei in the ascogonium have been united to a central hollow sphere, the septum in the trichogyne neck is temporarily dissolved, the male nuclei migrate into the ascogonium and there, for the most part, pair with the somewhat larger female nuclei. ...anth an, Fig. 220. — Development of sexual organs of Pyronema confluens. 1. Tuft of ascogonia, ascg, with trychogyne, tr, and antheridia, anth; P, sterile hyphae. 2. The nuclei of the trichogyne degenerate; the antheridium is in open communication with the trichogyne. 3. The male nuclei migrate into the trichogyne; P, sterile hyphae which will develop the paraphyses. 4. The basal wall of the trichogyne disappears, the male nuclei migrate into the ascogonium which is already beginning to produce ascogenous hyphae, asc. h. 5. The basal wall of the trichogyne again formed; nuclear pairing is completed and several dicaryons have migrated into the ascogenous hyphae. (After Harper, 1900.) After a few hours, ten to twenty ascogenous hyphae grow out of the ascogonium and take up the dicaryons (Fig. 220, 5). They branch very much and the dicaryons increase by conjugate division (Fig. 221, 1) Finally the ascogenous hyphae are broken up by septa so that two to eight dicaryons are present in the vicinity of the ascogonium, and at a distance from it, only one is present (Fig. 221, 2). Which nucleus of the pair is female and which is male is not determinable, as their size differ- ences have disappeared. 334 COMPARATIVE MORPHOLOGY OF FUNGI The cell with a single dicaryon develops sidewise, with conjugate division of its nuclei, in a hook-shaped process which was described in the introduction to the Ascomycetes as a transitory hook tuft (Fig. 79), and finally forms eight-spored asci. This tuft-like branching of the asco- genous hyphae is one of the grounds for the conical widening which the older fructifications of the Pyrenomemaceae and many other Discomycetes often show. Already at the time of copulation the sexual organs are surrounded by a loose layer of sheath hyphae. Later, these branch very much, while the sexual organs are crushed and resorbed, and form the paraphyses between which later the asci penetrate (Fig. 222). Fig. 221. — Pyronema confluens. Development of ascogenous hyphae. 1. The asco- genous hyphae are aseptate and have numerous dicaryons. 2. Development of hooks. (After Claussen, 1912.) In P. domesticum (Tandy, 1927) the first and often the third division in the ascus is a meiosis; both diploid and tetraploid nuclei being found in the young ascus. The development of this species follows closely that reported by Harper for P. confluens. The sexual development of Pyronema is connected directly to that of Monascus among the Plectascales. As there the female sexual apparatus is divided into a unicellular ascogonium and an unicellular trichogyne, and as there is a plurality of sexual acts, there follows a multiple plasmog- amy between the male and female gametangial nuclei. It is nevertheless characteristic of Pyronema confluens (and the Pezizales generally) that its ontogeny can take place in this manner only when definite nutritive relations occur. If these are absent, the antheridium still may be formed PEZIZALES 335 but is no longer functional or it may be absent. In Pyronema confluens var. inigneum (Brown, 1915), even under the most favorable conditions, fusion no longer occurs between antheridium and trichogyne, although f/l'r mm 'M»d ft j* I - , ft*;' Hu '' ' -; ' ¥ mm Fig. 222.- — Pyronema confluens. Section of an almost mature fructification. The ascogonium has collapsed. At the top of the fructification, the ascogenous hyphae have penetrated between the paraphyses and formed asci. Only in the apical portion of the fructification may they be distinguished from the haploid hyphae. ( X 290 ; after Claussen, 1912.) the trichogyne wraps itself around the antheridium several times. In both cases the female nuclei form dicaryons autogamously in the ascogo- nium and migrate normally into the ascogenous hyphae. The amphi- 336 COMPARATIVE MORPHOLOGY OF FUNGI mictic sexual act is no longer obligatory for Pyronema confluens, but is facultative; its presence or absence and the necessary compensation by autogamy depends only on nutritive relationships. In contrast to Pyronema, the second genus, Ascodesmis (Claussen, 1905; Dangeard, 1907), is connected ontogenetically to the Amauroascus- Aphanoascus type of the Plectascales. Ascodesmis nigricans (Boudiera Claussenii) is coprophilous on rabbit dung. In the development of fructifications, a thick branch on any hypha is raised perpendicular to the substrate and after a short time attains a T shape by forking (Fig. 1 "' ■StF15 -,-.V. J#» ^.:-v.; vl-Ra. fJjf?SW* Fig. 242. — Genea Thwaitesii. Development of fructification. (1 to 3 X 100; 4 X 24; after E. Fischer, 1909.) *^ilii^ 9 Fig. 243. — Genea (Myrmecocystis) Vallisumbrosae. 1. Section of fructification (X 6). Genea (Myrmecocystis) cerebriformis. 2. Section of hymeniuin (X42). (After Bucholtz 1901; E. Fischer, 1908.) TUBER ALES 361 endogenously. In the youngest known stage, measuring about 34 mm. (Fig. 242, 1), as in many lichens, e.g., Physcia pulverulenta, Anaptychia ciliaris and Usnea barbata, the hymenial palisade is formed angiocar- pously at the tip of the fructification under the outer rind Ra. In course of further development, the margins bend over strongly so that the fertile layer becomes patelliform (Fig. 242, 2 and 3). Later, by a strong lateral growth, it gradually forms a comparatively smooth hollow sphere, in which the hymenium (Fig. 242, 4) is not free but covered by the rind Ri which consists of swollen and septate paraphyseal tips and corresponds apparently to the epithecium of the Pezizales. From Genea Thwaitesii, the development may be followed in two directions. In Genea the same process which we have met in the develop- ment of ascocarps of Tuber, is repeated. In the subgenus Heterogenea, (G. (Heterogenea) Gardneri and G. (Heterogenea) Harknessii) numerous ingrowing projections of the cavity tend to separate the fertile areas, while the spores become less ellipsoid. In the subgenus Myrmecocystis, Fig. 244. — Genabea fragilis. (X 5; after Tulasne.) however, the spores have become spherical and verrucose. If we only had the end members of the series we would probably regard them as separate genera, but the transition forms seem to indicate that they are better kept together. Thus the hymenium is no longer laid down in a continuous layer, but separated into several parts by sterile ground tissue, as may be seen in Fig. 243, 1, in (?. (Myrmecocystis) Vallisumbrosae, which consists of irregular, spherical, hollow fructifications, occasionally slightly plicate, about 1 cm. in diameter with one or two round fissures. Thus the sub- genus Myrmecocystis differs from Eugenea, as Piersonia from Pachy- phloeus, by the localization of the hymenium on limited areas. As in the Sphaerosoma-Hydnotrya series, here the wall of the fructification curved into the interior of its cavity with folds and projections and thereby, as in G. (Myrmecocystis) cerebriformis (Pseudogenea californica) became an entirely irregular, tortuous structure. The single hymenia are more or less bent, being concave toward the central cavity of the fructification; the ascus tips, therefore, lie toward the interior of the hymenophore on the 362 COMPARATIVE MORPHOLOGY OF FUNGI exterior of the hymenium. From the hymenophore, a bundle of para- physes penetrates the hymenium and passes through it into the inner rind Ri (Fig. 243 , 2). This is more strongly developed than in Eugenea and forms a pseudoparenchymatous rind, which is elevated in spots to pyramidal warts. Delastria rosea, formerly included in the Terfeziaceae, seems to show the highest development in this series. If the cover layer Ri is further developed, so that the hymenium lies farther in the interior of the fructification, we have Genabea, shown some- what schematically in Fig. 244. Because of the irregular course of the folds and canals, most of the hymenia are cut obliquely and hence appear irregularly arranged. In cross-section, however, they are crescent shaped with the concave side toward the hollow passages. If we review the genera of the Tuberales here discussed, their relation- ships may be approximately given in the following scheme : Tuber Hydpotfya Pachyphloeus Stephensia Pseudobalsamia TUBERALES Choiromyees Piersonia Hydnotryopsis Balsamia Geopora Mycogalopsis t Sphaerozone * t Sphaerosoma. , - - - t - ' Hydnbcystis Diagram XXIV. Genabea t I Genea t Gyrpcratera Thus the Tuberales form two convergent series, the probably gymno- carpous Sphaerosoma-Choiromyces series and the hemiangiocarpous Genea-Genabea series. In the former, from the Sphaerosoma-like Rhizi- naceae, the Hydnotrya-Balsamea group arises by a strong lateral develop- ment of the hymenium which causes a deepening of the folds and by a localization of the asci in the interior of the passages. The hollow pas- sages are filled by a loose pseudoparenchyma arising from the paraphyseal layer, so that the structure of the fructifications becomes massive (Pachy- phloeus-Tuber group). Subsequently the formation of hymenia is more and more limited to the last blind ends of passages (Piersonia) and finally these passages coalesce completely and the hymenia lie in closed chambers (Choiromyees). The relationships of the Genea-Genabea series are not so simple. There is no doubt that in the formation of their fructifications, the same mor- TUBERALES 363 phogenetic forces (unequal growth of outer and inner fructification layers and consequent folding and curving of fructification wall, localization of formation of asci, etc.) have been active, as in the Sphaerosoma-Choiro- myces series. The significance of. the layer Ri, and consequently the whole position of the series, however, is still obscure. The development of Genea Thwaitesii leads one to suppose that the layer Ri is a true epithe- cium, that has developed after the fraying of the parts of the outer rind Ra lying above the fructification. In this sense, Genea might be con- nected to the hemiangiocarpous Pezizales, particularly to the Pezizaceae. After Genea, the epithecium has undergone a special development to a pseudoparenchymatous cover layer which possesses no analogue in the Discomycetes. Thus an explanation can only result from an ontogenetic investigation of the young stages. CHAPTER XXIV LAB OULBENI ALES The Laboulbeniales form their fructifications only on the chitinous integument of living insects. When examined in situ they appear like minute, dark-colored or yellowish bristles or bushy hairs, usually scattered, but often densely crowded over certain areas on which they form a furry coating. Although they may be said to produce a contagious cutaneous disease, they give rise to no fatal epidemics, such as are sometimes associ- ated with Cordyceps and Entomophthora. The very existence of these parasites seems to depend on the fact that the host is not destroyed, since their own life ends with that of the insect. The habit of growth is exter- nal, unassociated with extensive development of haustoria, except on certain groups of soft-bodied insects, where widely divergent groups have developed extensive rhizoidal processes of the basal cell, which penetrate the interior of the host. Such an external parasitism on living and usually actively locomotive, often aquatic hosts, is associated with a comparatively simple structure adapted to the exigencies of such a life. A simple receptacle is fixed by means of a usually blackened base or foot, to the integument of the host. This receptacle gives rise to certain appendages, commonly connected with the production of the male sexual organs, while perithecia are usually produced from the same receptacle, except in certain dioecious groups. Most species of Laboulbeniales are limited to definite genera of insects and in a few instances, e.g., Chitonomyces on Gyrinidae and Lacco- phili, even to definite restricted areas of attachment in different host individuals of different species, from even different regions. For example, not only will the distance from the apex of the elytron of the area occupied by a given species always be about the same, but its relation to either margin will be more or less definitely fixed. Of species inhabiting the left elytron, none will be found even in a corresponding position on the right. The Laboulbeniales may be divided into three families, distinguished by the relative development of the male sexual apparatus. In the more primitive Ceratomycetaceae, the antheridia are exogenous, bearing free spermatia on the specialized branches of appendages. In the Laboul- beniaceae, the spermatia are produced in unicellular, flask-shaped anther- idia, while in the Peyritschiellaceae the antheridia are compound, discharging the spermatia into a common cavity, from which they are subsequently expelled. 364 LABOULBENIALES 365 Ceratomycetaceae. — This family of a few small genera on aquatic insects contains some of the most striking forms, yet little studied ontogenetically. In Ceratomyces mirabilis, the young individual consists of a simple series of superposed cells, of which the distal begins to branch at an early age. One of the intercalary cells of this series divides longitudinally, the upper cell becoming a finger-like projection, the primordium of the peri- thecium. The primordium divides into three cells, the upper becoming the simple trichogyne, the middle the trichophoric cell and the basal, not projecting from the axis of the plant, becoming the carpogenic cell. The sister cell to the primordium divides into an outer and an axial cell. The lower cell has also divided longitudinally into two cells, one of which grows outward and upward, forming one row of the wall and canal cells of the mature perithecium. The axial cell apparently gives rise to the other three rows. These wall cells grow beyond and around the carpogenic and trichophoric cells and, by subsequent division, form the perithecium. The development of the perithecium will be described in greater detail in the Laboulbeniaceae (p. 369). The spermatia develop from the segmen- tation of slender branches into bacilliform bodies which fall from their attachment as soon as formed. Rhynchophorotnyces rostratus {Cerato- myces rostratus) has the same general ontogeny (Fig. 253, 1) except that the whole base of the appendage becomes incorporated with the develop- ing venter of the perithecium until it seems to arise from the wall cells. The neck in this species becomes abruptly reflexed at maturity. In Coreomyces we have a new type of perithecial development. The young individual of Coreomyces Corisae consists of three cells, from the uppermost of which appendiculate cells are cut off distally. Above the appendiculate cells is a series of four to six superposed cells terminated by a sterile appendage. Thus there are three regions of which the two basal cells form the receptacle, the appendiculate cells the antheridia, while the distal region forms the perithecium. As the development proceeds, the sub-basal cell of the distal region proliferates into the cell above, while the sterile appendage above breaks off (Fig. 245, 3). The penetrating branches, usually two corresponding to the posterior basal cell and the secondary stalk cell of the ordinary perithecium (p. 370), con- tinue to develop the perithecium. The developing perithecium destroys the septa of the cells above, sending the trichogyne through the septum at the base of the previous sterile appendage (Fig. 245, 4). At maturity, the vestigial wall cells of the perithecium degenerate, leaving the develop- ing ascogonium surrounded only by the walls of the original cells of the distal region, a pseudoperithecium (Fig. 250, 2). Thus the asci and spores finally float free within a structure resembling a perithecium and performing the same function, but ontogenetically having little in common with a perithecium. 366 COMPARATIVE MORPHOLOGY OF FUNGI The antheridia are the lower cells of the appendage or its branches which function as discharge tubes through which the spermatia make their way. This character forms a transition to that of the Laboul- beniaceae (Fig. 250, 5). The highest vegetative development in the order is found in Zodio- myces (Fig. 246). The spore (Fig. 247, 6) germinates by forming many Fig. 245. — Amorphomycrs Falagriae. 1. Male and female individual developed from same spore pair. Coreomyces curvatus. 2. Mature individual. 3. Upper portion of young individual beginning to form the archicarp in the upper cells. 4. Older individual, showing trichogyne. 5. Male appendage, showing spermatial formation. (1 X 880; 2 X 200; 3 X 410; 4, 5 X 705; after Thaxter, 1908.) transverse divisions in both segments. The distal cell gives off a variable number of branches, the future primary appendage. Longitudinal divi- sion sets in until there is a massive clavate structure terminated by a tuft of the primary appendage (Fig. 247, 1 to 3). A more rapid growth at the base of this appendage causes the wall cells of the region to arch out forming a cavity within (Fig. 247, 4). As the cavity enlarges, secondary appendages begin to grow upward and inward from the inner surfaces LABOULBENIALES 367 of its lateral walls. These rupture the outer wall at the base of the primary appendage. The cavity continues to grow until the perithecia form from the base of the circle of secondary appendages. The anther- idial appendages (Fig. 247, 7) usually consist of three superposed short cells bearing at the tips one to three large, bacilliform spermatia, which soon fall off and are sought by the trichogynes. Although the perithecia arise endogenously, their development is normal (Fig. 247, 8). Fig. 246. — Zodiomyces vorticellarius. Mature individual. (X 195; after Thaxter, 1896.) Laboulbeniaceae. — The central family which has given the order its name is the largest in the order with about thirty genera, parasitic on most of the groups of insects. The ontogeny has been more fully studied and will be given in detail. The ascospores are formed in asci, occasionally eight, usually four by the degeneration of four nuclei (Fig. 252, 7 and 8). Very early they are unicellular, later except in Amorphomyces dividing into a long basal and short apical cell (Fig. 252, 9). They are oriented in the ascus accord- ing to their later bipolar development, with the basal cell uppermost and are surrounded by a gelatinous, sticky sheath, which is usually 368 COMPARATIVE MORPHOLOGY OF FUNGI characteristically thickened at the base (Fig. 252, 9). At first it provides for the attachment of the spore to the substrate. The plants developing from the ascospores are regularly surrounded by a thin, homogeneous, impermeable membrane, developed from the gelatinous sheath of the ascospore, which by its blackening, often conceals the structure of the plant. It protects the plant from drying out during sudden changes of humidity (even fixatives do not penetrate it well). The ascospores Fig. 247. — Zodiomyces vorticellarius. 1 to 4. Young individuals; at x, a cavity forms. 5. Section through periphery of mature fructification; at the right, secondary appendages which surround the edge of the cup. On the floor of the cup, antheridia and perithecia in various stages of development. 6. Mature ascospore. 7. Spermatial branch. 8. Young perithecium whose trichogyne has copulated with a spermatium. (1 to 4 X 145, 5, 6 X 260, 7 X 850, 8 X 1,170; after Thaxter, 1896.) are not generally discharged singly but cling together in pairs, thus guar- anteeing continuity for the dioecious species. In Amorphomyces Fala- griae (Fig. 245, 1), generally a male and female stand so close together that they seem to have arisen from the same foot. In Moschomyces, the ascospores are discharged in small groups, and the young plants may form small tufts. If the ascospore reaches its proper host and succeeds in adhering by the basal end, the basal cell divides, cutting off a small basal cell, the foot (Fig. 248, 2). Then the upper cell of the now three-celled plant LABOULBENIALES 369 begins to develop differently in different genera. Stigmatomyces Baeri on the housefly in Europe may be taken as an example with a slightly developed receptacle (Thaxter, 1896). The apical cell divides by an oblique septum into two cells of which the upper is divided by a second oblique septum into two daughter cells. 12 b~M HH tj |-d u c F S<' i- iisl-i c a" if-3" p"' S-f-an f f-y1 W-f — --a" Fig. 248. — Stigmatomyces Baeri. Development. (X 340; after Thaxter, 1896 Thus three daughter cells are formed, which we will number, beginning with the lower, as 1, 2 and 3 (Fig. 248, 3). The lowest cell, 1, divides by an oblique septum, perpendicular to the original one, into a small apical cell and a large basal cell. The new apical cell grows rapidly and pushes cells 2 and 3 somewhat to one side (Fig. 248, 4). 370 COMPARATIVE MORPHOLOGY OF FUNGI Meanwhile the third cell is again divided by an oblique wall, parallel to the first, so that there are now four cells in the row. Also cells 2 and 3 have divided successively by new oblique walls perpendicular to the first, as earlier happened with cell 1, into a small apical and a larger basal cell. Again these cells increase in size and push still further to the side the series of cells above (Fig. 248, 5). Meanwhile cell 4 is divided by a septum again so that the cell row has increased to 5. Besides, the apical cell has divided into a tip cell and basal cell; the tip cell functions as a spermogenous cell and discharges tiny bacilliform spermatia, at first naked or only covered by a very thin wall; Gaumann prefers to call them conidia, consequently he calls the flask- shaped antheridium a conidial mother cell from their superficial similarity to the conidia of Thielavia. Meanwhile the basal cell of the ascospore, which had already cut off the foot, has resumed its development. First, it divides by an oblique septum into a small upper cell b and a larger lower cell y (Fig. 248, 6). Later cell b becomes the stalk cell of the appendage and persists without further development. On the other hand, cell y divides into a basal cell y' and into cell a (Fig. 248, 7) which itself divides into the daughter cells a' and a" (Fig. 248, 8). The sequence of this division is not absolutely constant. Thus it may also occur that, as in Fig. 248, 7, the basal cell is first cut off and only then do cells a and b arise as daughter cells of a common mother cell, completing the development of cell a"; in common with cell y', it forms the extramatrical part of the vegetative body; with increasing age these cells elongate to many times their original length and later, some- what as indicated for Stigmatomyces Sarcophagae (Fig. 250, 2), bear the perithecium in the form of a stipe. This extramatrical part of the thallus in the Laboulbeniales is called the receptacle. In Laboulbenia e.g., L. Gyrinidarum and L. chaetophora, the walls are formed of two to five layers; outermost, a layer of radially placed plates which degenerate in age to a granular network, and within, several layers of homogeneous, structure- less plates penetrated by some thread-like veins. In contrast to cell a", cell a' continues to develop the ascogonia and perithecium. At first it grows upwards and outwards (Fig. 248, 9) and divides into two daughter cells c and d (Fig. 248, 10) ; the first forms the primordial cell of the perithecial wall, the latter the primordial cell of the archicarp, the so-called procarp. The cell c proceeds first to divide by a more or less oblique wall into two daughter cells c' and c" (Fig. 248, 11). Cell c" elongates and divides into the daughter cells z and p (Fig. 248, 12). The latter has hereby completed its development; it later forms the stalk cell of the perithecium ; the former z will divide further. The cell c' divides also into upper and lower cells, i and h (Fig. 248, 12). The lower cell we will call the secondary stipe cell of LABOULBENIALES 371 the perithecium. It lies directly beside p. The cell i, however, divides in the plane of the picture into two daughter cells, so that one lies in front and one behind, and hence cannot be shown in the picture. Cells ii and z begin to grow upwards and surround cell d, the primordial cell of the archicarp. The cell z subsequently divides into o' and n (Fig. 248, 13) ; one of the cells, ii divides similarly into cells o and n, while the other, here not indicated, divides into a lower and two upper cells. Those three cells, o, o' and o" , not indicated in our figure, which arose from the division of the second cell ii, form the true basal cells of the perithecium. They remain undivided while the four cells n in time will develop to the four cell rows of the outer perithecial walls. Meanwhile cell d has divided into two daughter cells / and g (Fig. 248, 13). The former is surrounded by the four cells n and the three cells o, the latter projects into the open. The cell e cuts off the small tip cell e' (Fig. 248, 14) which develops terminally to a trichogyne. In sexually mature individuals, the archicarp consists of three distinct parts which, as far as known, are present in all Laboulbeniales ; a trichogyne which in the present example is unicellular, the cell e" which is called the trichoporic cell and cell / which is called the carpogenic cell, since it forms the true fertile cell. During this time numerous spermatia have clung to the receptive prominences1 of the trichogyne, and apparently, as in Collema crispum, there occurs a sexual act and nuclear migration ; in any case the trichogyne collapses shortly, while the carpogenic cell divides into three daughter cells (Fig. 248, 16), into the superior supporting cell ot, the inferior sup- porting cell ut and the middle ascogonium /'. This divides again into two daughter cells, a lower sut and an upper f". The lower remains unaltered and forms the secondary supporting cell. The cell /" divides by longitudinal walls into four daughter cells, of which, in the figure, only the front two are indicated (Fig. 248, 17) ; these are the four ascogenic cells which successively produce two rows of asci as in any other Laboulbeniales. Meanwhile the perithecial wall has continued to develop. The three basal cells o, o' and o" ', have developed in the interior the four original primary cells n of the outer perithecial walls to four new secondary wall cells n" , which alternate with the four primary. The outer wall cells n divide each into an upper daughter cell w and a lower daughter cell n' ; then the inner wall cells n" each divide into a lower daughter cell pc and an upper daughter cell nc (Fig. 248, 16). The four 1 Doctor Thaxter informs me that the structures represented on the trichogynes in these figures are not adherent spermatia as formerly supposed, but are receptive prominences of the trichogyne itself, similar to those figured in Acompsomyces (Thaxter, 1908, pi. 42, figs. 8 and 12). 372 COMPARATIVE MORPHOLOGY OF FUNGI cells nc become the canal cells, the four cells pc the parietal cells. In Fig. 248, 17, the former have divided into an upper daughter cell nc" and a lower daughter cell nc'; at the same time the outer wall cells w have divided into two daughter cells wo and wx. The perithecium remains a long time in this condition. Before the maturity of the asci, the cells nc" divide into four upper cells tc and four lower cells c; and, Fig. 249. — 1. Rhachomyces velatus. Habit; the perithecium has been liberated by pressure on cover glass. 2. Stigmatomyces Sarcophagae. Normal and dwarf individual where the perithecium aborted. 3. Kainomyces isomali. Mature individual. (X 195; after Thaxter, 1908.) the cells wo into four cells wy and the four wz (Fig. 248, 20). The cells wz are called lip cells, the cell rows tc, c and nc' , the canal cells; the lowest row nc' gradually thicken their walls. The perithecium consists of 37 cells, the primary stipe cell p, the secondary stipe cell h, and the three basal cells o, o' and o", the 12 wall cells n', wx and wy, the four lip cells wz the four parietal cells pc, and the 12 canal cells tc, c and nc'. The genetic homogeneity of these different cell groups may occasionally be verified in the mature individuals by means of the protoplasmic LABOULBENIALES 373 connections, as in the Pezizales, etc., (Meyer, 1902, among others) and in Polysiphonia in the higher Floridaes (with the exception of the septa of the original perithecial cells, of the trichogyne and the appendages) septa between cells of the same origin show perforations in the middle lamella penetrated by protoplasmic threads. In the course of this whole development, which takes about three weeks, the perithecium has developed to a large cell body which, as is shown in Fig. 249, 2, in Stigmatomyces Sarcophagae, projects far beyond the sympoclial antheridium and has pushed it to one side. By the pressure of the developing asci, the superior supporting cell ot, the second- Fig. 250. — 1. Dichomyces biformis. Mature individual with six, horned perithecia. 2. Rhizomyces crispatus. Mature individual. The ends of the appendages are more curved in nature. 3. Laboulbenia elongata. Abnormal individual; the perithecium aborted, antheridial appendages borne on the blackened bases where perithecial normally develop. (1 X 400; 2 X 195; 3 X 145; after Thaxter, 1896 and 1908.) ary supporting cell sut and the parietal cells pc are gradually destroyed; and often even the inferior supporting cell ut. The ascus walls dis- integrate so that the ascospores asc lie free in the perithecial cavity. They are pressed out between the thickened lower canal cells nc' , destroy the upper canal cells c and tc, and are thus liberated between the lip cells wz. Individuals which mature in the fall may discharge ascospores through the whole winter into spring. In other Laboulbeniaceae, numerous variations from this scheme are known. As already mentioned in the introduction, certain forms possess not a foot but a well-developed haustorium. There is also a 374 COMPARATIVE MORPHOLOGY OF FUNGI great variability in the number of receptacle cells. The maj ority of genera as Amorphomyces (Fig. 245, 1) and Arthrorhynchus (Fig. 251, 1) show only two receptacle cells. In other genera, the receptacle may develop to a small, flat cell complex. The perithecial receptacle arises directly from Fig. 251. — 1. Arthrorhynchus Cyclopodiae. Showing well-developed haustorium. 2. Rhizomyces ctenophorus. Haustorium. 3. Enarthromyces indicus. Showing three mature and three aborted perithecia. (1, 3 X 195; 2 X 145; after Thaxter, 1896 and 1908.) the basal cell of the germinating ascospore; hence it is called the primary receptacle. In Dichomyces (Fig. 250, 1) the secondary receptacle is a direct continuation of the primary and hence is not recognizable as such. In Herpomyces, the secondary receptacle crawls along the substrate, so that the fertile secondary branches seem to branch from a stroma. In LABOULBENIALES 375 H. Periplanetae the basal cells of the primary and secondary receptacles develop fine rhizoids which penetrate the host wherever they are in contact with it. In Stigmatomyces, the appendages are only slightly developed (Fig. 248, cell b) and may grow from either the cells of the ascospore or their derivatives; those from the upper cell of the ascospore are called primary appendages, all others secondary appendages. They attain their greatest development in some species of Rhachomyces where they seem to surround the whole plant (Fig. 249, 1) and occasionally project above the peri- thecium. They probably serve for protection and the holding of condensed water. In most genera the antheridia are localized in a definite manner in certain positions on the appendage, e.g., at the base, somewhat as in Rhizomyces crispatus (Fig. 250, 2). These simple antheridia may stand in a definite order, as in vertical rows in Stigmatomyces, three vertical rows in Idiomyces, four in Arthrorhynchus, or they may be entirely irregu- larly arranged and (as in certain cases where the perithecium fails to develop) may subsequently multiply in number (Fig. 250, 3). In still other species, as Laboulbenia Gyrinidarum and L. chaetophora, no sper- matia have been observed. The Laboulbeniaceae show some variations in perithecial development. The direction of the rows of wall cells may twist in age (Fig. 249, 2), or the perithecial tip may bear appendages known as trigger organs (Fig. 250, 1 ) or the number of wall cells in a row may exceed four (in Moschomyces and Compsomyces five, in other genera entirely variable). The archicarps of the Laboulbeniaceae have very uniform relation- ships. In all forms studied, the division into the trichogyne, trichophoric cell and carpogenic cell has been observed. Often the trichogyne attains a higher development than in Stigmatomyces. Thus in Amorphomyces, it is still unicellular, but definitely lobed (Fig. 245, 1). In most other genera it is multicellular, at times much branched, either straight, more or less as in Laboulbenia Gyrinidarum (Fig. 252, 1) or helical, as in Comp- somyces verticillatus. How fertilization and nuclear migration occurs in these tufted trichogynes, is still unknown. In some of these forms with complicated trichogynes, as L. Gyrinidarum, spermatia have not been seen and the asci perhaps may develop parthenogamously as in Poly stigma rubrum and various species of Pezizales. These relationships were cytologically studied in two very closely related species, Laboulbenia Gyrinidarum and L. chaetophora (Faull, 1912) on the elytra of Gyrinus sp. Fig. 252, 1 shows the archicarp mature for fertilization; it suggests Stigmatomyces Baeri (Fig, 248, 5) and consists of carpogenic cell, trichophoric cell and trichogyne. All of these cells in the Laboulbeniales are uninucleate. The nuclei of the carpogenic cell and the trichophoric cell (Fig. 252, 2) each divides. The septum is dis- 376 COMPARATIVE MORPHOLOGY OF FUNGI solved and the four nuclei lie in one cell (Fig. 252, 3). Now the basal cell is formed, so that the lowest of the four nuclei is separated in a restored trichophoric cell. The middle nuclear pair increases in size and Fig. 252. — Development of asci in Laboulbenia Gyrinidarum and L. chactophora. 1. Mature archicarp. 2. The nucleus of the carpogenic cell has divided, that of the tricho- phoric cell is dividing. 3. Plasmogamy completed. 4. Row of cells consisting of the basal uninucleate supporting cell, the basal binucleate supporting cell, the fertile cell and the upper binucleate supporting cell. 5. Longitudinal section of ascogenous cell. 6. Two active ascogenous cells. 7 to 9. Development of ascospores. (1, 4 X 300; 2, 3, 5 X 400; 6 X 900; 7, 8 X 1,200; 9 X 600; after Faull, 1912.) divides conjugately. The upper cell becomes a sterile cell and the lower alone remains fertile. Its nucleus divides again and cuts off a binucleate fertile cell (Fig. 252, 4). Hereupon it may form the fundament of the LA BO ULBENIALES 377 asci or first divide longitudinally (Fig. 252, 5). The fundament of the asci develops by a conjugate division of the ascogenous cells; a daughter pair migrates into the young ascus, the other daughter pair remains in the ascogenous cells. This process is repeated (Fig. 252, 5). The fusion of the carpogenic cell and trichophoric cells probably is a plasmogamy similar to that of Poly stigma rubrum. Of other differences between the Laboulbeniales so far known and the Stigmatomyces type, only the variation in number of ascogenous cells will be mentioned. While there are four in Stigmatomyces and two in myces inset Htncro- X 200, Laboulbenia, there is only one in Amorphomyces, and in Polyascomyces about thirty-two ; in the latter the ascogenous cells form a sort of placenta from which the asci develop. Peyritschiellaceae. — In this family the antheridial cells have united into a specialized organ and do not discharge their spermatia directly from their opening, but extrude them into a common cavity from which they are liberated (Fig. 253, 2 to 7), hence they are called compound antheridia. This family contains about 25 genera, some of them very large, and seems to reach the height of its development in the tropics. Rickia may be taken as an example of the Peyritschiellaceae with a highly developed and variable receptacle. While the axis is often simple, 378 COMPARATIVE MORPHOLOGY OF FUNGI it may be branched, either normally (as in R. dichotoma, Fig. 255, 4) or as the result of injury. The cells of the receptacle, exclusive of the smaller cells which are separated from them and which give rise to antheridia or secondary appendages, may be less than 10, as in R. Sylvestri, (Fig. 254, 1) while in R. Discopomae (Fig. 254, 7) and R. dichotoma there may be more than 100. Their number is usually somewhat indeterminate. The primary axis is usually triseriate, consisting of two marginal series, that on the perithecial side called the anterior; that on the opposite Fig. 254. — Rickia Sylvestri. 1. Mature individual. 2. Showing aborted perithecium with secondary one proliferating from its base. Rickia macrandra. 3. Old individual denuded of antheridia and appendage. 4. Young one with five large, and one small, antheridia. 5. Antheridia of 4 enlarged. 6. Mature individual with dimorphic antheridia. Rickia Discopomae. 7. Mature individual. (After Thaxter, 1926.) side, definitely related to the primary appendage, called the posterior, the third, median or axial series which may consist of a single cell, as in R. Sylvestri (Fig. 254, 1), or may be as highly developed as in the other two (R. Discopomae, Fig. 254, 7) or may be wholly absent in the biseriate types (Fig. 257, 4) (formerly distinguished as Distichomyces). The axial series is normally associated with the inner margin of the perithecium, sometimes extending far below the latter, as in R. admirabilis (Fig. 256, 4) often reaching nearly to its apex or even higher than the posterior series in R. elegans. Ordinarily the cells of the axial series produce neither antheridia nor appendages, although in R. pallida (Fig. 255, 1) LABO ULBENIALES 379 and R. encijmonalis (Fig. 256, 5) appendages may develop from the distal cells. Thus the receptacle is a flat ribbon lying upon the substrate, usually attached by a unicellular, abruptly differentiated stalk with the usual black foot. Fig. 255. — 1. Rickia pallida. Blackened cells, disorganized. 2. Rickia papuana. Immature individual. 3. Rickia introversa. 4. Rickia dichotoma. Showing two parallel axes. {After Thaxter, 1926.) Growth may be either apical or trichothallic as found in the basal cells of the brown and red algae or a combination of both types. The terminal cell of the germinating spore develops a primary appendage with a two-celled base. The basal cell divides, cutting off the stalk cell with the foot and leaving the upper cell from which all secondary growth 380 COMPARATIVE MORPHOLOGY OF FUNGI proceeds. This cell divides by an oblique wall to an anterior lower and a posterior upper cell, both of which then divide transversely, the two lower of the cells thus formed corresponding to the basal pair of the marginal cells in the adult. The anterior of the two upper cells continues Fig. 256. — 1, 2. Rickia circumdata, mature individuals. 3. Rickia inclusa. 4. Rickia admirabilis. 5. Rickia encymonalis. 6. Tettigomyces acuminatus. 7, 8. Rickia rostel- lata. 9. Rickia coptengalis. to divide transversely until the normal number of cells characteristic of the anterior series has been reached. The posterior of these two upper- cells, although it may divide transversely, eventually divides longitudi- nally, the inner of the resulting cells organizing the axial series by repeated transverse division, while the outer similarly organizes the posterior series. LABOULBENIALES 381 When no longitudinal division occurs, a biseriate axis results, as in R. biseriata (Fig. 257, 4) and R. dichotoma (Fig. 255, 4). These biseriate forms may be regarded as more primitive, since in cases of injury or peri- thecial abortion, secondary axes which develop from them adventitiously and might be expected to show an atavistic tendency, are biseriate. Occasionally apparently normal individuals of the biseriate type may develop in species which are ordinarily triseriate. At a definite stage of development, a longitudinal division occurs in the terminal cell of the anterior series. Of the two resulting cells, the inner becomes the primordium of the perithecium while the other either ceases its activity and subtends the perithecium, as in R. rostellata (Fig. 256, 7 and 8), or continues to divide transversely until it reaches the apex of the developing perithecium, as in R. circumdata (Fig. 256, 1 and 2). Similarly, the posterior series may end below the base of the primary appendage which at maturity may be subtended by the posterior terminal cell as in R. coptengalis (Fig. 256, 9), or it may push aside the primary appendage and continue along the edge of the perithecium, as in R. biseriata (Fig. 256, 4 and 7). Such a case illustrates the combination of trichothallic and apical growth, in which growth is trichothallic below the primary appendage and apical beyond it. The cells of the outer series may cut off one or two smaller cells, by single or successive separation downward from their upper, outer angle, which organize either single secondary appendages or antheridia. The relative position of the appendiculate cells may not always be the same, even in the same individual; they may be vertically superposed, horizon- tally seriate or separated from the mother cell in such a way that they lie crowded in different radii of the same circumference. A slight pro- trusion is abjointed and develops a simple unicellular appendage, while the septum becomes variously blackened and constricted. The antheridium begins to develop exactly as an appendage. The septum occasionally remains unmodified and the antheridium immersed. The primary division of the original appendiculate cell separates an inner stalk cell from an outer which organizes the venter and neck of the antheridium. In the venter a small basal cell may be seen, above which a group of two or more antheridial cells discharge spermatia through minute pores into the main cavity of the neck. These are evanescent, the whole content of the antheridium disorganizes, leaving a contin- uous cavity which might be mistaken for the simple cavity of the Laboulbeniaceae. In R. macrandra (Fig. 254, 6), besides the free antheridia of the normal type, giant antheridia (Fig. 254, 4 and 5) are produced in which numerous elongate antheridial cells arise directly from a hemispherical basal cell of the venter, arranged in a subterminal whorl. In this type the sperms are discharged in great numbers and pass through short pores into a chamber 382 COMPARATIVE MORPHOLOGY OF FUNGI formed by the expanded base of the neck, much as in the more highly compound types of other genera. In some species, as R. dichotoma (Fig. 255, 4), R. inclusa (Fig. 256, 3), R. introversa (Fig. 255, 3) and related species, there is no indication of Fig. 257. — Rickia rostrata. 1. Mature individual. 2. Simple secondary appendage. 3. Branched secondary appendage. Rickia biseriata. 4. Mature individual. 5, 6. Paired and single antheridia. 7. Apex of young individual, showing trichothallic growth. Rickia Coelostomalis. 8. Tip of young individual, showing cell arrangement. 9. Perithe- cium with recurved neck. 10. Appendage with umbellate terminal branchlets. 11. Two normal single, secondary appendages. 12. Mature individual. {After Thaxter, 1926.) antheridial formation; in R. Sylvestri only one is produced while in R. papuana (Fig. 255, 2) and R. coptengalis (Fig. 256, 9) they are very numerous, often a hundred or more in a single individual. In other LABOULBENIALES 383 species, as R. Coelostomalis (Fig. 257, 8 to 11) and R. rostrata (Fig. 257, 1), while functional antheridia have not been seen, vestigial structures were observed. Perithecial development is similar to that of Stigmatomyces Baeri. The trichogyne is often characteristically branched with slightly swollen Fig. 258. — Diaphoromyces marginatus. 1. Young individual showing the relation of the posterior series to the two-celled base of primary appendage (left). 3. Foot of adult showing striations. 4. Termination of young axis showing formation of the basal cells of secondary appendages by nuclei, at different stages. 5 Young individual showing primary appendage p and secondary appendages s. 6. Fully mature individual. Dia- phoromyces Lispini. 2. Form with branched and highly developed appendages, from Trinidad. 7. Smaller simpler type from California. {After Thaxter, 1926.) extremities. Its persistent base is usually evident on the anterior margin of the perithecium. Diaphoromyces (Fig. 258) has recently been separated from Rickia, on account of the peculiar ontogeny of its secondary appendages, which are successively developed from above downward by the activities of large free nuclei in the cells of the lateral series (Fig. 258, 4). One of its nuclei takes its position against the inner surface of the wall and together with a small portion of protoplasm organizes a small cell, surrounds itself 384 COMPARATIVE MORPHOLOGY OF FUNGI with a wall firmly attached to the inner surface of the wall of the mother cell. This small cell which ultimately becomes the basal cell of the append- age then perforates the wall of the mother cell, growing outward through it by a narrow extension of its protoplasm, which, finally reaching the outer surface, forms there a walled prominence from which the appendage is organized. In some species of Ilytheomyces, (Thaxter, 1917) Chitonomyces and various other unrelated genera, "trigger" organs develop in positions which affect the tension within the perithecium, on contact with another host Fig. 259. — 1. Chitonomyces longirostratus, showing tip of perithecium highly developed a-nd functioning as a trigger organ. 2. Chitonomyces oedipus, showing trigger organs. 3. Chitonomyces japanensis. 4. Chitonomyces introversus. 5. Chitonomyces ceroiculatus. {After Thaxter, 1924.) or any firm object, in such a manner as to induce a sudden discharge of spores e.g., C. oedipus, C. japanensis, etc. (Fig. 259, 2 to 5). In Chito- nomyces longirostratus (Fig. 259, 1) the cells of the perithecial tip are elongated into a slender, indurated tube. At the impact with another host, slight bending of the tube will produce a very great compression of the perithecium and cause an immediate ejection of spores while the chance of infection is greatest. With the degeneration of the ascus as a mechanism for violent discharge, its function seems to have been assumed by the whole perithecium. In Trenomyces, the basal cell of the receptacle directly penetrates the host without the formation of a differentiated foot, although this region may sometimes be colored. The intruded rhizoid swells more or less abruptly beneath the integument, so that the individual is firmly LA BO ULBENIALES 385 held in place. From this enlargement a single simple rhizoid in T. Lipeuri, or many branching ones in T. histophtorus, make their way into the body substance. The sub-basal cell, by the formation of tangential walls, separates a variable number of small cells which may multiply variously by division, even organizing definite short axes with growing points in T. Laemobothrii; and, as a result, the original cell may become more or less corticated. The process is more definite in T. Lipeuri in which these cells are comparatively larger and more regular, developing sidewise to form a pulvinate series. Fig. 260. — Polyandromyces Coptosomalis. 1 to 6. Development of male. 10 to 12. Mature females. 13 to 15. Male and two females of var. minor. Nycteromyces streblidi- nus. 7. Mature male. 8. Young female. 9. Mature female. (After Thaxter, 1924.) From a variable number of these cells, single-stalked perithecia arise in the female or antheridia in the male; of which there may be from one or two to more than a dozen in a single individual. The perithecia and antheridia closely resemble those of Dimeromyces, the walls of the basal cells in the former being absorbed at an early period so that the cavity of the highly developed stalk cell becomes continuous with that of the ascigerous cavity. In male individuals the cortication is usually much less complicated; and the cells which give rise to the stalked, com- pound antheridia much like those of Dimeromyces may be separated directly from the sub-basal cell without secondary division, as in T. 386 COMPARATIVE MORPHOLOGY OF FUNGI circinans. In an undescribed hermaphrodite genus from the old world tropics, a similar general habit occurs, the sub-spherical receptacle pene- trating the host by means of rhizoids and forming perithecia and simple antheridia in a somewhat similar manner. The development of a compound antheridium may be seen in the dioecious Polyandromyces Coptosotnalis of the Dimorphomyceteae (Fig. 260, 1 to 6). In the male, the basal segment divides but once, forming a two-celled receptacle, while the distal segment forms three cells which correspond to the three primary regions of the antheridium; the stalk cell which divides no further, the terminal cell which becomes pointed and forms the efferent region, and the middle cell which separates a single cell above and below, the secondary stalk cell. The middle cell divides and proliferates to form the very numerous antheridial cells whose necks push up through the upper cell which is destroyed and discharge their spermatia into the common cavity formed by the resorption of the cells of the efferent region, leaving only their outer walls. In the corresponding female individual (Fig. 260, 10 to 12), the upper cell of the spore remains a simple, two-celled, primary appendage, resting on the uppermost of four cells which are formed by oblique division of the basal cells of the spore. The single perithecium is ordinarily devel- oped from the second cell below. In Nycteromyces streblidinus, the antheridia are formed in a series from the basal cell of the spore, while the distal cell remains a two-celled primary appendage (Fig. 260, 7); in the female a solitary perithecium is formed from the upper of the two cells produced by the basal cell (Fig. 260, 8 and 9). In Tettigomyces, the antheridium may be clearly differentiated, as in T. Gryllotalpae (Fig 261, 8) and T. africanus (Fig. 261, 1 to 3), with the development of many antheridial cells ; or it may be represented by a small, undifferentiated group of cells at the base of a highly developed, copiously branched and otherwise sterile appendage; while in T. chae- tophilus (Fig. 261, 7) no antheridial cells have been observed. In T. africanus (Fig. 261, 3) the antheridia empty through short necks into a central cavity, filled with spermatia, but a definite opening for discharge from the cavity has rarely been seen. Such openings are irregular and seem to be the result of rupture or degeneration rather than a definite pore such as found in Eucantharomyces, Cantharomyces or Haplomyces. Local disorganization, followed by general disintegra- tion of the antheridial cells occurs as development progresses, while in allied species, as T. vulgaris, T. gracilis (Fig. 261, 6) and T. intermedins (Fig. 261, 4 and 5), such degeneration is complete at maturity, and may involve the whole appendage in T. vulgaris (Fig. 261, 9 to 12). The double rows of antheridial cells arise as paired branchlets from marginal cells of a typical appendage, as the result of the activity of a corresponding LABOULBENIALES 387 Fig. 261. — Tettigomyces africanus. 1. Mature individual. 2. Young antheridium showing relation of adnate trichogyne to antheridial cells and carpogenic cell. 3. Older antheridium; the adnate trichogyne with two free branchlets seen sidewise, and showing necks and discharging spermatia. 4, 5. Tettigomyces intermedins, showing the antheridia disorganized. 6. Tettigomyces gracilis. 7. Tettigomyces chaetophilus, showing free tricho- gyne. 8. Tettigomyces Gryllotalpae . 9. Tettigomyces vulgaris, showing the tip of anther- dial appendage beginning to disorganize and free spermatia. 10. Distal portion of young ndividual showing terminal spine. Adnate trichogyne, x; ascogonium, y; young anther- idium not fully mature, paired daughter cells below indicating intercalary division. 11. Small individual; antheridial appendage partly disorganized. 12. Large individual with antheridial appendage completely disorganized. {After Thaxter, 1926.) 388 COMPARATIVE MORPHOLOGY OF FUNGI number of terminal cells which cut off basal segments successively. Later they usually divide once, resulting in the association of antheridial cells in pairs (Fig. 261, 9 to 10). The opposite series, arching somewhat, become separated by a space which forms the central chamber into which the spermatia are discharged. In T. africanus the trichogyne develops at the same time with the antheridial branchlets and is ordinarily in close contact with them, perhaps in actual contact with the cavity containing the spermatia (Fig. 261, 2). Fertilization might thus occur directly from this cavity, making an actual discharge unessential. This possibil- ity is further suggested by the fact that the exposed portions of the trichogynes are relatively thick-walled, without the usual thin-walled receptive region. Where no individualized antheridium is produced, the appendage becomes more or less indeterminate in growth, producing a variable number of sterile branches, as in T. acuminatus (Fig. 256, 6). In T. chaetophilus, (Fig. 261, 7), which produces no visible antheridial cells, there has been seen a trichogyne, sometimes found between the perithecium and the base of the appendage. Since there is such complete disagreement in the interpretation of many phenomena in this group between Gaumann and Thaxter, in the following discussion, I have attempted to present accurately Gaumann's views and Thaxter's unpublished criticism of them. In the Laboulbeniales the asterinoid habit has become most strongly developed; but it has undergone extensive morphological degeneration owing to extreme xerophyt- ism. Biologically, they seem to have undergone a development from endo- to com- plete ectoparasitism, like that we have met in the Perisporiales and Sphaeriales. A few species, as Trenomyces histophthorus on Mallophaga, are endoparasitic, like Leveillula taurica of the Erysiphaceae and Lanomyces tjibodensis of the Perisporiaceae, and with their well-developed haustoria penetrate the whole fatty tissue of the host. Other forms, as Dimeromyces rhizosporus, Ceraiomyces Dahlii and Arthro- rhynchus Cyclopodiae, correspond to the Phyllactinia type of the Erysiphaceae; they form richly branched, intramatrical haustoria which spread only in the immediate vicinity of the point of infection. Other forms, as Rhizomyces ctenophorus and Moschomyces insignis, penetrate the chitinous integment of the host and form a lobate haustorium on its interior (Fig. 251, 2). In most species the intramatrical portion of the thallus is reduced to an ungulate haustorium, the black foot, which is let into the integument of the host, goes no further into the interior of the body and apparently takes its nourishment through the host integument (Fig. 251, 3). Analogies to this relationship are rarely known in fungi; one was earlier described for Harpochy- trium Hyalothecae (Fig. 23, 1) ; another may be seen in Fig. 262, 1. On the basis of the observation that the insects suffer no serious injury and the assumption that a suffi- cient intake of nourishment through the integument is impossible, the idea has been expressed that the purely ectoparasitic Laboulbeniales are only saprophytes like the epiphytic Sphaeriales of the Limacinia-Teichospora type. This idea is hardly correct, since many species are adapted to definite genera of insects. It seems rather a question of end forms of an asterinoid developmental series in which the step from ectoparasitism to epiphytism is small, as in the Erysiphaceae. LABOULBENIALES 389 That the food is not rich may be assumed from the small size of most species, which have comparatively few cells. That they are xerophytic is immediately clear if one considers that many Laboulbeniales live on dry legs and elytra of beetles. Physically, their habitat may be damp, as in species on aquatic and swamp insects. Physiolog- ically, the point of food intake is very dry. The Laboulbeniales, as all the other asterinoid groups, must have undergone an exceptionally far-reaching degeneration; in contrast to the simplicity of the thallus, there is an astonishingly high development of sexual organs and fructifications. The critical point lay in the ectoparasitism on insects, whose leveling influences have been felt by other entomogenous Ascomycetes and imperfecti; many of them also show a Laboulbenial habit as a convergence phenomenon (Thaxter, 1914, 1920). The meaning of these observations is controversial. Are the Laboulbeniales reduced Florideae and their spermatia really spermatia or are they reduced Pyrenomycetes and, therefore, their spermatia are really only originally conidia? To answer these questions which are of fundamental meaning for the phylogenetic derivation of Asco- mycetes and fungi in general, and not to anticipate, the discussion of the Laboulbeniales was postponed to the close of the class, although it is completely isolated there. Their derivation from the Florideae is suggested by the habitual similarity of the Laboulbeniales to some parasitic red algae, and by the type of fertilization by sperma- tia, which in the endogenous forms are at first surrounded by a very thin membrane. This hypothesis is wrecked in the morphology of the gonotoconts, the asci. It seems improbable that so highly a specialized organ which as regards the free cell formation of its daughter cells, the ascospores, depends upon such definite phylogenetic condi- tions (coenocytic gametangial copulation, privileging of certain sexual nuclei) could suddenly arise in the short distance from the Florideae to the Laboulbeniales. If one rejects this possibility and regards the Laboulbeniales as reduced Pyreno- mycetes, one is obliged to seek another explanation for the antheridia. The exogenous spermatia of Zodiomyces vorticellarius (Fig. 247, 7) and Rhynchophoromyces rostratus (Fig. 253, 1) and for the oidia of some species of Ceratomyces might be explained as conidia although their germination is still unknown. Morphologically, they are undoubtedly conidia. In any case it is noteworthy that at least in Zodiomyces vorti- cellarius, and probably in Tettigomyces vulgaris, as in Collema pulposum, they must be sought for by the trichogyne. Thus they must have undergone secondarily a definite sexual differentiation. The interpretation of the endogenous spermatia is more difficult. In Stigmatomyces Baeri they are formed long in advance of the formation of ascogonia (Fig. 248, 8) and their production is continued throughout the life of the plant, even to old age, when the perithecia have finished development and are discharging ascospores. If one wished to explain this spermatial formation on the young plants as extreme protandry, the continuation of spore formation past perithecial maturity must be confusing; such behavior is shown only by imperfect forms, not antheridia. It is equally confusing that the antheridia may arise from either cell of the germi- nating ascospore, while the ascogonia arise only from the basal cell. It must appear still more unusual that in Coreomyces any cell in any appendage may form spermatia. Such a relationship argues for conidial formation, not for antheridia. Similar considerations arise in the dioecious forms, the Dimorphomyceteae of the Peyritschielliaceae and the Amorphomycetae and Herpomyceteae of the Laboulbenia- ceae. It may be granted that a figure such as we have for Amorphomyces Falagriae argues strongly for the conception we reject here: we have male and female plants, the former form spermatia, the latter ascogonia^ which are fertilized by spermatia. The two sexes remain connected in pairs because in the ascus the sexually different ascopores already cling together. Unfortunately, this group has not been studied cytologically. 390 COMPARATIVE MORPHOLOGY OF FUNGI Against this interpretation two objections may be raised, one on the basis of Thaxteriola and Endosporella, and then on the basis of Stigmatomyces Sarcophagae. Thaxteriola and Endosporella (Fig. 262, 2 to 4) are two entomogenous imperfect genera which superficially resemble the male plants of the Laboulbeniales and undoubtedly may be regarded as such. If the spores formed by them are spermatia, one must assume that these in some mystical manner reach a distant, still unknown female plant. It is more reasonable to regard them as conidia and their mother plants as imperfects, thus explaining their isolated growth. The relationships in Stigmatomyces Sarcophagae are similar. There we have normally male plants with "antheridia" and female plants with ascogonia. Besides, the same "antheridia" also occur on female plants. It is not feasible to consider the male plants as reduced and their generation as a cause of androgyny, for their antheridia are morphologically and functionally equivalent to those on monoeci- ous plants. It seems much simpler to assume that the supposed antheridia are conidiophores. Fig. 262. — 1. Amphoromorpha blattina. Mature plant on the antenna of a Blattidae. 2. Thaxteriola nigromarginata. 3, 4. Endosporella Diopsidis. Young and mature individ- ual. (X 600; after Thaxter, 1920.) Thus these conidiophores belong to the same type which we have described for Thielavia and Pyxidiophora. In all the antheridia for which we at present have no direct parallel in the Ascomycetes, their formation from single cell may always be referred to meristogenous pycnia, such as we have shown in Teichospora salicina (Fig. 177). The smallness of all these objects may be connected with the general degeneration of the Laboulbeniales in which occasionally all that remains of the thallus is the two basal cells. If the conidia should prove to be no longer capable of germination, they would be morphologically similar to the microconodia of the Sphaeriales and Phragmobasidiomycetes. According to this conception, the Laboulbeniales would have a position in the Pyrenomycetes like that of the Uredinales in the Phragmobasidiomycetes. Most would have had a dioecious sexual differentiation; the male individuals bore antheridia such as are still present in the Plectascales; the female bore ascogonia such as we still LABOULBENIALES 391 know. Besides, both have imperfect forms, as still happens in dioecious Ascomycetes. The perithecia arose in a way such as still occurs in relatives of the Plectascales, the Sphaeriales (Sordaria and Teichospora) by division of a single mother cell. The male sexual organs, as happened in the Plactascales, Pezizales, etc., degenerated so that in the male individual only the imperfect stage remains. In this manner, the numerous sterile (imperfect) mycelia of the Ascomycetes might be explained simultaneously. They are male mycelia without sexual organs. In compensa- tion for lost gametangial copulation there followed a deuterogamous fertiliza- tion of ascogonia by conidia. In the dioecious forms, chiefly, the conidia of the male individual may have served as these secondary spermatia and have apparently secondarily retained some sexual tendencies or affinities. Apparently the conidia of the female individuals can fulfil the sexual function as the example of Stigmatomyces Sarcophagae allows one to assume. Thus in the Laboulbeniales, as in the Pezizales and in the Discomycetous lichens, the function of the conidia as spermatia would be a secondary phenomenon, a conse- quence of the degeneration of the male sexual organs. Their copulation with tricho- gynes would be fundamentally the same process as copulation of oidia and hyphae in the Basidiomycetes except that in the Ascomycetes the female organs are recognizable as such, while in the Basidiomycetes they have disappeared like the male sexual organs, so that the sexual act occurs pseudogamously between the hypha and imperfect form. It is clear that these suggestions do not solve the problem of the phylogenetic derivation of the Laboulbeniales. We were only attempting to show that in case one wishes to maintain the phylogenetic unity of the Ascomycetes, it is possible to regard the Laboulbeniales as degenerate Pyrenomycetes. Many problems await explana- tion. Thus in the Ascomycetes we know no other group like the Laboulbeniales, which possesses a definite number of ascogenous cells with unlimited capacity for division. At present such cells are known only in the Basidiomycetes. Similarly, the significance of the appendages is still puzzling; the example of the Coreomyces where the lower cells of all appendage cells are adapted to conidial formation, tempts one to assume that the appendages were originally conodiophores which, however, like the sporangiosphores of Chaetoshjlum Fresenii and Chaetocladium Brefeldii, because of scanty nourishment have ceased conidial formation and have Undergone a functional change to become setae. If, however, one is not inclined to the derivation of the Laboulbeniales and the Pezi- zales from the Florideae, as was proposed sixty years ago by Sachs and more recently by Vuillemin (1912), B. O. Dodge (1914) and Fink (1915), there still remain as roots of the Ascomycetes two orders, the Oomycetes (Bary's school) and the Zygomycetes (Bref eld's school). The derivation from the Oomycetes is based chiefly on the similarity in manner of formation of eggs and ascospores and on external morphological relationships between copulation tube and trichogyne. The comparison of egg and ascospore presupposes a homologization of oogonia with asci; this is untenable, how- ever, because of the different positions of these organs in the change of nuclear phase. Besides, Wettstein (1921) points out that the Oomycetes known at present have a cellulose membrane but the Ascomycetes, like the Basiomycetes and Zygomycetes, have a chitinous wall. The above speculations are partially open to criticism on the ground of insufficient knowledge of variation which results from a study of a large series of specimens of a group. Thus, it may be pointed out that the discussion of the transition from endo- to ectoparasitism is of no phylogenetic significance, since this habit has arisen inde- pendently in unrelated groups. Biologically, it is an adaptation to the host, haustorial development being usually related to the softness of the body of the insect, and to the nature of the integument. Ordinarily the foot penetrates the integument over a pore canal and the organism is able to get sufficient nourishment from the blood of the 392 COMPARATIVE MORPHOLOGY OF FUNGI insect through the unthickened portion of the foot, while the hard integument fur- nishes the necessary support to prevent the fungus being knocked off during the movements of the insect. If the integument is soft, the haustorium may provide additional support as well as nourishment, since it is highly branched and ramifies through the rich, fatty portion of the insect. In part the above series results from the difficulty in technique of carefully dissecting out the rhizoidal portion of the haus- torium, hence figures often give an inadequate impression as to the development of the haustorium. The assumption that the food is not rich is incorrect, since the foot is always bathed by the body juices of the insect, and the cells of the fungus usually contain large numbers of fat globules. As in all other cases where a large amount of reserve energy must be stored in a small space, it is stored as fat. They can hardly be called xerophy- tic, since their base is always bathed in a suitable supply of water and they spend most of their life in a humid atmosphere. They are well protected, however, against sudden changes in humidity such as might occur if the host temporarily moved into a drier situation. It is very questionable whether this adaptation has influenced their phylogeny. It is also questionable whether they should be regarded as a degenerating group. It is true that they are small, as an adaptation to a highly specialized environment which has also greatly influenced the development of the thallus in other parasites of living insects, but they have a highly specialized thallus in many forms, usually much more highly differentiated than the individual cells in other groups of fungi. Without entering the controversy on the derivation of the Ascomycetes from either Florideae or Zygomycetes, certain statements in the argument need correction. It seems just as reasonable to regard the spermatia of Zodiomyces which are often sought out by the trichogyne as spermatia as to regard them as conidia which have secondarily been differentiated as spermatia. In many groups spermatial formation ceases soon after fertilization, and a case like SHgmatomyces Baeri is an exception rather than the rule, in fact it is not a characteristic of this species. Even in the red algae the formation of spermatia is not closely linked with the presence of a mature tricho- gyne on a given individual. While as a rule antheridia may arise from either cell of a germinating ascospore, in some groups it is confined to one cell, as in Rickia (the basal). The perithecium usually is developed from the basal cell, but in Coreomyces from the terminal. The condition mentioned in Amorphomyces Falagriae is the typical condition in all dioecious forms, although in other respects Amorphomyces is an aberrant type. Since the trichogyne is a very evanescent structure, and since the perithecium grows rapidly after fertilization, eventually the antheridia may be far removed from the mouth of the mature perithecium, yet when young, the trichogyne is usually close to the mouth of the antheridium. In these dioecious types, sex differentiation seems absolute. No instances are known where the females produce antheridia or the males perithecia, even in such unusual types as Dimeromyces adventitiosus, in which antheridia and perithecia are developed, not only in the normal position from the receptacle, but adventitiously from the ordinarily sterile portions of the male and female individual, as the case may be. Unfortunately these forms have not been studied cytologically. While Gaumann states that the entomogenous genera of imperfects, like Thaxteriola and Endosporella, may "undoubtedly be regarded" as male plants of Laboulbeniales, he presents no evidence in support of his statement, and such an interpretation seems incorrect in the light of our knowledge of sex differentiation and the discharge of ascospores in all the dioecious groups of Laboulbeniales. In the example given of SHgmatomyces Sarcophagae to which might be added Laboulbenia elongata and others, the plants are normally dioecious, and " male individ- LABOULBENIALES 393 uals" only result when for some reason the perithecium aborts, and an abnormal multiplication of antheridia sometimes results as a teratological phenomenon. The "female plants" always have antheridia in the usual position. The simple antheridia seem to have little in common with the conidial forms of Thielavia and Pyxidiophora, either in appearance or ontogeny, although no cytological studies have been undertaken on either group. Summary. — The derivation of Ascomycetes from Zygomycetes, which forms the basis of our treatment, is built on the following conceptions. In the Zygomycetous series there are present the beginnings of a three- fold development. In the first place, in the privileging of sexual nuclei : all the gametangial nuclei are no longer activated as sexual nuclei or, in any case, do not all take part in the sexual act, but the sexual function is fulfilled by a small portion of them and finally by only one gametangial nucleus (Endogone). Secondly, in the Zygomycetes there appears the beginning of a delay in caryogamy which no longer normally takes place in the gametangium, but in outgrowths of it (Phycomyces, Endogone). And thirdly, the zygospore germinates increasingly by a germ sporangium (Polyphagus, Phycomyces) rather than a germ tube. According to the theory presented here, these three tendencies are realized in the lowest Ascomycetes. Dipodascus differs from the Endo- gone only in forming a sporangium instead of a zygote as the product of the sexual act. This difference, however, may rest chiefly on biological relationships. In Dipodascus, as in Endogone, two coenocytic copulation branches enter into open communication. As in Endogone lactiflua, how- ever, only one gametangial nucleus from each gametangium participates in each sexual act, so that all other gametangial nuclei are superfluous. While in Endogone the supernumerary nuclei soon disintegrate, in Dipodascus they are retained longer. Thus between Endogone and Dipodascus there is a difference like that between the Pythium-Phytoph- thora group and the higher species of Peronospora of the Oomycetes. In the latter, the supernumerary peripheral oogonial nuclei persist and are used for secondary vegetative purposes. In Dipodascus the supernumer- ary nuclei are used for accessory structures, apparently in connection with the surplus protoplasm. This similarity in functional differentiation of gametangial nuclei has led in both groups to similar morphological developments. In the higher Oomycetes, the egg cells were differentiated by free cell formation from the oogonial protoplasm about the sexual nuclei, while the supernumerary nuclei lay outside in the peripheral periplasm. Similarly in Dipodascus, the spore portions about the daughter nuclei of the primary ascus nucleus are cut out of the ascus protoplasm by free cell formation while the sexu- ally inactive nuclei remain undivided in the periplasm. If all the nuclei lying in the young ascus were equivalent, as they are in the sporangium of Polyphagus, this complication would never have arisen; but the ascus 394 COMPARATIVE MORPHOLOGY OF FUNGI protoplasm, as in the sporangial protoplasm of Polyphagus and the Mucoraceae would have been divided by direct cleavage into the individual spore, portions. The nuclei in the young ascus of Dipodascus are not equivalent to each other, however, since true ascospore nuclei, i.e., prod- ucts of the sexual act and meiosis, and ordinary vegetative or sexually inactive gametangial nuclei appear side by side or intermingled. In such a cleavage the vegetative and ascospore nuclei would both enter into the ascospores. This could be avoided only by free cell formation. According to this conception, free cell formation in the higher Oomy- cetes and in the ascospores of Dipodascus is only a convergence phenome- non, since in coenocytic gametangia, only a selected number of sexual nuclei participate in fertilization, while the others are vegetative and do not enter the new organs (egg cells, ascospores). The ascus of the Dipo- dascus and of the Ascomycetes altogether and the oogonium of the Oomy- cetes are analogous not homologous organs, as Bary assumed. Whether in both cases the cytological processes are identical to the smallest detail, can be explained only by a closer investigation of Dipodascus. From the Dipodascus type a further stabilization of the ascus has occurred since its spore number, corresponding to the number of the tetracyte nuclei, is fixed at eight. The ascus is phylogenetically a germ sporangium become gonotocont, with the correspondingly fixed spore number. Thus the sporangia of the Zygomycetes would have undergone a cleavage, those which normally served further as imperfect forms gradu- ally change to conodiophores as in the Choanephora-Aspergillus-Peni- cillium series; those which functioned as gonotoconts, however, retained their sporangial character at first and only lost it later in the transition from Ascomycetes to Basidiomycetes. In contrast to this morphological stability, biologically the ascus undergoes a manifold functional develop- ment which reaches its high point in the discharge organs of the Discomycetes. In the second place, from the Dipodascus type, a development of the female copulation branch (e.g., differentiation into the ascogonium and trichogyne) has occurred while the male copulation branch shows a great constancy and degenerates early. Consequently, in place of the original gametangial copulation, there appear all sorts of deuterogamous processes, the most noteworthy of which is copulation with conidia. The fact that in certain parthenogamous forms the trichogyne is lacking, while in others it has reached a high degree of development, leads one to suppose that in the latter it was made to serve secondary purposes. In the third place, the retardation of caryogamy which has already caused fertilization to be transferred from the gametangium to ascus continues still further, so that meanwhile the dicaryon divides repeatedly. Consequently the gametangia do not develop directly to asci, but, in a certain sense, vegetatively to dicaryotic hyphae, the ascogenous hyphae, LABOULBENIALES 395 which can branch and proceed independently to form asci. By this insertion of a new phase, the activity of the gametangia increases; from a gametangium may arise several gonotoconts. Thus, phylogenetically considered, the reduction caused by the privileging of a small number of gametangial nuclei was overcome. Still the phylogenetic development of the Ascomycetes is most obscure. We need only cite the contradictions between the Pencillium and the Pyronema types, the Taphrina type and the Laboulbenia type. In any case, within the Plectascales has somehow been developed the hook form of the Pyronema type which, on account of its distribution in the Ascomy- cetes and its character as bridge to the clamp mycelium of the Basidio- mycetes, has become the most significant form of ascogenous hyphae. While in Pyronema confluens, the hook tip can occasionally fuse with the stipe cell, whereby the stipe nucleus migrates into the tip and develops it to a branch, in some higher forms, as Helvetia elastica and Parmelia acetabulum, this fusion of hook tip with stipe cell becomes the rule. Only in them the nucleus of the tip migrates back into the stipe, so that branch- ing is absent and clamp formation is entirely similar to that of the Basidiomycetes. Simultaneously with the degeneration of sexuality, the ascogenous hyphae lose their specific character. They still arise only as a result of pseudogamous copulation between vegetative hyphae somewhere in the tissues of the fructification, and penetrate it for a long distance. Since these ascogenous hyphae more and more assume the character of vegeta- tive hyphae, it is comprehensible in certain forms, as in Ascocorticium, that asci appear to arise directly from vegetative mycelia. If we imagine this development proceeds one step further, in that the ascogenous hyphae (like vegetative hyphae) become adapted to independent food intake (which is perhaps already the case in some Ascomycetes, as the Ascocor- ticium group) we come to the clamp mycelium of Basidiomycetes. And finally, from Dipodascus there has been an ascent in formation of fructifications so that in the highest forms, as in the higher Hypocreales and Pezizales, are evident the same principles of increase of surface which we shall again meet in the Basidiomycetes. Hand in hand with degenera- tion of sexual organs goes the shifting of their formation in respect to that of fructifications; while in the lower forms the ascogonium introduces the development of the fructification, in the highest forms, the fructifications arise by vegetative stimulation and the functionally and morphologically degenerating ascogonia (generally in the majority) develop on them. Here also is a short step to the Basidiomycetes. CHAPTER XXV BASIDIOMYCETES In the Basidiomycetes, the gonotocont forms its spores exogenously in the manner of conidiophores instead of endogenously as in the Asco- mycetes. The sporophore is called the basidium and the spores basidiospores. The mycelium of the Basidiomycetes is divided, according to its morphological and cytological relationships, into three classes which are called primary, secondary and tertiary, because of their sequence in time (Falck, 1909; Bensaude 1918). The primary mycelium comes directly from the germinating basidiospore and in most families is developed as the usual vegetative hyphae; in a few, it possesses the character of sprout mycelium, for the most part transitorily and under definite conditions of nourishment. The hyphae are comparatively slender; they intertwine irregularly and anastomose so generally that sometimes a real mycelial net results. The branches are approximately equal to the main axis in form and size. According to the cytological relation- ships, these mycelia produced from the basidiospores may be divided into four types, partly related to the nuclear condi- tions of the basidiospores themselves. In the first type, to which, among others, belong Corticum varians, Peniophora Sam- buci (C. serum), and Collybia conigena (Kniep, 1915, 1917, 1919) and most of the Uredinales, the mature basidiospores and the cells of the primary mycelium are uninucleate (Fig. 263, 2 to 4). In the second type, which includes Peniphora gigantea (Kneiffia gigantea), the mature basidiospores are binucleate, but only one nucleus 396 Fig. 263.- — 1. Collybia conigena. Uninucleate hyphae producing oidia. 2 to 4. Corticium varians. Germination of basidiospore. ( X 670; after Kniep, 1917.) BASIDIOMYCETES 397 migrates into the germ tube, while the other remains in the spore. A septum is formed between them and the germ tube grows to a more or less elongate uninucleate mycelium. In the third type, which includes Coprinus fimetarius, Pholiota praecox, Hypoloma perplexum and Ar miliaria mucida (Nichols, 1905, Levine, 1913; Bensaude, 1918), the mature basidiospores may be uni- or binu- cleate. The two nuclei migrate rapidly into the young germ tube (occasionally branched) and complete a large number of mitoses without laying down septa (Fig. 264, 2). In certain species, e.g., Coprinus fimetarius, one nucleus remains behind in the basidiospore and the further development proceeds from the nucleus which migrates into the germ tube. After a few days, the primary coenocytic mycelium (often with thirty nuclei) becomes septate, and consequently uninucleate (Fig. 264, 3). After this happens, these first three types cannot be differentiated. Fig. 264. — Coprinus fimetarius. 1. Germ tube with two nuclei. 2. Coenocytic hypha. 3. Hyphal cell with oidia. ( X 700; after Bensaude, 1918.) In the fourth type, which includes Corticium bombycinum (C. ter- restre) (Kniep, 1913) and most Gasteroinycetes, the mature basidiospores are always binucleate, and, in contrast to the second and third types, the nuclei always appear as a dicaryon, (Fig. 265, 2 to 6). They migrate together into the germ tube and thereafter divide conjugately; therefore we must regard this last type as secondary mycelium and conclude that the uninucleate, haploid, primary mycelium found in the first three types is lacking. From the standpoint of change of nuclear phase, the haploid mycelium corresponds to the usual vegetative mycelium of the Ascomycetes, and is propogated (as in the latter) by all sorts of secondary spore forms, as conidia, oidia and gemmae. The "conidia" (spermatia) show types of organization similar to those of the Ascomycetes and for the most part may not be distinguished from them. In some parasitic families (Uredinales), as in the Sphaeriales of the Ascomycetes, they are cut off 398 COMPARATIVE MORPHOLOGY OF FUNGI within pycnia. In the Basidiomycetes, they do not reach the stage of development they do in the Ascomycetes; for example, the type of conidiophores of the Plectascales are unknown in the Basidiomycetes. Fig. 265. — Corticium bombycinum. 1. Group of basidia. 2. Mature basidiospore. 3 to 6. Germination of basidiospores. 7 to 11. Development of basidia. 12 to 14. Development of basidiospores. (1 to 5, 7 to 14 X 1,000; 6 X 700; after Kniep, 1913.) In the Basidiomycetes, conidia play an altogether subordinate role. Their existence can, for the most part, be determined only in artificial culture; they appear regularly only in the lower orders and disappear entirely in the higher ones. The oidia arise, as in the Ascomycetes, in BASIDIOMYCETES 399 the breaking up of vegetative hyphae (Fig. 263, 1) or of hyphal branches; in many forms, the latter are differentiated as fertile hyphae and then may be recognized by their limited elongation and fasciculate arrange- ment (Fig. 264, 3). In the Basidiomycetes, they are very frequent, and in the higher orders represent the normal asexual form of multiplication. In these they replace the conidia. Gemmae arise in the Basidiomycetes in a manner and frequency similar to that in the Ascomycetes. In contrast to the extensive correspondence to the vegetative myce- lium of the Ascomycetes, the haploid mycelium of the Basidiomycetes produces no functional sexual organs. Recent investigations, however, have shown that it is sexually differentiated, as in many Ascomycetes and Phycomycetes, and is divided into monoecious (homothallic) and dioecious (heterothallic) types. True homothallism is rare; it was experimentally demonstrated for Corprinus narcoticus, C. sterquilinus, C. stercorarius, C. lagopus, C. niveus (Lendner, 1920, Brunswick, 1924; Mounce, 1921, 1922). They can pass through their complete life cycle in single spore cultures. As in the heterothallic forms of Phycomycetes and Ascomycetes, the single spore cultures of heterothallic forms, e.g., C oprinus fimetarius , C. radians, C. papillatus,C.micaceus,Anellaria separata (Panaeolus separatus) , P. campanulatus, Armillaria mucida, Schizophyllum commune and Corticum polygonium (Aleurodiscus polygonius, Gloeocystid- ium polygonium) (Bensaude, 1918, Kniep, 1919, 1923, Vandendries, 1923, 1925, 1925a, 1926; Brunswik, 1924, 1926; Hanna, 1925), may (with the exception of a few cases of parthenogenesis to be discussed later) be culti- vated indefinitely as haploid sterile mycelium. This forms only second- ary spore forms and continues development only if brought together in mixed culture with the dynamically opposite mycelium (often somewhat differing morphologically in growth form). C oprinus Rostrupianus, studied by Miss Newton (1926), is peculiar in that the spores and young mycelia are typically heterothallic, while about half the mycelia, six months or more in age, are homothallic. The mycelium becomes binu- cleate in some unknown manner. Only the binucleate mycelia produce sclerotia capable of forming fructifications. The sclerotia from uninu- cleate mycelia germinate with only mycelium. In a few Basidiomycetes, however, as in Corticium polygonium, Coprinus stercorarius, C. niveus, C. lagopus and Schizophyllum commune, the sexual differentiation has apparently gone still further than in the Phycomycetes and Ascomycetes so far as known ; their mycelia are not differentiated into + and - strains but into several strains. In Corticium and three species of Coprinus, four sexually differentiated types have been noted; in Schizophyllum there are still more types, e.g., A, B, C, D, E, etc., of which A may be brought together with B and C, B with A and D not with C, C with A and E but not with B and D. After a time secondary mycelium and fructifications develop. In these forms, heterothallism appears to rest 400 COMPARATIVE MORPHOLOGY OF FUNGI ( a \i upon a minimal quantatitive difference of sex factors. These differences generally change, and may thereafter be fixed as genotypes (multiple allelomorphs) (Kniep, 1923). It is always possible to explain these forms of heterothallism as different stages of self sterility. According to this explanation, the Coprinus fimetarius type might be called homo- thallic with a sterility factor, the Corticium type homothallic with two sterility factors (Brunswik, 1924). The difficulty in this second inter- pretation lies in the frequent alteration in 1 (T^S Z resulting fixation of the genotype of the sex "A factors of Schizophyllum commune. The cytological processes which take place in the further development of the primary mycelia have been studied for the heterothallic forms only, e.g., for Coprinus fimetarius and Pen- iophora Sambuci (Corticium serum) (Bensaude, 1918; Lehfeld, 1923). There were observed anastomoses between the + and — mycelia whereby the nucleus of one cell passed through the clamp connection into the corresponding cell of the other hypha (Fig. 266, 1). This anastomosis may also take place, instead of be- .£ tween two vegetative primary hyphae, between one vegetative hypha and the germ tube of an oidium which has arisen elsewhere in the culture Salbuci.2 l6: Two yoZTserZ and has been brought to the place in question, tubes anastomosing and form- Generally the entire uninucleate mycelium is "^mClaTwobranrhTs^fseT- exhausted in the formation of binucleate cells, ondary hyphae, A, B, have so that at a certain stage one finds no more nor- apptaring!16 W^™ LehjlTd, mal uninucleate hyphae in the culture. The 1922; Bensaude. 1918.) binucleate cells develop laterally into binucleate hyphae. The dicaryons which have resulted from these processes normally keep on dividing conjugately throughout the entire life cycle, until the formation of the fructification and the hymenial fundaments (as the equivalents of the paired nuclei in the ascogenous hyphae of the ascomycetes). The processes which led to their formation must consequently be interpreted as the remains of a pseudoagamous sexual act (plasmogamy) ; for hybrids may be formed between two differ- ent species as between Panaeolus campanulatus and P. fimicola (Vanden- dries, 1923). In the homothallic forms, the binucleate condition arises in some way by an autogamous process, which is apparently pushed back into the basidiospores as in the Corticium bombycinum type and in the Gasteromycetes. This last type approximates apogamy; pure apogamy, however, is found only in the Uredinales. BASIDIOMYCETES 401 With the first conjugate division of the dicaryon, clamp connections are formed in Coprinus fimetarius and Peniophora Sambuci. In other species, ' as Typhula erythropus (Lehfeld, 1923), the relationships appear to be more complicated. In these, the anastomoses do not immediately succeed the germination of the basidiospores, but later when the primary haploid mycelia have reached a definite point of development (sexual maturity); thereby the relationships become obscure. Further, plasmogamy does not lead directly to the formation of a dicaryon, but the migrating nucleus passes (in several divisions) through the new, unre- lated hypha, whereby the septa are dissolved and thereafter are partially regenerated. Suddenly clamp connections appear in different places, often at some distance from the anastomosis. These develop laterally into binucleate mycelia. This new binucleate mycelium formed by plasmogamy is called second- ary mycelium, in contrast to the earlier uninucleate mycelium. It is differentiated from the primary mycelium by the formation of clamp connections, by its differentiation into main axis and branches, by the vegetative character of its anastomoses and by the virtually binucleate character of it coenocytic cells. The clamp connections arise as follows : Before the dicaryon prepares to divide, a small, bow-shaped outgrowth is formed usually in the middle of the cell between the two nuclei (Fig. 267, 1). The two nuclei move to the place of branching and one of them penetrates a distance into the clamp while the other remains behind in the base of the clamp (Fig. 267, 2); whereupon they begin conjugate division (Fig. 267, 3 and 4). The axis of the spindle of one nucleus lies in the direction of the main hypha, the axis of the other spindle lies obliquely in the clamp. Before the four daughter nuclei have completed the telophase, two go toward the end of the hypha, one goes basipetally and the fourth remains in the clamp (Fig. 267, 5). The two nuclei of the developing end of the hypha are separated from the basal cell (previously uninucleate) by a septum which is formed directly under the base of the clamp ; the nuclei are arranged in the usual manner in the middle of the cell. The uninucleate clamp cell is cut off from the terminal cell by a second septum which forms with the first an oblique angle, opening apically (Fig. 267, 6). After a short time, the end of the clamp cell fuses with the uninucleate basal cell into which its nucleus migrates (Fig. 267, 7). Thus the basal cell gains its usual binu- cleate condition. In this relationship, however, many anomalies occur; the fusion of the clamp cell with the basal cell may be retarded or entirely omitted, in which case the clamp nucleus degenerates; or the formation of the septa may be retarded or may take place in unusual sequence. Still further, in Coniophora (Fig. 269, 1) and Stereum at the same septum, there appear whole whorls of clusters of clamps whose method of development 402 COMPARATIVE MORPHOLOGY OF FUNGI is still unknown. Apparently, several dicaryons are present in the cells in question. Fig. 267/ — Corticium varians and Peniophora Sambuci. Development of clamps. (1, 2, 5 to 8 X 500; 3 X 670; 4 X 1,000; after Kniep, 1915.) With the first of the nuclei which are formed in the uninucleate hypha is bound the first conjugate division and with it the first clamp formation and true branching, in which the clamp cell develops laterally to a normal BASIDIOMYCETES 403 hypha (Fig. 267, 8). In many species the branches develop later, pref- erably from the clamp. Although clamp connections are by their nature connected with binu- cleate mycelium, they appear in exceptional cases, e.g., Stereum hirsutum, in uninucleate mycelium (Kniep, 1919) and in Coprinus narcoticus in multinucleate primary mycelium (Brunswik, 1924). Conversely, the extension of binucleate condition is much curtailed in certain cases. While the clamp connections in Lenzites abietinus, Merulius lacrymans, Daedalea unicolor and Fistulina hepatica are to be found regularly at each septum and are not influenced by conditions of growth; in Coniophora cerebella, Clitocybe expallens, Lepiota rhacodes and Lycoperdon pyriforme, they occur only irregularly. Under natural conditions, they may be numerous in certain stages of development and be lacking in others or in artificial cultures may be made to disappear in submersed mycelium or by other interference. In still other species, as Corticium bombycinum, Armillaria mellea and Calocera viscosa, they are entirely lacking and the dicaryon divides without this indirect mechanism (Rumbold, 1908; Kniep, 1913, 1918). The significance of this clamp formation is still obscure and will be discussed along with the phylogeny of the Basidiomycetes. The differentiation into main axis and branches, the second character- istic of secondary mycelium, is easily noted in artificial cultures. The main axes are well developed; in contrast to hyphae of the uninucleate mycelium they run almost parallel to each other and lend themselves easily to the formation of rhizomorphs. The branches are smaller and thinner without marked polarity; under abnormal conditions of nourish- ment, however, they may develop into main axes. As in the case of uninucleate hyphae, anastomoses are formed between the branches. In contrast to the anastomoses of the uninucleate hyphae, however, they do not result in developmental stimuli : after the cell fusion, one dicaryon dissolves, leaving the double cell binucleate (Fig. 266, 2). The same thing occurs in the anastomoses of primary and secondary hyphae, where- by the fusion cells occasionally become uninucleate. These fusions are only vegetative (Bensaude, 1918). In a large number of higher Basidiomycetes, usually at some distance from the hyphal tip, the divisions of the dicaryons are not followed by wall formation. Consequently, in time, the number of nuclei in these cells mounts as high as twenty, and the cells become ceonocytic, as in the uninucleate mycelium. There proceeds a more or less synchronous divi- sion of these nuclei which is then followed by the formation of septa. In contrast to the coenocytic cells of the primary mycelium, which sepa- rate into uninuclear cells, these coenocytic cells of the binucleate mycelium behave as binucleate cells, in spite of the transitory loss of their binu- cleate character in the different phases of their development. They contain many dicaryons but, by an increasing limitation of the number of 404 COMPARATIVE MORPHOLOGY OF FUNGI dicaryons participating in mitoses and by an increased septal formation, the cells in the lamellae become binucleate (Hirmer, 1920). Except for clamp formation, true branching, vegetative anastomoses and the virtual binucleate character of the coenocytic cells, which characteristics are not similar in all forms and may not always be recog- nized with sufficient certainty, the appearance of the secondary diploid hyphae agrees so closely with the primary haploid hyphae that it has been possible only by the use of cytological methods to demonstrate the cor- rectness of the differentiation into primary and secondary mycelia. In rare cases, e.g., Corticium roseo-pallens (Lyman, 1907), the secondary hyphae may form conidia which appear entirely similar to those formed on the primary mycelium ; or they break up into binucleate oidia which are not separable from the uninucleate oidia (Fig. 355, 1); or they may form gemmae which rarely show a further morphological differentiation from the haploid gemmae; or they may develop into sprout cells, only distinguishable from the uninucleate cell by cytological study; or, in certain cultural conditions, apparently by a process of degeneration, they may regain a uninucleate condition. In the Uredinales, the secondary mycelium differs markedly in biological relations and in secondary spore forms. There is no fundamental difference between haploid and diploid myce- lium in the Basidiomycetes such as there is in the Ascomycetes. In many species, it is almost impossible to determine microscopically the point of origin of the diploid mycelium, which grows gradually from the haploid mycelium and develops similarly. In other forms, as in Merulius lacrymans and in some species of Coprinus, the types of mycelium show small physiological differences, e.g., different moisture relations, so that the diploid mycelium is elevated as an aerial mycelium above the haploid mycelium which is repent or submersed. Both are culturable in the same substrate, both are adapted to independent existence; the diplont, in contrast to the ascogenous hypha of the Ascomycetes, no longer needs to be nourished by the haplont. It is rather the vegetative mycelium par excellence which winters over in the earth in many species, e.g., mush- rooms, and forms lichens and mycorrhizas. Where we find free Basidio- mycete mycelium in nature, we are generally dealing with secondary mycelium. This has led many authors to call the clamp-bearing, diploid mycelium the true characteristic mycelium of the Basidiomycetes. Since it is vegetative mycelium (in contrast to the ascogenous hyphae of the Ascomycetes), the secondary mycelium of the Basidiomycetes is the final mycelial form only in the parasitic forms (as in the simpler Auriculariales and Polyporales as well as the Uredinales, Ustilaginales and Exobasidiaceae) ; in these the hyphal ends are transformed directly to basidia. In all higher forms, the secondary mycelium does not proceed as such to the formation of basidia but its hyphae intertwine with exten- BASIDIOMYCETES 405 sive change of form and often with loss of individuality to form fructifi- cations, tissues and organs which in their structure and functions are specialized like those of the Cormophyta. All these tissue-like hyphal systems (plectenchyma, etc.) which have grown from the original, uni- form, secondary mycelium are called tertiary mycelia, and develop either as rhizomorphs and sclerotia or as fructifications. The mycelial threads develop in connection with fructification and sclerotial formation. Their existence may be easily understood, from an anthropocentric point of view, by considering that an enormous store of G, Gj Fj Gs ♦ ♦-Hm-* Fig. 268. — Mcrulius lacrymans. 1. Portion from mycelial strand. 2. Section of fructification. H, ordinary vegetative hyphae; Fi to F3, developmental stages of filamen- tous hyphae; Gi to Gt, developmental stages of vascular hyphae; G5, degenerating hypha; Hm, hymenium; Tr, trama. (1 X 240; 2 X 120; after Falck, 1912.) nutrient is necessary in order to develop in a short time the large and complex structure which we call the mushroom. The ordinary vegeta- tive hyphae with their clamp connections would hardly be adapted to rapid translocation. At the base of the fructification, mycelial threads of variable thickness, originally formed of a few hyphae, penetrate further into the ground, and gradually fuse with other threads to larger structures. Their anatomical and ontogenetic relationships are still little known. By the investigations of Falck (1909, 1912) on Lenzites and Merulius, it was shown that in these two genera the original, central hyphae have largely disappeared and new hyphal systems, "vascular" hyphae and " fibre" hyphae, are formed whose structure and grouping are character- 406 COMPARATIVE MORPHOLOGY OF FUNGI istic for the individual species and afford important diagnostic points (Fig. 268, 1). The vascular hyphae (Fig. 269, 2) form the real conducting elements; in their formation the hyphae swell, increase the diameter of their lumen, thicken their walls, dissolve the septa, transform their clamps to open tubes and increase their resistance to pressure by ring and spiral thicken- ings and by moniliform trabeculae across the lumen. Functionally, they are comparable to the sieve tubes of the flowering plants. The fibre hyphae are the mechanical element of the rhizomorphs. As a rule they Fig. 269. — 1. Coniophora cerebella. Two whorls of clamps, the lower of which has developed branches. 2. Lenzites abietina. Portion of vascular hypha. S, former clamps ; H, unaltered parts of hyphae. (1 X 500; 2 X 240; after Falck, 1909, 1912.) surround the vascular hyphae on all sides as a protective coat; their walls are considerably thickened with a corresponding diminution of lumen, their septa and clamp connections are degenerate, contents are conspicu- ously lacking; in short they resemble closely the wood fibers of the Cor- mophyta. Similar relationships have been determined by Bambeke (1901, 1914) for Lepiota meleagris and Phallus impudicus. Occasionally the mycelial threads do not function as conducting organs, but acquire a more sclerotial structure with white core and brown, brittle, pseudopar- enchymatous rind ; the individual hyphal elements give up their individ- uality entirely and apical growth follows by an apical meristem, as in BASIDIOMYCETES 407 the root tips of Cormophyta. These sclerotic, thread-like and apically growing structures are called rhizomorphs. While all these threads with marked growth in length, especially in their development as rhizomorphs, can penetrate far over unfavorable areas, the tertiary mycelium of the sclerotia and fructifications (sporo- phores) is characterized by very small power of growth and particularly by the lack of a definite growth in length. The sclerotia result directly from the secondary mycelium ; in structure they are similar to the rhizo- morphs, consisting of a compact pseudoparenchymatous rind and a core formed of laminated cells. Occasionally they are formed in large numbers, reach only a small size and are called bulbils. When brought into favorable surroundings, they usually develop to secondary mycelia, seldom to fructifications. In contrast to the Ascomycetes, basidial fructifications arise, as the sclerotia, from a tangle of secondary hyphae, seldom indirectly from sclerotia, rhizomorphs or mycelial threads. In the latter case, their tissues develop by degeneration from the tertiary tissue. In contrast to the simple Ascomycetes, their appearance does not coincide with plasmo- gamy, for in Basidiomycetes this is shifted into the vegetative mycelium and the hyphae which form the fructifications have been binucleate for considerable time. Fructifications in nature apparently are a complex of numerous loosely intertwined, diploid individuals which have developed from different spores and have copulated independently of one another a long time before the formation of the fructification. In some species, as in Coprinus nycthemerus, Armillaria mellea, Schizophyllum commune Panaeolus campanulatus and Anellaria separata (Kniep, 1911, 1913, 1919; Vandendries, 1923), the fructifications occasionally may develop parthe- nogenetically from the uninucleate hyphae but they certainly develop much later than normal fructifications. Purely physiological fac- tors such as humidity, light relations, nutrition, etc., determine the exact moment for the beginning of the fructification (Wakefield, 1909). In many terrestrial species in which the mycelium grows centrifugally, the fructifications appear in concentric rings often called fairy rings; these increase each year in diameter, e.g., in eastern Colorado, U.S. A., 12 cm. per year with 60 cm. in very favorable years, and in unfavorable years none at all (Shantz and Piemiesel, 1917). As the mycelium takes a part of its organic substance from the ground, and returns it later in concentrated form with the decomposition of the intertwined hyphae within a narrow circular zone, they bring about definite ecological successions. In Lycoperdon, Marasmius and Calvatia the growth is locally stimulated by generous nitrogenous fertilization, in others, e.g., in Psalliota tabularis, the plants are damaged or entirely killed, for some unknown reason. The fructifications are generally fibrous or gelatinous; at other times, because of the thickening of the hyphal walls, they are firm; in the higher 408 COMPARATIVE MORPHOLOGY OF FUNGI forms they are differentiated into numerous layers of tissue; in many genera they are permeated by latex and fat-containing ducts, which are elongate, branched, non-septate, labyrinthiform, anastomosing hyphae of variable thickness. These ducts arise as branches of mycelial threads and contain within a multinuclear, vacuolate cell, milky or colored emul- sion or a hyaline sap which colors on exposure to light or possesses other characteristic properties. Occasionally some of the branches rise from the subhymenium between the basidia (Fig. 270) and end on the upper surface of the hymenium (Fayod, 1889; Istvanffi and Johan-Olsen, 1887, Istvanffi, 1896). In the simplest case, the fructification represents a more or less thick hyphal mat which lies on the under side of the substrate, grows radially in an umlimited manner, bears the hyme- nium on the lower side and differentiates new young hyphal and basidial elements at its periphery (Fig. 380). Fructifica- tions of this type are called resupinate. Often they persist and renew their hyme- nium in every subsequent period of growth on the same surface, so that they finally develop to a thick crust formed by annual layers. The development from these resupi- nate crusts has proceeded in two direc- tions, one mainly hypogaeous, the other epigaeous. In the hypogaeous types, the fructification becomes tuberiform and is differentiated into a firm rind or peridium, and a fertile interior which develops later into a basidia-bearing tissue, the gleba (Fig. 314). In the higher groups, Gasteromycetes, the gleba is freed from its surrounding peridium and elevated by a special structure. In the epigaeous types, the crust form is retained; but in these the hymenium continues to show a tendency to develop underneath. If for example, the crust spreads over the surface of a horizontal substrate, it generally remains sterile on the upper surface, raises the margin from the substrate and forms the hymenium on the lower surfaces of these margins. If, on the other hand, the mycelium lies on a vertical substrate, occasionally the hymenium may form on the vertical surface; generally it develops horizontally in zones forming characteristic brackets which bear the hymenium only on the lower side (Fig. 291). Doubtless the number of factors which can have favored the placing of the hymenium on the lower side is very great. The hymenia are protected from rain and dew, from falling leaves and from undesirable fSg ~s=#€yj-?^7k-=r'^-2?,=s=i« ^£ Fig. 270. — Corticium seriate. Latex vessels penetrating hymenium from below. ( X 150; after Istvanffi, 1896.) BASIDIOMYCETES 409 transpiration in dry weather; they are withdrawn from direct insola- tion, a fact which may be important in the lower forms with hyaline spores whose power of germination may be influenced by direct sunlight. Thus the spores of Schizophyllum commune and of Daedalea unicolor germinate more slowly when they have been placed in the sunlight a few hours than when kept in the dark. Finally, spore discharge may be influenced in different ways, since in the Basidiomycetes the spores are not shot out over a large area, as in the Ascomycetes, but are dissemi- nated passively (by wind in the epigaeous forms). From these bracket fructifications, there is an uninterrupted transition to stipitate forms; first, to those whose stipes are inserted laterally (Fig. 348), later (apparently for the better division of the static moments), to the centrally stipitate pilei. Which irritability complex and what correlated response conditions the hereditary form of the manifold fructifications is still unknown. In any case, it is certain that as the humidity and light relationships were determining factors for the forma- tion of the fructifications, so also these factors materially influence their form; thus, in the dark, Polyporus squamosus does not form a pileus but its fructifications are branched like antlers and sterile. In cultures of Lenzites saepiaria (Zeller, 1916) the early fructifications are clavarioid although fertile, while the later ones more closely resemble the normal daedaloid or lamellate forms found in nature. Along with this transition from resupinate crusts to centrally stipitate pilei, there is a remarkable increase in mass, i.e., in weight and food content of the fructification. Its dry weight amounts to approximately 10 per cent, and contains 30 to 50 per cent nitrogenous material, mostly proteins of unknown composition, 20 to 40 per cent carbohydrates, chiefly mannite and glycogen, and 2 to 6 per cent fat. Because of this wealth of nutrients, those fleshy fructifications which are used for human food are most ephemeral and will not withstand even transitory desicca- tion; while those which are poor in digestible nutrients, the woody fructifi- cations, are often adapted to extreme xerophytism; they can resume their life processes after desiccation for a year and, consequently, may attain an age of eighty or even more. Morphologically, as a consequence of the limitation of lateral growth, there follows, with the transition from the resupinate crust to the hypogaeous tuberous form, and to the epigaeous, centrally stipitate fructifications, a general change in principle of growth. The resupinate crusts and the brackets arise from a more or less expanded unlimited hyphal tissue and consequently may become a meter in breadth, if there is no limiting factor of growth. The fructifications of the higher forms, however, arising from a spatially limited mycelium and tuberiform tangles of hyphae, are somewhat influenced in size by the dimensions of these tuberiform fundaments. With the lower forms, this limitation 410 COMPARATIVE MORPHOLOGY OF FUNGI does not seem obvious because in them the fructifications may grow actively during and after their formation. In the higher forms, as in the Agaricales and Gasteromycetes, the fructifications are formed from the interior of hyphal tangles; consequently, active growth ceases as soon as differentiation of these hyphal masses is ended. Since their size chiefly depends on the dimensions of their original fundaments, they develop further only by expansion (elongation) and similar processes. There- fore, these fructifications are mature when differentiation ceases. No longer, as the resupinate crusts, are they a complex of relatively inde- pendent elements of unequal age (e.g., the older in the middle and the younger at the edge), but an organic entity which is young as a whole and matures as a whole. Parallel with this gradual limitation of the dimensions of the fructifi- cations, and with their development out of tuberiform hyphal tangles, hymenia are formed in the interior of the fructification. In this, one may distinguish three stages which merge into each other. The first, or gymnocarpous, stage includes all crust and bracket forms and some pileate forms of simple structure, where the basidial layer is formed on the free surface of the fructification (Fig. 286). In the second, or hemiangiocarpous, stage, which includes the majority of the pileate forms and in which the fructifications develop directly from the tuberiform fundaments, the sporiferous layer is differentiated from the tissue in the interior of the fundaments. Before the completion of their development, they are freed from the universal veil and pass through the last stages of their development as in the gymnocarp type (Fig. 293); their ontogeny is the reverse of their supposed phylogeny. Finally, the third and highest, or angiocarpous, stage includes the Gasteromycetes, where the sporiferous layer remains enclosed in the universal veil (Fig. 319 to 321) until the basidia mature. The structure of the hymenia is apparently correlated with the tran- sition from growth unlimited by time and space, to morphological com- pactness at maturity and, from the gymnocarpous to angiocarpous origin of the hymenia. In the resupinate forms, in which the hymenia can spread out laterally in an unlimited manner by the successive addition of new elements, the surface is smooth and level. These smooth hymenia occur also in some of the higher families which are directly connected to these resupinate crusts; all sorts of indentations, elevations, folds, teeth, spines, tubes, etc., help to increase the area of the hymenium (Fig. 290). In the higher forms, these structures increase and result in the lamellae, alveoles, tubes, etc., of the mushrooms. In the selection of these forms, the production of the greatest possible number of spores with the smallest possible use of material will not have been of prime importance; for the senescent fructifications (e.g., the edible mushrooms) still possess lavish amounts of food material which BASIDIOMYCETES 411 would have made possible a many-fold increase of their spore production. The critical point for the differentiation of the hymenophore seems to lie more in the fact that the lateral elongation of the fructification is limited in nature by practical bounds (especially in the stipitate forms, by the static moment) and that, with the increasing development of the angio- carp, the surface necessary for spore formation is forced into narrower limits. Thus, this differentiation of the sporiferous layer reaches its maximum in those forms where, as a result of the development of the fructification (maturity), a supplementary enlargement of the ground plan is no longer possible. The effectiveness of this principle of folding is shown by the following coefficients (Buller, 1909) : in Russula citrina the hymenial surface is seven times larger than it would be if the hymenophore on the lower side of the pileus were smooth; in Amanita rubescens ten to twelve, Armillaria mellea about thirteen, Hypholoma sublateritium seventeen to eighteen, in Psalliota campestris about twenty, Fomes igniarius about thirty-eight, F. applanatus about 164, etc. In these last forms, one must also remem- ber that the fructifications are perennial and each year form a new hyme- nial layer over the old one so that their coefficient increases in geometric progression. Thus the numbers of spores is enormous : a cap of Polyporus squamosus produces over 100 billions of spores per annum. At the time of spore production it discharges at least a million spores a minute and continues this production through several hours or days. The Basidiomycetes (as the Ascomycetes) fall into two groups according to the development of the sporogenous parts. In one group, the basidia develop irregularly throughout the sporiferous tissue, as do the asci in the Plectascales ; this group presents no peculiarities. In the other groups, the basidia develop to uniform, palisade layers, i.e., to hymenia. This second group may be divided into two types; in the first type the parallel hyphal ends forming the fundaments are not themselves transformed into basidia but they remain sterile and form their own layer of paraphyses; the basidia are distributed in the subhymenial tissue and grow singly through the layer of paraphyses forming a continuous layer rather late (e.g., Fig. 343). In this type the sequence of paraphy- ses in time and space (looked at from incongruence of the cytological development of the paraphysis) conforms with the hymenium of the Discomycetes and suggests Exobasidium (p. 532) in which the new basidia arise directly on the secondary mycelium and gradually force their funda- ments between the older basidia; consequently, it is regarded as primitive and is called the protohymenial type (Maire, 1902). In the second type, the collective development of the parallel hyphal ends proceeds at a uniform rate (Fig. 294). As this type has developed the individual characteristics of the Basidiomycete hymenium, it is called the euhymenial type. The hyphal ends of its young hymenial 412 COMPARATIVE MORPHOLOGY OF FUNGI fundaments are differentiated in two directions, as sterile organs and basidia. In the hyphal ends destined for sterile organs, the nucleus of the ter- minal cell degenerates. According to their further relations, they may be divided into paraphyses and cystidia. In the development to paraph- yses they increase in width, and serve to keep the basidia apart and, by their elongation, to aid in the expansion of the pileus. In the development to cystidia, they elongate greatly (even reaching a length of 0.2 mm.), rise far above the hymenium, then swell greatly (Fig. 294, 1) and often are covered with slimy excretions or with crystals. They are distinguished from paraphyses by their peculiar form and smaller numbers. Usually they may be traced back deep into the tissue layer and are probably located at the ends of the "vascular" system; occasion- ally they may be only basidia whose reproductive function has been hindered by oily and fatty substances. Their walls are occasionally thickened (except at the tip). Their form is very variable but usually constant for a given species (Demelius, 1911). Their function is still unknown. Knoll (1912) held them to be hydathodes, which give off the end products of their metabolism in the form of drops of liquid. Levine (1913) laid more stress on the slimy property of the drops of liquid, as often drops of water may be given off from any portion of mycelium of fructification (Merulius!) . He held them to be druses similar to the druses of higher plants. In any case, it is notable that the gel given off from larger groups of cystidia is visible to the naked eye. In the course of their development, the cystidia in certain families, e.g., the Coprinaceae, seem to have undergone a change of function and no longer serve excretory but rather mechanical functions, especially as supports of the lamellae. Special forms of cystidia with oily, granular content are called gloeocys- tidia. Observations on Sebacina gloeocystidiata show curious bands of deeply staining material along the cell wall, after the nucleus has com- pletely disappeared (Kuhner, 1926). In the development of the basidia, the dicaryon of the terminal cell fuses (as in the young ascus) to a single large diploid nucleus. The terminal cell functions as a zeugite, just as the hook cell of an ascogenous hypha (e.g. the terminal cell of the Plicaria type). It elongates and becomes a basidium. In many species, this development proceeds very irregularly so that mature basidia are frequently intermixed with young ones and the usual hyphal ends. These latter, although they are only undeveloped basidia, have been erroneously called paraphyses in system- atic literature. The basidia may be divided into several types according to the peculiarities of their further development. The basidia in which nuclear division is not followed by formation of septa are called auto- or holo- basidia. In the first type they are mostly cylindrical, elongate con- BASIDIOMYCETES 413 siderably during their further development (they increase in breadth only slightly) and, at maturity, project considerably above the hymenium. The spindle of the first nuclear division (meiosis) is sometimes longitu- dinal, more often oblique (Fig. 271, 2). The spindles of the second nuclear division are situated at unequal heights and are more or less longitudinal. The diploid nucleus generally passes through three steps of division, so that the young basidium is eight nucleate. This special type, within which are placed longitudinal or oblique nuclear spindles, where the basidia are cylindrical or variable in form, is designated as the stichobasidial type. The example given here, the Cantharettus basidium, is, consequently, a stichobasidial holobasidium or, more briefly, a sticho- basidium (Fig. 265, 7 to 12). The young basidium becomes clavate, Fig. 271. — Cantharettus cibarius. Development of basidia. (X 1,20U; after Juel, 1917.) lengthens only slightly and is very constant in form. The spindles of all nuclear divisions lie approximately at the same height and near the tip, mostly directly under it, and crosswise. This second type of holobasidium, which is distinguished by the constant clavate form of basidia and by the apical nuclear spindles placed crosswise at the same level, is called the chiastobasidial type and the resulting basidium, chiastobasidium. These two developmental types of holobasidium, the sticho- and chiastobasidium, are notable, even in a group in which they appear beside each other, in possessing no transitional forms. In the cases in which it is believed that transitional forms have been found, e.g., Boletus (Levine 1913) the published figures, 58, 62 and 77, may easily be explained by the sections being cut in an oblique plane.1 1 This summary dismissal of Levine's figures does not apply to Exobasidium Rhododendri (Eftimiu and Kharbush, 1927), where figures 32 and 34 show respectively a sticho- and a chiastobasidium, or figure 36 where two spindles are transverse and one is longitudinal. The same is shown in figures 5 and 5' in E. discoideum. This con- vincing evidence of the absurdity of recognizing the Cantharellales as a separate order was received after this book was in press, too late to make such radical changes as the suppression of the Cantharellales would make necessary. 414 COMPARATIVE MORPHOLOGY OF FUNGI Further development of the sticho- and chiastobasidia proceeds similarly. In the next step, the daughter nuclei of the primary basidial nucleus remain passive. Independently of the position of the nucleus, the basidia form small protuberances equal to the number of the nuclei which are usually differentiated into sterigmata and young spores (Fig. 265,12). Sometimes this process proceeds very rapidly; thus in the forms with smooth, hyaline spores, there elapses 0.5 to 1.5 hours between the first appearance of the spores on the ends of the sterigmata and the discharge of these spores. In the form with thick-walled, colored spores, the time is occasionally greater, in Coprinus sterquilinus, 32 hours; nevertheless, even with the latter forms, the chief time for maturing, i.e., growth in size, takes only V± to l\i hours (Buller, 1922). After the young spores are already formed, the nuclei pass into them and they are ab jointed from the mother cell. Spore formation is exogenous on the sterigmata (in con- trast to the ascus), independent of the action of the nuclei. If the sterigmata are apical, the basidium is called acrosporous (Tieghem, 1893). This insertion has been found for all chiastobasidia and a large majority of stichobasidia. In Tulostoma (Fig. 369, c) the sterigmata and spores are lateral, i.e., on the vertical sides of the basidia and are, therefore, called pleurosporous. Thus, the stichobasidium is divided into two types, an acrosporous or Cantharellus type and a pleuro- sporous or Tulostoma type . The development of the pleurosporous sticho- basidium is imperfectly known (as can be concluded from the single figure of Tulostoma) although the nuclear division is reported to be longitudinal. Consequently, if one speaks simply of stichobasidium, one understands the Cantharellus type in contrast to the Corticium bombycinum type. While in the holobasidium, no formation of septa follows nuclear divi- sions, in the phragmobasidium, septal formation follows directly the first and the second stage of division of the primary basidial nucleus (only two stages of division are completed) so that the mature basidium is divided into four cells. As in the holobasidium, it is divided into two types according to its form and the direction of the nuclear spindles. In the first type, the basidium is slender and the nuclear spindles lie longi- tudinally at unequal levels; consequently the septa are placed crosswise (Fig. 360). This type is called the Auricularia type after the first example studied in detail. It corresponds to the stichobasidium. In the second type, the basidium is spherical or pyriform; the nuclear spindles lie at equal heights and are transverse. It is called, again for historical reasons, cruciate or Tremella type and corresponds to the chiastobasidium. Each division of the phragmobasidium forms a protuberance which is differentiated into a sterigma and spore. The nucleus migrates into the spore, which is abjointed from the mother cell and is ready for discharge. In the Auricularia type, the sterigmata are inserted laterally; the Auricu- laria basidium is, consequently, a pleurosporous phragmobasidium. In BASIDIOMYCETES 415 the Tremella type, they are inserted apically and the cruciate basidium is an acrosporous phragmobasidium. It is noteworthy that the difference between the acrosporous and pleurosporous phragmobasidium is not much sharper than that between the stichobasidium and chiastobasidium. In some orders, acrosporous basidia appear in a pleurosporous basidial group and vice versa. These relationships are significant for the systematic arrangement of Basidiomycetes. The essential facts in the development of the basidium are the fusion of the dicaryon to a diploid nucleus in the young basidium and the reduc- tion of the chromosome number and the genotypic separation of unit characters and of sex factors as it matures. Consequently, at this stage the basidium is both zeugite and gonotocont as in the ascus. In some forms fruiting directly on the mycelium, there is a tendency for the caryogamy to take place in the terminal cells of the hyphae and to await particular conditions in the environment for further development. Meanwhile the terminal cell swells more or less, stores up large quantities of foodstuffs and the primary basidial nucleus enters into synapsis. Under favorable conditions, the enlarged terminal cell forms a basidium which completes meiosis in the usual way and proceeds to spore formation. The terminal cell of the hypha, which in the previously described forms is itself enlarged to a basidium, is used here only as a preliminary stage in basidial formation; i.e., basidial formation is deferred and the functions of zeugite and gonotocont, which were originally joined in the same organ, are divided between two organs, the enlarged hyphal cells and the basidium. This enlarged hyphal cell which functions as zeugite and thereby forms the first stage of the basidium (in Neuhoff's sense an epibasidium) is called probasidium (Tieghem, 1893) or hypobasidium (Neuhoff, 1924). One can hardly go astray — and in the Auriculariales (p. 415) we will discuss this question — if one seeks the original cause for the forma- tion of this new organ mainly on biological grounds. Since imper- fect stages are usually wanting, these fungi are dependent upon the basidia as the only organs of fructification, and those individuals can best survive selection which are able to wait for the favorable moment to form basidiospores. Subsequently, probasidia and basidia still further diverge morpholog- ically. The wall of the probasidium thickens, encysts (to a certain degree) and becomes a resting cell, very resistant to external conditions (Fig. 364, 9 and 10). This gemma-like structure is called a sclerobasidium by Janchen (1923). In parasitic forms, the direct connection between sclerobasidium and basidium gradually disappears. These scerobasidia arise at the beginning of unfavorable conditions, e.g., in temperate climates, in the fall; they pass the winter in this state and in the spring germinate to a 416 COMPARATIVE MORPHOLOGY OF FUNGI basidia. This expression, germination, shows as nothing else, how far these two structures have become separated from each other in time and how much we perceive them as two organs in our use of terms, in spite of their original unity. Finally the sclerobasidium is set free from its hypha, becomes a spore and fills, in addition to its function as resting cell, also the function of propagation in some Uredinales (teliospore, Fig. 389) and also in the Ustilaginales (smutspore, chlamydospore, Fig. 399). Here, internally as well as externally, it has nothing in common with the basidium and its original connection can only be determined by phylogenetic comparison. After this digression, let us return to the basidium at the point where we left it on page 414, after the maturing of the spores. Beside the narrow isthmus in the sterigmata next the lower end of the spores, a small drop of liquid appears at a definite moment a few seconds before the discharge of the spores; this rapidly reaches its maximum size, approximately half the diameter of the spore; if the secretion of the drop of liquid is suppressed or if it is abnormally large, the discharge of the spore is also suppressed. The isthmus gelifies more or is ruptured, and the spore, together with the drop, is suddenly discharged for a distance of 0.1 to 0.2 mm., i.e., ten to twenty times its own length and the sterigma collapses. Although the mechanism of discharge is still vague, in some cases it is certain that the separation of the spores is completed actively (as with the asci) by a forcible discharge ; the efficiency of this discharge is much smaller, however, than that in the Ascomycetes and is never sufficient (e.g. in resupinate forms, if the hymenium were on the upper surface) to shoot the spores over the edge of the crust or to shoot them up high enough so that they may be taken up in the currents of air and be carried off. It is, consequently, apparent that the tendency of the Basidiomycetes to bear their hymenia on the under side of the fructifi- cations where free fall aids dissemination, is connected with this small range. With the average rate of fall of 1 to 5 mm. per second, the spores of a terrestrial fungus reach the surface of the earth in approximately one minute. This time, under normal conditions, would suffice to allow them to be carried off by currents of air. It is even possible that the enormous masses of nourishment of the fructification, regarded teleo- logically, are used in spore dissemination. Falck has demonstrated that these fructifications always have a higher temperature than their sur- roundings and that this warmth suffices, at least in limited spaces (e.g., under leaves, etc.), to create small currents of air which carry the spores by convection. This small range of a few tenths of millimeters explains why the pezizoid fructifications of the Basidiomycetes (with the hymenium on the inner side) are so seldom formed and why, if they do occur, they are inverted, i.e., with the cavity of the cup beneath. The spores could not BASIDIOMYCETES 417 be shot out over the rim of the cup, and consequently would remain in its interior. Inversely, this small range has enabled the Basidiomycetes to develop the hymenophore into lamellae and tubes. If the explosive mechanism were as powerful as in the Discomycetes, the spores would be discharged upon the opposite lamella and would remain hanging there. The weak force in the Basidiomycetes just suffices to separate the spores from the hymenium and to permit free fall from the spaces between vertically placed hymenia to the open air. The basidia depend upon wind dispersal of spores. This goes so far that, e.g., in germination of teliospores, under water they either abort or grow so long that they may discharge their spores above it. With the progressive development of fructification from gymnocarpous to angio- carpous forms, this wind dispersal becomes decreasingly effective. The hymenia lie in the interior of the fructification and, until the maturity of the basidia, remain surrounded by layers of tissues. Just as in the Tuber- aceae, the ascus ceases to be an apparatus for the discharge of spores, but is a round structure possessing a soft, flaccid wall without cover, so in the basidia the ability to discharge spores is suppressed, the sterigmata degenerate, the spores appear sessile and their dissemination is entirely passive, either by wind (e.g., Lycoperdon), by insects (e.g., Phallaceae) or by rodents (e.g., Hymenogasteraceae). In the Phallaceae, the mature hymenia are imbedded in a slimy, sweetish mass which sends out a power- ful odor perceptible by man at a distance; the spores are enclosed in this slime during their whole life, and fall with it to the ground or cling to the insects eating it. Thus the original organization of the basidium as an apparatus of discharge has only a historical significance : in the transition from wind dispersal to insect dispersal the basidia have lost their biolog- ical value. Similarly in many of the Hymenogasteraceae and Hysteran- giaceae, the fructifications possess a strong odor which attracts rodents to them. In some places they form the chief food supply of the rodents for several months of the year, and their spores are disseminated with the excrement of the animals. The basidiospores are entirely unicellular, in the lower forms hyaline, thin walled, ephemeral, in the higher forms colored, thick walled, some- times having a germ pore, mostly resting spores very resistant to external influences. In the forms with ephemeral basidiospores, the function of the biological protection is generally assumed by the sclerobasidia. In their totality as spore dust, they possess a very constant and character- istic color for each species, but these colors probably are of no significance in determining relationships. It appears much more probable that, in the different series, a development of color from light to dark has taken place in which yellow is more primitive than red and red more primitive than blue. 418 COMPARATIVE MORPHOLOGY OF FUNGI In most forms the mature basidiospores are uninucleate. In some the nucleus divides immediately after it enters the spore, so that the spore is early binucleate (Fig. 265, 14). The fact that this early division regularly appears in the four-spored chiastobasidia, especially in the higher families, e.g., Lycoperdaceae, Nidulariaceae and the Sclerodermataceae, leads to the assumption that there may be a question here of a third division of the primary basidial nucleus which has been delayed and transferred to the spore. In other cases, the reasons seem to be of a more local sort and e.g., to lie in ratio of nucleus to cytoplasm as sometimes divisions begin without being successfully completed. Finally, in still other cases, it is, perhaps, only a question of premature germination. The basidiospores, especially in the colored spored forms, often germinate only under definite and narrowly limited conditions (Cool, 1922) ; if these are not fulfilled, no germination takes place. If one con- siders that the number of fructifications remains approximately constant and that the same mycelia, as they are often perennial, may produce for years a large number of fructifications, one may have an approximate idea of how seldom in nature these conditions can be realized, and what an enormous amount of material is squandered, since from several billion spores only one succeeds to the formation of a fructification. In the lower, thin-walled forms, germination chiefly follows (with some even regularly) with a secondary spore or sprout mycelium which only later develops to a true mycelium. These forms were grouped together by Patouillard (1900) into a class, the Heterobasidiae, since the basidia are often indefinite in form. In the higher forms with thick-walled spores, they develop directly to mycelia; as the basidia are more stable in form, they comprise a class, the Homobasidiae. These mycelia, whether they proceed from the sprout cells or directly from the basidiospores are usually the uninucleate primary mycelia which we discussed earlier. We have, thus, completed a survey of the life cycle of the Basidiomycetes and now present schematically the different possibilities of this life cycle. Here the Uredinales and Ustilaginales, which will be discussed in detail later, are excluded. As an example of the first type a heterothallic form, Coprinus fimeta- rius, whose life cycle is as follows may be cited: + Basidiospores r Uninucleate + imperfect form} Binucleate ± imperfect form ^Uninucleate --mycelium r — Uninucleate— imperfect form C R Uninucleate + mycelium ^ --^Binucleate + myceliunAFructification-*Basidia — Basidiospores Diagram XXV. BASIDIOMYCETES 419 Between two haploid, dynamically different, primary mycelia, there occurs pseudogamous plasmogamy either between two hyphae, or between a hypha and a germinating secondary spore, or between two sprout cells, or between two germinating secondary spores, or it may be shifted forward into the basidiospores (as in the Ustilaginales, particularly in Tilletia Tritici), and take place between two basidiospores. Their prod- ucts are chiefly binucleate cells which develop into neutral, diploid, secondary mycelia which are not differentiated from the haploid mycelia in their fundamental relationships, and which in the Tremellales may proceed to the formation of secondary imperfect forms. Under definite external conditions, these secondary mycelia (in the higher forms) pro- ceed to the formation of fructifications upon which the basidia arise in definite layers; in these caryogamy occurs, directly followed by meiosis and segregation of sex. The tetracytes (basidiospores) germinate again to primary haploid, dynamically distinct mycelia. The second, homothallic scheme of development takes a somewhat simpler form, as in meiosis, the segregation of sex is omitted and the haploid mycelia are neutral and equivalent to each other. Although as yet no forms of this type have been investigated cytologically, there can be no doubt that in the ideal case, their development will proceed accord- ing to the following scheme: ± Basidiospores P -Uninucleate ± imperfect former Binucleate + imperfect form; I — Uninucleate ±impertect torm^ "Uninucleate -fmvceliunr > R Uninucleate ± myceliunr^— — ^Binucleate ± mycelium ^— ^Fructification -+Basidia Diagram XXVI. Mutatis mutandis, what has been said for the first, holds for this scheme, only the binucleate hyphae do not result from a pseudogamous plasmo- gamy between two vegetative hyphae but apparently from the resorption of a septum or from a nuclear division which is not followed by septal formation in a single hypha. Just as in the Coprinus fimetarius type, plasmogamy is shifted forward under certain conditions into the basidiospores (in Tilletia Tritici, Fig. 399) so this critical nuclear division, which is not followed by septal for- mation, may take place in the basidiospores. Therefrom results the following scheme which will be indicated as the third, or Gasteromy- cetous type: i — Binucleate imperfect form C R / ^Binucleate! myceliurii->Fructification->Basidia-»uninucleate then-»binucleate basidiospores Diagram XXVII. 420 COMPARATIVE MORPHOLOGY OF FUNGI Thus plasmogamy is suppressed and the haplont is limited to a short period in the basidiospore, from the entrance of the spore nucleus until its first division. In this type, where imperfect forms appear, they are binucleate, in contrast to Corticium. Comparing these three types of life cycle with the diagrams of the Ascomycetes, we observe that the haploid mycelium (the thallus in the Ascomycetes) is much reduced ; it is usually ephemeral and in the Gastero- mycetous type is entirely suppressed; the conidia and the other imperfect forms, as they occur in some Ascomycetes, are unknown in the Basidiomycetes. Parallel with this recession of the haplont, there is a complete disap- pearance of functional sexual organs in the Basidiomycetes known at present. Consequently plasmogamy takes place (as in the higher Asco- mycetes) pseudogamously between two hyphae ; but it is transferred from the hyphae of the fructifications into the vegetative mycelium; subse- quently it is shifted forward into the basidiospores {Tilletia Tricici) and is finally suppressed, i.e., replaced by a nuclear division which is no longer followed by septal formation (G aster omycetous type). In contrast to the Ascomycetes, the rhythm of development is relaxed, plasmogamy has become labile in time and place, and the Basidiomycetes are diffusely fruiting (perittogamous sensu Killian, 1924). Because of the insignificance of plasmogamy, its products exhibit no new important characteristics, i.e., after plasmogamy the diplont contin- ues to develop vegetatively (in contrast to the ascogenous hypha of the Ascomycetes, which cannot nourish itself). It is so well adapted to the vegetative function that it develops simple imperfect forms which are not fundamentally different from the imperfect forms of the haplonts. Long after plasmogamy and fixation of the binucleate character, the diplont forms fructifications, which (in contrast to many Ascomycetes) bear no direct relation to plasmogamy. Because of their diploid charac- ter, they attain to a much higher differentiation than the haploid fructifi- cations of the Ascomycetes. In most cases, their basidia occur in special layers just as do the asci of the Ascomycetes. Similarly in the young stages of these basidia, caryogamy immediately followed by meiosis occurs. In spite of the labile character or entire absence of plasmogamy, the position of caryogamy and meiosis remains unaltered in the basidia. The tetracytes are not individualized within the mother cells but arise exogenously on sterigmata. After this exposition of the course of development of Basidiomycetes, we approach the question of their origin. In this respect there are two historical schools. The school of Bary considers the Basidiomycetes as members of the Ascomycetous series, and the school of Brefeld, Tavel and Moller regards the Basidiomycetes as polyphyletic derivations of the Phycomycetes (and eventually of the Ascomycetes). The Brefeld- BASIDIOMYCETES 421 Moller attitude rests upon the external similarities which exist between basidia and conidiophores, and consequently conceives the basidia as conidiophores which have become constant in form and spore number. The Bary hypothesis, at the time of its foundation, rested mainly upon intuitive considerations and, after the death of its creator, was not further developed until recently. We will proceed through the series to the more important points of discussion. The haploid mycelium of the Basidiomycetes possesses the same characteristic habit as that of the Ascomycetes, but it is considerably more highly developed than that of the higher Zygomycetes which has hardly developed beyond the coenocytic stage. The imperfect forms of the Basidiomycetes show a striking resem- blance to those of the Ascomycetes and those of the Phycomycetes ; thus the Oedocephalum type is common to all three. The sexual organs cannot present any direct points of discussion as they are lacking in the Basidiomycetes. An extensive separation of plas- mogamy and caryogamy occurs, however, in all the higher Ascomycetes while it is only suggested in the Phycomycetes. In the Zygomycetes, pseudogamous plasmogamy is unknown, while in certain Ascomycetes, it is the rule. Since plasmogamy and caryogamy coincide in time and space or follow each other directly in the Phycomycetes, they lack the dicaryo- phase which is so common in the Basidiomycetes and which appears in the ascogenous hyphae of the Ascomycetes. One only has to imagine that in the Pyronema type, the internodes arising from the outgrowth of the hook hypha between two hook formations become longer, and one obtains a Basidiomycetous hypha as shown in Fig. 272. In the Basidio- mycetes, the complicated apparatus which is connected with the forma- tion of the ascogenous hypha has disappeared and the close relationship which exists between clamps and asci is less apparent with the great increase of the clamp containing mycelium and of a more vegetative character. Although the forms without clamps may be explained thus, or by derivation from the Plicaria type, there is still more to the matter. In any case, the clamp formations would be incomprehensible if one could not explain them as a relic of the Ascomycetes. Because of the lack of dicaryophase, zeugites are unknown in the Phycomycetes, whereas in the Ascomycetes they precede the young ascus in the form of hook hyphae. From these considerations it appears probable that the Basidio- mycetes stand closer to the Ascomycetes than to the Phycomycetes; the derivation from the latter leads to great cytological difficulties while the derivation from the former is based upon many analogies. The critical question is whether one should consider the basidia derived from conidio- phores or from asci. 422 COMPARATIVE MORPHOLOGY OF FUNGI With the derivation from conidiophores, one must consider that in the Basidiomycetes secondary spore forms may appear in the diplont. With the decline of sexual organs and of sexuality, the original zeugites and gonoconts, the asci, were lost; caryogamy and meiosis had been transferred to the secondary spore forms and fixed there; they had stabi- le V '.'-■.-*- Fig. 272. — Diagrammatic comparison of ascogenous hyphae of Pyronema with clamp hyphae of Basidiomycetes. lized the form and spore number in secondary forms by limitation of nuclear divisions and developed them to organic entities, the basidia, characterized by simultaneous spore formation. This process could have happened several times within the Ascomycetes so that the basidia, particu- larly the different types of phragmo- and holobasidia, were distinguished as convergent polyphylectic structures. On the other hand, one might BASIDIOMYCETES 423 consider, as Brefeld originally did, that this stabilization occurred first in the "protobasidium," hence its name, and that the holobasidium had arisen from it by suppression of the septa. As evidence for the deriva- tion of basidia from conidiophores, one may compare the Auricularia basidium with many earlier described conidiophores of the Ascomycetes. Furthermore, one may point to the conidiophore of several Polyporales (Hirsutella and Fomes) which apparently resemble basidia. Unfortu- nately these conidiophores have not been cytologically investigated, so that it is unknown whether in the conditions of the nucleus, such transi- tions appear and whether the conidiophores in question actually belong to the diploid and not rather to the haploid phase, in which case the whole argument fails. In any case, it is difficult to understand (and in this connection one has no indication of the essential facts) why the asci should be lost without a trace. Either caryogamy and meiosis have been retained as in the higher Ascomycetes and then the reason for the disappearance cannot be found, or they are actually parallel (with the sexuality sup- pressed) and then it is not clear why, after transfer into conidiophores, they can transform the latter to basidiospores while they retain such a fixed form throughout the Basidiomycetes. Consequently the deriva- tion of basidia from conidiophores meets with great difficulties. With the derivation of a basidium from an ascus, one may best start with a stichobasidium. Its young stages and its nuclear divisions agree closely with a young ascus and in the octonucleate stage it may not be distinguished from an octonucleate ascus. This correspond- ence becomes even more striking if one considers forms in which the clamp formation extends into the hymenium and in which also the last hyphal septum is provided with a clamp. The first difference appears in spore formation; the spores are not individualized within the mother cell but formed exogenously on sterigmata. We have a parallel to this transference of spore formation from the interior of a sporangium to the surface, in the Choanephora-Piptocephalis series of the Mucoraceae where we may follow step by step a transition, in part limited by nourishment, from endogenous to exogenous spore formation. In both cases it is a question of analogy, deferring of spore formation. The transference of spore formation to the exterior offers no difficul- ties. It is the retardation of a process which we often meet in fungi. According to this, a basidium would be an ascus with exogenous spore formation; or, as Vuillemin wrote more than thirty years ago (1893), in a much overlooked work: "La baside est an asque dont chaque cellule- fille, avant de passer a Vetat de spore, fait saillie au transport par le vent." From this primitive eight-spored basidium the four-spored and two- spored basidia would be produced by reduction of the spore number. 424 COMPARATIVE MORPHOLOGY OF FUNGI This acquires greater probability from the numerous examples in which the nuclear number still remains eight or four while the spore number is smaller. A similar origin for the chiastobasidium may be proposed. Trans- verse nuclear spindles often appear in the first division of the primary ascus nucleus, as we have shown in Taphrina and Podospora (Figs. 102, 3 and 6; 174, 3); in Hydnobolites of the Tuberaceae they lie just below the tip of the ascus. By similar considerations, spore formation would then be transferred from the interior of the ascus to the outer surface, and the spore number would be reduced from eight to four and two; thus the chiastobasidium might be considered an ascus with exogenous spore formation. Maire (1902) suggested that the stichobasidium had been transformed in different parts of the system to chiastobasidium, and in the main builds his phylogeny of the Basidiomycetes accordingly. It is difficult to see what reasons he had for this transposition. The longitudinal nuclear division is undoubtedly freer and a transverse position of the nuclear spindles may be explained, especially where it is connected (as in Vuilleminia) with a marked broadening of the basidial tip, only by a phylogenetic limitation reaching far backward, not by a casually appearing arbitrary fluctuation. Furthermore Juel (1898) suggested the possibility that the chiastobasidium may have proceeded from the TremeUa basidium, by loss of the septa. On the other hand, Juel (1916) has called attention to the fact that the eight-spored chiasto- basidium could not be explained in this manner (as the TremeUa basidium is four-spored) and he proceeded to consider the chiastobasidial forms as a separate line. The derivation of the phragmobasidium appears considerably more difficult than the derivation of the autobasidium from the ascus. A sentence of Maire (1902) appears to "hit the nail on the head," if one substitutes phragmobasidium for ascus: "La baside, a peine eclose de Uasque s'essaie pour ainsi dire dans diverses directions avant de prendre un type definitif et constant;" in other words, the ascus which has developed in the form of an eight-spored sporangium from the Protoascineae into its character as gonocont, has again relaxed from an inflexible form; it came again into a state of flux and transferred its spore formation from its interior to its surface. As in the Mucoraceae, the development of these does not remain stationary but proceeds, favored by the labile condition of the primitive basidium, in different directions; this divergence of the direction of development appears all the more natural since the possi- bilities of development for a conidiophore are far more varied than for a sporangium. We do not know what factors were decisive in this septation ; perhaps the type of spore discharge contributed. Similarly, it remains an open question whether this septation has appeared already at the ascus stage BASIDIOMYCETES 425 or has only appeared after spore formation had become exogenous and the ascus had been transformed into a holobasidium. That the families with phragmobasidia possess many more imperfect forms and conse- quently much more highly developed haplonts than the families with autobasidia, suggests direct derivation from the Ascomycetes; one must seek the point of departure, however, with the four-spored asci as the spore number of the phragmobasidium attains a maximum of four, gener- ally (in spite of four nucleation) only to two. One cannot determine when this divergence occurred. The lack of fossils, the small variety and the small extent of develop- ment of the fructifications of the orders with phragmobasidia suggests a comparatively recent date. On the other hand, this may be attributed to the fact that when the pragmobasidium loses its character of sporo- phore it suggests great age. The pragmobasidium may, in some Uredi- nales, be separated into daughter cells which develop to mycelia without further development, particularly without the formation of basidio- spores. In many Ustilaginales its typical structure and its ability to form basidiospores is altogether lost and it develops directly after the germination of the smut spores to a sprout mycelium. It may indeed be that parasitism has produced these modifications, but there are also parasitic, much modified holobasidiomycetes, e.g., Exobasidium and Brachybasidiam in which such a decadence of the basidium has not appeared. In the Uredinales and Ustilaginales, such phenomena occur much more frequently than in the high Oomycetes and Zygomycetes, particularly in the Pythium-Pei'onospora series of the Peronosporaceae and the Thamnidum-Chaetocladium series of the Mucoraceae, in which the spore formation gradually disappeared and the sporangium assumed the functions of spores. All these considerations, however, as long as they do not rest upon intermediate forms which are accessible to study, and upon geological evidence, have only a speculative character. Considering the vagueness of all these relationships, it has seemed desirable to use the neutral expres- sions phragmobasidia and holobasidia instead of protobasidia and auto- basidia with which definite phylogenetic conceptions are connected. In this connection there arises the question whether the cruciate basidium has developed independently within the Heterobasidiae or whether, connected by a preliminary foreshortening with a new orienta- tion of the septa, it has arisen from the Auricularia basidia. That they are connected with each other by transitional forms, particularly in the Tremellaceae; and that they have in part the same imperfect forms and that in both the zeugites show a tendency to develop into probasidia, suggests a close relationship. In the same way, it is still unsettled whether the phragmobasidium has developed to the Tulostoma type and the cruciate type to the Tulas- 426 COMPARATIVE MORPHOLOGY OF FUNGI nella type by suppression of the septa. The possibility of a development of this sort can hardly be questioned if one admits that the phragmoba- sidia have developed from conidiophores or otherwise ascribes to them a great age; but if one considers that they are a recently developed form, the conception of a further development of that type will meet with greater difficulties. Perhaps in this connection serological investigations might clarify the situation. While it is probable that the Basidiomycetes have developed from the Ascomycetes, it is at present impossible to say exactly when, where and how the different steps proceeded. The discussion of the question whether the Basidiomycetes are a natural or an artificial group, is futile. If one considers the transition from the endogenous to the exogenous spore formation as a single occurrence, and consequently the different types of basidia as having developed successively from each other, then the class of Basidiomycetes is a natural one. If one is inclined, as the author is, to the view that this transition was made in different parts of the system of the Ascomycetes and that extensive possibilities for develop- ment were realized within the Basidiomycetes themselves, then the Basi- diomycetes are an artificial class and, with increasing knowledge, we may determine the individual stocks more exactly. The present arrangement of Basidiomycetes is not considered final, but states the problem. It rests, in contrast to that of the typical Ascomycetes, not on the structure of the fructifications but on the struc- ture and course of development of the basidia. The Basidiomycetes are divided into Heterobasidiae and Autobasidiae. This arrangement was originally conceived as horizontal in the sense that from the lower stage with conidiophore-like basidia (Protobasidiomycetes) to the highest stage of the more extensively modified Autobasidiomycetes, there arose several parallel vertical lines of development. According to our concep- tion, this arrangement should be understood in a vertical sense. The Phragmobasidiomycetes and Autobasidiomycetes are connected by common roots and have developed considerably parallel to each other. If this conception should prove correct there should be substituted as above mentioned for the expression proto- and autobasidiomycetes, the more neutral expressions phragmo- and holobasidiomycetes. Whether one will place the Holobasidiomycetes at the beginning and the Phrag- mobasidiomycetes at the end as Patouillard (1900) and Rea (1922) advocate, or whether one will leave them in the order previously used in Germany, the future alone must show. Didactically, the placing of the Autobasidiomycetes first is better and will be followed, since the tradi- tional German arrangement has not become general among English- speaking peoples. The Phragmobasidiomycetes are distinguished by gelatinous fructifi- cations often comparatively poor in nutritive matter, by generally irregu- BASIDIOMYCETES 427 lar hymenia (protohymenial type) and by the germination of their spores with imperfect forms. Some of these characteristics, e.g., the gelatiniza- tion of the fructifications (water adsorption!) and the germination of the basidiospore, may be influenced much by environment, but these condi- tions in the same environment have affected the Phragmobasidiomycetes more strongly than the Holobasidiomycetes. The further subdivision of the Phragmobasidiomycetes rests upon the arrangement of the septa; the Auriculariales, Uredinales and Ustilaginales possess Auricularia basidia, the Tremellales cruciate basidia. The Holobasidiomycetes are distinguished by decreased conidial formation, by increased oidial formation and by fibrous fructifications, often filled with nutrients, by regular hymenia (Euhymenial type) and by the germination of the basidiospores by germ tubes. Some of these characters may be determined by other influences, e.g., the decrease of conidial formation by the suppression of the haplont, and the direct germination of the basidiospores by the thickening of the spore walls, which is unfavorable to the formation of sprout cells (cf. in the Phragmo- basidiomycetes, Phleogena with thick-walled basidiospores, germinates directly with a germ tube). The further arrangement of the Autobasidiomycetes is still an un- solved problem. Formerly a few characteristic orders, the Dacryomyce- tales, the Plectobasidiales and the Gasteromycetes were distinguished and the rest were left in the Hymenomycetes, as if the majority of the Basi- diomycetes did not possess hymenia. In order to meet this difficulty, we will attempt to segregate the orders on the basis of stichobasidium and chiastobasidium. It is true, indeed, that the phylogenetic significance of both these types still remains an open question, that this system becomes rather incomplete by the use of cytological characters (on account of the small number of investigated forms) and that a separation of the converging forms, conducted on cytological foundations is tiresome for the systematist of the herbarium. On the contrary the contrast of stichobasidium and chiastobasidium within the fluctuating forms of the Autobasidiomycetes which are connected by numeroust ransitional forms, is the only constant recognizable pair of characters at present, and, consequently, is more reliable than the structure of the hymenium and of the fructification. It is not the problem of a work of this kind to make easy the recognition and identification of an unknown fungus, but to discuss fundamental questions of relationships and to point out gaps in our knowledge. The stichobasidial group is still poorly known. It is divided accord- ing to the structure of its basidia into two orders, the Dacryomycetales and the Cantharellales. The chiastobasidial group contains a large majority of the Autobasi- diomycetes. They are divided into three forms on the basis of their devel- 428 COMPARATIVE MORPHOLOGY OF FUNGI opment: gymnocarpous (Polyporales), hemiangiocarpous (Agaricales) and the angiocarpous (Gasteromycetes) . The Polyporales and Agaricales are included in the earlier term Hymenomycetes ; their division does not rest, as might be supposed from the typical genera Polyporus and Agari- cus, on the tube and gill structures of the elevations of the hymenophore but upon the gymnocarpous or hemiangiocarpous method of development of their fructification. In this sense, the Basidiomycetes fall into nine orders. Within these, the simpler ones begin with loose hyphal wefts and solitary basidia and develop successively to the higher forms, the gymnocarpous and angio- carpous fructifications, wherein they generally converge to similar types of organization. The main outlines of the phylogeny in this sense has been completed, therefore it may be observed that individual forms pass through these stages ontogenetically in artificial culture. The probable relationships between these orders are presented diagram- matically at the end of the book. The left wings include forms with septate basidia, which are apparently derived from these; in the middle are both orders with stichobasidia; the right wings contain the orders with chiastobasidia. It is self-evident that the relationships existing between the different orders in a horizontal direction cannot be sufficiently expressed in this scheme as it must of necessity be two dimensional; e.g., the Dacryomycetales and Cantharellales are more closely related to the Auriculariales, and the Polyporales more closely allied to the Tremellales than is to be inferred from this scheme. If in the future the chiasto- basidia, contrary to the hypothesis stated here should be proved to be cruciate basidia without septa, the whole right wing should be placed above the Tremellales. CHAPTER XXVI POLYPORALES The Polyporales include the gymnocarpous stage of the Chiastobasidio- mycetes and ascend from simple forms with a hymenium which is spread out over the substrate in an arachnoid layer without definite margins to resupinate crusts, to typical pileate fungi, and finally form the starting point for the angiocarpous line of development which attains its maximum in the stink-horns of the Gasteromycetes. The hymenophore is always on the outside and, in the simpler forms, is smooth. In the higher groups, it forms anastomosing wrinkles, folds or lamellae, which sometimes have shallow grooves between them, some- times deep, tubular or elongate cracks or holes. In the highest forms, it is generally divided into pores which have given the scientific name, Polyporales. The hymenia, in contrast to the Agaricales (except Lactariaceae), are often formed in youth when the hymenophore is still smooth. With the development of folds and tubes, new and younger elements are always added laterally. Similarly, in a given zone, they develop successively rather than simultaneously, so that old and young basidia are inter- mingled. In many species with perennial fructifications, in each growing period a new hymenophore is laid down over the old hymenium, so that these are equivalent to annual rings of vascular plants. In contrast to those of the Cantharellales, the basidia (Fig. 340) are very regular in their structure and generally have four spores. By maturity they become more or less clavate without noticeable elongation, the spindles of all the nuclear divisions lie transversely at the same height near the tip, mostly directly under it (chiastobasidial type). The diploid nucleus divides only twice so that the young basidium is generally quadrinucleate. A third nuclear division appears rarely or not at all; possibly it is removed to the spore whose nuclei generally divide in the young stage. This division, however, is not always completed. As imperfect forms, oidia are known in many genera, in some also gemmae and typical conidia. The Polyporales contain over a hundred genera with several thousand species; they include heterogenous types which in their extremes are very characteristic but pass through numerous intermediate forms retro- gressively toward ancestral types. Therefore systematic classification cannot be accomplished according to fundamental characters, but only 429 430 COMPARATIVE MORFHOLOCY OF FUNGI W 2 $ w «*: w o < £ 03 c P 3 co 1-4 fe \M w < CO o3 K hO U >> > w . « i- > .gig J E.3 ft, J Q Ph Ph fe H Ph ►* C S —'-2" C S3 - ,«i 4)5 O O O «< O w < w CO 3 o o < o3 .2 J o3 = * "S «- . -1 .2 >>.£ Ph fflUO< >* U w W u Q J* a 3 O fi 4) O-C c P o -o-o ■« S-S'C o 3' S aj"C.E o3 5 =i ! 5 ^ C 4< v-aTS o *■ c e 2 o g OT3 t- KS(gawS^S£S(i2K«<6o 'co Q w > j >.-S o H «£ o (— 1. S5 Q POLY TOR ALES 431 according to the end forms of the different series toward which they develop. In this sense, the following ten families, whose characters will be given in the course of the discussion are different. Their probable relationships are given in the scheme on page 430. Tulasnellaceae. — Perhaps in Tulasnella we have an example of the transition from the endogenous spore formation of typical Ascomycetes to the exogenous formation in the Basidiomycetes. The family presents a series with gradual adaptation to parasitism, accompanied by the develop- ment of the zeugite to a special storage organ. This development is analogous to that we shall find in the Auriculariales and Uredinales. The highest stage attained seems to be that reached by Cystobasidium. Tulasnella iPrototremella, Pachysterigma, Muciporus) is mostly saprophytic on bark or dead wood, occasionally parasitic on leaves £ Q Fig. 273. — Tulasnella deliqucscens. 1, 2. Basidia with basidiospores. 3, 4. Basidia developing uninucleate conidia (X 355; after Juel, 1897.) Tulasnella helicospora. 5, 6. Young basidia. 7. Basidium with basidiospores. 8, 9. Development of basidiospores to conidia. 10. Development of conidium to secondary conidium. (After Raunkiaer, 1917.) {e.g., T. grisea on Eichhornia speciosa in Java and T. anceps on Pteris aquilina in Europe). On the substrate they form a bloom which may thicken to a smooth corticiaceous crust. In T. deliquescens its consistency is slimy; in others, as T. thelephorea, the gelatinization of the hyphae is not marked and the consistency is waxy. T. cystidiophora, T. hyalina and T. traumatica have gloeocystidia in their hymenia and are often segregated as Gloeotulasnella. In about half the species the spores are nearly spherical while in the other half the spores are long fusiform, and sometimes curved. The hyphae are binucleate and much branched; in T. deliquescens, there are no clamps and the basidia, which are terminal on the ultimate branches, are irregularly placed and imbedded in the gel, while in T. thelephorea, clamps are abundant, the basidia are more fascic- ulately arranged and form a simple layer on the young crust which does not show the regular parallel structure of a typical hymenium. The basidium is pyriform and is cut off by a septum (Fig. 274, 3). The nucleus goes through two stages of division. At the tip, seldom 432 COMPARATIVE MORPHOLOGY OF FUNGI laterally, arise four, occasionally five or six, protuberances which become ellipsoidal, sessile spores (Fig 273, 1 and 2). In damp weather they germinate while on the basidium without being ab join ted, and each forms a short germ tube (Figs. 273, 3 and 4; 274, 8 and 9) which may branch and swell terminally to a conidium, slightly curved and pointed at the end. The conidia abjoint and germinate immediately, in T. helicospora by further sprouting. In T. deliquescens, the basidiospore, the germ tube and conidia are uninucleate; in T. thelephorea, the basidial nucleus, immediately after its entrance into the spore, passes through a third division (Fig. 274, 7); hence its mycelium is wholly binucleate (Brefeld, 1889; Juel, 1897, 1898, 1915; Raunkiaer, 1918). Fig. 274. — Tulasnel la thelephorea. 1 to 5. Development of basidia. 6. Basidium with four basidiospores. 7. Caryogamy in the basidiospores. 8, 9. Germination of basidio- spores with conidium. (1 to 7, 10, 11 X 535; 8, 9 X 355; after Juel, 1897.) The above interpretation of the reproductive organs follows that of Juel. Patouillard (1888) regarded the "basidia" of the above descrip- tion as probasidia, the "spores" as basidia, the "germ tubes" as sterig- mata and the "conidia" as basidiospores. The spores were regarded as the four separate cells of the cruciate basidium and hence related to the Tremellaceae. Neuhoff (1924) revives this conception, replacing the probasidium by the term hypobasidium and the cruciate basidium by epibasidium. Hoehnel and Litschauer report that there is a complete series of transitions between the slender sterigmata of the Corticiaceae and the "spores" of Tulasnella and consequently regard the sessile spores, which are never ab jointed, as swollen sterigmata and the conidia as true basidiospores. Raunkiaer (1918) and Burt (1919) agree with this conception and the latter places Tulasnella in the Thelephoraceae (sensu latiore) near Aleurodiscus, where the sterigmata are often swollen at the base. POLYPORALES 433 If Juel's interpretation is correct, Tulasnella with its sessile basidio- spores germinating in situ is unique in the Basidiomycetes, and does not seem closely related to any other group. If the basidium is con- ceived as developing from an ascus by gradual exogenous spore production, perhaps Tulasnella represents a transitional stage where the spore mass, without secreting a wall about itself, is pushing out of the gonotocont without having reached the stage of a separate entity before it germinates. The very primitive (or reduced) structure of the thallus points in this direction. On the other hand, such a conception would indicate that it had not yet reached a suitable mechanism for spore discharge, having lost that of the ascus without having attained that of the basidiospore. A study of the mechanism of spore discharge, as proposed by Buller, to see whether the "conidium" of Juel's interpretation is discharged as a conidium or a basidiospore, would do much to clarify the situation. Vuilleminiaceae. — The only species of this family, Vulleminia come- dens (Corticium comedens) (Maire, 1902), grows on dead oak twigs where Fig. 275. — VuiUeminia comedens. 1. Germinating zeugite. 2, 3. Young basidia. 4 Mature basidium. 5, 6. Germinating basidiospores. (X500; after Maire,190 2.) it separates the bark from the wood and forms gelatinous corticiaceous crusts 0.1 to 0.2 mm. thick. The basidia are formed in the interior of the hyphal tissue and emerge singly at the surface. The hyphae are binu- cleate, the terminal cell of a branch swells, the dicaryon fuses and the zeugite puts forth a slender basidium (Fig. 275, 1) which reaches the open air, broadens considerably at the tip and, after a second nuclear division with transverse spindles, forms four uninucleate basidiospores, in which the nuclei divide and sooner or later a septum is laid down (Fig. 275, 6). Brachybasidiaceae. — The only species of this family, Brachybasidium Pinangae, parasitic on the pinang palm in the rain forest of West Java, bears the hymenium erumpent from the stomata as a small granule on the under side of the leaf. As in VuiUeminia, the terminal cells of the hyphae swell to form storage cells, which in this species are united into a small sorus and possess a firm wall (Fig. 276). From time to time such a pro- basidium swells, protrudes its tip above the sorus and becomes a basidium which (in contrast to VuiUeminia) is not swollen at the tip, but bears two sterigmata. As in VuiUeminia, the basidia are chiastobasidia. 434 COMPARATIVE MORPHOLOGY OF FUNGI Brachybasidium is very interesting from the viewpoint of comparative morphology; for there can be no doubt that this thick-walled probasidium affords protection and makes it possible for the basidium to await favor- able conditions for germination. In this sense, it is comparable to the sclerobasidia of the Phragmobasidiomycetes. The chiastobasidial Auto- basidiomycetes have attained the same degree of development in this family as the stichobasidial Phragmobasidiomycetes in the Septobasidia- ceae, and the lepto-forms of the Uredinales. Corticiaceae. — This family includes the simplest forms of the Poly- porales; they show beginnings of the various directions of development and form thereby, as is shown in the scheme on page 430, the key to the Fig. 276. — Brachybasidium Pinangae. Section of zeugite sorus with three germinating zeugites. ( X 390; after Gaumann, 1922.) whole order. Their representatives are mostly saprophytes on earth, wood or dead parts of plants. Their basidia are generally four, more seldom two, or six to eight spored. Usually their spores are hyaline and smooth, rarely, as in Hypochnus (Tomentella), rough and brown or yellow. According to the structure of their fructifications, they may be divided into three intergrading stages of development. The forms of the lowest stage, as Tulasnella of the Tulasnelaceae, Helicobasidium of the Auriculariales and Sebacina of the Tremellales, spread out on the sub- strate in an arachnoid covering; the basidia rise, like free conidiophores, at unequal heights on the same hyphae, singly or in candelabra (Fig. 265, 1) ; thus there are formed no, or only diffuse, fructifications and hymenia. In the second stage, the hyphae intertwine to homogeneous, leathery or POLYPORALES 435 fleshy cushions, as Platygloea in the Auriculariales and Sebacina in the Tremellales, and may be designated as true crustose fructifications. Their basidia rise to the same height, and crowd together as an even hymenium which is broken only by cystidia. In the third stage, the hyphal cushions increase to bracket or even centrally stipitate fructifications. The context loses its homogeneous structure and is differentiated into a sclerotic rind and solid middle layer. Thereby, they become very resistant to external influences ; while the hyphal tissue of the first two groups appears in damp weather and in drought collapses and becomes invisible, or is entirely ephemeral, the fructifications of this third group survive climatic varia- tions and at times attain great age. 1 -- **o^ ,s S_S Fig. 277. — Hirsutella varians. 1. Habit. 2. Conidia. 3. Apparently a transitional stage from conidia to one- and two-spored basidia. 4. Basidia. (1 X16;2, 3 X390;4 X 780; after Boulanger, 1893.) In the first group are many species of Exobasidium (see p. 413), Hypochnus, Hirsutella and a small group of semiparasitic species of Corticium, while the remainder of Corticium belongs rather to the second group. In Hypochnus and Corticium, the basidia are borne on a resupi- nate hyphal tissue, in Hirsutella, on coremia. All three groups form very loose, flocculent or mealy, white or bright-colored wefts which in the higher species thicken to a fibrous tissue. At maturity, the hyphae branch and form basidia on their ends. In many species, the sub- terminal cell grows laterally to a new basidium which pushes the old one aside and later is itself pushed aside by the younger ones. By the continuous formation of new basidia and groups of basidia, the basidial layer becomes thicker and thicker and in some species gradually develops to a more or less continuous hymenium. 436 COMPARATIVE MORPHOLOGY OF FUNGI In some species, the formation of a basidium is preceded by a luxuriant conidial formation. In Hypochnus isabellinus (Tomentella flava) (Bre- feld, 1889), there appear in certain parts of the hyphae, numerous lateral branches which, throughout their whole length, cut off a large mass of red-brown, echinulate spores on short sterigmata (Fig. 278). Before the connection of these spores and Hypochnus was known, they were called Botrytis argillacea. In Hirsutella varians (Matruchotia varians) the hyaline conidia are cut off over the whole expanse of the mycelium. With the exhaustion of nutri- ent solution, the hyphae collect in coremia which gradually proceed to the formation of "basidia" (Fig. 277). These appear to be connected with conidiophores by a continuous series of intermediate forms (Boulanger, 1893). The name Corticium from cortex, bark, indicates the fructifications of all these genera are resupinate, they are directly con- nected to the hyphal tissue of Hypochnus and in these simple forms are thin, mem- branous, at times arachnoid, while in the higher forms fleshy or leathery, and gener- ally attached to the substrate over the whole expanse; thus the cosmopolitan Cor- ticium vagum (C. botryosum, Rhizoctonia Solani), the cause of Rhizoctonia disease of potato and other vegetables, often subter- Fig 278.-Hypochnus isabeiu- sheathing the roots or stems, is nus. 1. Hypha with basidium. 2. > » Portion of a conidiophore. (X350; hypochnoid. C. salmonicolor (C . javani- after Brefdd, 1899.) cum), which causes serious necrosis of bark and twigs of tea, coffee, cacao and cinchona in the tropics, has more luxuriant coverings and a continuous hymenium. In C. Koleroga (Pelli- cularia Koleroga) which causes a thread blight of coffee, the basidia are borne directly on hyphae in mycelial strands covering the under surface of the leaves and extending down the twigs. C. Stevensii (Hypochnus ochroleucus), a thread blight of apple, pear and quince in Brazil and the southern United States, differs in having chestnut-brown sclerotia 3 to 4 mm. in diameter and slightly more compact masses of basidia-bearing hyphae. In genera of the second stage of development, systematic classification is founded on all sorts of artificial characters; thus one places in Corticium (spores hyaline, thus distinct from Hypochnus and Coniophora) chiefly those forms whose hymenia consist exclusively of basidia; in Peniophora POLY POR ALES 437 (spores hyaline) those with cystidia and gloeocystidia (Fig. 279); in Epithele (Fig. 280), Veluticeps and Mycobonia those with curious sterile hyphal pegs, etc., springing from the subhymenial tissue and projecting above the hymenium. In short the system only gives first aid and hence is variously treated by different authors. Cytologically, of all these forms only Corticium lacteum, C. bombycinum, Peniophora Sambuci and Hymenochaete tenuis (Hypochnus sub- tilis of Harper) (Maire, 1902; Harper, 1902; Kniep, 1913) have been studied. Fig. 279. — Gloeocystidivm clavuligerum. Fig. 280. — Epithele Typhae. Section of Section of hymenium showing basidia and hymenium showing a peg of hyphae. gloeocystidia. (X 385; after Hoehnel and (X 255; after Hoehnel and Litschaucr, 1906.) Litschauer, 1906.) Coniophora cerebella develops very thick (often 0.5 mm.) crusts, at first fleshy and membranous, later dry and brittle. This species is as important a cause of dry rot of coniferous timber in the United States as Merulius lacrymans in Europe. Corticium centrijugum, C. Stevensii and C. radiosum (C. alutaceum) form bul- bils (sclerotia) which when dried retain their ability to germinate for several years and under favorable conditions develop to mycelia. In Peniophora Candida (P. Aegerita and Kneiffia Aegerita) these bulbils Fig. 281. — Peniophora chordalis, showing Fig. 282. — Peniophora chaetophora. (X200; basidia and cystidia. ( X 265; after Hoehnel after Hoehnel and Litschauer, 1907.) and Litschaucr, 1906.) consist of single much-branched hyphae whose branches are much intertwined; generally, in the young stages, the peripheral hyphal ends swell terminally and each cuts off one, seldom several, thin-walled conidia. These bulbils often appear in such large quantities that the hymenium is not formed; they loosen from the hyphal cushion and undoubtedly play 438 COMPARATIVE MORPHOLOGY OF FUNGI an important role in the dissemination of the fungus. They are prob- ably homologous to the hymenial bulbils of Rhacophyllus lilacinus. In other species, e.g., Peniophora chordalis, the cystidia stand far above the hymenium (Fig. 281). In P. chaetophora, they are branched and project above the hymenium in the form of setae, serving as a support for the outer, loose hymenium which creeps up them (Fig. 282). When young, they are binucleate; after the degeneration of the nucleus they contain only a clear content. In many species they are covered with calcium oxalate. As imperfect forms, conidia have been demonstrated in Corticium and Peniphora (Kneiffia) (Lyman, 1907; Hoehnel and Litschauer, 1906). In C. radiosum, they arise (occasionally on the clamp-bearing mycelium itself) on short, characteristically branched conidiophores and are bacilli- form or oidia like. In C. roseopallens, they are usually cut off in tufts on short branches and are slightly curved. In C. effuscatum, they arise on the hyphae or on capitate swollen conidiophores, and are spherical, these capitate conidiophores correspond to the Oedocephalum type in the imperfects and are again met among the Polyporaceae in Fomes (Fig. 288). In Peniophora coronilla the conidia are cut off in groups of eight on short sterigmata and appear, externally, very similar to the basidiospores. In Corticium effuscatum and C. subgiganteum are formed thick-walled gemmae. In the latter species they appear subterminally on palisade hyphae and may then be regarded as a highly specialized gemma hymen- ium. This gemma fructification was earlier considered as a separate species. Similarly, the gemmae of Peniophora Habgallae were described as Artocreas poroniaeforme and Michenera Artocreas (Petch, 1926). Corticium niveocremeum has six-spored basidia of which two spores abort, since only four nuclei are formed in the basidium, and the four fertile spores are uninucleate (Kuehner, 1926). Hymenochaete belongs to the third stage of development. As the name indicates, this genus is characterized by the presence of elongate, conical, brown setae, which blacken promptly with a solution of KOH. The setae are arranged in layers often suggesting annual rings (Burt, 1918). Hymenochaete is predominantly tropical with a rapid decrease of number of species in the temperate regions. In these, the Corticiaceae reach the highest stage of development. Their fructifica- tions are leathery, woody or corky. Stereum also begins with simple resupinate forms, gradually raises its edges from the substrate, and extends horizontally, becoming laterally attached brackets and simple stipitate fructifications. S. hirsutum and S. fasciatum are instructive examples of the dependence of the form of the fructification on its position on the substrate. In horizontal substrates the fructifications are resupinate with up-turned margins, radial in structure with the hymenium downwards. On vertical substrates they extend horizontally POLY POR ALES 439 from the substrate, turn the hymenium downwards and are notably dorsi- ventral (Goebel, 1902; Burt, 1918). They may even become stipitate if growing on the upper surface of a log. They are generally gregarious and imbricate on trees, causing an asphyxiation of the wood. Another species, Stereum purpureum on fruit trees, raises the epider- mis of the leaves from the palisade layers in vesicles, which fill with air, obscuring the chlorophyll, hence the name "silver-leaf disease" Fig. 283. — Cora pavonia. 1. Thalli on tree trunk. 2. Section of fruiting thallus. The dark, spherical structures are gonidia. The reproductive layer is formed of papillae. (1 X %\ 2 X 33; after Johow, 1884.) (Brooks, 1911, 1913). A third species, S. frustulosum (Thelephora perdrix), causes the partridge-wood disease of oak. Hymenochaete noxia, an extremely polymorphous and plurivorous fungus, is a root parasite in the tropics seriously damaging Hevea, Theo- broma Cacao, Thea and dadap. Of special biological interest is the tropical Stereum which forms the lichen Cora pavonia with the alga Chroococcus as gonidia (Fig. 283, 1). 440 COMPARATIVE MORPHOLOGY OF FUNGI This grows epiphytically on shrubs and tree trunks, forming blue-green brackets, with lighter margins. At the beginning of the period of fructi- fication, they develop on the lower side numerous spreading hyphal fascicles, whose branches terminate in four-spored basidia (Fig. 283, 2). The fungus appears in Nature without the alga and forms brackets, in living with the alga, it attains much larger dimensions, and is able to thrive in places where it could not grow alone, e.g., in the forest crown. With another alga, Scytonema, it forms another lichen which is placed in Dichonema (Dictyonema) in systematic literature (Fig. 284, 1). Under certain conditions in this association, not the fungal hyphae, but the alga determines the form of the lichen, so that this lichen is modified to Fig. 284. — Cora pavonia. 1. Dichonema sericeum form; thallus on twig. 2. Lauda- tea caespitosa form; portion of bark and leaves covered with lichen thallus which bears parallel white hymenia. ( X H ; after Johow, 1884.) a special Laudatea form (Johow, 1884, Moller, 1893). The lichens, as those here, in which the fungus component is a member of the Basidio- mycetes, are classed together as Hymenolichenes. Cyphellaceae. — This family connects directly to the Corticiaceae, especially to the Corticium stage. By a strongly hyponastic growth, the fructification develops to a pezizoid cup which contains the hymenium in the interior. Some of the genera are distinguished by a gelatinization of the hyphal membranes. In the simpler genera, as in Aleurodiscus (fructifications waxy, leathery or fleshy) and Cytidia (fructifications gelatinous), the fructifica- tions are resupinate crusts in youth. During the course of development the edges are reflexed and the fructification becomes patelliform (Stork, 1920). In Aleurodiscus, the hymenia contain peculiar paraphysoid structures; these are thin- walled and smooth, swollen toward the top, and moniform (pseudophyses, Fig. 285, 1); or they may be thin- or thick-walled and covered throughout or in spots with crowded, gener- POLY PO RALES 441 ally branched, spines of variable length (dendrophyses Fig. 285, 2). Perhaps they are to be regarded as organs of protection. In addition, gloecystidia have been found in some forms. In the higher genera, as in Cyphella (fructifications membranous), Cytidia (Auricuiariopsis) (fructifications gelatinous), the fructifications are raised from the central point of attachment by a compressed, short stipe; they then assume an infundibuliform or cup shape, whose inner side is corrugated and bears the hymenium. In Solenia, finally, the hyponastic growth begins very early and causes elongate, cylindrical fructifications which are mostly joined gregariously in membranous colonies. Their edges often bend together and enclose the hymenium during drought. Fig. 285. — Aleurodiscus amorphus. 1. Section of hymenium with basidia and pseudo- physes. 2. Aleurodiscus sparsus. Section of an apical portion of fructification with basi- dia, dark gloeocystidia and denticulate dendrophyses. (X335; after Hoehncl and Litschauer, 1907.) Clavariaceae. — While the stichobasidial line discussed in the Cantha- rellales contains a few representatives of this family, the main group of several hundred forms is probably predominantly chiastobasidial and hence should be discussed under the Polyporales. The simpler genera, Pistillaria (two-spored basidia) and Typhula (four-spored basidia), develop clavate fructifications from sclerotia and are entirely covered with a hymenium. In a few species of Typhula, the hymenium is limited to the tops of the clubs. T. variabilis on dry stems and humus and T. Betae, on decaying roots of sugar and other beets, winter over with small sclerotia, each consisting of a light core and a dark rind which is cutinized on the outside. The sclerotia germinate in spring to a luxuriant mycelium whose hyphae, in T. variabilis, bear an immense number of elongate oidia on short branches (Brefeld, 1887). The hyphae intertwine to thick bundles which swell clavately and proceed to form hymenia. Kuehner (1926) figures typical transverse spindles in the basidial nucleus of Typhula Candida. In other genera, the fructifica- 442 COMPARATIVE MORPHOLOGY OF FUNGI tions are mostly strongly branched, as in Clavaria (fructifications fleshy) and Pterula and Lachnocladium (fructifications cartilaginous or horny). Simple undifferentiated forms are also found, however, as in Clavaria, section Holocoryne (fructifications single, e.g., C. pistillaris) and section Syncoryne (fructifications connivent at the base, e.g., C. fragilis). More important economically are members of the third section, Ramaria, with coralloid, branched fructifications, of which many species are used for food. Many of the larger species, as C. aurea, C. amethystina and C. formosa, develop from large, compact, spherical masses of mycelium which may live for more than one year (Weir, 1917). In Sparassis, the branches are flattened instead of terete and often crisped. The fructifications of S. crispa {S. ramosa) attain a cross- section of half a meter and are prized as food. S. radicata causes a yellow root rot of fir {Pseudotsuga taxifolia), spruce (Picea Engelmanni) and pine {Pinus monticola). The fructifications, as those of *S. spathulata, are thinner than in S. crispa. The perennial rooting base usually is attached to the deeper lateral roots of the host and may become 30 to 50 cm. long. The peripheral hyphae in the soil are modified into a hard, resinous encrusting layer. The mycelium at the base of the stalk cements the soil particles into a stony body, often of very large dimensions. The central cylinder is composed of a compact cellular tissue of longitudinal hyphae which become looser above. The mycelium lives in the bast until the root is killed, when its rhizomorphs invade and completely destroy the sapwood. The heartwood is attacked in spots. Apparently the decay never extends above the level of the soil (Weir, 1917). Dictyolaceae. — This family corresponds to the Cantharellaceae in the stichobasidial group (p. 533) and consists of species which, on account of their chiastobasidia, have been removed from that family. Neurophyl- lum corresponds to the stichobasidial Craterellus, Dictyolus to Cantharellus. The family is apparently connected to the Clavariaceae and merges with it. Neurophyllum pistillaris {Craterellus pistillaris) is difficult to distin- guish from a specimen of Clavaria pistillaris with a wrinkled hymenium. Dictyolus bryophilus and D. glaucus were shown by Maire (1902) to belong to the chiastobasidial group. In Dictyolus ? umbonatus {Cantha- rellus umbonatus) because of the loose character of the hymenium one may see the tufted arrangement of basidia which is characteristic for primitive genera. Such an arrangement is common in the lower Corti- ciaceae (Juel, 1916). Only Neurophyllum clavatum {Craterellus clavatus) is used for food. Radulaceae. — As understood here, this family includes most of the species placed in the Hydnaceae by the earlier writers. The family is distinguished from the Corticiaceae by the presence of spines or reticula- tions on the lower surface of the fructification, covered by a hymenium. The family includes all developmental stages from resupinate crusts to POLYPORALES 443 highly developed pileate forms similar to the higher Polyporaceae and Agaricaceae. The ontogeny has not yet been studied. Irpex with flattened teeth and Hydnochaete, a segregate from Irpex with setae in the hymenium, have many points in common with Polystictus, and have frequently been considered genera of the Polyporaceae. In the resupinate stage, the simplest form, Caldesiella, corresponding to Hypochnus of the Corticiaceae, is of loose, floccose texture with rough, colored spores and conical teeth with fimbriate tips. Correspond- ing to Corticium, Grandinia has small obtuse spines covered with a hymenium, while in Ada the spines are conical. In Grandinia crustosa (Odontia crustosa) bulbils like those reported for the Corticiceae, were observed by Hotson (1912). Ada omnivora (Hydnum omnivorum) has been reported by Shear (1925) as the probable perfect stage of Phymatrotrichum omnivorum (Ozonium omnivorum) the Texas root rot of cotton. Kneiffia is characterized by its gelatinous consistency and its sterile hyphal pegs which tower above the hymenium, as in Epithele. In Odontia, Hydnopsis and Radulum the projections of the hymeno- phore are more highly developed. In Odontia (spores white) and Hydnop- sis (spores colored) the spines are sterile at the tip and cystidia are present in the hymenium ; in Radulum the spines are blunt knobs often confluent and scattered irregularly over the fructifications. In Mucronella the crust is fugacious and the spines are several millimeters long, appearing deceptively like independent fructifications. In Phlebia the hymenophore is divided by uneven wrinkles which are partly irregular and partly arranged in regular folds or ribs. In many species, e.g., P. merismoides which forms orange- yellow or flesh- colored crusts on fallen cherry, the hyphae break up into large masses of ellipsoid oidia which develop in nutrient solutions to mycelia (Brefeld, 1889). In Merulius, the end member of this developmental series, the reticu- lations are more highly developed and often suggest the pores of the Polyporaceae, but the ontogeny is fundamentally different (Burt, 1917). In Merulius the fertile hymenium is at first plane; by further growth, the surface is thrown into folds and becomes porose but the hymenium con- tinues to cover the edges of the pores. In Poria of the Polyporaceae, the formation of pores precedes the development of the hymenium. Later a hymenium develops in each pore, as in Porothelium, but these hymenia are not continuous over the edges of the dissepiments. The lower forms are floccose and resupinate, as M. pinastri, with spines in the corners of the reticulations so that it was earlier included among the resupinate species of the Friesian Hydnum. Merulius lacry- mans (Gyrophana lacrymans, M. domesticus) , so called because its myce- lium is guttiferous in moist situations, is of great economic importance in Europe as a dry rot of timber, although rare in America. Its 444 COMPARATIVE MORPHOLOGY OF FUNGI rhizomorphs become several millimeters thick, terete, white, tough and flexible when young, gray to black and brittle in age. They consist of a ground tissue of thin-walled vegetative hyphae in which are imbedded a number of functionally specialized hyphae (fibrous, vascular, etc., Fig. 268). These enable the fungus to penetrate unfavorable regions, such as cracks in the walls, and thus reach fresh uninfected wood to continue Fig. 286. — Merulius lacrymans. Fructifications on rotting beam. (Natural size; after Falck, 1912.) their growth. Upon lack of nourishment, the protoplasm contracts into short sections, surrounds itself with a thick wall and produces gemmae. The next stage is reached by the reflexed forms, such as M. tremellosus which has a broad gelatinous subhymenial layer. The highest stage is reached in the dimidiate forms, which in M. rubellus form groups of POLYPORALES 445 imbricated, tomentose, coral-pink fructifications on hard woods, often accompanied by Stereum fasciatum in the Mississippi valley. Among the pileate genera, we have an ascending series, as in the Corticiaceae and Polyporaceae. In the epixylous genera we have a number of forms corresponding to genera of the higher Corticiaceae: e.g., Aster odon with stellate setae in the hymenium corresponding to Aster ostroma, Steccherinum, leathery with hyaline spores, as in Stereum, while the perennial woody Echinodontium resembles Fomes of the Poly- poraceae so much that it was originally described in the latter genus. E. tinctorium was formerly used extensively as a dye and war paint by the North American Indian. The tuberculiform, branched masses of Hericium have long been known as wound parasites and saprophytes, e.g., H. coralloides and H. caput-ursi. Finally, in the higher terrestrial genera they have reached the same height of development attained by the fleshy Polyporaceae. Sarcodon (spores colored, tuberculate) and Hydnodon (spores white, echinulate) sug- gest fleshy species of Pohjporus while Hydnellum (spores colored, tuber- culate) and Phellodon (spores white, echinulate) suggest Polystictus. Polyporaceae. — This family in the narrower sense is connected to the Epithele group of the Corticiaceae, to Odontia of the Radulaceae and perhaps more directly to Solenia of the Cyphellaceae. The fructifications in the simpler forms, as in the Radulaceae, develop resupinate crusts or brackets, while the higher forms develop laterally or centrally stipitate pilei. In many species they are tough and perennial. In this case they form a new layer of tubes over the surface of the old ones, either with or without a layer of context separating the layers of tubes. These growth zones resemble annual rings and like them may be used to determine the age of the fructification. The hymenium lines the tubes but their edges are always sterile, in contrast to those ofMerulius in the Radulaceae. The family includes several thousand species which merge into each other without sharp limits, hence they have so far escaped satisfactory systematic treatment. They have been classified mainly by macro- scopic characters, into a few rather large genera which have been differently defined by various authors. In many groups, microscopic characters which are reasonably constant are available (Overholts, 1915) but have been little used. The family may be divided into two large groups on the basis of their pores. In the first, the tubes are circular or hexagonal in cross- section while in the second the tubes are labyrinthiform (daedaloid) in cross-section. Except in Trametes, in the first group the context (sub- stance of the pileus) is distinct from the trama, usually of a different color. Porta includes all the strictly resupinate forms with fleshy, leathery or woody crusts on decaying wood. In Poria vapor aria, a cause of 446 COMPARATIVE MORPHOLOGY OF FUNGI timber decay, Brefeld (1889) reported that the hyphae first form a felt with groups of basidia which gradually become more numerous and form compact hymenia. Later, portions of the hymenophore grow rapidly, separating the hymenium into circular discrete areas. The growing edges remain sterile, although the hymenium continues to form on the walls of the developing tubes. On the other hand, Burt (1917) states that he has never found basidia in Porta until the pores are fully formed. The difference in many cases is dependent on subjective measurements, particularly of herbarium material. Fig. 287. — Fomes annosus. 1. Exterior of normal conidiophore. 2. Section of same. 3 to 5. Small branched conidiophores with heads of few spores in 5, partially reduced to four. 6. Single, basidium-like conidiophore heads with four spores each. 7. Four-spored basidia surrounded by paraphyses. (1 to 6 X 300; 7 X 350; after Brefeld, 1899.) Fomes annosus (Trametes radiciperda) is very destructive to pine. The hyphae penetrate the roots, mount the trunk and cause there a red rot of the wood. Fructifications arise at the roots and are mainly resupi- nate. Every year is formed a new layer of pores which largely covers the older layer like a membrane. There have been reported (Brefeld, 1889) conidia similar to those of Pustularia vesiculosa and Corticium effuscatum (Fig. 287). The hyphal ends swell to knobs and cut off numer- ous hyaline conidia on very fine sterigmata of variable length. These conidia can develop to new mycelia while still sessile on the heads. In exceptional cases, there occur little heads with few spores, which are then similar to four-spored basidia and were considered by Brefeld as the POLYPORALES 447 ancestral form of basidia. In good nourishment the conidiophores branch and form coremia. Some species are used as food, e.g., Polyporus confluens, P. frondosus, P. pes-caprae and P. sulphureus; earlier, others were used as medicines (Fomes officinalis from its quinine taste) ; others found technical uses, as P. betulinus in the manufacture of charcoal crayons. Still others cause disease of fruit and forest trees and destroy timber, as Fomes igniarius, F. fomentarius, from whose fructifications tinder was formerly made, Polyporus squamosus and P. sulphureus and, on old gooseberries and currants, Fomes Ribis. The fructifications of Fomes igniarius grow to as much as eighty years old forming a new layer each year. A few species of Polyporus form sclerotia up to the size of a human head, as P. Tuberaster (E. Fischer, 1891) in the north temperate zone, P. Berkeleyi, P. umbellatus and P. frondosus in the United States, P. sacer and P. Goetzii in Africa, P. Sapurema in Brazil, P. rhinocerotis in the Malay region and P. basilapidiodes and P. Mylittae in Australia. Those of P. Mylittae attain a weight of 15 kg. and earlier were eaten by the natives in Australia and called native bread. The species of Polystictus, which number almost a thousand, are saprophytes on wood. P. versicolor often attacks fruit trees as a wound parasite. P. pargamenus causes decay of a large number of woods. Trametes, as its character is not always recognizable, has been divided by many authors among the above three genera and Daedalea (Fig. 288). Trametes Pini causes great damage to pines by a red rot of wood. Under certain conditions of nourishment, their hyphae (as in most other Poly- poraceae) fall apart into oidia. Hyaline, pyriform or oval conidia have been noted in Cryptoporus volvatus (Zeller, 1915). The hymenium develops on the roof of a large central cavity opened in the interior of a spherical fructification, laterally attached to the substrate. Gradually the portion below the hymenium ceases to grow, the hyphae are stretched into a thinner layer and a small central opening is formed in the veil (" volva"). The spores are shed upon the upper side of the veil, whence they are dispersed by clinging to the legs of insects which crawl over it. The development is therefore hemi- angiocarpous, the only case known in the Polyporales and the only group in this order which depends on insects for spore dissemination. Fig. 288. — Trametes species on wood. Lower view of bracket fructifications showing Daedalea-like elevations of hy- menophore. (Natural size; after Falck, 1909.) 448 COMPARATIVE MORPHOLOGY OF FUNGI The second group of the Polyporaceae with labyrinthiform pores, shares the fate of the first group in its systematic disorder. Here only three genera will be discussed, Daedalea, Lenzites and Favolus. In the two former, the fructifications are woody, leathery or corky, in the latter Fig. 289. — Lenzites abietina. Resupinate fructification. At a, lie numerous denticu- late hymenial fundaments, at b, somewhat older radiating fructifications, at c, irregularly assembled fructifications with common growth zones. ( X ^5; after Falck, 1909.) more or less fleshy; in all three they are perennial, rarely resupinate, usu- ally brackets. In Daedalea the folds are labyrinthiform, seldom almost lamelliform; in Lenzites (Figs. 289 and 290) they are chiefly formed as definitely radiating lamellae (even though still tortuous), which from time to time anastomose leaving between them lengthwise slits where alone the hymenium develops. At the edge of the fructification, the partitions are often closer so that the hymenophore becomes more poroid. Occasionally the lamellae develop to serrate elevations and then appear quite similar to Phlebia. In the predominantly tropical Favolus, the la- mellae are similar to those of Lenzites except that they anastomose regularly forming a faveolate network which is even more regular in Hexagonia. In Cyclomyces, the lamellae are arranged in concentric circles. Favolus europaeus is a parasite of nut trees, Daedalea quer- cina a parasite of oaks and chestnuts. Lenzites saepiaria cause a very serious decay of coniferous timbers in buildings, where it assumes the importance of Merulius Fig. 290. — Lenzites abietina. Mus- sel shaped fructifications on fir beam. At b, several have coalesced to form a bracket. (Natural size; after Falck, 1909.) especially in America lacrymans in Europe. As far as the representatives of this group have been investigated, e.g., by Falck (1909), Zeller (1916), both in their natural habitats and in cul- tures (similar to the other Polyporaceae), they pass successively through POLY POR ALES 449 all stages of fructification formation occurring anywhere in the Polypor- ales. They first form arachnoid coverings, as those of Hypochnus, with the basidia on single hyphae; then the hyphae intertwine to single teeth, spines or plates, rising from the substrate; thereupon they join to form resupinate fructification similar to those of the Radulaceae; they then develop to bracket or centrally stipitate fructifications, sometimes to thelephoroid, or clavarioid, with poriform or elongate depressions, straight or daedaloid, finally ending in age as lamellate Lenzites fructifica- tions. This example shows the impossibility of bringing these sapro- phytes or facultative parasites into a system, according to our present ideas of species. Fistulinaceae. — This family is characterized especially by the struc- ture of its hymenophore, which is covered in youth with independent Fig. 291. — Ceriomyces citrinus. 1. Branched hypha, bearing gemmae, s, clamp con- nections. 2. Part of hymenium. Between the basidia lie hyphae with gemmae, c. 3. Basidia, bearing gemmae, c. Fistulina hepatica. 4. Gemmae-bearing hyphae. 5, 6. Gemmae-bearing hyphae of a fructification. (1 to 3, 5, 6 X 350; 4 X 400; after Brefeld, 1889.) warty or granular elevations. These later elongate to peg-like tubes which are closed during growth and covered in the interior with hymen- ium; they open first at maturity. The phylogenetic connection of the family is obscure. In the scheme on page 430 it is connected with the Cyphellaceae, as the genus Solenia shows similar ontogeny. Maire (1902) connects it with the Polyporaceae and derives these from the Cyphellaceae. The edible Fistulina hepatica, which forms brackets up to a half-meter on oaks, is best known. The hyphae in the interior are binucleate at first, becoming multinucleate by fragmentation. They are penetrated by latex vessels containing a dark red liquid. The upper surface of the fruc- 450 COMPARATIVE MORPHOLOGY OF FUNGI tification is covered by a gelatinous hyphal layer which swells much in damp weather. In the parts of the tissue lying beneath it, the hyphae of the context branch fruticosely during the young stage and at their ends cut off singly or in short chains, a large mass of thick-walled, ochraceous, binucleate gemmae (Fig. 29 1 , 5 and 6) . The flesh of the fungus is streaked dark and grayish by the large number of these gemmae. In the later stages of development, at the formation of the hymenium, formation of gemmae ceases (Seynes, 1874). The other species are confined to the southern United States. CHAPTER XXVII AGARICALES The Agaricales include the gymnocarpous and hemiangiocarpous stage of the chiastobasidial Autobasidiomycetes. They are directly connected to the Polyporales especially to the Dictyolaceae (Cantharella- ceae of most authors) and develop gradually in an angiocarpous direction where the hymenophore and hymenium develop successively in schizogenetically formed cavities within the fructification. The fructification is finally surrounded by a layer of tissue. .■/.ii ^: t v. few z ;:-':*-:- ■•■■■;-': j >-.'■ vyi, :::■■■ .*■;.* w.;\~ >.^'- ,">;■>«: wf;-"'v 5 Fig. 292. — Hygrophorous miniatus. Diagrammatic sections of developing fructifica- tions. 1. Young undifferentiated fructification. 2. Beginning differentiation into pileus and stipe. 3. Beginning formation of hymenium. 4, 5. Formation of lamellae. (X 20; after Douglas, 1918.) The fructifications usually develop as centrally stipitate pilei. In contrast to those of the Polyporales, they are mostly transitory, peren- nation with annual addition of growth zones is unknown in them. They rise on mycelium or mycelial threads as knobs the size of a pin head, elongate subsequently in the direction of the main axis and differentiate into pileus and stipe. In the lowest stage, the hymenophore, as in the Cantharellales and Polyporales, develops on the surface gymnocarpously (Fig. 292); the edge of the pileus, however, because of strongly epinastic growth, gradu- ally arches toward the stipe so that its hyphae occasionally intertwine 451 452 COMPARATIVE MORPHOLOGY OF FUNGI with those at the edge of the stipe. Here belong some Hygrophoraceae and Clitocybeae. In the middle stage the fundament of the pileus is always rolled up and its edge remains connected with the stipe primordium. Thus in the interior of the tissue an annular furrow, often with several chambers, encircles the fructification; in it the hymenophore is formed (endogenous, angiocarpous). The thin tissue, in the layer from the ground tissue connected to the stipe rind, which separates this cavity from the exterior and which, in a certain sense, is a continuation of the retroflcxed margin of the pileus, is called the partial veil or inner veil (Fig. 293, A, vp). It is frequently evanescent. At maturity when the pileus expands by strongly hyponastic growth and general elongation of its hyphae, the partial veil is torn to shreds. Its remnants separate into threads and disappear, and only an ontogenetic investigation can show its original presence. Such an evanescent partial veil is found in many Lactariaceae, Marasmieae and Coprinaceae. In other cases, the partial veil acquires, from the edge of the pileus and from the stipe, new hyphal elements and consequently forms a stronger structure. Thus, in the expansion of the pileus, it is retained as such and is either loosened from the edge of the pileus (Fig. 293, a), or from the stipe. In the first case, it remains with the stipe in the form of a closely attached collar which is called the inferior annulus or ring. In the second case it remains hanging from the edge of the pileus; these remnants are usually called cortina. In some forms it is first loosened from the stipe, then from the margin and remains as a movable ring surrounding the stipe. The ring occurs in Armillaria, Psalliota and Amanita, a cortina in Cortinarius and Hypholoma, and a movable ring in a few species of Coprinus and Lepiota. In the highest stage, finally, a cortical layer of mostly thick-walled hyphae, the membranous or blemmatogenous layer, is differentiated on the whole outer surface of young button. In most cases, as in the Tricho- lomeae and the Amaniteae, it remains connected with the tissue under- neath (especially with the cortex of the pileus and the partial veil) and is only recognizable in cross-sections of young stages by its different appearence and staining capacity. At times it cannot follow the expan- sion of the pileus and remains on the pileus, as scales or as a powder or becomes a gel. In some genera, as Amanita, Amanitopsis and Volvobo- letus, it is separated from the rest of the pileus by a swelling, sharply defined tissue and remains then in connection with the base of the often bulbous stipe only : this special peridial membrane surrounding the whole fructification like an egg shell, is called the teleblem (Fig. 293, B, vu). In individual cases it is covered by a loose flocculent layer which is called the primary universal veil or protoblem. The universal veil, not being able to follow the elongation of the stipe and the expansion of the pileus, is torn to pieces and then remains behind at the base of the AGARICALES 453 stipe, as sheath or volva (Fig. 293, C, v) and at the upper surface of the pileus, in the form of scales {e.g., the white scales on the reddish pileus of Amanita muscaria (Fig. 293, C, /). In this third type, the layer of the ground tissue corresponding to the partial veil undergoes a special development. Whereas generally the longitudinal axis of the lamellae forms an approximately right angle with the stipe axis, so that the partial veil is only contiguous to the stipe at its inner edge (somewhat as Fig. 293 A, b), occasionally in this third type, the two axes form a very sharp angle to each other. Consequently the lamellae run parallel to the stipe and the partial veil (the homologue) coalesces through almost its whole length with the rind of the stipe (Fig. 293, B, ar). It does not participate in the elongation of the inner stipe tissue, however, and at the expansion of the pileus, together with some Fig. 293. — Diagram of two types of agaric fructifications, cation of second stage. B. Immature fructification of third stage, tion of third stage. {After E. Fischer.) A. Immature fructifi- C. Unfolded fructifica- portions of the stipe rind, it is loosened from the stipe up to a narrow strip at the place of insertion of the pileus and spreads out with the pileus. Thereafter, it gradually becomes loosed from the edge of the pileus and the edges of the lamellae and hangs from the point of attachment in the form of a conical frill, broadening below (Fig. 293, C, ar). This ring, as its point of attachment lies higher than that of the earlier mentioned one, is called superior annulus, or armilla. Such an armilla is found in many species of Amanita. The substance of the fructification is fleshy or fibrous in character, more seldom tough, horny or leathery. In the peripheral layers of tissues, it generally is firm and forms a highly differentiated pellicle. In many species, this pellicle (on the pileus) is separable from the ground tissue by a layer with gelatinized cell walls and is then easily separable or torn into scales. In others, it fuses directly with the substance of the pileus so that the increasing humidity in the fructification penetrates the under- lying cells and often darkens them. These species are called hygrophan- 454 COMPARATIVE MORPHOLOGY OF FUNGI ous. Sometimes the pellicle is covered with cystidia-like cells, which at the edge of the pileus, gradually change to cystidia; possibly they function as hydathodes (Fayod, 1889; Istvaniffi, 1896; Knoll, 1912). The elevation of the hymenophore is generally caused by the sub- hymenial hyphae, as those of the Polyporales, increasing their growth over the original surface of the fructification. In the lowest forms, e.g., in the first gymnocarpous type, these elevations, as in the Dictyola- ceae, spread out centrifugally from the annular furrow to the margin in the form of a few comparatively broad fleshy, or spongy folds. In the hemiangiocarpous (second and third) types, the development is more complicated and hence in part still controversial. In the (probably) simpler forms, the tramal hyphae grow from above into the annular furrow, and, under certain conditions, enter upon a temporary union with the opposite side of the furrow, the partial veil. In the higher forms, as Amanita, Amanitopsis and Psalliota campestris, the numerous cavities into which the tramal plates grow (horizontal in cross-section and running a distance around the fructification) are vertical and radiate regularly. The tramal plates are formed from the ground tissue. The lamellae in this highest type arise, not from renewed growth of the ground tissue which covers the cavity, but from the original ground tissue. Throughout the whole development they are connected with the peripheral ground tissue of the partial veil and become partially loosened from it only at maturity. Every individual cavity is laid down singly and schizogenetically. In all these other angiocarpous forms, the lamellae are usually very numerous and very narrow; their characteristic structure has given to the order the name of gill fungi. The lamellae radiate and, in typical cases, are separate throughout their whole length. Only in a side line, which also differs in other respects (Paxillaceae, Boletaceae), are they connected by partitions into daedaloid structures. In contrast to the Polyporaceae, they proceed, in the higher forms at least, to form the hymenium when they have completed their growth and attained their final form. The hymenium forms over the whole fructification com- paratively rapidly and simultaneously. Exceptionally, e.g., in Armillaria mellea, basidia develop on the aerial mycelium, singly or in more compact layers which form a sort of hymenium. The basidia correspond in form and development to the four-spored basidia of the Polyporales. Exceptionally in the lower forms e.g., Mycena we find still a third step in the division of the basidial nucleus, without the spore number varying from four. Besides, in spite of the normal quadrinucleate condition of the basidia, in Amanita bisporigera two nuclei remain behind in the basidium (Lewis, 1906). As imperfect forms, oidia have been observed in numerous genera, occasionally also conidia, gemmae or bulbils. AGARICALES 455 The Agaricales include approximately 100 genera with about 10,000 species. They are of fatiguing regularity and hence, despite the numer- ous unanswered questions, have been little studied from the point of view of comparative ontogeny. Actual systematic classification will be largely influenced by considerations of the herbarium systematist, and founded on the consideration of the color of the mature fructification and spores. The color of the spores in mass has offered assistance in the preparations of keys; the genera with white spores have been grouped as the Leucosporeae, those with violet brown spores as Amaurosporeae, those with brown (red or ochraceous brown) spores as Phaeosporeae, those with pinkish or flesh-colored spores as Rhodosporeae, and those with black spores, generally glistening violet, as Melanosporeae. AGARICALES COPRINACEAE Coprinus Leucocoprinus Bolbituis LACTARIACEAE Lactarius Russula Amaniteae Psathyrella Hypholoma Stropharia. Psalliota Tubaria Pholiota Rozites Volvaria Amanitopsia Amanita Lepiota AGARICACEAE Schizophylleae Schizophyllum Marasmieae Lentinus Marasmius Clitocybeae Mycena . Entoloma Clitopilus Omphalia Clitocybe Trirholomateae Tricholoma Armillana Cortinarius Inocybe BOLETACEAE Volvobolpfus Boletapsi6 Boletus PAXILLACEAB Paxillus HYGROPHORACEAE Gomphidius Nyctalis Hygrophorua Diagram XXIX. A few representative genera of each of the seven families will be briefly discussed, but figures of the different species will be omitted because the necessary illustrative material, at least as far as it concerns edible or poisonous mushrooms, occurs freely in the numerous guides for mycophagists, as six of the families are more or less important as food : the Hygrophoraceae, mainly gymnocarpous forms with thick decurrent lamellae; the Lactariaceae, hemiangiocarpous forms without ring or cortina and with the peculiar rosette structure of the tissue of the fructification; the Coprinaceae, hemiangiocarpous forms with a character- istic structure of the hymenium; the Paxillaceae, mainly gymnocarpous forms with the tramal layer separable from the context; the Boletaceae (gymnocarpous or pseudohemiangiocarpous, whose tramal layer is sepa- rable from the pileus which, however, possesses tubes instead of lamellae; 456 COMPARATIVE MORPHOLOGY OF FUNGI and by way of an appendix, a still obscure family, the Hemigasteraceae, angiocarpous forms without lamellae. The seventh and largest family, that of the Agaricaceae, is entirely artificial and is mainly distinguished by a lack of marked characteristics. The especially striking morpho- logical relationships between the families are shown on page 455. Hygrophoraceae. — This family is connected with the Dictyolaceae both in structure and character of the fructifications; the elevations of the hymenophore are developed to true lamellae which rise freely, comparatively far apart, and have broad cross-sections (Battaille, 1910). They are alternately of different lengths; the longer ones are often decurrent; the surface of the pileus is slimy and the trama fleshy or waxy. As far as their ontogeny has been followed in detail, in Hygrophorus (Hygrocybe) miniatus, H. (Hygrocybe) nitidus, H. (Camarophyllus) borealis (Douglas, 1918), H. (Limacium) Karsteni, H. (Limacium) agathosmus, H. Langei (H. {Hygrocybe) constans) and H. (Hygrocybe) nigrescens (Kuehner, 1926), in the young fructification the lamellae develop exogenously in the annular furrow beneath the pileus fundament and centrifugally from the stipe. In the other species, H. (Limacium) olivaceoalbus (Kuehner, 1926) and Gomphidius, they appear to arise endogenously beneath an evanescent veil which extends from the edge of the pileus to the stipe. The basidia show some primitive characters in their development. Thus in Hygrophorus (Limacium) agathosmus (as in Neurophyllum clavatum, p. 442), there are three divisions of the diploid nucleus although only four (occasionally only two) basidiospores are formed (Maire, 1902). The other nuclei remain in the basidium and perhaps are used in the formation of a second spore generation. A very peculiar cytological relationship was found in H. (Hygrocybe) conicus (Godfrinia conica) and H. (Hygrocybe) Langei in which the cells of the mycelium and fructifi- cation are bi- and multinucleate, while the cells of the hymenium and subhymenium only contain one nucleus each (Maire, 1902; Fries, 1911; Kuehner, 1926). The primary basidial nucleus divides only once (occa- sionally twice in H. Langei), both daughter nuclei lie directly under the top and gradually migrate into the middle of the basidium. Here- upon two sterigmata are formed, each of which cuts off a large reniform spore. Before or during the migration into the spores, both daughter nuclei again divide so that at separation, the spores are binucleate. While the two nuclei were seen lying close together in pairs in the trama, fusion was not observed, although the hymenial nuclei are much larger than those of the trama. The significance of this relationship may be more fully explained when the development of the primary basidial nucleus is better known. In H. (Hygrocybe) nigrescens (Kuehner, 1926), very closely related to H. (Hygroajbe) conicus, the young basidia are binucleate and the subsequent development is the usual one for this AGARICALES 457 genus. In H. (Camarophyllus) virgineus (Bauch, 1926) both four- and two-spored races are formed. The four-spored races develop normally with clamp connections and binucleate mycelia, while the two-spored race is always uninucleate and develops parthenogenetically. The haploid chromosome number is four in both races. The basidiospores are smooth and hyaline except in Gomphidius where they are dark. Their germination was followed in Nyctalis asterophora (N. ly coper doides) and N. parasitica parasitic on Russula and Lactarius (Brefeld, 1889). In these, they develop to mycelia which under certain nutritive conditions, produce oidia capable of immediate germination. In time, oidial formation disappears and is gradually replaced by thick-walled, brown or ochraceous gemmae which are rich in reserve materials. In N. parasitica the gemmae are mostly intercalary and smooth, and in N. asterophora they are terminal and echinulate or verrucose. They are liberated by swelling of the intermediate cells. In natute, they are formed in the lamellae in N. parasitica and in the periph- eral layers of the pileus in N. asterophora. They are produced in such numbers that the lamellae below the pileus are stunted or only suggested, and never mature. In small individuals, the fundament of the fructification does not extend much above the thick mass of gemmae which have an odor like that of rancid meal. Under suitable cultural conditions, the gemmae may germinate to mycelia. Agaricaceae. — This family differs from the Hygrophoraceae by the higher development of its thin lamellae; the trama becomes very thin so the lamellae consists mostly of the two hymenia. Otherwise, the characters are mostly negative. To this family are assigned all those forms which for lack of special characters cannot be placed in the other families. In this sense, they include at least eight thousand species which one, according to his taste, may divide into a varying number of tribes and genera. Five of these tribes with about two dozen genera are briefly discussed. The Clitocybeae or Collybieae form a direct continuation of the Hygrophoraceae. They are also strongly reminiscent of the Cantharella- ceae and Dictyolaceae and pass over so gradually that Clitocybe auranti- aca is often considered a species of Cantharellus. Their fructifications are fibrous or fleshy, their lamellae are membranous; in part these are still decurrent and in the majority of species are exogenous, as in Hygro- phorus. In others, however, as in Gomphidius, they are formed endoge- nously within a partial veil. The first-named type was shown for Mycena subalcalina, Entoloma fiavi folium (Douglas, 1918), Omphalia chrysophylla, Clitocybe cerussata, Clitopilus noveboracensis (Blizzard, 1917) and Pluteus admirabilis (Walker, 1919), Collybia tuberosa&nd C. velutipes (Moss, 1923), Mycena pterigena, M. sanguinolenta, M. codoniceps (Kuehner, 1926), and the latter type for Clitocybe laccatus (Laccaria laccata) (Beer, 458 COMPARATIVE MORPHOLOGY OF FUNGI 1911), Omphalia integrella (Delicatula integrella) and Leucopaxillus paradoxus (Clitocybe paradoxa) (Kuehner, 1926). The basidia belong mostly to the four-spored type; the diploid nucleus, e.g., in Mycena galericulata, shows the primitive position of this tribe by three divisions, as in Hygrophorus agathosmus (Maire, 1902). The two-spored forms resemble Hygrophorus conicus and H. virgineus in that the spores develop parthenogenetically from uninucleate basidia and subhymenial cells (Kuehner, 1927). The basidiospores are smooth or echinulate. Oidia have been demonstrated for Collybia velutipes (Biffen, 1899); sclerotia have been found in Collybia. In biological relations, Collybia eurhiza is of special interest as it is cultivated by termites in their nests in Ceylon and Java, like the South American Rozites gongylophora. Many of the species are edible. The Marasmieae are an artificial group in which forms similar to those of the Clitocybeae are grouped. They are tough, persistent, collapsing in dry weather and reviving on return of humid conditions, membranous, horny or even woody. The basidiospores are hyaline and smooth. The two best-known genera are Lentinus and Marasmius. In Lentinus, the lamellae are adnate, in Marasmius they are free. Further, in Len- tinus the tramal hyphae project in the form of fringe or teeth. The edge of the lamella resembles a saw. This group is largely tropical. In Europe Marasmius oreades, which resembles a Collybia, is used for food. Marasmius perniciosus attacks Theobroma Cacao in Surinam, M. plicatus and M. Sacchari causes the root disease of sugar cane in Java. Schizophylleae. — The only well-known species of this tribe, Schizo- phyllum commune has long held an anomalous position in the Agaricaceae, and it seems probable from the studies of Essig (1922) that it should be transferred to the Cyphellaceae, or to the vicinity of Cladoderris in the Corticiaceae or Radulaceae. Adams (1918) reported that the hymenium was formed as a lining of radiating cavities, which finally split open. Essig was unable to confirm these observations. The stipe may be either central or lateral, but is always on the side of the pileus opposite the hymenium, as in the Cyphellaceae. The mycelium is provided with clamp connections and is binucleate throughout its development, since the spore is binucleate. The fructification develops as small clavarioid tuft with an apical pore. The hyphae just behind the apex differentiate into the hymenial palisade, which expands and pulls apart the hyphae of the tip. In this stage it resembles a large Cyphella or a Peziza. The "lamellae" arise as short isolated ridges upon the surface of the hymenial primordium. The primary ridges arise successively from a point beneath the attachment of the stipe and radiate outward until they fuse with the margin of the pileus. The secondary "lamellae" arise between them and are not attached to the primary ones as sometimes reported. The AGARICALES 459 palisade layer splits over these ridges as it often does in Cladoderris, and the edges grow downward, followed by a growth of the hymenial plates. This growth continues throughout the life of the fructification. Earlier authors, as Fries, Fayod (1889) and Buller (1909), had sup- posed that the lamellae were first formed and later split due to hygro- scopic tension. While Schizophyllum commune is a weak wound parasite, it is probable that most of the damage attributed to it is caused by other Basidiomycetes which grow more slowly and hence do not reveal their presence by production of fructifications as soon as this species. Tricholomateae. — This tribe is connected to the higher Clitocybeae from which it is often difficult to separate. Some species whose lamellae are separable from the pileus {e.g., Cortinarius largus) remind one of the Paxilleae. Tricholoma nudum (Rhodopaxillus nudus) and T. Georgii are gymnocarpous (Kuehner, 1926). The partial veil is retained in some genera, in Armillaria as a ring and in Cortinarius as a cortina. As far as the ontogeny of the fructifications has been investigated, as in Inocybe (Douglas, 1920), Cortinarius (Douglas, 1916; Sawyer, 1917; Kuehner, 1926) and Armillaria (Fischer, 1909; Beer, 1911; Atkinson, 1914, 1915), a blemmatogenous layer is differentiated at the periphery of the fundament of the fructification. This layer generally remains connected with the underlying layer of tissue, particularly in the pileus and partial veil; the remnants may be observed as scales on the upper surface of the pileus after the expansion of the fructification. Armillaria mellea (Clitocybe monadelpha, Armillariell melleaa) has an enormous economic significance as a destroyer of forests. Its brown to black rhizomorphs, often anastomosing to layers of tissue in tree trunks, at times phosphorescent, spread through the ground for considerable distances. They send slender hyphae which penetrate the collar and the roots of frondose species, destroy the cell walls at the butt and cause a white rot of the wood and the death of the tree. Amaniteae. — In this tribe, the Agaricaceae reach their highest point. Differentiation has proceeded further than in the previous subfamilies: pileus and stipe differ from each other in structure and usually may be easily separated from each other. In all genera recently investigated, as in Hypholoma (Allen, 1906; Beer, 1911), Tubaria (Walker, 1919; Kuehner, 1926, Lepiota (Atkinson, 1914), Myxoderma {Limacella,Lepiota) (Kuehner, 1926), Pholiota (Sawyer, 1917) Rozites (Kuehner, 1926), Psalliota (Atkinson, 1906, 1914, 1915; Levine, 1922), Stropharia (Zeller, 1914; McDougall, 1919), Amanitopsis (Atkinson, 1914, 1915) and Panaeolus (Kuehner, 1926), the development of the fructification takes place, as in the Tricholomateae, hemiangiocarpously. In Amanitopsis, the blemmatogenous layer is differentiated into a true universal veil. The subfamily is divided into several parallel series, first recognized by Patouillard (1900), which, however, in many respects are in need of 460 COMPARATIVE MORPHOLOGY OF FUNGI consistent working out. The series of Amanitinae includes fleshy forms whose spores possess no germ pore, as Lepiota (white spored, with ring, without volva), Amanita (white spored, with ring and volva), Amanitop- sis (like Amanita without ring) and Volvaria (pink spored without ring with volva); the Pholiotinae includes similar types with ochraceaous spores, with or without germ pore, among the fleshy forms Rozites (spores warty), Pholiota (spores smooth), among the cartilaginous forms Tubaria (lamellae decurrent); the Agaricinae with spores of various colors (not ochraceous) with a germ pore, Psalliota (with ring, cap separable, spores brown) Stropharia, (like Psalliota, pileus and stipe not separable), Hypho- loma (with cortina, spores as Psalliota), Psathyrella, spores black, etc. Biologically, one species of Rozites is especially interesting. R. gongylophora (Moller, 1893) in Brazil is cultivated by several genera of ants, especially the leaf-cutting species (Atta sp.), in subterranean laby- rinthine fungus gardens. The substance of these spongy masses consists of an enormous number of little globules of up to }i mm. in diameter which are formed from the kneaded-together remains of leaves which the ants have carried into their nests as substrate for their fungi. In freshly made spots they are dark green, in older almost black, and in still older yellowish brown; they are permeated and loosely held together by white hyphae. In the upper surfaces of the gardens, the hyphae join into small fascicles measuring about 1 mm.; their ends become clavate and filled with highly refractive protoplasm; these groups form the chief, if not the only food for these ants. If the ants are removed and the gardens abandoned (as also in artificial cultures) aspergilloid conidial chains are cut off from the slightly clavate branches of the thick aerial mycelium. In poor nourishment, peculiar pockets appear on the hyphae, and the conidial fructification passes into a second stage with more oval conidia which are cut off in long chains directly from the hyphae. It is noteworthy that in the cultivated strains of Psalliota campestris, the basidia are mostly two-spored, in the wild strains usually four-spored. Perhaps the two-spored condition is a sign of degeneration in the culti- vated strains. Lactariaceae. — This natural family is characterized by decurrent, comparatively thick, fragile lamellae and rough, echinulate, mostly colorless spores. The tissue of the fructification, above all of the trama, consists of a mixture of ordinary hyphae and of sphaerocysts generally arranged in rosettes, thus appearing vesiculose to the naked eye. The sphaerocysts are swollen, originally binucleate, hyphal cells, filled with a clear liquid, whose nuclei fragment. Their ontogeny and function is still unknown. In Lactarius rufus (Kuehner, 1926), the young primordium is differ- entiated into an outer layer of vacuolate hyphae and an axis of slender hyphae with prominent nuclei and reserves at the base of the fructification. AGARICALES 461 Gradually there is formed near the top an annular furrow and the rosettes of sphaerocysts begin to appear in the interior of the stipe portion. The lactiferous ducts develop in the surface of the stipe and in the context of the pileus, perhaps derived from the auxiliary hyphae. At the upper end of the stipe the palisade, intermingled with sharp binucleate cystidia, gradually grows out over the lower side of the pileus as it expands. Sphaerocysts then appear in the pileus and the lamellae begin to form. Thus, in this species at least, development is strictly gymnocarpous and quite comparable to that of the Polyporales. In Lactarius deliciosus (Maire, 1902), the diploid nucleus divides twice, and immediately after migration into the spores, the daughter nuclei divide a third time. Imperfect forms have not yet been observed. Only inL. sanguifluus do the hyphae appear to form gemmae on short branches (Rouge, 1907). The family includes only two genera, Lactarius, whose fructifications are permeated by latex vessels and hence on wounding exude a turbid, often colored liquid, and Russula, whose fructifications lack these vessels. Numerous species belonging here are palatable and prized as food. Coprinaceae. — This family is reminiscent of the simpler Agaricaeae in the structure of its fructification (Levine, 1914; Atkinson, 1916; Kueh- ner, 1926). In the lower forms, the partial veil is evanescent, in higher forms it is retained as a ring, and in the highest it is covered by a blemmatogenous layer, occasionally by a universal veil. In contrast to the Agaricaceae the pileus does not expand at maturity like an umbrella but because of lack of geotropic stimulation, hangs campanulately from the place of attachment at the stipe. The lamellae are thin and weak, at times not over 200^ thick, often hygrophanous and subject to rapid deliquescence, as is the whole fructification. In a few species, as in Copri- nus comatus and C. sterquilinas, they are held apart by a thickening of the rim and prevented from sticking together : in others, as C. atramentarius, they are separated by large, projecting cystidia (75 to 100 per square millimeter) which reach the opposite side of the interlamellar space and bore firmly into the trama (Fig. 294, 1) (Buller 1910). The basidia do not stand, as in most other Agaricales, uninterruptedly beside each other, but they are separated by numerous, regularly arranged "paraphyses." They belong to the usual four-spored type; in many species, as C. comatus, C. atramentarius, C. stercorarius and C. ephemerus, they are constructed in two forms, one long, one short (Fig. 294, 2). The significance of this dimorphism is still obscure; it is noteworthy that the long basidia shed their pores earlier than the short (Buller, 1915). In contrast to the other Agaricales, maturation of the basidium does not take place simultaneously over the whole fructification, but gradually inwards from a small zone at the margin of the pileus. One can, as Buller (1909), designate the general Agaricales type as the Equihymenial 462 COMPARATIVE MORPHOLOGY OF FUNGI type or, according to the best-known example, as the Psalliota type, and distinguish this as the Inequihymenial or Coprinus type, which should not be confused with the earlier described ontogeny of the Polyporales. In the latter, the hymenophore begins the formation of the basidia before the fructification has attained its final form and before the folds and elevations of the hymenophore are laid down. The trama occasionally continues its growth for months and thus adds new and younger lateral elements to the hymenophore and hymenium. In the Coprinus type, as in the other Agaricales except the Lactariaceae, the hymenium is formed Fig. 294. — Coprinus atramentarius. 1. Section of two lamellae with supporting cys- tidia. Autolysis beginning (X 75). Coprinus sterquilinus . 2. Section of two immature lamellae with thickened ends and dimorphous basidia. Cystidia absent (X43). 3. Section of a lamella of mature fructification. Spore liberation and autolysis have begun ( X 120). (After Buller, 1910 and 1915.) over the whole hymenophore after the tramal plates have completed their growth. The difference between the Coprinus and Psalliota type, therefore appears only at maturity of the individual basidia in the spore discharge, which in the former takes place in steps from the periphery (Fig. 294, 1 and 3), in the latter evenly over the whole hymenial surface. Along this zone of mature basidia in Coprinus, an enzymatic autolysis of the exhausted lamellae proceeds from the edge of the pileus to the stipe. The margin bends outward and upward and the tissue dissolves to an inky liquid which gradually drops from the fructification (Weir, 1911). Probably this peculiar condition is connected with the structure and orientation of the lamellae. While the lamellae in many agarics have a AGARICALES 463 triangular cross section below, e.g., grow narrow toward the edge and leave open a widening space for the spores to fall through, in the Copri- naceae the walls are parallel and the space for discharge and fall is just as narrow at the distal end as at the proximal. Further, the lengthwise axis of the lamellae in mature fructifications does not lie parallel to the ground, as in many other Agaricales, but is more or less perpendicular to it. Since this axis runs in the direction of fall, a spore under some conditions would fall several centimeters along its surfaces. There is danger that the spores in question may hit the cystidia or the lamellae and thus fail to reach their destination to allow dispersal by wind. By this differential maturing of the spores and the immediate subsequent autolysis of the exhausted tissue, there is an elimination of those parts of the lamellae which have already fulfilled their function and whose longer presence would hinder the fall of the remaining spores. The cystidia are autolysed somewhat earlier (often less than a half hour) than the remaining tissue. The fact that in those species in which the lamellae spread at the expansion of the pileus, e.g., in C. niveus, autolysis is weak and limited to the edge of the pileus, also points to the correctness of this interpretation of autolysis. The basidiospores are thick walled and provided with a terminal germ pore. Their germination was discussed in detail on page 397. In some species, as C. ephemerus and C. lagopus, there occasionally arise on the primary mycelia small fascicles of short side branches which, as in numerous other Basidiomycetes, break up into bacilliform oidia. Generally these oidia are formed in such large masses that they obscure the cultural characters (Brefeld, 1877). In some species, as C. ster- corarius, the hyphae later intertwine to dark-coated sclerotia up to the size of hazel nuts which, under certain conditions, develop to fructifications. The Coprinaceae may be divided into two genera, Coprinus (spores black or brownish black) and Bolbitius (spore ochraceous, yellow under the microscope). The majority of these two genera are found on dung. Many are palatable when young, as Coprinus comatus, the shaggy mane. Paxillaceae. — In this family the lamellae are easily separable from the pileus; as, however, this character appears occasionally in other families, especially the Clitocybeae, its consideration as a separate family is open to question. Its significance lies in the fact that in many species the lamellae, particularly at the fundament of the stipe, anastomose like veins and finally fuse to Polyporaceous tubiform networks (e.g., Paxillus rhodoxanthus) . This peculiarity forms the point for the connection of the Boletaceae which are always tubiform and hence generally placed beside or in the Polyporaceae, although their ontogenetic characters suggest the Agaricales. 464 COMPARATIVE MORPHOLOGY OF FUNGI In their present provisional limits the Paxillaceae ascend from resupinate to infundibuliform and finally Agaricaceous, apparently gymnocarpous fructifications. Their flesh is firm; the lamellae are decurrent and membranous. Some species are used for food. Boletaceae. — The fructifications are always pileate, and centrally stipitate. The tube layer is easily separable from the flesh of the pileus. Many species contain fat reservoirs in special hyphae from which on injury flows a colorless fluid which colors intensely in air. The basidia correspond to the usual four-spored type. The young nucleus in all species so far studied passes through its usual division shortly after its entrance (Levine, 1913). In Boletus Zelleri (Ceriomyces Zelleri) (Zeller, 1914) and Boletus parasiticus (Kuehner, 1926) development is gymnocarpous. In Boletus flavus (Ixocomus flavus) and Boletinus cavipes the annular furrow is at first on the surface then in the young stage, the hyphal tissue of the margin of the pileus is continued in a more or less definite partial veil to the rind of the stipe and the tubes and the hymenium arise with an arched annular cavity. Basidia and spores are produced in a hymenium which covers the top of the annular furrow before the tubes are formed, as in the Polyporales (Kuehner, 1926, 1927a). In most species the remains of the veil disappear in the course of development so that the mature condition is no longer reminiscent of the pseudohemiangiocarpous young stage. In others in which it is strongly formed, as in Boletinus cavipes and Strobilomyces, remnants remain on the stipe as a ring, or on the margin of the pileus as a cortina. In still others, unfortunately imperfectly known genera, e.g., in Volvoboletus, a universal veil is differ- entiated as in the Amaniteae in the formation of the fructification. All these characters raise the Boletaceae above the Polyporales in which they were usually placed and place them among the Agaricales. These relationships are reinforced in that the Boletaceae also histolog- ically stand considerably higher than the Polyporales and here again have attained the stage of the Agaricales (Yates, 1916). Patouillard (1900) and Maire (1902) — who have been followed in this book — advocated that the Boletaceae should be connected to the Paxillaceae, in the Agaricales, where the tramal layer also is easily loosened from the flesh of the pileus. This removal indicates a further step in the recognition that the lamellae and tubiform tramal plates are of secondary importance in a systematic treatment of the Basidiomycetes, and that a natural classification of this order can be completed only with histological and cytological characters. Many species are edible. As an appendix to the Agaricales, Rhacophyllus lilacinus on dead wood in the tropics should be considered, since it undoubtedly has affinities with this family, although its ontogeny and cytology are only partially AGARICALES 465 known. Superficially the fungus resembles an agaric but produces sheets of biconvex bulbils in the place of lamellae. The mycelium develops readily from bulbils on blocks of porous wood which are not too wet. The stipe primordium of large and longitudinal hyphae is early developed. The pileus is covered by a universal veil. Trabeculae, the primordia of the lamellae, extend from the pileus to the ground tissue, but no annular gill cavity is formed. The pileus becomes broadly conical, the tissue between the pileus and the stipe begins to produce bulbils, which arise singly, not in continuous sheets. They are of loose texture at first, often hollow and lined with a palisade layer or, if solid, with two opposed palisade layers in the center. The cells of the palisade layers produce cylindrical or oval spore-like cells at their apices within the Fig. 295. — Rhacophyllus lilacinus. Caryogamy and plasmogamy in the bulbils. (After Moreau, 1913.) developing bulbil. These cells do not become free but remain united in short chains. The bulbils never include hyphae of the ground tissue and at maturity are shed instead of spores (Petch, 1926). While in the normal agaric the gill primordia develop into plates of tissue which produce palisade layers of basidia externally relative to the primordial tissue; in Rhacophyllus the "gill primordium" or trabecula develops a palisade tissue internally from either side, like the hymenium of the Gasteromycetes. The bulbils contain mostly binucleate cells. The nuclei approach and fuse (Fig. 295, 1 and 2), the resulting nucleus divides twice so that there are four nuclei. Two of the four nuclei degenerate and the primitive nu'clear number is restored. Thus the nuclear behavior is similar to that of a basidium (Moreau, 1913). Often the septa dissolve and the protoplasts fuse (Fig. 295, 7 and 8). The material on which these studies were based was such that further details were not obtainable. Here apparently we have groups of basidia (or perhaps spores) taking the place of normal basidiospores in reproduc- ing the organism. The relationships of this genus are very obscure. A 4G6 COMPARATIVE MORPHOLOGY OF FUNGI single collection by Duss from Guadaloupe contained a specimen of Psathyra near P. gyroflexa, but with no indication that it came from the same mycelium. Subsequent field studies over a long period by Petch have failed to find a normal agaric growing with this genus. While superficially Rhacophyllus resembles the agarics, its ontogeny suggests rather Gasteromycetous affinities, such as Podaxon, Gyrophragmium, etc., but none of these genera have been sufficiently studied to determine relationships. Hemigasteraceae. — As an appendix, we have retained this interesting form in the position suggested by Juel (1895) although it might be interpolated in the developmental series leading to Secotium in the Hysterangiaceae as suggested by Gaumann (1926). Its development suggests that of Boletus flavus on a smaller scale. In Hemigaster candidus .»■**<■;.' ■::•• .vv.. ■ ■* •• ;i.^:V ■j'-i-.v-V ■"•l*v>. 1 m f*Mm Fig. 296. — Hemigaster candidus. 1. Coremium of diverging hyphae which form the fundament of the pileus. 2. Older stage. Pileus more distinct, with the young hymenium below. 3. Immature fructification. On the sides of the middle column grow the gemmae- forming hyphae. (1, 2 X 50; 3 X 27; after Juel, 1895.) on rabbit dung in Sweden, the fundament of the fructification consists of a spherical knob of closely intertwined hyphae (Fig. 296, 1) which extend to the top of the head, almost parallel, then outward and down- ward. The tips bend downward at a right angle on the lower side, forming the fundament of the hymenium (Fig. 296, 2). Eventually the hyphae on the margin of the pileus grow to and fuse with those of the stipe, forming a closed annular chamber (Fig. 296, 3). The outer layer of the pileus differentiates into a loose outer and a firm inner layer sur- rounding the pileus. The outer two thirds is occupied by hymenium con- sisting exclusively of four-spored basidia with small, smooth, ellipsoidal spores. The inner third is filled by a hyphal tissue which grows from the stipe within the annular furrow and develops on lateral branches, numerous, sub-sessile, occasionally catenulate gemmae. In the following period, the head containing the chamber expands horizontally and is almost filled by increasing masses of gemmae. At maturity, the gemmo- phores disintegrate and the chamber contains a powder of free basidio- spores and gemmae. CHAPTER XXVIII GASTEROMYCETES This traditional group of fungi, originally contrasted with the Hymeno- mycetes, includes an assemblage of families of angiocarpous Autobasidio- mycetes which undoubtedly belong to several developmental series. Lack of ontogenetic investigation prevents a satisfactory regrouping up to the present although numerous attempts have been made. These attempts have been based upon too few data to justify themselves. The segregation which has survived the longest was based upon the arrange- ment of basidia, but, like similar segregation of the Hypochnaceae for a few species of Hypochnus and Corticium, this segregation of the Plecto- basidiales (Fischer, 1900) is untenable. It consisted in removing the Podaxaceae, the Sclerodermataceae, the Calostomataceae, Tulostomata- ceae and the Sphaerobolaceae from the Lycoperdaceae and Nidulariaceae in their broader limits and erecting them into a single polyphyletic order, on the basis of single character. In the Gasteromycetes, the hymenia arise on irregular plates of tissue anastomosing to form a chambered, fertile tissue called the gleba, which is usually surrounded by a cover of sterile tissue called the peridium. The basidia are mostly four, occasionally two to three or six to eight spored and, except in Tulostoma, develop chiastobasidially as far as known. In all forms previously studied, as Lycoperdon excipuliforme, Geaster fimbriatus, Nidularia farcta (N. globosa) (Maire, 1902), N. pisiformis (Fries, 1911), Cyathus striatus (C. hirsutus) (Maire, 1902), Secotium novae-zealandiae (Cunningham, 1925) and Lycoperdon depressum (Cun- ningham, 1927) the nucleus divides soon after it enters the spores, so that the mature spores and all the resulting mycelium is binucleate. In Nidularia, especially in impure or poorly nourished cultures, the hyphae tend to break up into oidia. Apparently oidia are produced in the outer layer of the peridium of Arcangeliella caudata (Zeller and C. W. Dodge, 1919), although no attempt was made to germinate them. In Leucophlebs, which probably represents the conidial stage of Leucogaster, clusters of conidia on rather elaborate conidiophores fill the cavities of the fructification before the formation of the basidia. The primitive members of the group are mostly hypogaeous, although there is a strong tendency to elevate the gleba above the earth to secure the dissemination of their spores by wind or insects. With the complete angiocarpous development of the hymenium, the original mechanism of 467 468 COMPARATIVE MORPHOLOGY OF FUNGI the basidium to secure spore dispersal has been lost and its function assumed by the fructification as a whole, e.g. , by the odor attracting rodents which eat the fructifications and disperse the spores in their feces, by the dustiness and capillitium of the gleba which enables pressure by wind or animals upon the sides of the fructification to puff out a cloud of spores, whence the name puff-balls, or by the elevation of the gleba upon a stipe, attracting insects which carry away the spores from the autolyzing gleba. The peridium in the lower forms is a simple layer of plectenchyma undifferentiated from the ground tissue of the developing fructification. From these we may get a gradual disappearance of the peridium or its differentiation into several layers with varied and important ecological functions. The Gasteromycetes are a mixture of various genera which possibly belong to entirely different development series. The following classifi- cation rests upon the differences in the place of the hymenial fundament and the direction of growth of the tramal plates. The first group in which the hymenium is formed in thick, more or less isodiametric knots of tissue (which have arisen by the pulling apart of the ground tissue) almost simultaneously from the center outward, throughout the whole fructification, includes the Rhizopogonaceae, Sclerodermataceae and Lycoperdaceae. A second group, in which the hymenium arises within a few closed chambers isolated at maturity, includes the Sphaerobolaceae and Nidulariaceae. In the third group the tramal plates are regularly arranged, start at definite points and grow in a definite direction. In the Hymenogasteraceae they grow basipetally, in the Hysterangiaceae and Clathraceae they grow centrifugally from a central part and in the Phallaceae, centripetally from the periphery. Rhizopogonaceae. — This family includes hypogaeous or epigaeous genera with a gelatinous gleba of schizogenetic cavities. The fructifica- tion is surrounded by a surface layer of ground tissue (simplex peridium of Zeller and C. W. Dodge, 1918), or by a more or less differentiated peridium outside the ground tissue (duplex peridium of Zeller and C. W. Dodge) . One of the more primitive forms is the cosmopolitan Rhizopogon rubescens. Its fructification arises as a small knob, on a slender mycelial thread, whose rind becomes the peridium and whose core, which consists of hyphae of variable thickness, continues in the ground tissue of the fundament (Rehsteiner, 1892). The ground tissue is differentiated by a separation of the hyphae into compacter and looser tissues. The looser parts which run between the thicker knots, become still looser and finally form irregular cavities which are penetrated by single, thick, septate hyphae. From the periphery (Fig. 297, C), new hyphal knots are con- tinually differentiated along with the increasing growth of the fructifi- GASTEROMYCETES 469 cation. Subsequently, the hyphae of the surface of the cavities come together into a hymenial palisade. By growth of the palisade, the tramal plates become increasingly irregular and finally occupy most of the gleba (Fig. 297, B). In some species, as R. luteolus, the trama tend to split, suggesting conditions in Pisolithus in the Sclerodermataceae. In other species there is differentiated, outside the ground tissue, a peridium which may be m0§m& Habit (natural size). Fig. 297. — Rhizopogon luteolus. A fructification (X 14). C. Part of gleba (X450). Rhizopogon rubescens section of young fructification ( X 28). (After Tulasne and Rchsteiner.) B. Portion of periphery of D. Median evident only by the different character of the cells (swollen and irregular in R. diplophloeus) or by different color and its sloughing off in spots, giving a characteristic ragged appearance to the fructification, as in R. pannosus and R. Briardi. Melanogaster variegatus is similar to R. rubescens in appearance, but its spores are black instead of light yellow and its basidia are short, pyriform and not arranged in compact hymenia. The latter character led some 470 COMPARATIVE MORPHOLOGY OF FUNGI authors to place this genus in the Sclerodermataceae. It seems to be a transition form in many of its characters but it has not been investigated ontogenetically nor cytologically. In Leucogaster we have another interesting genus, perhaps even more primitive than Rhizopogon. As in R. rubescens, the cavities develop centrifugally from the ground tissue. In L. floccosus the cavities are first filled by spores borne acrogenously on short branches of zigzag hyphae, or sometimes terminally on large hyphae springing from the trama. These consititute the Leucophlebs stage which is also known in L. odoratus, L. foveolatus and L. citrinus. If these are not disseminated they disinte- grate in situ, filling the cavity with a dilute gel into which the basidia penetrate. The basidia are sometimes long pedicellate, pyriform, often with pedicels 200 to 300^1ong, and solitary in L. araneosus and L. rubescens. In other species, as those of Europe and L. citrinus of California and Australia, the basidia are short and united into compact hymenia. The *a«*- Fig. 298. — Scleroderma vulgare. A section of young fructification. B. Portion of gleba. (After Tulasne.) spores are very highly sculptured and enclosed in a gelatinous sheath. A true peridium is only developed in L. luteomaculatus and even here it is not so highly differentiated as in some species of Rhizopogon. Many features of this genus are suggestive of the Sclerodermataceae, but unfortunately it has been little studied. It is possible that other genera which have not yet been studied ontogenetically may belong here, but such fragmentary statements as have been made lead one to classify them elsewhere for the present. Sclerodermataceae. — This family includes a group of simple forms with a simple peridium which splits irregularly at maturity (except in Scleroderma Geaster) and a chambered gleba, penetrated by a slightly developed capillitium, and becoming dusty at maturity. The fructifi- cations of S. Bovista and S. vulgare are usually epigaeous, arising laterally or terminally on mycelial threads, from a homogeneous tissue of thin- walled, tangled hyphae which radiate toward the periphery. These GASTEROM YCETES 471 hyphae form the fundament of the coarse fragile peridium, usually scaly on the outside, and quite distinct from the gleba. At numerous points on the ground tissue, the hyphae branch more strongly, intertwine within (Fig. 299, 1, Kn) and rise as dark, deeply staining knots from the sur- rounding undifferentiated ground tissue (Rabinowitsch, 1894). The knots are loosened later with the swelling of the hyphae whose branches are directed toward the middle of the knot. These terminal cells become Fig. 299. — Scleroderma Bovista. 1. Median section of periphery of young fructifica- tion. Per, peridium; Kn, knots of hyphae; Tr, tramal hyphae between the knots. 2. Knot at the beginning of basidial formation. 3. Basidiospore with nurse hyphae. (1 X 65; 2 X 375; 3 X 570; after Rabinowitsch, 1894.) basidia (Fig. 299, 2) which absorb the content of the knot hyphae, so that during the later development of the basidia there are no traces of the knot fundaments. The vacuolate, collapsed hyphae of the ground tissue surround the spores and cling to them so that these are more or less covered with a thick sheath of intertwined hyphal cells (Fig. 299, 3). At maturity the gleba disintegrates into a powdery mass with a few hyphae remaining behind as a simple capillitium; finally, the peridium 472 COMPARATIVE MORPHOLOGY OF FUNGI ruptures irregularly and the spores are blown away by wind or washed away by rain. In the cosmopolitan Pisolithus (Polysaccum), the fructifications are similarly formed but the maturing process takes place basipetally. When the gleba is colored dark above, the lower portion is still white. The trama splits, allowing the single spherical cavities to be dispersed separately after the disappearance of the peridium. This mechanism we shall see more highly developed in the Sphaerobolaceae and Nidulariaceae. While no true stipe is formed in this family, in both genera when growing in sandy soil, the rooting base may be so highly developed as to resemble a stipe. Lycoperdaceae. — In Bovista nigrescens, investigated by Rehsteiner (1892), the fructifications arise either laterally or terminally on mycelial threads. In contrast to other Gasteromycetes, its rind does not seem to continue into the peridium of the fructification, but forms only a patelli- form sheath which surrounds and protects the delicate basal part of the young fungus. Furthermore, the thick, wide-lumened hyphae of the core do not continue into the core of the young fructification, but the fructifica- tion is built of thin-walled, narrow hyphae which run in the core of the rhizmorph beside the conducting hyphae. These hyphae radiate more or less distinctly toward the periphery; they are parallel and wide lumened, with clavate or flask-shaped tips, and they form the fundament of the outer peridium. Later, as in Rhizopogon, there are differentiated from the homogeneous core thicker and looser por- tions of tissue; the latter develop to cavities, the former to the knots with the outgrowing tramal pads. For a long time, from the original ground tissue at the edge of the fructification, new hyphal knots are laid down. This tissue, after fulfilling its function, grows only by the expan- sion of its elements and the formation of new tramal plates. By these increases in size the periphery of the ground tissue expands passively and is forced apart; its tangled hyphae become solid, arranged tangenti- ally and form the fundament of the inner peridium. As in some species of Rhizopogon, the fructifications are surrounded by tramal tissue peridium but, in contrast to Rhizopogon, the outer peridium is further differentiated into a radially disposed outer and a tangled inner layer consisting of slender hyphae. In time, the outer parts of this tangled zone swell up strongly and expand to a pseudoparen- chymatous tissue. Consequently, the mature fructification is surrounded by four layers : the compact trama or inner peridium, the narrow zone of tangled, unthickened hyphae gradually merging with the broad pseudo- parenchymatous zone which bears the outermost layer of swollen radiat- ing cells. With increasing age, the outer layer becomes frayed and dried. In the course of the development of the gleba from the slender tramal hyphae, there are differentiated solid, mostly aseptate branches which GASTEROMYCETES 473 gradually swell, increase their membranes and become brown. These are the future capillitium threads; their form and sculpture are important systematic characters in separating Bovista from related genera, as Globaria and Mycenastrum. At maturity, the peridium opens at the top, the gleba disintegrates into a dry powder which is penetrated by a tangle of capillitium. In the cosmopolitan Lycoperdon, which has given this family its name, formation of the fructification takes place as in Bovista, only the gleba G is differentiated into a fertile and sterile zone (Fig. 300, B). Thus, as in Bovista, the whole interior of the fructification is constructed of a thick tissue knot covered with a hyphal palisade. In the lower columnar part of the fructifica- tion, the later stipe st, glebal de- velopment is retarded; the glebal chambers retain their original rounded form and the hyphal Fig. 300. — Lycoperdon gemmatum. A. Exterior of fructification (X \i). B. Section of young fructification ( X 2). Pa, outer peridium; Pi, inner peridium; Zw, middle layer; C, rudimentary columella; G, gleba cavities, sterile below, fertile above; St, stipe. (After Rehstciner, 1892, and Strasburger's textbook.) palisade remains sterile. In the upper capitate part (Fig. 300/), how- ever, the cavities become compressed by rapid growth of the tramal plates, into long and narrow labyrinthine, radiating and often tortuous slits in which the hymenia deposit their spore masses. In the species with more or less cylindrical fructifications, as in L. gemmatum, the sterile part gradually passes over into the fertile; in the species with capitate fructifications, as L. depressum, there is a sharp line between the rapidly developing fertile and the retarded sterile part. This line has been formed by a horizontal pulling apart of the fertile and sterile chambers the transition zone (Rabinowitsch, 1894). The exoperidium in is 474 COMPARATIVE MORPHOLOGY OF FUNGI differentiated as a single layer of pseudoparenchyma, forming warts which disappear at maturity of the fructification. The endoperidium also of a single layer begins as radial, loosely-woven, thin-walled hyphae. As it matures, thick-walled hyphae, similar to the capillitium, replace the early tissue, finally forming a compact, persistent tissue. The gleba forms a number of large, subspherical primary cavities which are later cut up into numerous secondary ones by growth of the tramal plates (Cunningham, 1927). During the maturing of the spores, the hyphae in the interior of the peridium become loose at the top of the fructification and short geniculate ; the distinction between outer and inner peridium, Pa and Pi, disappears, the top is ruptured as a mouth, and the spores, penetrated by capillitium, becomes a dusty mass. Several species of Lycoperdaceae are palatable when young, as long as the gleba is white, as Lycoperdon gemmatum, Calvatia ^ caelata and C. maxima. The fructifica- tions of the latter attain the diameter of Fig. 301. — Broomeia congregata. A. Portion of stroma with fructifications, of stipitate stroma. {After Berkeley and Murray.) B. Section more than half a meter. According to Buller (1909, 1924), a specimen of normal size contains 7,500 billion spores, approximately as many as 4,000 average fructifications of Psalliota campestris. Thus, this is the most fruitful organism known. Were these spores all to germinate and each form a fructification the size of the parent and if all the spores of these were to form fructifications, there would be produced a fungus mass 800 times the size of our planet. In two further genera, Diplocystis and Broomeia (Fig. 301), found in South Africa and the West Indies, there are joined together on a stroma 17 by 15 cm. over 900 fructifications (Pole-Evans and Bottomley, 1918); each is surrounded by its own two-layered peridium which at maturity tears stellately at the mouth. Unfortunately, the development GASTEROMYCETES 475 of these unusual genera is unknown and hence their systematic position is still uncertain. Throughout the family we have found an increasing differentiation of the peridium. The fructifications of Astraeus hygrometricus stellatus (A.Geaster hygro- metricus) are hypogaeous and surrounded by mycelium. The peridium consists of a thin, papery endoperidium and a stronger exoperidium, of three layers, an outer, thin, looser, a thicker, corky, middle layer and a horny collenchyma, inner layer (Fig. 302). In both outer layers, the hyphae are irregularly intertwined. At maturity the whole gleba is disorganized and there remain only the spores with the thick-walled capillitium. The exoperidium dehisces stellately, the fructification rises above the soil. Because of the hygroscopicity of the innermost radially fibrous layer, the exoperidium curves inward in dry weather and expands FiG. 302. — Astraeus hygrometricus. 1. Mature fructification. 2. Section of young fructification, i, i', i", endoperidia; a', a", exoperidia; g, gleba. (Natural size; after Tavel and Bary.) in damp. The endoperidium ruptures irregularly or stellately at the top and the spores are dispersed. In Geaster velutinus (Cunningham, 1927), the mycelial layer consisting of a dense palisade, 1 to 2 mm. thick of coarse, deeply colored hyphae, is first differentiated from the ground tissue. In the next stage the primor- dia of the fleshy and fibrillose layers of the exoperidium, the gleba and the sterile central tissue, the columella, are differentiated. The fibrillose layer consists of periclinally arranged large and small hyphae with later the addition of some hyphae similar to those of the mycelial layer. The fleshy, or inner layer of the exoperidium begins as a layer of large, com- pactly woven hyphae between the fibrillose layer and the gleba. The cell walls gelify and the tissue gradually becomes pseudoparenchyma. It is interrupted by the thickened base of the columella. Shortly after the differentiation of the fleshy layer begins, a dome of cavities appears between this layer and the columella. The cavities vary in size and shape, apparently being formed by the tearing apart of the hyphae. These cavities become lined with large inflated cells, the 476 COMPARATIVE MORPHOLOGY OF FUNGI primary basidia, which compress the ground tissues into the tramal plates. The primary basidia arise directly from the tramal hyphae without the subhymenium characteristic of most Basidiomycetes. Meanwhile the outer portion of the ground tissue differentiates the endoperidium, which is composed of slender hyphae similar to those of the fibrillose layer. They are intricately interwoven and partially gelatinized. Differentia- tion of the glebal tissue is rapid, the younger basidia being much smaller than the primary basidia. Both types of basidia are typically four spored but spore numbers from one to eight are not uncommon. A period of rapid spore production follows, until the trama is practi- cally exhausted. Capillitium threads, hyphae similar in appearance to those of the mycelial layer, grow out from the columella. p< Fig. 303. — Geaster coronatus. A. Schematic section of young fructification. Geaster marchicus. B. Mature fructification. (Natural size; after Rehsteiner, 1892, and E. Fischer, 1900.) Shortly after the endoperidium has been formed, the hyphae of the apex of the endoperidium become more loosely interwoven and form a thickened apical disc. The disc assumes a radial arrangement, a small irregular cavity appears in the center and becomes Lined with hyphae from the inner portion of the endoperidium. Then the disc collapses, is depressed and gives rise to the peristome. Finally the exoperidium ruptures and exposes the endoperidium. Differing from most other Gasteromycetes, the basidiospores, myce- lium and young basidia are uninucleate. When the sterigmata develop, the nucleus divides a sufficient number of times to provide a single nucleus for each spore. Development is essentially similar in Geaster coronatus (Fig. 303) . First the fundament of the exoperidium is differentiated from the ground tissue, GASTEROMYCETES 477 which is only partially fertile; in the columella C and in the apical, conical D, it remains sterile. Perhaps the columella is analogous to C of Lyco- perdon gemmatum (Fig. 300, B). The peripheral ground tissue, which later forms the gleba, functions only a short time; long before the columella and the differentiation of the outer peridium is recognizable, it is changed into the inner peridium Pi. Its hyphae assume the typical periclinal direction and their mem- branes thicken considerably; they remain very closely intertwined, however, and form a compact membrane covering the gleba, which is interrupted only at the base and top of the fructification. At the base, its hyphae are lost into the undifferentiated stipe St; at the top, they loosen and thereby indicate the spot K where later the peristome will appear. The outer peridium is also differentiated into three layers, a mycelial layer M, the fibrous layer F, the pseudoparenchymatous layer Ps. The first and third are also present in Lycoperdon and Bovista, but the fibrous layer is new. Mycelial and fibrous layers surround the whole fructifi- cation. Their connection is gradually loosened so that the former may be separated from the latter as a firm membrane; only at the top of the fructification does the connection of the two layers continue. The pseudo- parenchymatous layer is not continuous but is interrupted at the base and top of the fructification where it joins with the hyphae of the inner peridium. In the remaining area, the connection with the inner peridium is lost. Whereas originally it was connected with it by a loose hyphal tissue, with increasing age its elements were more and more separated until finally, at the loosening of the pseudoparenchymatous layer, they were torn apart from the inner peridium. At spore maturity the gleba goes through the same changes as in Lycoperdon. The trama disappears and only its firmer hyphae withstand disintegration as capillitium. Similarly, the more delicate elements of the sterile tramal tissue, the columella and the layers S swell and disintegrate, leaving only the capillitium. The hyphae of the peridium become loose at the top leaving a small opening. Their membranes thicken very markedly in the manner of the capillitium and in this species forms a cover of the peridium which is lacking in others. Growth in breadth begins in the pseudoparenchymatous layer and the cross-section of the large, thin-walled cells doubles. The pressure thus created ruptures the peridium at the top, the point of least resistance ; it splits into three layers, the mycelial layer, the fibrous and fleshy layer and the inner peridium. The mycelial layer remains, as Fig. 303, B shows, in the form of a subterranean, cup-like sheath whose upper third has been torn into four lobes. The earlier place of fusion of the mycelial layer and fibrous layer is retained; consequently the deeply split, fibrous and pseudoparenchymatous layer is turned inside out at the end of 478 COMPARATIVE MORPHOLOGY OF FUNGI the four lobes, so that the pseudoparenchymatous layer comes to lie on the convex side. By this process, the gleba which is surrounded by the inner peridium is raised above the ground. It opens, as in Lycoperdon, and allows its spores to scatter as dust. The meaning of the whole apparatus is obscure. In hypogaeous forms, as in G. coronatus, one might consider it a means of better dissemina- tion of spores, but in the epigaeous species this interpretation fails. Apparently none of the stipitate species have been studied intensively. The peridium is still more developed in Colostoma WalUsii (Mitre- myces WalUsii), perhaps not distinct from the common C. cinnabarinum Fig. 304. — Colostoma WalUsii. A. Section of young fructification. B. Section of mature fructification. Explanation of letters in text. (After Fischer, 1884.) (Mitremyces lutescens) of North America (Fig. 304). Outermost lies a thick, white, gelatinous tissue aP; next within follows a tough, cartilagi- nous, brightly colored, hollow spherical layer K, at whose top there is early formed a stellate, red-edged opening Z. In the interior lies the endoperidium S, which at maturity hangs from the top as a thin-walled sac. From the base of the layer L, as the fructification matures, there grows a stipe or rooting foot F, which chiefly consists of numerous, irregu- larly arched, cartilaginous threads which rupture the outer peridium aP; this stipe gradually elongates and raises the fructifications. At the approach of maturity, the layer K expands considerably, the layer aP is thereby torn, disappears and the endoperidium £ hangs as a small sac from the mouth into the interior of the fructification and discharges GASTEROMYCETES 479 the spore powder. This genus also possesses a true capillitium (Fischer, 1884). Astraeus and Calostoma are sometimes placed in the Calostomataceae in the Plectobasidiales on account of the more irregular arrangement of their basidia. Tulostomataceae. — This family is characterized by the two-layered peridium, rind-like on the outside, papery-firm within, and the irregular gleba, penetrated by capillitium. As its development is as yet insuffi- ciently investigated, the classification is only provisional. If the assertion of Tieghem is confirmed (see also Schroeter), that their basidia behave according to the stichobasidial type, they should be removed to the Phleogenaceae. Tulostoma is the best-known genus, especially the cosmopolitan T. bru- male and T. squamosum (T. mammosum) (Schroeter, 1876; Bessey, 1887; Fig. 305. — Tulostoma squamosum. A. Habit and section of fructification. B. Median sections of fructification before and during elongation of stipe. C. Basidium. (After Vittadini and Schroeter.) Petri, 1904). Their fructifications appear from fall to spring and lie in the earth 2 to 3 cm. deep. They are laid down as small, sclerotial swellings of the mycelium; the rind consists of compactly intertwined, slender hyphae, the core of broad, short, inflated cells, barrel shaped in the middle, between which run at large intervals, threads of thinner, parallel- walled hyphae. The rind then differentiates into a brown crust and a firm, papery interior. The core differentiates into a middle and lower layer (Fig. 305, B). The core layer is approximately spherical. It is loose in texture and remains white, even through the maturation of the spores. The lower core layer is blunt, conical and consists of a cylindrical column and covering. The column is composed of parallel, slightly branched hyphae and forms the fundament of the later stipe. The covering, consisting of tangled hyphae, dries after spore maturity, leaving a small cavity between peridium and stipe at the base of the fructification. 480 COMPARATIVE MORPHOLOGY OF FUNGI The middle core layer appears almost reniform in cross section. It consists of a smooth tissue of slender, ramose hyphae which form club- shaped basidia at their ends. The sterigmata are laterally inserted at unequal heights. Numerous unbranched, thick-walled, undulate hyphae, the capillitium threads, grow out from the core fibres. The basidia degenerate and only the capilli- tium and the ochraceous spores remain in the peridium. At maturity, the stipe elongates to 3 to 6 cm., the peridium tears at the spot where a small cavity is formed by the drying of the stipe covering (Fig. 305, B) and the gleba, together with the peridium, rises above the ground. During the winter the outer layer of the peridium becomes loosened with bits of earth adhering like scales, exposing the inner, lighter-colored layer (305, A, left) whose opening was originally closed by a solid plug, the dried upper core layer. The stipe is still more strongly developed in the predominantly subtropical Battarrea, which is insufficiently known. Here it attains a length of over 20 cm. so that the fertile portion, consisting of endoperi- dium and gleba, projects above the ground like the pileus of a small agaric. The peridium is circumscissile, the edges roll upward and back- ward exposing a narrow ring of capillitium and spores. As these are carried away by the wind, the drying action of the latter cause the edges of the peridium to shrivel and roll up more, exposing more spores. This is continued until the upper half of the peridium has shriveled and blown away and there remains only a shallow cup of the lower half containing a few spores, which are finally washed away by rain. Sphaerobolaceae. — In this family, the cosmopolitan Sphaerobolus stellatus has been investigated (E. Fischer, 1884; Rabinowitsch, 1894; Pillay, 1923; Walker, 1922, 1927; Walker and Andersen, 1925). The fungus grows on rotting wood preferably. The mycelial strands are surrounded by an upper brownish (Fig. 306, OR) and a lower white rind (Fig. 306, UR) and possess a comparatively loose core. At the point where the fructification will arise, one or rarely several tissue bodies are differentiated from the core. Each of these divides into a looser ground tissue (Fig. 306, GF) and a firmer gelatinous rind which itself differentiates into two layers, a narrow intertwined outer and a looser inner layer (Fig. 306, GR and IR). Only in the interior of this body is the true fructifi- cation laid down as a more solid tissue (Fig. 306, SA) and always at the upper edges of the rind. Generally a single fructification develops in each tissue body, occasionally two. On further growth, the fructification arches over the rind layer of the tissue body and that of the mycelial threads; when these layers dis- integrate, the fructification appears above the mycelial threads (Fig. 307, 2) . It is differentiated into peridium and gleba. The first is composed of four layers: the gelatinous mycelial layer M (which biologically corre- GASTEROMYCETES 481 sponds to the volva of the Clathraceae), the pseudoparenchyma layer P, a thin, tough, periclinal, fibrous layer F, and the collenchyma layer C. The outer cells of the collenchyma layer elongate radially, become prismatic and assume a peculiar palisade structure; the innermost layer next the gleba consists of large spherical cells, called cystidia by earlier writers but from their cytology probably basidia. At the top of the fructifica- tion the peridium is weaker; there it is chiefly composed of isodiametric lis. .'GF ■:>;.iVJX;:">0R v * ■ . • ••-. '•*■' *#• '%•■' ■••'.'•:'.' * • •.'^^^^•vk,v ^UR , • *F*f3cijfiB0tV' »* .*. isA f. .; ■ •'■':• •'•.■ '•■•", •V--&3 y'v/.,.i'-:'N" 4 2 3 Fia. 306. — Sphaerobolus stellatus. 1. Median section of young hyphal strand with fundament of fructification. OR, outer rind; UR, under rind; GR, rind layer of tissue knot; JR, inner rind of gel; GF, ground tissue of tissue knot; FA, fundament of fructifica- tion. 2-4. Diagrams showing structure of fructification and discharge of gleba. (1 after Pillay, 1923; 2-4 after E. Fischer, 1884.) The gleba *S develops rapidly. The nine-spored basidia, which soon disintegrate, are formed in regular nests so that by the time the collen- chyma has differentiated, they have collapsed. Further, the hyphae, which form the trama collapse and the gleba becomes a slimy mass in which are imbedded the spores, and gemmae. In youth the spores are uninucleate but soon become binucleate. At maturity the isodiametric zone of the collenchyma layer splits periclinally, so that the gleba, surrounded by the inner and the proximal portion of the collenchyma, separates from the remaining peridium. Because of the stronger surface growth of the collenchyma layer, this splits, tears stellately at the top and slowly bends outwards, exposing the 482 COMPARATIVE MORPHOLOGY OF FUNGI spherical gleba. The collenchyma layer continues its growth, so that a strong tension exists between it and the fibrous layer. This is increased by the hydrolysis of the glycogen in the collenchyma layer to maltose and by a consequent increase of osmotic pressure. Thereupon the fibrous layer F separates from the pseudoparenchymatous layer P and turns inside out, with the attached collenchyma, quickly and forcibly (at times with a small report) ejecting the gleba S over 4 m. high (the size of the fructification is a few millimeters!). Occasionally the process is so forcible that the reversed part is thrown off. The gleba that has been shot off germinates as a whole by putting forth numerous germ tubes which largely develop from the gemmae, not from the basidiospores. The gemmae are capable of germination for at least seven years. In S. iowensis, development is similar to S. stellatus (Walker, 1927). The secondary basidia by mutual pressure produce a chambered gleba with well organized hymenia. The chambers early become filled with spores. The palisade layer and the pseudoparenchyma next the gleba is interrupted by strands of conducting tissue which connect the inner and outer portions of the fructification. This species lacks the gela- tinous layer in the peridium. Nidulariaceae. — The members of this family are characterized by gleba chambers formed only in small numbers, surrounded by a special sclerenchymatous wall and hence disseminated as a unit. The tendency for the trama to split (which we found in Rhizopogon luteolus and in Pisoli- thus) culminates in this family. In the forms so far studied, Crucibulum vulgare (Sachs, 1855), Cyathus olla (C . fasicularis) (Walker, 1920) and Nidularia pisiformis (Fries, 1910), the fructifications arise epigaeously on rotten wood as small knobs of tissue (Cyathus olla may also be cultivated on artificial media). At the periphery, the hyphae intertwine to a solid brown layer covered with hair- like hyphae. This layer, the outer peridium ap, subsequently assumes a corky consistency. On its interior, the light inner peridium ip is differentiated by a predominantly peripheral arrangement of the hyphae and a gelatinization of the hyphal walls. Shortly after the appearance of the inner peridium, the gleba chambers are laid down in the ground tissue, and in Crucibulum (Fig. 307) and Cyathus from the bases of the fructification toward the top, in Nidularia in the apical part of the fructification only, while the basal part becomes lacunose and its hyphae gelify. The formation of glebal chambers proceeds in such a way that at any spot in the ground tissue the young basidia, gradually increasing in number, grow toward the common center where their ends come in contact. By the growth of the basidial layer and by the enlargement of their surfaces, the basidial tips are pushed apart so that in the chamber fundament is formed a GASTEROM YCETES 483 central cavity which constantly enlarges. This is filled by a gel which probably results from the disintegration of vegetative hyphae. The origi- nally spherical chambers become lenticular, whereby the thicker wall tissue is formed first on the flat side, while the curved, narrow sides remain connected with the ground tissue. By secondary alterations, the wall tissue attains a very complicated structure and, in N. pisiformis for example, is composed of not less than five layers. Outermost there is a thin, hyaline, hyphal layer with gelatinous walls, then a brown layer Fig. 307. — Crucibulum vulgare. A. Habit, young and mature opened fructifications. B. Section of young fructification showing peridioles. (After Sachs, 1855.) formed of slender, compact, thin-walled hyphae, then a thin sheath of dark brown, much-thickened, coarse strands, then a true, strong, lacu- nose wall tissue, formed of thin-walled, brown hyphae and, finally, a pseudoparenchymatous layer upon which rests the hymenium. The basidia are four spored; the diploid nucleus divides twice (Fig. 309); in the basidium it begins a third division which is only completed in the spore, hence, as far as known, the spores are binucleate from youth. The basidia degenerate, the spores absorb the gel in the glebal cavity, fall off 484 COMPARATIVE MORPHOLOGY OF FUNGI the sterigmata, collect in the cavity of the glebal chamber, fill it and are further nourished by vegetative hyphae which grow out of the subhy- menium, surround the spore, fuse with it and nourish it as in Scleroderma (G. W. Martin, 1927). The ground tissue outside of the gleba chambers gelatinizes; in Crucibulum and Cyathus, however, on the side of each chamber next the cup wall, a funiculus attaches the chamber to the peridium. In Cyathus especially, it is a very complicated structure; in C. striatus, it consists Fig. 308. — Crucibulum vulgare. Portion of fructification somewhat older than that shown in Fig. 307, B. {After Sachs, 1855.) of a cylindrical basal portion, a thin middle section, and an upper por- tion. This is a hollow pocket which is penetrated by a funiculus fastened above to the glebal chamber and below coiled into a knot. In damp weather the funiculus may become 12 cm. long. Perhaps it aids dis- semination by fastening the chambers to animals. At maturity, the fructification degenerates at the top which, in Cyathus and Crucibulum, is a sharply denned circular cap (epiphragm). The gelatinous ground tissue liquefies and hard round gleba chambers lie, GASTEROMYCETES 485 like eggs, at the base of the fructification. These have the unfortunate name "peridioles." They do not open by themselves and the spores are only freed by injury or by decay of the hard wall. At high temperatures they germinate to strong, binucleate, clamp mycelia, which break up into oidia under certain conditions of nutrition. In the Nidulariaceae, a part of the fructification, the peridiole assumes the task of propagation instead of the basidiospores, which, on account of their angiocarpous formation, are no longer shot away, and which, surrounded by a gel, are set free very late. Thus the biological effect of the functional degeneration of the basidia is partially compensated. Fig. 309. — Nidularia pisiformis. Development of basidia. (X 1,200; after R. E. Fries, 1911.) Hydnangiaceae. — In this family we return to the stage of Leucogaster of the Rhizopogonaceae. Here the echinulate spores are no longer imbedded in a gel and the hymenium is always compact. The first member of this series is Hydnangium in which we find the beginnings of several divergent lines within the family. The ontogeny of this large genus has been little studied. The majority of species have a simple peridium, not greatly differentiated from the texture of the trama. Apparently as a degeneration phenomenon, we have a series of light-spored species with progressively thinner peridia, until finally the peridium is absent in some Californian species, as Gymnomyces Gardneri and G. Stillingeri. In the opposite direction we get a gradual thickening of the peridium and darkening of the spores, reaching a climax in Hydnan- gium Fitzpatrickii, with nearly black spores and a thick peridium of pseudoparenchyma. A still higher group of species has the peridium differentiated into two layers and nearly black spores, typified by H. citrinum. Such data as are available, lead one to believe that the cavities form in a hemispher- ical dome just under the peridium and develop basipetally until the whole glebal tissue is filled with cavities. The immature condition of a number 486 COMPARATIVE MORPHOLOGY OF FUNGI of species was misinterpreted and at one time the nsane' Octavinia was applied to them, incorrectly since it was originally used as a synonym of Melanogaster. In some species, as Hydnangium pusillum, there remains a hemi- spherical base of sterile tissue which is prolonged below into a short stipe, reminiscent of conditions in Jaczewskia and Hymenogaster Behrii. Perhaps a continuation of this tendency is found in the poorly known Lycogalopsis, the only genus of the family which is not found in or on the ground. In the Javan L. Solmsii (E. Fischer, 1886), the fructifications are 4 to 5 mm. in diameter (Fig. 310, a) and occur on the fruits of Parinar- ium scabrum. The fundaments appear as inverted patelliform portions of hyphal tissue, in which thick, concentric layers, tapering at the edge, a^sm^w Fig. 310. — Lycogalopsis Solmsii. A. Habit (natural size). B. Vertical section of imma- ture fructification. (X 26; after E. Fischer, 1886.) are separated by loose layers; apparently the layering results from periodic unequal growth, as in the formation of annual rings. When the gleba is formed, a peripheral tissue, which may include one or more layers, becomes grayish and develops to a peridium (Fig. 310, b). In one of the inner layers, rapid intercalary growth occurs, forming a hemisphere. Within, a hyphal palisade develops along with the glebal chambers in an unknown manner. At maturity, this degenerates, the peridium shrinks and a few remains of the tramal plates jut into the cavity, forming a rudimentary capillitium. Returning to Hydnangium, in H. sociale, a caespitose species in California, we frequently have a partial fusion of fructifications. In section, therefore, we frequently find deeply penetrating layers of peridial tissue, closely resembling sections of Protubera in appearance. This should probably be interpreted, however, as a convergence phenomenon rather than an indication of phylogenetic relationships. GASTEROMYCETES 487 In Hydnangium carneum, which alone has been cytologically investi- gated (Ruhland, 1901; Petri, 1902; Bambeke, 1904), there are extensive irregularities in the development of the basidium, which sometimes forms only one spore, into which occasionally all four nuclei migrate. As far as is known, an early division occurs in the normally developing spores, as is usual in most Gasteromycetes. Stephanospora carotaecolor differs from Hydnangium only in having a conspicuous collar at the base of the basidiospore. In an unidentified species, tentatively placed in Hydnangium by E. Fischer (1925), development is gymnocarpous at first and similar to that in Elasmomyces, but eventually the columella is obliterated by the for- mation of new cavities suggestive of those in Chamonixia and Gallacea. In Arcangeliella, a columella penetrates the gleba branching into tramal plates, as in Elasmomyces, but distinguished from it by the presence of latex ducts similar to those of Lactarius, and by slightly differ- ent spore markings. In A. caudata, the peridium is thin, with the outer hyphae perpendicular to the surface of the fructification. The cells of these hyphae break apart easily as oidia, but it is unknown whether they are capable of germination (Zeller and C. W. Dodge, 1919). In the cosmopolitan Arcangeliella Stephensii {Hydnangium Stephensii) E. Fischer (1925) reports the development similar to that of Elasmomy- ces. In A. violacea (Hymenogaster violaceus) the peridium becomes viscid, as in some species of Hymenogaster, and the spores are more ellipsoidal. The highest member of the series is Maccagna, where the tramal plates are differentiated into two kinds: the thick primary branches of the forked columella, composed of varicose hyphae and abundant latex ducts, and the secondary branches of tramal tissue composed of slender, compact hyphae without latex. Neither M . carnica nor M. tasmanica has been studied carefully, but the structure of the mature plant is sug- gestive of conditions we shall meet again in Phallogaster. The main line of development proceeds through Elasmomyces, which lacks the latex organs of the Arcangeliella — Maccagna series. In Elasmo- myces krjukowensis (Secotium krjukowense) the fructifications are devel- oped gymnocarpously (Bucholtz, 1901); the columella is percurrent and continuous with the peridium at the top. The peridium (pileus, of some authors) rolls in toward the bottom without being connected to the stipe; a few of its hyphae, however, may intertwine with the stipe hyphae, but the line between the two tissues may be easily recognized. Both peridium and stipe are composed of strands of slender hyphae and nests of pseudoparenchyma similar to the structures found in the Lactariaceae. The tramal plates grow further from the pileus toward the interior of the cavity, intertwine at their tips with hyphae from the columella and form numerous folds which anastomose with each other. This 488 COMPARATIVE MORPHOLOGY OF FUNGI results in a confused mass of chambers, whose cavities were originally- connected and open at the base of the pileus. At maturity, the peridium cracks off, allowing the basidiospores to be disseminated. This line culminates in Macowanites, where some of the larger Cali- fornian species, still undescribed, reach a height of 7 cm. with a flat, agari- coid cap 14 cm. in diameter. These larger forms are suggestive of the higher Agaricales and were it not for the large number of intermediate forms in this series, would be placed in that order, as Conard (1915) and Gaumann (1926) are inclined to do in the case of Endoptychum. Hymenogasteraceae. — This family is characterized by the colored, fusiform to citriform spores, and closely parallels the Hydnangiaceae in many respects. We may look for its origin in forms like Melanogaster of the Rhizopogonaceae. The first stage is represented by Hysterog aster, with deep yellow, smooth, fusiform spores, somewhat similar in shape to those of Hysterangium. Its ontogeny is not well known, but the gleba is filled with labyrinthiform cavities at maturity, as in Rhizopogon. The peridium is somewhat differentiated from the trama and the septa are said to be somewhat thicker in the center than next the peridium in //. luteus (Hymenogaster luteus), but there is no trace of a columella (E. Fischer, 1927). The details of the formation of tramal plates and cavities was not studied. The peridium of H. fusisporum {Hymenogaster Barnardi) is less well developed. The large, central genus of this family is Hymenogaster, corresponding to Hydnangium of the Hydnangiaceae. Here we have an assemblage of species which ontogenetic investigations will probably show to belong to several series, if not to different genera. The spores are usually citriform, yellow to brown, and often variously roughened. In an unidentified species which Fischer (1927) places in the group of H. lilacinus or of H. populetorum, probably in the former if my inter- pretation of his figures of immature specimens is correct, cavities form in a dome-shaped area under the pseudoparenchymatous(?) peridium and gradually develop basipetally. Growth is centrifugal from the central ground tissue. If this method of development should be found typical, it might explain a large section of the genus where the basal portion of the fructification remains sterile until quite late in its development, such as we find in the H. tener group (Fig. 311, A to C). In //. Behrii this tissue remains as a highly differentiated hemispherical basal portion from which thick septa radiate toward the peridium, as we have seen in Hydnangium pusillum and Lycogalopsis and shall see again in Jaczewskia. In Hymenogaster fragilis this base is prolonged into a stipe below, sug- gesting Lycoperdon in appearance. In Dendrogaster we have a persistent columella. Perhaps the most primitive species is D. candidus, where the sterile base is prominent and the columella relatively small. The peridium is pseudoparenchymatous GASTEROM YCETES 489 and thin, while the septa are thick and composed of slender tramalhyphae. The spores are small, ellipsoidal and minutely verrucose. In an unnamed California species, the columella penetrates only about half way through the fructification, and is but slightly branched, while the septa are much mwmmkk Mmtw< **thkS ■ --. v...vft \5 Fig. 311. — Hymenogaster tener. A. Habit (natural size). S. Section of fructification (X3.5.) C. Portion of gleba. (X 120.) D. Basidium and spores. (X 450.) After Tulasne.) Hymenogaster Rehsteineri. E to G. Sections showing development of fructifi- cation. ( X 450; after Rehsteiner.) thinner and the spores much larger. In D. cambodgensis, the peridium is distinguished by fascicles of erect yellow hyphae. In the other sub- genus, marked by a gelatinous sheath about the spore and a disappearance of the sterile base, we get a gradual development of the columella from D. 490 COMPARATIVE MORPHOLOGY OF FUNGI utriculatus, where it penetrates the center of the fructification, and, in an undescribed species from Tennessee, ends in a spherical knob from which the septa radiate. In forms like D. globosus (Hymenogaster globosus), it is dichotomously branched and nearly percurrent, as in the Elasmo- myces group of the Hydnangiaceae. The spores in this species are longi- tudinally ribbed suggesting Gautieria where the spores are characterized by 8 to 10 longitudinal ribs. Fig. 312. — Gautieria graveolens. A. Habit. B. Section of fructification, showing colum- ella and tramal plates. ( X 2; after E. Fischer, 1900.) In Gautieria we have a gradual degeneration of the peridium from such species as G. Rodwayi and G. Parksiana with thick peridia, through undescribed species with thin evanescent peridia, to species where the peri- dium is absent at maturity, although still present in young individuals. Only this last group has been studied ontogenetically (Fitzpatrick, 1913). The fructifications are spherical, furrowed and 0.5 to 2.5 cm. or more in £•.•,.•, ::,—Per Fig. 313. — Gautieria graveolens. Development of fructification. Per, peridium; z. str, columella; H. A., hymenial fundament; Tr, tramal plate. (After Fitzpatrick, 1913.) diameter (Fig. 312). They develop from clavate ends of rhizomorphs. The rind consists of loosely interwoven inflated hyphae, incrusted with calcium oxalate; it continues unaltered into the peridium of the young fructification (Fig. 313, 1). Similarly, the core of the rhizomorph becomes the columella of the young fructification. Its hyphae are inter- mingled somewhat with swollen hyphae, and run parallel to the axis. In the peripheral parts, they radiate toward the peridium and form dense GASTEROMYCETES 491 palisades (Fig. 313, 2, H, A). Further development proceeds from these palisades. The subhymenial tissue grows outward, forming tramal plates which anastomose freely and form the cavities of the gleba, lined with the developing hymenium. The peridium is pushed outward by the growth of the gleba, and since growth ceases early, the hyphae are torn apart and gradually disappear, leaving the glebal cavities exposed at maturity, as in Gymnomyces. As the tramal plates grow out from the central strand it gradually collapses and forms a cartilaginous forked columella. At maturity, the fructifications give off a pungent odor which attracts rodents and thus secure dissemination. In Gautieria plumbed the columella is much more highly developed, being nearly percurrent and having broad primary branches, as well as a slender stipe. The end member of this series is apparently Chamonixia caespitosa (Hymenog aster caerulescens, if the synonymy given by Fischer (1925) is correct). The fructifications at first develop gymnocarpously, then the peridial hyphae unite with the stipe. Finally the columella disap- pears as its sterile tissue is completely differentiated into gleba. The original figures of Rolland rather suggest a coalescence of caespitose fructifications such as we have found in Hydnangium sociale. Two anomalous species which perhaps should be transferred to form a new genus, Hymenog aster verrucosus and H. Rehsteineri, occur in eastern Europe. In young individuals (Fig. 311) the peridium Pol consists of closely interwoven hyphae surrounding a loosely tangled ground tissue BB, and the fundament of the gleba. The tramal plates grow downward from the upper part of the peridium into the glebal chamber Km, like the lamellae of the Agaricales. The tramal plates branch, anastomose form- ing the glebal cavities and finally fuse with the ground tissue at the base (Fig. 311, G.). The mature fructification has the same structure as that of the H. lilacinus(?) group, which has a different ontogeny. At present there is no way of knowing which method is followed by the greater number of species. Hysterangiaceae. — In this family we again return to the Rhizopogon- aceae. A primitive (or reduced?) form, Gallacea Scleroderma resembles Rhizopogon at maturity and is sometimes classified in that genus {e.g., Zeller and Dodge, 1918, under Rhizopogon violaceus). The fructification first appears as a pyriform branch of a rhizomorph (Cunningham, 1924). A dome-shaped zone in the outer portion of the glebal primordium cuts off the future peridium, composed of compact, ramose hyphae, the outer portion, of which is violet in color. The first cavities are few and large. The secondary cavities are successively differentiated from the columella tissue or formed by the rapid growth of tramal plates into the large primary cavities, eventually cutting them up into a large number of small ones. Cavities are also formed from the inner portion of the peridium, as in Rhizopogon. When the columella, which here acts as a ground 492 COMPARATIVE MORPHOLOGY OF FUNGI and nurse tissue, has all been used up, the whole gleba gelifies and forms a thin, collapsed lining of the peridium, leaving a large, empty space in the middle. The mycelium is wholly binucleate. As usual, fusion of the dicaryon occurs in the basidium. The fusion nucleus forms six nuclei which migrate into the spores and divide once, producing binucleate basidiospores. In Jaczewskia, a rare genus found once in Russia and once in British Columbia, the fructification consists of a gleba supported on a large sterile base which is slightly prolonged below into a short stipe. Several primary tramal plates grow upward from this base and give rise to the anastomosing secondary tramal plates (Mattirolo, 1912; C. W. Dodge unpublished observations). In Hysterangium the well-developed columella is persistent to maturity. In H. nephriticum the sterile base is prominent and persistent, with the columella scarcely more than a branch rising from it. As we saw in Dendrogaster, the columella becomes increasingly well developed as the sterile base disappears. H. inflatum is also reminiscent of Dendrogaster, Fig. 314. — Hysterangium clath- roides. Section of mature fructifica- tion. ( X 2; after E. Fischer, 1900.) -i-S-Z-str ^'■>KV:^r Vi&" Fig. 315. — Hysterangium clathroides. 1, 3. Median sections of young fructifications. 2. Section of periphery of young fructification. (1 X 10; 2 X 7; 3 X 270; after Reh- steiner, 1892.) Rhopalogaster transversarium. 4. Diagrammatic section of young fructi- fication. Gl. Km, gleba cavities; Tr, tramal plates; Per, peridium; Z. str, columella; Bas, basidial fundaments. ( X 10; after Johnston, 1903.) with its inflated, gelatinous sheath about the spore. In this group, the peridium, although of different texture from that of the trama, is homo- geneous and composed of slender parallel hyphae. From forms like these, there is a series to those with a highly developed columella and a peridium of coarse, thick-walled hyphae, and, finally, a well-developed pseudo- GASTEROMYCETES 493 parenchyma, such as we find in Hysterangium clathroides (H. stoloniferum var. americanum) , the only species to be reported upon ontogenetically (Rehsteiner, 1892; Fitzpatrick, 1913). In this species, the tramal plates arise from the columella and anstomose in all directions (Fig. 315, 1 and 3). Where the hyphal palisade borders the glebal cavities it forms a hymenium. The ends of the tramal plates next the peridium fuse with it (Fig. 315, 2). At the proximal side of this zone, the tramal hyphae may pierce the palisade in a tangential direction and approach the peridium laterally. In this species the bulk of the peridium is composed of pseudoparenchyma. In an undescribed species from California, the columella is very thick and the ends of the tramal plates rarely reach the peridium, leaving a single large cavity lined with a hymenium. The columella suggest a pine cone projecting into the cavity. In another undescribed species from the same region, the columella ends in a spherical knob in the center of the fructification, from which radiate the primary tramal plates. From this point, the columella is percurrent and develops along two diverging lines, one main line with the tramal plates continuing to develop from the columella, the other with the tramal plates developing increasingly from the top of the columella and the adjacent peridium, suggesting the Agaricales in both ontogeny and final product. In this latter line, which we will discuss first, the tramal plates disappear at maturity } leaving the spores as a powdery mass within the dry peridium, as in Endoptychum and Podaxis. The main line continues through Rhopalog aster and Phallogaster to the Clathraceae and perhaps the Phallaceae. In Secotium we have the counterpart of Elasmomyces and Macowan- ites in the Hydnangiaceae. In fact these genera, along with several other poorly known genera, are often included in a separate family, the Secotiaceae. Conard (1915) and Gaumann (1926) regard this group as an aberrant member of the Agaricales, modified by its hypogaeous habitat. On the other hand, Loh wag (1924, 1927) and Cunningham (1925), following the traditional viewpoint, consider this group as a family of the Gaster- omycetes, forming the culmination of the Hymenogastraceous line. Seco- tium is confined to S. Africa, Australia, New Zealand and the west coasts of South and North America. The fructifications are fleshy and firm and the gleba is never fragile and powdery, as in Endoptychum and Podaxis. Both Secotium erythrocephalum and S. Novae-Zelandiae have been studied ontogenetically (Cunningham, 1925), the latter in most detail. Although most of the species of this genus are hypogaeous or epigaeous, both these species are found on decaying wood in New Zealand. The plants are gregarious, enabling one to find many developmental stages on a single piece of wood. The first stage shows a furrow separating the stipe 494 COMPARATIVE MORPHOLOGY OF FUNGI fundament from that of the pileus, such as we find in the gymnocarpous Agaricales. The fundament of peridium and gleba shows a deeply staining ring containing a small radial lacuna, below which is a cuneate ring of loosely woven hyphae, the primordium of the partial veil. The lacuna, which extends as a ring around the base of the columella, enlarges and the hyphae lining its roof arrange their tips in a palisade which gradually covers the whole cavity except its floor. The tramal plates grow downward from the top of the cavity until they meet and anastomose with the walls of the cavity, dividing the large cavities into smaller ones, such as we have seen in Gallacea Scleroderma, and somewhat resembling the growth of the lamellae or tubes in the higher Agaricales. At the same time, other cavities are formed in the undifferentiated gleba above the original cavity, corresponding to those formed from the inner portion of the peridium in Gallacea ; but different from any structures reported in the Agaricales. About the time basidia appear in the palisades of the cavities, the peridium is differentiated and as the pileus expands, the furrow between it and the columella widens and deepens. The partial veil makes little growth after it is differentiated, and hence is torn apart and disappears at maturity. A few remnants persist about the stipe, giving it a fibril- lose appearance similar to that of the cortina in mature species of Cortinar- ius. The columella pushes gradually up into the developing ground tissue of the pileus, just ahead of the formation of cavities, reaching and merging with the peridium when the fructification is about half grown. S. erythrocephalum agrees with this development in most particulars. Its peridium is more highly differentiated, becoming covered with a defi- nite gelatinous layer, filled with pigment granules which originally lined the walls of the cells. In material collected by Zeyher at Uitenhage, South Africa, and determined as S. Gueinzii, Berkeley (1843) reports a well- developed volva which persists as polygonal areoles in mature specimens. The spores are also said to be similar to those of Hymenogaster albus, rather than the ellipsoidal, smooth or asperate spores of other species of Secotium. Cytologically, the life cycle is the same as in Gallacea, all portions being binucleate, with fusion of the dicaryon and meiosis in the basidium and a mitosis in the young basidiospores. Endoptychum, similar to Secotium and often included in that genus, is confined to the drier regions of the north temperate zone. The only well-known species is E. agaricoides (Secotium agaricoides, S. acuminat- um?), with a purely angiocarpous development similar to that of Secotium (Conard, 1915; Lohwag, 1924a). The youngest fundaments of the fruc- tification form a homogeneous body of tissue, surrounded by a firm peridium. A closed annular hymenial cavity is developed within the tissue. By increased local growth of certain subhymenial tissues, lamellae with cystidia grow toward the stipe and columella. On account of the GASTEROMYCETES 495 limited space, these lie in numerous folds and finally fuse with the hyphae of the stipe. At maturity the peridium breaks or is loosened from the stipe at its lower margin and expands, as in some species of Secotium and Macowanites. As a last member of this series we may mention Podaxis carcinomalis (Podaxon carcinomale) with much the same geographical distribution as Endoptychum, being confined to the warmer, drier regions. The fructifica- tions consist of a solid woody stipe and columella, a fusiform glebal tissue and a fragile, scaly peridium (Fig. 316) which separates from the top of the columella and from the stipe, and cracks longitudinally around the lower edge. The gleba is spongy with the tramal plates reduced to strands of hyphae bearing tufts of basidia. Maturation proceeds from below up- wards, the gleba eventually forming a dusty mass of capillitium and spores, as in the Lycoperdaceae ; Gaumann (1926) places it in a separate family as an appendix to the Agaricales, empha- sizing its similarity to Endoptychum (Secotium) which he also placed in this order. The main line of the family, leading toward the Clathraceae, develops from forms similar to Hysterangium fuscum (H. Gardneri), but having a completely percurrent columella and a more highly developed stipe. The small spores and the more or less gelatinous consistency is retained. Rhopalogaster transversarium (Caulo- glossum transversarium) of the south- eastern United States, continues this tendency. The shape of the mature fructification is similar to that of Podaxis (Cauloglossum), in which group it was formerly placed, or still more like that of Clavaria pistillaris (Johnston, 1902). The primordium of the gleba is first seen as a ring of small chambers surrounding the upper third of the club. The tissue outside this ring, the fundament of the per- idium, which consists of loosely interwoven hyphae, ceases growth and is gradually stretched by the developing gleba until it becomes thin and torn Fig. 316. — Podaxis car cinomalis. A. Exterior. B. Section of fructification. ( X }/% ; after Schweinfurth.) 496 COMPARATIVE MORPHOLOGY OF FUNGI in many places, very much as we have seen in Gautieria graveolens. As the gleba develops, the tramal plates bend and anastomose, forming cavities similar to those of Rhizopogo?i, which the gleba resembles in general appearance (Fig. 315, 4). Phallogaster continues this tendency with more highly developed tramal plates. P. saccatus, on rotten wood in North America, has been more fully studied (Thaxter, 1893; Fitzpatrick, 1913). Here the tramal plates are definitely differentiated into primary and secondary plates, the primary lacking a hymenium (Fig. 317, J.). In longitudinal section, they appear as branches and hence are called columella branches (st. zw); laterally they anastomose, forming radial, polyhedral cavities, opening outward, whose tips lie at a on the upper surface of the colu- Fig. 317. — Phallogaster saccatus. B. Section of mature fructification. after Thaxter.) A. Diagrammatic section of young fructification. C. Habit, showing dehiscence. (Natural size; B, C mella. In tangential section the walls of the cavities form a mesh. The tips of the primary branches spread out under the peridium to scutellate plates, which are called volva gel plates Vg. Rudiments of these struc- tures are also present in Hysterangium Fischeri of California where the ends of the tramal plates broaden so much that inside the peridium they form a narrow layer, only occasionally pierced by tortuous cavities (Fischer, 1908). This layer is more or less gelatinous. The fertile secondary plates arise from the primary plates, as in Maccagna; thus being retarded both in time and place of formation. They push into the polyhedral cavities and converge between the plates VG. In the limited space they lie in labyrinthine furrows and fuse with the neighboring plates into a very tangled group of chambers. Although the course of individual gleba chambers can no longer be followed, one must still assume that they remain open outward toward the peridium. The surface of the tramal plates is covered by a hymenium of 6- to 8-spored basidia. At the ends of the tramal plates in the gaps between GASTEROMYCETES 497 the volva gel plates VG, the palisade remains sterile and changes into a pseudoparenchyma. At maturity, the secondary tramal plates and hymenium become a dark, olive-green gel containing the primary tramal plates, the columella and portions of the volva gel plates (Fig. 317, B, C). The portions of the peridium lying between the volva gel plates develop zones of dehiscence D, resulting in a ragged peridium through which the spores escape. Mutatis mutandis the changes from Hysterangium to Phallogaster are parallel to the Pachyphloeus-Piersonia series. Pachyphloeus and Tuber would correspond to Hysterangium, Piersonia with its localization of the fundaments of the asci to the inner folds, to Phallogaster. Clathraceae. — While in the previous family, the tramal plates grow into a free space which the branches of the columella create by pushing the peridium outward, in this family, they grow into an intermediate tissue which is subsequently absorbed, leaving the cavities. In the Brazilian Protubera Maracuja (Moller, 1895), the youngest stages show a clavate widening of the mycelial strand, whose rind passes into the peridium and whose core becomes the gleba of the young fructi- fication. The branches of the columella arch outward enclosing portions of peridial tissue, which is not pushed outward. This included tissue is called intermediate tissue or peridial plates, Zw.Gefl. (Fig. 318, 2). With increasing size of the fructification, it also grows in breadth (Fig. 318, 3). In the meantime, a centrifugal growth of the columella branches sets in, expanding it radially. Its fate is variable; in the peripheral parts it is crushed into narrow peridial plates Zw.gefl.pl. by the branches of the columella which there spread out to the scutelate volva gel plates VG (Fig. 318, 4 and 5). These peridial plates persist and separate the volva gel plates at maturity. Further toward the interior, the branches of the columella do not spread out to such a degree; here, their longitudinal growth forms an elongate cavity Gl.Km, which is still filled with the loose remnants of the peridial plates. These cavities, which correspond to the polyhedral glebal chambers of Phallogaster, are not originally developed as cavities but result from the disintegration of the intermediate tissue. In a corner between the branches of the columella HA, the hyphae which radiate from these branches are arranged (even in the stage of Fig. 318, 3) in a palisade which spreads laterally and covers the walls of the cavities. As in the Hysterangiaceae and Phallogaster, tramal plates, which develop to the labyrinthine tangle of the mature gleba, are formed by the local growth of the tissue beneath. The mature fructification (Fig. 318, 1) has a diameter up to 5 cm. The peridium Per is at most % mm. thick, and consists of a brown, pseudoparenchymatous tissue. It does not contrast with the gleba, but lies upon the white or often almost bluish volva gel VG, 2 to 3 mm. thick which is connected through the gel-plates, the branches of the columella 498 COMPARATIVE MORPHOLOGY OF FUNGI Z. str. zw., with the gel mass at the base of the fructification (the earlier columella Zstr.). At maturity the peridium bursts open irregularly. The volva dissolves into a white slimy solution with which the greenish spore mass mingles. It has a strong odor, reminiscent of the flowers of Passiflora alata. This new formation of an intermediate tissue in Protubera attains a full development in Clathrus. This may be exemplified with C. cancella- -Z.str. Zw. tr. Zw. _ .4,^^f^w;-ivw-2w. " ■= '; ; ' '■"*, 5 ;> ■ •'■'.■.■.. .'».''••••:••■• ;i.'.'V.; 1 ... ,. , .j. .. ........ „. ••'".•• • ■ v.. ■ ■ ■ vs* I str. ***#/ Per ?-'■' & V. G ^er V.ll *, . /1V.-. . ... ..i..... ..- .•x;-.,i.«-iVrfi*<''T.--.'$;*-q;i;V./: r ! ! t I A m ' '-- -'•.■.>'.■;■•• ■ .-.• 'I. •• .•• .V,J,\'.:-.v----':;--.- •-■ •• ;••• aw.g.fr.p£ Gf.Km. Iw'^tfCf Fig. 318. — Protubera Maracuja. 1. Section of mature fructification. 2. Section of young fructification. 3. Advanced stage. 4, 5. Section of periphery. (1, natural size; 2 to 5 X 11; after M oiler, 1895.) tus (C. ruber,1 found in Europe and North America, and in C. columnatus, in North and South America (E. Fischer, 1891, 1900; Burt, 1896). As in all the order, the fructifications develop from rhizomorphs in which the core and rind both increase in thickness. As in Protubera, the branches of the columella grow out of the core and spread out later to volva gel plates. In contrast to both of these, in Clathrus the branches of the columella are not plates but true 1 Clathrus ruber is the correct name for this plant according to the International Rules of botannical nomenclature, but most authors since Persoon have preferred C. cancellous [Tournef] L. ex. DC. Hence I prefer to do likewise and intend to offer this case to the next Botannical Congress for inclusion in a list of nomina conservanda. GASTEROMYCETES 499 columns. Our Figs. 319, 320 may be distinguished from the corre- sponding stage in Protubera (Fig. 318) by the smaller number of branches of the central columella and by a greater development of the separating portions of intermediate tissue: further, the separation into columella and tangled intermediate tissue spreads over the whole fructification. In the Protubera stage (Fig. 318, 2), the articulation of the columella is still incomplete, as the tissue indicated as such includes the whole central and basal mass of the fructification. In Clathrus, however, the separation continues to the base, and the columella becomes a true central axis surrounded by peripheral tissue. As in Protubera, the hyphal palisade HA, which later expands later- ally, is laid down in the corners between the branches of the columella (Fig. 319, 2), and the intermediate tissue is compressed by the developing columella branches, especially at the periphery where these branches spread out into gel plates VG. In the central parts, however, there remains more space for the intermediate tissue. In contrast to Protubera (herein lies the distinct progress over this genus), these parts of the intermediate tissue are not dissolved and there are differentiated from them, at least in Clathrus cancellatus (toward the hyphal palisade HA), a thicker hyphal knot Rp (the first fundament of the receptacle, which is separated from its surroundings by a loose layer of tissue. In time the peripheral hyphae become arranged in a palisade. The strong sidewise growth of branches of the columella is very marked (Fig. 319, 3); in section, the parts VG represent polygonal areas which are continued by the narrow plates of intermediate tissue and separated from one another, but are beginning to gelify. Further, especially in the upper portions of HA , the columella branches elongate radially, whereby the hyphal knot Rp is pushed away from the palisade HA, and shoved outward so that a cavity arises between Rp and HA. This cavity is surrounded by a hyphal palisade, the lateral continuation of the original palisade, and is the first glebal chamber Gl. Km. In the distal side of the first hyphal knot Rp, in C. cancellatus, further knots are separated from each other and their surroundings by a narrow layer of loose tissue, the separation being most complete in the older inner knots, less complete in the outer. By the radial elongation of the columella branches, the gleba chambers increase in size (Fig. 319, 4). Meanwhile individual portions of the wall of the branch of the columella, covered by the hymenial palisade, arch over in ridges, elongate, increase in number, branch and eventually form the labyrinth of cavities and tramal plates which characterizes the gleba of the Gasteromycetes. In the distal parts of the gleba, where this touches the intermediate tissue, the hyphae of this tissue grow into the glebal chambers, fill them, hinder the change of the palisade to hymenium and intertwine repeatedly to a pseudoparenchyma. Similarly, the palisades 500 COMPARATIVE MORPHOLOGY OF FUNGI S'~ ||^--Zstn Zw. r^a^.JZ Sir. •Vi; • ■'-'•■ .-%.:■ .■ j> ,.-".; £ -Z> -Per 2?,; ■'. :■. • • ; ' -S -*« Jtlt Cat. Km ;%..-•■•...••.: • :• .' ha'# \;: ?) Z.str.-— fV;:,.:?.^ Per, 4 ■=.:./ :l Zw/ cpff.pt tp. 4-:';.:w< :;•,••«:■.->.: fe'S:. "•:•; V,:' ■. 1 . .::'.•;■■.*; •■ ■'.■ •'.':■> * Tii '•<■ . .' '■ .•!.■•'!■-■■•- • ••*'.'. •.,*.■• t' . . « \. / % •vV-.-.v.-:-.-.V-:-:-.?'.; *!.-•■. r/.'A'^w v-v.' Km Rp\vd Fig. 320. — Clathrus columnatus. 1. Vertical section of fundaments of a fructification. 2. Horizontal section. 3. Same, older stage. 4. Older stage, showing fundaments of first glebal cavities and tramal plates. 5. Older stage. Intermediate tissue has grown into the peripheral chambers forming pseudoparenchyma, Rp. wd. 6. Longitudinal sec- tion of mature egg at beginning of elongation of receptacle. Letters as in 317, except Rp. Km. receptacle chambers; Rp. wd., wall of receptacle chambers. (1 to 4 X 30; 5 X 17; 6 X 3; after Burt, 1896.) Toward the end of the development, the hymenial palisade changes to hymenia of eight-spored basidia. The parts of the intermediate tissue and gleba surrounded by the receptacle walls gelify, so that recep- tacle cavities result. Figure 319, 7 is a medial cross-section through a so-called egg, i.e., an immature fructification shortly before expansion. The axis of the greenish gleba Gl, occupying the greater part of the space, is penetrated by the columella which soon swells. The rays which proceed from it are the branches of the columella. On account of their tortuous course they cannot be followed to the volva in a section; furthermore, in contrast to Hysterangium, they are very thin in comparison to the gleba and 502 COMPARATIVE MORPHOLOGY OF FUNGI inconspicuous. Around the gleba are found volva plates VG separated from each other by parts of the intermediate tissue (Zw. gefl. pi.). Within the volva, there are transverse or oblique branches of the receptacle Rp; its pseudoparenchymatous walls grow unusually strong and, because of lack of space, lie in thick folds: as the receptacle branches spring from the same tissue as parts of the inter- mediate tissue, in Fig. 319, 7 the cross sections of receptacle branches always lie inside the plates of inter- mediate tissue. The result of the development is shown in Fig. 321. While all mature fructifications of the Hyster- angiaceae appear tuberiform, the Clathraceae show a marked change. The folds of the receptacle branches elongate at maturity, because of an increase of turgor, rupture both rind tissue and volva and elevate the gleba from the sheath of these two layers. The gleba liquefies, drops away and the basidiospores are spread, possibly by wind or insects. Finally, there remains only the receptacle whose form for C. can- cellatus is shown in Fig. 321. In C. columnatus, the branches do not form a lattice but they resemble the ribs of a dome. In the Brazilian Blumenavia rha- codes (Fig. 322), in the curve between the branches of the columella, one trama plate TVi is formed earlier or is better developed than the others (Moller, 1895; E. Fischer, 1900). This elongates until its ends press against the receptacle fundament Rp, spreads out here and surrounds the fundament with a bifurcation. While in further development, the hymenium normally is formed on the proxi- mal part of these plates, there arises on the distal bifurcations R in direct continuation of this hymenium, a pseudoparenchymatous layer Ps; the tissue R, surrounded by the pseudoparenchyma Ps, thereafter behaves as a receptacle chamber and is organically united with the remaining receptacle chambers. Hence on the outside of ripe fructifications (Fig. 322, 3) lies the rind layer Per, which surrounds the volva gel plates VG. These are connected with the columella Zstr. by its branches Z. str. zw. Between the volva gel Fig. 321. — Clathrus cancellatus. Expanded receptacle. (After Fayod.) GASTEROMYCETES 503 plates lies the torn portion of the intermediate Zw. gefl. pi. whose proximal end extends into the receptacle branches Up. In cross section, these form the outline of an acute sector with the base outward and the sides closely connected with the gleba Gl. The apex continues through the plate TVi to the columella. In contrast to Clathrus cancellatus, the central branches do not anastomose with one another but, like those of C. columnatus, rise from the base to the top of the fructification like the ribs of a dome. In the unfolding of the fructification, the plates of the intermediate tissue, the branches of the columella, the tramal plates Tr\ and the tissue R gelify; the peridium and the volva gel burst, and the receptacle rises out Fig. 322. — Blumenavia rhacodes. 1. Mature fructification. 2. Section of receptacle branch of immature fructification. 3. Section of immature egg. natural size; after Moller, 1895, and E. Fischer, 1900.) (1 X 2 X 8; 3, of it with a rapidity of up to 1 mm. per minute. As the eight columnar gleba portions are only connected with the receptacle columns, they are shifted outward through the papery aliform layer Ps, and exposed to the air from the interior of the lantern. The layer Ps, however, is not able to follow the stretching of the receptacle branches; it tears to pieces and remains hanging from the margins of the orange-yellow receptacle branches as bizarre rags, carrying on their exterior the dirty green gleba which soon drops away. In the Brazilian Clathrella chrysomycelina, during the earlier stages, a rind layer Rd is differentiated about the columella (Fig. 323, 1; Moller, 1895; E. Fischer, 1900, 1910). This follows the branches of the columella (which, here in contrast to Clathrus and like Hysterangium, are plates and not columns) and surrounds it even when these ends have spread to the 504 COMPARATIVE MORPHOLOGY OF FUNGI volva gel plates (Fig. 323, 3). This gelified rind Rd also surrounds the parts of the intermediate tissue, in the form of horns whose points lie in the angles between the branches of the columella. As in C. cancellatus, the 1 .#^!^vr^-.--Per %'■ ■■•..' .'• .■•■•'•'.'• '■■*" %\ is** m $:.''■•■■■ :*< ■>&••• ■/* :1 V. ■•:•*■•? •'■¥ ^ .rfSSSWRfc*., /Zw 9ef P« .#.>V^.V:».\:..'J?», ,- -Kct ft-- &;■ v. ^£.U;Sfr-Z 5tr. -*;*« Fig. 323. — Clathrella chrysomycelina. 1. Section of young fundament of fructification. 2. Beginnings of columella branches. 3. Later stage showing fundament of hyphal pali- sade. 4. Part of section of an almost mature egg. (1 to 3 X 15; 4 X 30; after Moller, 1895.) tramal plate is formed in these angles and (in the intermediate tissue) the receptacle chambers; in contrast to C. cancellatus (Fig. 319), however, the tramal plates are not irregularly arranged but grow up on the inmost, oldest receptacle chambers and surround them on three sides, (Fig. 323, 4, Rpi) whereby they inter- twine closely with the pseudoparenchyma of the chamber wall. The receptacle chambers Rp2, which later are formed further out, do not come into contact with the first receptacle chamber Rpi. They do not come into close contact with the tramal plates, however, but remain separated from them by a layer of gelatinous hyphae. Therefore, the gleba in the mature expanded receptacle does not hang as a whole (as in C. cancellatus) from the interior of the receptacle branches but only in small portions, surrounded by the torn Rd in the corners of the nets in small knobs, the original receptacle chambers Rpi (Fig. 324). It is further characteristic of Clathrella, that at its base the latticed branches fuse to a tube. The receptacle, thus, no longer rises in these lower parts, corresponding to the splits in the branches of the columella, in the form of single columns but as a hollow cylinder around the columella. Fig. 324. — Clathrella chry- somycelina. Unfolded recep- tacle. ( X % ; after Moller, 1895.) GASTEROM YCETES 505 This formation of a basal tube leads from Clathrella to a series of other genera whose receptacle extends into a longer or shorter stipe, as Simblum (Fig. 325) and Colus (Fig. 326). Both may be considered as stipitate Clathrus or Clathrella forms, but with the gleba confined to the apical portion of the receptacle (Conard, 1913). In contrast to these forms is the Chinese Lysurus Mokusin, where the distal parts of the branches of the columella, not the proximal, show intercalary growth (Fig. 327, D). The receptacle fundament Rp remains lying in the curve of the branches of the columella pi and the originally narrow cavities Gl. Km. do not arise, as in Clathrus (Fig. 319), between Rp and HA, but on both the exterior, distal sides of Rp. As the receptacle lies directly on the columella, there is no space there for the development of the tramal plates ; these grow rather from sides of the branches of the columella PI into the free space outside the receptacle, so that the gleba finally lies between the receptacle Rp and the volva gel plates G, and consequently clings to the un- Fig. 325. — Simblum sphaero- cephalum (S. rubescens) Mature specimen. (X^! after Gerard.) Fig. 326. — Colus Garciae. Mature fructification (Natural size; after Moller, 1895.) folded fructification (as will be discussed in the Phallaceae) on the other side of the receptacle branches. A development probably similar to that of Lysurus, is that of the South African Kalchbrennera corallocephala (K. Tuckii) whose ontogeny is incompletely known (Fig. 328). A pallid stipe, cylindrical or thicker toward the top, rises from the volva. At the clavate tip, the stipe wall disappears into a narrow-meshed lattice whose ribs (the continuation of the stipe wall) are colored an intense cinnabar red and are a cross- wrinkled above. Up to this point the receptacle corresponds to that of 506 COMPARATIVE MORPHOLOGY OF FUNGI Simblum. Here, there rise from the lattice bars toward the outside, cinnabar red and cross-wrinkled processes which, however, generally end free but occasionally do anastomose at their ends with neighboring processes. These ends are often broadened into two short aliform proc- Fig. 327. — Lysurus Mokusin. A. Habit of mature fructification. B. Section of the upper portion of young fructification. A, gleba; PI, plates of intermediate tissue; G, volva gel; Pi branch of columella; Rp, receptacle; S, columella. (A, natural size; 2? X 4; after Cibot and E. Fischer, 1893.) esses. Generally a process corresponds to every mesh of the lattice and bends obliquely over its mesh. On the processes and between them, traces of dark spore masses still remain (E. Fischer, 1891). As in Lysurus, the gleba develops toward the exterior of the receptacle lattice; thus the tramal plates proceed in all directions from the columella, GASTEROMYCETES 507 as in Clathrus. On the fourth side, the columella branches differenti- ate new hyphal knots rp, which are surrounded later by receptacle chamber walls and connect with the remaining lattice receptacle further inwards. The parts of the receptacle in question lie directly along the whole length of the columella branches and form the thorn-like processes. Anthurus, leading from Colus Garciae, has receptacle branches which no longer anastomose at the top and hence, in mature specimens, surround the gleba from below like the fingers of an open hand. Figure 329 shows this for Anthurus Sanctae-Catha- rinae, which has not been studied Fig. 328.— Kalchbrennera corallocephala. Fig. 329.— Anthurus Sanctae-Catha- Mature individual. (Nearly natural size; after rinae. Mature individual showing gleba. Kalchbrenner.) (Natural size ; after E. Fischer.) ontogenetically though a related form A. borealis (Aysurus borealis) (Burt, 1894) has been thoroughly investigated. The polymorphous Aseroe, which is closely related to Anthurus, will be discussed more thoroughly on account of its relationship to the next family. In Aseroe arachnoidea (Penzig, 1899; E. Fischer, 1910) the ground plan of the fructification is similar in principle to that of Clathrus. From the columella Z. str., there proceed (Fig. 330, 1) the vertical plates Z. str. zw. (branches of the columella) which later divide the gleba into a corresponding number of similar vertical flabella with the alternate plates 508 COMPARATIVE MORPHOLOGY OF FUNGI of intermediate tissue Zw. gefl. PL and the fundaments of the receptacle branches Rp. The plates of intermediate tissue, however, no longer extend to the rind of the upper part of the fructification but end blindly. The corresponding young stages have not yet been investigated, but A . ' ■ ' V.'- '•&»&*.('-?' Zwyfirt Zit. Gf- Km Fig. 330. — Aseroe arachnoidea. 1. Section of upper portion of young fructification, where the formation of the first tramal plates has begun ( X 13). 2. Diagram of egg after removal of rind tissue. 3. Diagrammatic section of a portion of a fructification in the direction of the arrow in 4. 4. Section of fructification in the direction of the arrow in 3. At the right, a branch of the receptacle in median section, at the left a branch of the colu- mella. 5. Median section of immature fructification. Aseroe rubra. 6. Diagram of upper portion of fructification in the direction of the arrow in 7. 7. Diagram in the direction of arrow in 6. 8. Median section of immature fructification. (After E. Fischer, 1910.) perhaps this results because the loose intermediate tissue in the upper part of the fructification loosens from the rind tissue and is pushed inwards by the swelling volva gel plates; thus in the upper part of the fructification the separate volva gel plates fuse into a continuous cover. GASTEROMYCETES 509 Near the base of the fructification, plates of intermediate tissue remain in contact with the rind and, as in Clathrus, extend from the columella to the surface (in Fig. 330, 2 the rind tissue is removed and the volva gel laid bare) : the volva gel VG, adhering above, splits below into a number of lobes corresponding in number to the receptacle arms. The lobes which separate the Zw. gefl. pi. continue as meridional pads through the interior of the fructification to the top. As in the other Clathraceae, tramal plates Tr. proceed from the branches of the columella; they converge more or less toward the recep- tacle arms and intertwine with the pseudoparenchyma. Figure 330, 3 gives a cross section through the upper part of a young fructification. Outside is the continuous volva gel layer VG which continues inward to the branches of the columella Z. str. zw. into the columella Zstr. Between the branches of the columella there lie the cavities Gl. Km. into which grow the tramal plates Tr. converging in the direction of the receptacle arms Rp. Figure 330, 4 gives a cross section in the direction of the arrow in Fig. 330, 3. From the inside, the top of the tramal plates Tr push against the receptacle branch Rp and lie next it. As a peculiarity of Aseroe, these tramal plates arise only on the sides of the branches of the columella but not on their lower edge. This lower basal edge spreads horizontally, remains in contact with the receptacle fundament and divides, in the formation of a pseudoparenchyma, the "margin" of the stipe wall. It is characteristic of A. arachnoidea that the receptacle branches elongate considerably and grow from above, bending over into the gelatinous columella Z. str. One can best conceive the whole arrangement of a young Aseroe fructification by comparing the volva VG with the pileus of a young Coprinus whose edge reaches the base of the fructification and splits into several lobes. The columella would then correspond to the stipe, and the vertical, plate-like branches would be comparable to the lamellae. A marked difference lies in the new tissues which form the trama, and which grow out from branches of the columella and fill up the spaces between "lamellae." Thus, in a mature fructification, the gleba occurs between the lamellae in the proximal zone, the receptacle branches in the distal. Less marked but distinctive for the appearance of the fructification is the fact that the "pileus" (volva) is ruptured at the top, the "stipe" (columella) and the "lamellae" (columella branches) dissolve, and only the con- siderably enlarged receptacle expands and spreads out the gleba on its arms. In Aseroe rubra (E. Fischer, 1893, 1910; Bernard, 1908) still more modifications of the plates of intermediate tissue and of the trama occur. As here also no young stage has been investigated adequately, we must rely on schematic reconstructions (Fig. 330, 6 and 7). In con- trast to A. arachnoidea, the plates of intermediate tissue no longer fuse 510 COMPARATIVE MORPHOLOGY OF FUNGI with the outer part of the fructification. It is always possible, however, that a few of them, as indicated in the scheme, are more strongly developed and extend to the rind. Similarly, the narrow cavity Gl.Km., together with the tramal plates which converge toward the receptacle branches, is only slightly developed or has almost disappeared; only the receptacle branches remain. Along with this degeneration, the fundaments of the tramal plate have undergone an important change. They no longer arise on the ver- tical sides of the columella Z. str. and the branches of the columella (in cross section invisible, Fig. 330, 6), but only on the underside of the columella which is swollen capitatively over the mouth of the stipe, out of the columella Z. str., as well as from the capitate end S and from the volva. Fig. 331. — Aseroe rubra. Mature fructification after the disappearance of the gleba. ( X 2 3 1 after Berkeley.) Hence they cannot converge toward the branches of receptacle but run downwards toward the disciform margin which surrounds the stipe mouth and fuses with it. As the tramal mass can only expand upward in its further development, the gel S is pushed toward the top and the receptacle branches. It covers the gleba thinly, thereby preventing the tramal plates from becoming connected with the receptacle branches, as in A. arachnoidea. In the mature fructification the spore mass only clings firmly to the horizontal disc, about the mouth of the stipe. In contrast to A. arachnoidea the receptacle arms no longer bear a spore mass (Fig. 331). Thus, the older portion of the receptacle has lost its original function as support of the gleba. Thus the Clathraceae show three stages of development. In the first stage, as Protubera, there arise sterile plates or branches of the columella GASTEROMYCETES 511 which grow out into the interstices created by the columella branches, and filled by intermediate tissue. On the distal ends, the columella branches spread into scutiform structures, the volva gel plates, which surround the interior of the fructification like an endoperidium. In the second stage, which begins with Clathrus and Clathrella and extends to Anthurus, there arises in this intermediate tissue a new organ, the receptacle, which comes into close connection with the gleba, raises it from the ground and from the sheath of the volva and the peridium and makes possible an entomophilous dissemination. In the lower forms, as in Clathrus, the receptacle is everywhere in contact with the gleba. In the higher forms, there is differentiated an increasingly insignificant apical part which serves as the point of attachment of the gleba and a basal part, always increasing in importance, which fulfills the true mechanical function of the receptacle. In the highest forms of the third stage, in Aseroe rubra, the apical part the connection between receptacle and gleba becomes lost, the gleba lies on the top of the columnar receptacle stipe and is raised up by it. The vestiges of the earlier receptacle branches which bore the gleba are functionless, the plates of intermediate tissue are degenerate and in the egg stage the fructification is completely surrounded by the volva gel. If one now imagines the receptacle branches are entirely degenerated, so that only receptacle stipe remains, one has the forms which will be discussed in the following family. Phallaceae. — The organization of the fructification of the Phallaceae shows great similarity to that of the Clathraceae; as in the latter, there is formed a receptacle, a gleba and a volva. Similarly, the ripe fructi- fications of many species, as in the higher Clathraceae, emit an offensive, penetrating odor which attracts insects. The Phallaceae, however, differ from the Clathraceae in many details. As in the Clathraceae, the fructifications of Mutinus arise as terminal swellings of rhizomorphs, whose core (Fig. 332, 1) passes over into the columella Z. str., and whose rind becomes the loose rind R of the young fructification. At the top of the columella the hyphae radiate to a sheaf-like head K (E. Fischer, 1887, 1891, 1895, 1900, 1922, 1923; Moeller, 1895; Burt, 1896; Petch, 1926). Most of the subsequent development takes place in this head. It swells much, forces the rind apart and is differentiated (Fig. 332, 2) into a loose layer VG, which soon gelifies, and to a closely intertwined central portion 0, where the differentiation of the columella continues (Fig. 332, 3), dividing into an axial gelatinous column Z. str. and to a cap AP which surrounds the top of the elongated columella. The cap is differ- entiated (Fig. 332, 4) into the loose intermediate tissue A and more solid peripheral zone P. On the inner proximal side of the zone P, there arises as a cylindrical cover, a hyphal palisade H.A., which arches over in pads and forms the fundament of the future gleba. 512 COMPARATIVE MORPHOLOGY OF FUNGI Only a portion of the following stage can be shown at once since in the meantime the fructification has grown too large. Such a section is given in Fig. 332, 5, where the rind and the volva gel Vg are separated. The differentiation of the columella proceeds through the cap P to the volva gel. Similarly the stipe St of the fructification has elongated; subsequently its bulk increases still further and soon exceeds the sporif- erous part. Along the columella Z. sir. there has been differentiated from tissue A, a thicker chambered cover, the fundament of the future 1 ..VG, &—0. .-.. R ■''."■- A' TTA •• ■'*■'. :■'■■■■ • V-*"-.-V. • . u Fig. 332. — Mutinus caninus. Development of fructification. (1,2 X 70; 3 X 44; 4, 5 X 24; 6 X 6; after Burt, 1896.) stipe walls of the receptacle. The members of its hyphae swell gradually so strongly that the chamber walls in the lower part of the receptacle stipe lie in folds. This receptacle corresponds to the receptacle stipe of Colus, Anthurus and Aseroe in the Clathraceae. A longitudinal section through an immature fructification is given in Fig. 332, 6. The gleba Gl. has already darkened, and is separated from the volva gel by a narrow layer, the compressed zone P, and from the stipe wall by the vestiges of the intermediate tissue A. In the South American Mutinus Muelleri, these vestiges become large spherical cells; in M. GASTEROMYCETES 513 A fog 8 zwm Fig. 333.— Mu- tiny, s caninus. Mature fructifica- tion, showing gleba. (Natural size; after Fischer, 1900.) nMM m Pi It! bambusinus of the tropics, this change occurs only in the proximal portion of the stipe and is entirely absent in M . caninus of the north temperate zone. The habit of a mature fructifi- cation is shown in Fig. 333. The stipe of the receptacle is white or reddish, the sporiferous part is dirty purple-red. The pileus is lacking and the gleba lies directly on the sides of the receptacle. In the other genera of the Phallaceae, the fructifications are formed according to the plan of Mutinus, but the intermediate tissue A undergoes a higher differ- entiation. A first step in this direction, we find in Phallus tenuis of southern Asia (E. Fischer, 1887). In it, the top of the tramal plates which press inward toward the layer A are not, as in Mutinus (and in the Hyster- angiaceae), covered with a hymen- ial palisade. Their hyphae develop (as mutatis mutandis in Hysteran- gium of the Hysterangiaceae) into the intermediate tissue A and con- nect laterally with the outgrowing hyphae of the neighboring tramal plates. Thereby a continuous layer H, divided by elevations and depressions (Fig. 335), shuts off the gleba chamber on the inside. At its apex it connects with the top of the stipe wall (receptacle) ; further down it is separated from the stipe wall by the remains of the layer A . The gleba does not lie directly on the stipe, as in Mutinus, but on the new campanulate tissue plate, which subsequently becomes the pseudo-parenchymatous pileus of the young fructification. When, at maturity, the receptacle elongates by straightening the folded chamber walls, the pileus with the gleba is raised out of the volva gel and the gleba drops off. The representation of such VI* •c „ TUJ. Fig. 334.— Phal- lus tenuis. Unfolded fructification after d i s a p p earance of gleba. (Natural size ; after Fischer, 1887.) 514 COMPARATIVE MORPHOLOGY OF FUNGI a fructification whose gleba has already flowed away is given in Fig. 334; in nature, it is isabelline. In Phallus impudicus (E. Fischer, 1891, 1893; Bambeke, 1910), the development proceeds in such a manner that the layer A undergoes a stronger development and in the stage corresponding to that shown in Mutinus (Fig. 332, 4) and P. tenuis it is differentiated into three layers Fig. 335. — Echinophallus Lauterbachii. 1. Median section of upper portion of fructi- fication. Phallus tenuis. 2. Median section of mature egg. Dictyophora indusiata. 3. Median section of mature egg. (2, 3 X 2; after E. Fischer, 1887, 1900.) (Fig. 336, 1). The outermost zone H, directly bordering on the tramal pads, assumes a somewhat different character and is more refractive. The middle, thick zone I is campanulate and parallel to H but, instead of reaching the columella, passes over laterally into knotted cover St.w. The inner zone A has a structure corresponding to that of the original intermediate tissue with hyphae more or less definitely radiating from the stipe axis toward the periphery. From the layer H and from the GASTEROMYCETES 515 outermost part of /, the pileus of the receptacle arises, as in P. tenuis, but with less cooperation of the hyphae radiating from the tramal plates. The layer A and the greater part of / develop no further; they remain as simple hyphal tissue and are torn and destroyed by the unfolding of the receptacle. In the mature egg, differentiation is similar to that of P. tenuis but the vestiges of the tissue A (A and the inner part of I) occupy much more space than in the latter. The part which interests us here, corresponding to the top in Fig. 336, 1, is given in Fig. 336, 2 for a somewhat older stage. The small projection V suggests the spot where in Fig. 336, 1 the inner layer / was attached to the stipe wall. VGN ."•■*-■ • xS " '*"£*:!* .C/;rfV-f ' ..-■• - . --.*!. .-K> .-..• ' . _. T #|;;/:;.fli::-;.; 2.Str. 3 V ' A>. — . " Fig. 336. st.w. astp. St.** V -Phallus impudicus. Median section of top of young fructification. (X 18; after E. Fischer, 1891, 1893.) This species is popularly called stink horn. Its eggs are eaten at times in Europe. Earlier both these and the ripe fructifications were used as drugs in the preparation of salves and powders for rheumatism and pestilence. In the Polynesian Echinophallus Lauterbachii (Fig. 335, 1), which is known only in the young stages, the zone I increases markedly at the expense of zone H (E. Fischer, 1900) which is very narrow and much curved outwards. In contrast to Phallus and the other Phallaceae here discussed, it forms no continuous layer but is discontinuous like a lattice. In longitudinal section (Fig. 335, 1) it shows only as short pieces, sepa- rated from one another and much enfolded in the gleba. At approximately two-thirds of its height, there arises a campanulate appendage /, 2 to 3 mm. broad, consisting of a simple layer of closed cham- 516 COMPARATIVE MORPHOLOGY OF FUNGI bers filled with gel like those of the stipe wall. Similarly, there arises a small projection V which in Echinophallus attains a greater development (Fig. 336, 1, 2). The space between it and the pileus H is occupied by an opaque gel / which in some spots is directly connected with the gel of Fig. 337. — Dictyophora indusiata. 1. Section of fructification in which the stipe of the receptacle has elongated and the gleba has mostly disappeared while the indusium is folded and hidden under the pileus. 2. Fructification, showing unfolded indusium. (1, natural size; 2 X %\ after E. Fischer, 1887, and Moller, 1895.) the stipe chamber. Below the zone /, in the space between the stipe wall St.W. and the pileus, i.e., the gleba, lies the bluish-gray, comparatively loose tissue A. These tissue differentiations have arisen in the same manner as their homologues in P. impudicus; there they have vanished GASTEROM YCETES 517 in the course of development and consequently in the stage of Fig. 336, 1 are recognizable as such only in the apical end of the egg. This tissue I reaches its greatest development in Dictyophora; here it develops to a beautiful structure (E. Fischer, 1887, 1890, 1891, 1900, 1910; Moeller, 1895; Burt, 1897; Atkinson, 1911). It is chambered, like the receptacle, and follows the inner side of the pileus from the top to the base of the egg (Fig. 335, 2). When the stipe elongates at the unfolding of the fructification, the layer I, together with the pileus and the gleba lying on it, is raised. Then the folded chamber walls elongate in this layer, as did the receptacle stipe (Fig. 337, 2), and the layer/ expands like a crinoline toward the bottom and unfolds to a latticed indusium. This indusium is only an appendage of the receptacle stipe and, in con- trast to the pileus, is not directly connected with the gleba. It is formed when the gleba is just beginning to form and its ends are still far removed from the stipe. Its significance is not yet clear. Fig. 338. — Section of hypothetical transitional form between Aseroe and the Phallaceae. 2. Diagram of young fructification of Phallus. Letters as in Fig. 332. (After E. Fischer, 1910.) A majority of the Clathraceae and Phallaceae are entomochorous and by their strong odors attract attention from a distance. The fructifications generally unfold at night and at dawn, the gleba has mostly dropped off. As Lohwag (1924) has demonstrated, in this grouping the Phallaceae would be regarded as derivatives of the Clathraceae. In both families the organization is fundamentally the same, only in the former the tramal plates grow centripetally, in the latter centrifugally. If one imagines that the development which leads from Protubera, Clathrella, Anthurus through Aseroe arachnoidea to Aseroe rubra, continues, and that the widening of the central strand S (Fig. 330, 7), appearing above the stipe orifice, is more strongly developed and arched over slightly with the edge in the shape of a bell, and that the splits between the branches of the columella and thereby the plates of the intermediate tissue and the receptacle branches (which in Aseroe rubra have been already alienated from their original function) progressively degenerate and finally disappear, one arrives at a form like that represented schematically in Fig. 338, 1. Its longitudinal section is like that of Aseroe rubra, but the receptacle 518 COMPARATIVE MORPHOLOGY OF FUNGI branches are rudimentary and the intermediate tissue is limited to the basal half of the fructification. Also the letters are changed to corre- spond to those in the scheme for the Phallaceae. From this form, the transition to a simple species of Phallus, e.g., P. tenuis, is easy. It must be remembered, however, that the intermediate form represented in Fig. 338, 1 is only a theoretical construction and has not yet been found, and that it is still uncertain whether we may regard the Phallus as primitive or whether, perhaps, some of its species, e.g., P. impudicus, should not be regarded as degenerate species of Dictyophora with reduced indusium. Similarly, it is still uncertain whether Mutinus may be considered a degenerate form, as by this conception, it must seem even more primitive in several respects. It is further obvious that even if these intermediate forms were found, it would not yet be proved that the development proceeded in the manner suggested. This deriva- tion of the Phallaceae from the Clathraceae through Aseroe and Phallus seems much more probable than the other possibility. It is more plausi- ble than the direct derivation of the Phallaceae from the Endoptychum, for it would be difficult to understand why, as an indication of conver- gence, the Clathraceae and Phallaceae have attained an equal stage in differentiation of their tissues, when there were so many other possibilities. The transition from the Clathraceae to the Phallaceae is marked by the following three points: the plates of intermediate tissue, which in the Clathraceae cause a separation of the volva gel into plates, have entirely disappeared after Aseroe so that in the Phallaceae, the volva gel forms a continuous cap. Similarly, the development of the central strand is backward and no longer divides. And, thirdly, the development of the gleba, which in Aseroe rubra is removed from the central strand, in the Phallaceae is shifted outwards and connected with this strand at its upper end only. A schematic presentation of these mutual relationships is given on page 519. With increasing knowledge, the above systematic classi- fication of the Gasteromycetes, like that of the Polyporales and Agaricales, will undoubtedly be entirely rearranged. GASTEROM YCETES 519 «8 H 31 "© 00 _ « o [accag cangeli >» a. go <*. t8\ o to - 1 L P < *. o \ 3 •z. c 6 F \'3> Q o -^os C c 03 CO OS -a a w E 00 U H U O >< <-. o a: w ■n < O < a o <: ■j •j < x - 9J.2 O o3 till < o P a <*A o 09 ■< a e u O o as ■2*- !Y1 _ « t-s5 cu o easter straeuf roomei - 9- a oi >, 03 0 ►JOPQ -j 0.>, ■S5 O Q&.BB W ■OB *-» f'. 1~ X < a o < CHAPTER XXIX TREMELLALES In the Tremellales, we return again to the threshold of the Basidio- mycetes. They represent the chiastobasidial counterpart of the Auricu- lariaceae and have rounded, pyriform basidia, longitudinally divided into four cells. They begin as the Polyporales with forms without well- developed fructifications and end with forms having gymnocarpous or even angiocarpous fructifications. The gymnocarpous species are placed in the Tremellaceae, the angiocarpous ones in the Hyaloriaceae, while two species of doubtful position are placed in the sirobasidiaceae. Their most marked morphological relationships are shown in the scheme below. TREMELLALES HYALORIACEAE HyaToria TREMELLACEAE Tremellodendron Protomerulius Tremellodon Clavariopsis / Protohydnum Gyrocephalus / ^^ Tremella / ^^ Ditangium / ^^ Exidia / /^ Eichieriella / ^^ Heterochaete Sebacina SIROBASIDIACEAE Sirobasidium Diagram XXXI. Tremellaceae. — This family forms a series parallel to the Poly- porales, developing from arachnoid coverings to compact, bilateral, gymnocarpous fructifications. According to the structure of these fructifications, they may be divided into four subfamilies: the Sebacineae, the Tremelleae, the Protomerulieae and the Tremellodonteae. The Sebacineae correspond to Corticium of the Corticiaceae. In the primitive forms with cruciate basidia, there is no well-defined hymen- ium, the basidia appearing irregularly scattered on the mycelial felt. Sebacina papillata (Stypella papillata) and S. minor (Stypella minor) (Moller, 1895) on mouldy wood in Brazil, form small, gelatinous cover- ings with papillose elevations which consist of peculiar, long, tubular, aseptate cells (Fig. 339, 1). At the ends of hyphae, the cruciate basidia 520 TREMELLALES 521 develop at variable heights above the substrate. Occasionally the second septum fails to develop in them. In the higher forms, the hyphal tissue is waxy, membranous or cor- iaceous and the basidia form smooth hymenia. Sebacina uvida (Exidi- opsis effusa) is also poorly developed. The basidiospores germinate with falcate conidia of the Auricidaria type (Brefeld, 1888). Before basidia develop, thick branches of the sub- hymenial hyphae form special con- idiophores which project above the hymenium and cut off little heads of Fig. 339. Fig. 340. Fig. 339. — 1. Sebacina minor. Showing irregularly arranged basidia in hyphal tissue. 2. Heterochaete Sanctae-Catharinae. Section of fructification, showing portion of hymen- ium. 3. Sebacina incrustans. Young hymenium, showing conidiophores. (1 X 180; 2 X 100; 3 X 270; after Brefeld, 1888, and Moller, 1895.) Fig. 340. — Sebacina ciliata (Exidiopsis ciliata). Habit. (Natural size; after Moller, 1895.) long, oval, conidia (Fig. 339, 3). In Sebacina (Bourdotia) gloeocys- tidiata (Kuehner, 1926), caryogamy occurs in the young basidium followed by meiosis and the formation of the usual septa. The basidio- spores are uninucleate. Heterochaete Sanctae-Catharinae (Moller, 1895), in Brazil, appears on tree trunks as resupinate, very thin, gelatinous 522 COMPARATIVE MORPHOLOGY OF FUNGI membranes, with irregular borders, covered between the setae by an even hymenium (Fig. 339, 2). The Tremelleae bear the same relation to the Sebacineae as Stereum to Corticium, or Auricularia to Platygloea, only their fructifications are even Fig. 341. — Tremella compacta. Habit and cross section. (Natural size; after Moller, 1895.) more gelatinuous than those of Auricularia. These gelatinous masses are hygroscopic, having the ability to swell greatly in wet weather, while in dry weather the imbibed water readily evaporates, producing great Fig. 342. — Tremella fuciformis. Habit. (Natural size; after Moller, 1895.) shrinkage and change of form, as well as practical suspension of life processes. With the return of rainy weather, they renew their growth and spore formation. They are very resistant to temperature changes and endure —20° C. without injury. TREMELLALES 523 The systematic differentiation of these forms is very difficult because marked morphological characters are lacking and because the form of the fructifications, depending upon their environment, may alter beyond recognition. The conidia are, therefore, often used to distinguish the genera. The simpler genera, as Eichleriella, Exidia (Ulocolla), Ditangium (C rater ocolla) and Tremella, are directly connected with Sebacina in the structure of the fructifications. Eichleriella is more or less coriaceous and bears the same rela- tion to Sebacina which Stereum and Cyphella bear to Corticium, E. spinulosa has a tuber- culate hymenium resembling Radulum and forms a transition to Protohydnum in the Tremellodonteae. The other genera are gelat- inous to cartilaginous, tuberiform to turbinate, generally much lobed and branched, often cerebriform (Figs. 341 and 342), bearing a hymenium on the outer surface, but sterile next the substrate. The higher genera, Gyrocephalus, Clavariop- sis and Tremellodendron develop forms reminis- cent of the higher families of the Polyporales. Gyrocephalus forms stipitate, infundibuliform fructifications, bearing the hymenium on the inner side. In form they suggest Craterellus cornucopioides and the Cantharellaceae. Clava- riopsis forms cylindric or coralloid fructifications similar to Clavaria, while Tremellodendron has flattened branches, resembling Sparassis, Pterula or Thelephora. In the basidia, the spindle is transverse at the division of the diploid nucleus. At the end of the first division, the first septum is laid down from the basidial wall. The nuclei divide again, their spindles are transverse and approximately parallel to the first septum, hence perpendicular to the plane of division of the first nucleus. After this division, a new septum is formed perpendicular to the first (Juel, 1898; Neuhoff, 1924; Kuehner, 1926). In the rare cases where the septa are not always transverse, e.g., in Tremella compacta, they may be parallel, as in the Auricularia type, or in T. lutescens, they may be irregular, (Fig. 343), or they may be absent. Sometimes the basidia, instead of forming spores, may develop directly to mycelia. In Clavariopsis prolifera, as in Eocronartium and Iola, new basidia are always formed by lateral growth of the subterminal cells on the same hypha. Fig. 343/ — Tremella lute- scens. Basidium with irregu- lar septa, germinating to mycelium. (X 720; after Coker, 1920.) 524 COMPARATIVE MORPHOLOGY OF FUNGI The germination of basidiospores has only been reported in the last three genera. A basidiospore of Exidia repanda divides into two daughter d$*s* Fig. 344. — Exidia repanda. 1. a, tip of mature sterigma with reniform basidiospore; b, germination of basidiospore with falcate conidia. 2. Exidia saccharina, var. foliacea. (Ulocolla foliacea) . b, germinating basidiospore; c, germinating conidia. Tremella lutes- cens. 3. Mature basidium. 4. Germinating basidiospores, one surrounded by sprout cells. 5. Sprout mycelium. 6. Sprout cells developing hyphae. 7. Conidiophores. Ditangium Cerasi (Orbilia rubella). 8. Conidiophore. (la, 3 X 450; 16, 5, 6 X 500; 1 c, 7 X 420; 2 X 320; 4 X 400; 8 X 300; after Brefeld, 1888.) Fig. 345. — Tremella mesenterica. Section through periphery of young fructification. 1. Oidial stage. 2. Beginning of basidial formation. 3. Mature basidia. (X600; after Dangeard, 1894.) cells which in dilute nutrient solutions develop directly to slender septate mycelia without clamps. In E. saccharina var. foliacea, bacilliform TREMELLALES 525 conidia are produced (Fig. 344, 2). In Tremella, the conidia are spherical, and may sprout in nutrient solution (Fig. 345, 3 to 7) . In Tremella lutescens they are found in Nature on young, still felt-like fructifications where they are cut off in large numbers on branched conidiophores (Brefeld, 1888). In T. mesenterica they are replaced by uni- or binucleate oidia which result from the breaking up of the terminal portions of hyphae (Fig. 345, 1 and 2) and multiply by sprouting (Dangeard, 1895). With the appearance of basidia and the increase of gel secretion, conidial formation decreases and their remains are imbedded in the gel. A similar succession was reported Fig. 346. — Protomerulius brasiliensis. Habit. (Natural size; after M oiler, 1895.) for Ditangium. A young fructification, which appears in the fall, consists of a swollen hyphal felt whose mature top has crateriform open- ings, covered by stratose, branched conidiophores (Fig. 344, 8). The conidia resemble the basidiospores but are only half as large. During the winter, the hyphal membranes swell, the fructification gelifies and basidia appear. The basidiospores germinate without division either by conidia or germ tubes. As far as known, the secondary spores formed on the mycelium are uninucleate, those on the fructifications binucle- ate (Neuhoff, 1924); hence the former are haploconidia, the latter diploconidia. 526 COMPARATIVE MORPHOLOGY OF FUNGI In the Protomerulieae, the convolutions of Exidia become folds and reticulations. In Protomerulius brasiliensis (Moller, 1895) and P. Farlowii from New Hampshire (Burt, 1919, a) the reticulations gradu- ally grow upwards, producing a tangle of tubes resembling the hymenium of Merulius (Fig. 346). Bracket forms, somewhat resembling Auricu- laria, are sometimes formed under favorable conditions. Similarly, the Tremellodonteae resemble the resupinate genera of the Radulaceae, e.g., Tremellodon cartilagineum (Moller, 1895). In Proto- FlG. 347. — Tremellodon cartilagineum. Habit. (X M; after Moller, 1895.) hydnum lividum, var. piceicola, Kuehner (1926) reports the usual nuclear phenomena in the basidium and young basidiospores. In the highest form, Tremellodon gelatinosum (T. crystallinum), the fructifications are often laterally stipitate with teeth resembling those of the higher Radu- laceae (Fig. 348). Hyaloriaceae. — This family is the angiocarpous homologue of the Phleogenaceae and Gasteromycetes. The basidia arise irregularly within the fructification, and are not united into hymenia. The only well-known TREMELLALES 527 species, Hyaloria Pilacre (Moller, 1895), forms shining, almost transparent stipes which taper upwards and bear at the tip a small head (Fig. 349). This consists of a tangled felt of slender hyphae imbedded in a gel. The hyphae radiate toward the outer wall, within which they form on branches, a compact layer of cruciate basidia. The structure of the fructification is similar to that in Phleogena, except the hyphal ends remain smooth and do not coil, allowing the spores to be liberated between them. Fig. 348. — Tremellodon gelatinosum. Habit. (Natural size; after Moller, 1895.) Fig. 349. — Hyaloria Pilacre. Habit. (Natural size; after Moller, 1895.) Sirobasidiaceae. — As an appendix, we will discuss two interesting forms whose position is still obscure. Sirobasidium Brefeldianum, on rotting wood in Brazil, forms shining, later white, gelatinous fructifica- tions up to 3 mm. in diameter. They consist of numerous, loosely tangled hyphae radiating from a single point and imbedded in a transparent gel (Fig. 350, 1). Clamps are abundant at the septa. The terminal cell of the hyphae swell to elongate ovoids and divide by usually oblique 528 COMPARATIVE MORPHOLOGY OF FUNGI septa into two daughter cells, each of which cuts off a basidiospore without a sterigma. The next cell below then swells and repeats the process basipetally. The basidiospores germinate with germ tubes or sprout conidia. S. albidum, on dead twigs in Ecuador, has true four-celled cruciate basidia. Fig. 350. — Sirobasidium Brefeldianum. Habit, enlarged, showing basidia. (X145; after Moller, 1895.) Sirobasidium albidum. 2 to 5. Development of basidia. (X250; after Lagerheim and Patouillard, 1892.) Whether these two species are related to each other and are rightly placed in the same genus, can only be decided by their cytological rela- tions. Moller (1895) considered them as transition forms between the Phragmobasidiomycetes and the Autobasidiomycetes, which latter had developed from the former by a change in orientation of the basidial walls. CHAPTER XXX CANTHARELLALES The Cantharellales ascend, as do the Polyporales, from resupinate types to gymnocarpous forms. Anatomically, even the highest forms retain primitive characters, the uniform structure and slight differentia- tion of hyphal tissue, hymenophore and hymenium. The basidia corre- spond to the stichobasidial type, simple in form and variable in spore number. The diploid nucleus (as in asci) generally proceeds through three divisions, hence the young basidium is octonucleate and in this condition appears entirely similar to a Hypocreaceous or a Discomycetous ascus (Fig. 353, 3). Similarly, in some species, usually eight basidio- spores are formed; in others, in spite of the octonucleate basidia, the spore number is reduced and finally fixed at a two-spored type, although the stichobasidial method of division is retained (Fig. 353, 10). These two-spored basidia suggest conditions we will find in the Dacryomyce- tales, since their sterigmata often swell at the base, forming a cone. Perhaps both orders have developed from simple resupinate crusts with normally eight-spored basidia. At present no imperfect forms are known, but two parasitic genera have been reported to form sprout mycelia. As already briefly indicated on page 427, the Cantharellales is only a provisional order. This transitional state is explained by the lack of cytological information. Until this has been obtained, it seems better to leave the species in the chiastobasidial orders, which are much larger and have realized more varied possibilities of development than the stichobasidial type. Therefore we will place in the Cantharellales only those forms in which stichobasidia have been demonstrated, and make no nomenclatorial changes to carry out this classification. The value of this separation of the stichobasidial types from the chiastobasidial types is extremely doubtful (Juel, 1916). These forms may be placed in three families: the Exobasidiaceae, resupinate forms, often modified by their parasitism, usually lacking a compact hymenium, so that their basidia emerge singly or in groups from the stomata of the host; the Clavulinaceae with fructifications similar to those of the Clavariaceae discussed in the Polyporales; and the Cantharel- laceae, whose fructifications are differentiated into pileus and stipe. Their possible phylogenetic relations are shown in the following diagram : 529 530 COMPARATIVE MORPHOLOGY OF FUNGI DACRYOMYCETALES CANTHARELLALES DACRYOMYCETACEAE Dacrvomyees Caloeera GuepiniaN Dacrvomyees Ceracea X CANTHARELLACEAE Hydnum Cantharellus Thelephora Craterellus CLAVULINACEAE Clavulina t EXOBASIDIACEAE Exobasiclium Kordyana Peniophora eorticalis Ascocorticium group - Diagram XXXII. Exobasidiaceae. — This family, usually included in the Corticiaceae by systematists (e.g., Burt, 1915), contains primitive, resupinate species. The only saprophytic species, Peniophora eorticalis (P. quercina, Kneif- fia eorticalis), forms resupinate crusts on twigs. The hyphal cells are originally binucleate but later, by nuclear division without septation, they become multinucleate (Maire, 1902) . Clamp connections are abund- ant. The smooth hymenium consists of four-spored basidia and cystidia which are sunk deep, so that only the tips project beyond the basidia. All the other species of this genus which have been investigated belong to the chiastobasidial type. The germination of the basidiospores is unknown. Kordyana is parasitic on leaves of tropical species of Commelinaceae, causing brown spots, surrounded by a light green zone. The hemispher- ical hymenia, white or yellowish, are erumpent from a hyphal tissue in the substomatal air passage on the underside of the spots (Fig. 351). They consist of basidia and sterile hyphae (paraphyses) exceptionally of basidia only. The basidia are rather variable in form. At maturity they gener- ally contain four nuclei; usually producing two spores. In damp nights, there may be formed successively, small fascicles of as many as six spores in which mature and immature spores are intermingled. They germinate either by germ tubes or by sprout mycelia (Gaumann, 1922). Exobasidium biologically bears a relationship to Kordyana, similar to that of Albugo and Peronospora to the Pythieae in the Oomycetes. The hyphae of Kordyana penetrate the infected tissue in all directions and kill it; those of Exobasidium have adapted themselves to the host and stimulate it to form galls and witches' brooms, rather than kill it. In this respect, Exobasidium resembles Taphrina in the Ascomycetes. Exobasidium Vaccinii, parasitic on many Ericaceae, especially on Vaccinium Vitis-Idaea (Fig. 352), has been studied in great detail (Woronin, 1867; Brefeld, 1889; Maire, 1902; Burt, 1915; Eftimiu and CANTHARELLALES 531 Fig. 351. — Kordyana Polliae. Section of hymenium on underside of leaf. (X450; Gaumann, 1922.) Fig. 352. — Exobasidium vaccinii. Section of periphery of stem of Vaccinium Vitis- idaea, showing hymenium; ep, epidermis; p, bark parenchyma; m, hyphae in intercellular spaces; b, erumpent basidia; b', basidium, still without sterigmata; b", basidium after formation of sterigmata; b'", basidium with mature basidiospores. ( X 620; after Woronin, 1867.) 532 COMPARATIVE MORPHOLOGY OF FUNGI Kharbush, 1927). The hyphae occupy intercellular spaces. The cells of the host are stimulated to hypertrophy and hyperplasia, forming swellings on the leaves or thickening and lengthening of the whole shoot. The chlorophyll is destroyed and replaced by red pigment. The basidia (in contrast to Kordyana) penetrate between the epidermal cells and form a thin, white hymenium on the under side of the leaf. They arise singly on hyphal branches, bearing two to six spores. At germination, the spores form one to three septa, each of the cells putting forth a slender germ tube, which, on reaching air, cuts off several narrow, filiform sprout cells, pointed at each end. Sometimes the basidiospores proceed directly to the formation of sprout cells which continue budding without falling off at the tip, thus forming small fascicles. E. discoideum on Azalea and E. Rhododendri on Rhododendron ferrugineum frequently have chiastobasidia and should be placed in the Corticiaceae (Eftimiu and Kharbush, 1927). Clavulinaceae. — This family corresponds in most details to the Cla- variaceae as discussed in the Polyporales. At present only four species of Clavaria (sensu latiore) are known to belong here. The limits of Clavaria as given in systematic manuals include both sticho- and chiastobasidial types. As the chiastobasidial forms are more numerous and the type species of the genus occurs among these, the name Clavaria, according to the rules of nomenclature, must be limited to the chiastobasidial forms. In this case a new name should be created for the stichobasidial Clavaria falcata. Schroeter proposed Clavulina for the other sticho- basidial species, C. rugosa, C. cinerea and C. cristata (C. grisea) on other grounds. The white or ashy fructifications of these five species grow in damp woods or glades. In C. falcata, they are simple and unbranched (subgenus Holocoryne); in C. rugosa, slightly forked, and in the other three, variously branched, fruticose or dendroid (subg. Ramaria). The hyphae bear numerous clamps and in the interior of the fructification are parallel to the axis. At the periphery, they bend perpendicularly and form the hymenium by their compact ends. The hymenium consists of basidia of very unequal age; in old collapsed specimens, one may find very young basidia, which have not yet formed sterigmata. At maturity, the basidia contain 8 nuclei as a result of a triple division of the diploid nucleus. The number of sterigmata is very variable: in Clavaria falcata six to eight, mostly seven, in Clavulina rugosa, in time, for they are not formed simultaneously, mostly four, seldom two and in C. cinerea (Fig. 353, 6 to 10) and C. cristata always two (Maire, 1902; Juel, 1916). As each spore contains only one nucleus, a variable number of nuclei degenerate in the basidium. The third division is sometimes lack- ing in C. cinerea (Bauch, 1927). The germination of basidiospores is unknown. C. cristata, C. cinerea and C. rugosa are edible. CANTHARELLALES 533 Cantharellaceae. — This family contains the stichobasidial segre- gates from the Thelephoraceae, Hydnaceae and Agaricaceae of the earlier writers, and is characterized by a differentiation into stipe and pileus. In the young buttons, the hyphae radiate in the upper part and are much branched. As in Gyrocephalus of the Tremellales, an infundi- buliform structure develops by strong epinastic growth. In Craterellus 4« J Fig. 353. — Development of basidia of Craterellus cornucopioid.es. 1 to 5. Of Clavulina cinerea. 6 to 10. (1 to 5, 10 X 1,200; 6 to 9 X 1,400; after Juel, 1916.) the hymenophore is smooth or slightly wrinkled, in Cantharellus it con- sists of parallel folds similar to the lamellae of the Agaricales, but less well developed. These differences are only quantitative and many inter- grading forms are seen. Cytological investigation extends to only eight species: Craterellus cornucopioides, C. lutescens, Cantharellus cibarius, C. cinereus, C. tubae- formis, Thelephora palmata, T. anthocephala and Hydnum repandum 534 COMPARATIVE MORPHOLOGY OF FUNGI (Maire, 1902; Juel, 1916). The structure of the hymenia and basidia agree with that of the stichobasidial Clavariaceae. As in the latter, the diploid nucleus usually, but not always, divides thrice into eight nuclei; the number of sterigmata is variable, e.g., Cantharellus cibarius five to seven, mostly six (Fig. 271), C. cinereus and C. tubaeformis two to five, mostly four, Craterellus lutescens three to five, mostly five, and C. cornu- copioides two to four, mostly two (Fig. 353, 1 to 5). The fate of the remaining nuclei has not been carefully followed. The basidiospores are smooth, hyaline or slightly yellowish. The fructifications of Thelephora correspond to those of the stipitate species of Stereum or Lachnocladium, being leathery or woody, and more or less infundibuliform or branched. Their hymenium is smooth and confined to the lower surface of the pileus. The basidiospores are echinu- late and colored, as in Hypochnus of the Corticiaceae. The fructifications of Hydnum repandum bear long teeth on the under side of the pileus, as in the higher Radulaceae. Since this species is the nomenclatorial type of Hydnum, the traditional family, Hydnaceae, is considered under the Radulaceae (p. 442). CHAPTER XXXI DACRYOMYCETALES This order is characterized by narrow basidia, apically forked and bearing two basidiospores on long, gradually tapering sterigmata. They ascend from simple forms in which the hymenia are resupinate to those Fig. 354. — Types of fructifications. 1. Ceracea Lagerheimii. 2. Dacryomyces delique- scens. 3. Guepinia ferns joeniana. 4. Calocera cornea. 5. Dacryomitraglossoid.es. 6. Calo- cera viscosa. (All approximately natural size; after Brefeld and Patouillard.) with stipitate fructifications and, in this respect, form a series parallel to the Cantharellales. Their probable relationships are shown in the diagram on page 530 in connection with the Cantharellales. Only a single small family is known. 535 .->:$() COMPARATIVE MORPHOLOGY OF FUNGI Dacryomycetaceae. — Ceracea and Dacryomyces occupy the lowest stage. C. Lagerheimii is resupinate on rotting wood in Ecuador and forms thin, flat, waxy crusts with loose hymenia (Fig. 354, 1). In Dacryomyces these crusts are thicker, pulvinate, gelatinous when moist, drying carti- laginous, smooth at first, becoming cerebriform in age. They are usually yellow and indistinguishable externally from Tremella (Fig. 354, 2). The best-known species, D. deliquescens, frequently found in winter on dead wood, has both an oidial (Figs. 355, 1 ; 357, 4) and a basidial stage of development. Its cushion is tomentose in the early years; the usual hyphae have hyaline, binucleate cells. Between these run thicker hyphae, colored orange-red by a lipochrome; they extend far over the Fig. 355.- — Dacryomyces deliquescens. 1. Section of fructification with binucleate oidia, O, at left; a young basidium, B, at the right. 2. Same, with mature basidia. (X 600; after Dangeard, 1895.) stroma and at the periphery break up into an immense number of orange, binucleate oidia which give a yellowish color to the whole stroma. They generally divide before their separation into two daughter cells and, in suitable nutrient solutions, develop to mycelia. In a second or later winter the amber-colored basidia begin to appear on the hyphal cushions; the dark-yellow fructification assumes the consistency of a gel by the gelatinization of the cell walls. As in Tremella lutescens, here also a succession of sexual and asexual fructifications are present except that in Dacryomyces they extend over several seasons. The basidia arise as thick, binucleate branches of the subhymenial hyphae, and are early arranged in regular hymenia. The dicaryon fuses and meiosis, with longitudinally placed spindles, begins. Meanwhile the basidia have attained full length, DA CR YOM YCE TALES 537 fork at their tip and develop two long sterigmata into each of which a nucleus migrates (Fig. 356, 1 to 3). When the sterigmata have reached the outer surface of the gel, each cuts off a hyaline ovoidal spore, into m Fig. 356. — Dacryomyces dcliquescens. Development of basidia. (X 1,330; after Juel, 1898.) which the nucleus migrates. The two nuclei remaining in the basidium degenerate (Gilbert, 1921). At germination, the basidiospore divides into four daughter cells, each of which cuts off on one or two short germ tubes small fascicles of 0 0 Fig. 357. — Dacryomyces deliquescens. 1. Germination of basidiospores in water. 2. Germination in concentrated nutrient solution. 3. Portion of conidial hyphae. 4. Diagrammatic section of an oidial fructification. Dacryomyces ovisporus. 5. Germination of basidiospores. (1 to 3 X 240; 4 X 40; 5 X 200; after Brefeld, 1888.) tiny conidia (Fig. 357, 1) which are correspondingly more luxuriant in nutrient solution and sometimes surround the basidiospores with a felt (Fig. 357, 2). The conidia develop to mycelia again on suitable sub- 538 COMPARATIVE MORPHOLOGY OF FUNGI strates (Fig. 357, 3) (Brefeld, 1888; Dangeard, 1895; Juel, 1898). In the cultures reported by Gilbert, the daughter cells germinate directly to uninucleate mycelia; clamp connections were not observed; binuclea- tion was first observed at the base of the fructification without discover- ing how it had occurred. The other species of Dacryomyces which have been investigated agree with D. deliquescens; only in D. ovisporus the sterigmata arise somewhat below the tip. The number of daughter cells of the basidiospores in D. longisporus is 12 to 15; and in D. ovisporus a multicellular tissue is formed by repeated transverse and longitudinal division (Fig. 357, 5). Beyond Dacryomyces the development of the fructifications takes place in two directions. In some forms they gradually differentiate into head and stipe, with the hymenium limited to the head; thus in Guepinia (Fig. 354, 3) the fructification resembles that of Peziza or Coryne. In Fig. 358. — Calocera viscosa. Section of hymenium. (X600; after Dangeard, 1895.) Dacryomitra (Fig. 354, 5) this differentiation into pileus and stipe is still more marked. The upper surface of the head is cerebriform and the whole structure resembles a Helvetia. In other forms, as in Calocera, the development proceeds in the direc- tion of the Cantharellales, with the hymenium completely covering the fructification. In the simpler species, as C. cornea, the fructifications, like those of Eocronartium, are small, unbranched, clavate, cartilaginous or slightly gelatinous (Fig. 354, 4) ; in the higher species, as C. viscosa (C. flammea), they ascend to structures which externally correspond to Clavaria and may only be distinguished microscopically (Fig. 354, 6). Gel formation disappears more and more, occurring only in the basal layers of the hymenium (Fig. 358). Consequently the fructifications attain a rough appearance and thus lose the last character which superfi- cially connects them with the tremelloid Dacryomyces. In the germination of the basidiospores and the form of the conidia, these three genera agree with Dacryomyces, but no oidia have been reported. The phylogeny of the Dacryomycetales is altogether obscure. Juel (1898) and Maire (1902) consider them to have arisen, by the sup- DACRYOMYCETALES 539 pression of the septa and subsequent terminal insertion of the sterigmata, from the Auriculariaceae with which they show a remarkable correspond- ence in gel secretion, in method of basidiospore germination, in longi- tudinal orientation of the nuclear spindles and in the four basidial nuclei. Consequently, they would be the most primitive stichobasidial Auto- basidiomycetes and a link between the Auriculariales and the Cantharell- ales. The structure and relationships of the basidia present the only objection to this concept. It is difficult to explain why such a rearrange- ment of the phragmobasidium should have occurred, as in the Auricular- iaceae with compact gelatinous hymenia the problem of spore discharge is satisfactorily solved by the elongation of the sterigmata. Also in the Tulostomataceae, the only family in which the basidium could have arisen directly from the phragmobasidium by the suppression of a septum, the lateral insertion of the spores is retained in spite of this suppression. It is impossible to say how this rearrangement could have taken place, for no transitional forms between the phragobasidium and the Dacryo- myces basidium are known. Similarly, there is difficulty in the extension of this assumed developmental line to the eight-spored stichobasidium of the Cantharellales, which one would have to consider as formed de novo from the four-spored phragmobasidium and subsequently two- spored basidium of the Dacryomycetales. The latter difficulty was raised by the attempt on page 423 to derive the stichobasidial Holobasidiomycetes directly from the Ascomycetes, not from the sticho-Phragmobasidiomycetes. In this case, the Dacryo- mycetales would be primitive only in the structure of their fructifications, while their basidia would indicate an end stage like the two-spored Canth- rellales. Their long sterigmata might then be considered an adaptation for penetrating the gel and, in this sense, a convergence to the sterigmata of the Tremellales, which also are broad at the base and taper upwards. A certain relationship with the Auriculariales need not be rejected; thus one may consider that both these stichobasidial orders (as indicated on p. 530) have their roots in the same Ascomycetous line and from it have retained their common primitive characteristics. CHAPTER XXXII AURICULARIALES This order includes an ontogenetic series which ranges from forms without well-developed fructifications to those with characteristically gymnocarpous or angiocarpous structures. In most genera the hyphae secrete a gel and are able to withstand great changes in temperature and moisture. In some genera which lack this gel, the zeugites develop to special organs of protection called sclerobasidia. The Auriculariales fall more or less definitely into three families: the Auriculariaceae, Septo- basidiaceae and Phleogenaceae. Their characters will appear in the following discussion, while their probable relationships are shown in the diagram on page 613. Auriculariaceae. — This family is gymnocarpous; it develops from primitive arachnoid forms in which the basidia arise directly on the diffuse, flocculent mycelium to those with bracket fructifications, very much as we have seen in the Corticiaceae. The primitive stage is suggested by Helico- basidium (Stypinella) . The white, clamp-bearing hyphae intertwine to a loose felt where they radiate and end usually in small, four-celled basidia which project above the felt. The sterile mycelium of H. purpureum has long been known as a plant pathogen under the name Rhizoctonia Crocorum (R. violaceum) (Buddin and Wakefield, 1927). The mycelium in the vicinity of the fructification is binucleate. The fusion nucleus remains until the basidia have assumed their crozier form. Subsequent nuclear division was not observed but the basidium divides into four uninucleate cells by transverse septa. During spore formation, these nuclei divide, producing binucleate spores and mycelium. Since some uninucleate strains of Rhizoctonia Crocorum are known, it is not clear whether these strains belong here or whether the last nuclear division fails to occur. On germination the spores produce a branched, purplish mycelium and binu- cleate conidia, belonging to the Imperfect form-genus Tuberculina. On germination of the conidia, both nuclei pass out into the mycelium. In the Brazilian H. orthobasidion, the hyphal cell which bears the basidium (Fig. 359, z) shows a tendency to assume a definite form when 540 Fig. 359.- — Helicobasi- dium orthobasidion. Show- ing clamps and basidia. ( X 330; after Moller, 1895.) AURIC ULARI ALES 541 it approaches the other hyphal cells. It becomes shorter and stouter than the others, collecting the protoplasm of the cells immediately behind it and passing this into the basidium. Close below this appears the usual branch which projects over the empty basidium and itself develops to a basidium. Platygloea (Achroomyces) represents the next step in the formation of simple resupinate fructifications. The hyphae secrete a gel, hence the texture is waxy to gelatinous, often convoluted when fresh. The basidia are united into a loose hymenium, interrupted by paraphyses (?). As in H. orthobasidion, so in Platygloea nigricans {Achroomyces Tiliae), the probasidium, in which nuclear fusion occurs, remains in the mature basidium, recognizable as a slight swelling (Neuhoff, 1924) similar to that shown in Fig. 359, z. The sterigmata of the lower basidial cells continue their growth until they have reached the surface of the gel and then cut off their spores, so that the latter do not adhere to the gel. In P. Lager- stroemiae, the basidia begin to collapse and become distorted as the basidiospores form. The basidiospores germinate in nutrient solutions with sprout cells or secondary spores which are similar in form to the basidiospores, but smaller (Moller, 1895; Coker, 1920). In P. caroliniana there are no sterile hyphae in the hymenium. Swellings at the base of the basidia have not been reported in the North American species. In Eocronartium, the fructifications become more definite in form, being cylindrical or clavate in E. muscicola, (Fig. 360, 1, sp.) a perennial parasite on mosses in Europe and North America (Fitzpatrick, 1918). The hyphae penetrate the whole stem, but haustoria and clamp connec- tions are not reported. The origin of the binucleate cells is unknown. The nuclei divide conjugately, with the spindles often perpendicular to the axis of the hypha. Shortly before the formation of the fructification, the intramatrical hyphae emerge between the folded leaves, intertwine and elongate to a cylindrical fructification. In case the sporogonium of the host is already formed, it is surrounded by hyphae. At the sur- face of the fructification, in the terminal cells of the hyphae, the two nuclei approach and fuse (Fig. 360, 4). The zeugites (Fig. 360, 5, z) swell slightly and develop to long basidia (Fig. 360, 6 to 13) bearing four basidiospores on long sterigmata. In nutrient solutions they germinate with germ tubes whose cells are uninucleate. Perhaps plasmogamy occurs early, but it was not observed. In Auricularia, the highest member of this family, the fructification is a broad, bilateral bracket. The cosmopolitan A. Auricula- J udae is irregularly lobate, sometimes conchiform or auriform. In fresh condition, it is more or less gelatinous or cartilaginous, drying hard and horny, to revive again when moistened, as in the Marasmieae and Schizo- phylleae of the Agaricales. The hymenium and the sterile surface is smooth or slightly rough in this species, but in tropical species the hymen- 542 COMPARATIVE MORPHOLOGY OF FUNGI ium becomes reticulate until it is almost merulioid, while the sterile surface may be strigose to tomentose (Fig. 361). As usual, the hyphae of the fructifications are binucleate; the basidia are united in a palisade and at their base may show the place of nuclear fusion by a slight swelling. They are entirely imbedded in a gel (Fig. 362, 1) and, as those of Platygloea, elevate their spores on long sterigmata to the surface. At germination, the basidiospores may be abjointed I 1 L^ SHk M \f M * \W^~ ,11 % W..nF Fig. 360. — Eocronartium muscicola. 1. Moss with sporogonium, Sp. 2, 3. Hyphae in host tissue. 4 to 9. Development of basidia. Z, zeugite. 10, 11. Formation of basidiospores. 12. Migration of nuclei into basidiospores, B. 13. Basidiospore before abscission. (1, natural size; 2 to 13 X 1,400; after Fitzpatrick, 1918.) into two daughter cells which may again become septate. If germination occurs in water, these daughter cells develop short, branched germ tubes which cut off masses of small, uninucleate, falcate conidia on short sterigmata (Fig. 362, 2 to 4). If germination occurs in nutrient solutions, conidial formation may at first be retarded, and the basidiospores develop luxuriant mycelia, on which later may occur coremia of ramose conidio- phores bearing masses of falcate conidia at their tips (Fig. 362, 6). The AURIC VLARI ALES 543 conidia develop to mycelia in nutrient solutions (Brefeld, 1888; Moller, 1895; Istvanffi, 1895; Sapin-Trouffy, 1896; Juel, 1898; Maire, 1902). Fig. 361. — Auricularia Auricula- J rudae. Five fructifications showing transition from smooth to faveolate hymenium. ( X J4 ; after Moller, 1895.) Fig. 362. — Auricularia Auricula- Judae. 1. Section of hymenium. 2 to 4. Germina- tion of basidiospores with falcate conidia. 5. Falcate conidium, C, germinating to slender mycelium. 6. Conidiophore from a coremium of falcate conidia. (1 to 5 X 280; 6 X 66; after Sappin-Trouffy, 1896, and Brefeld, 1888.) Septobasidiaceae. — This family includes four genera which are not very closely related, but present a series with increasing differentia- tion of the zeugites. 544 COMPARATIVE MORPHOLOGY OF FUNGI Iola, mostly parasitic on moss sporophytes, continues the tendency of Helicobasidium and Platygloea nigricans to store up reserves in the zeugites which are developed to characteristic organs called probasidia. The mycelium grows through the cap of the sporogonium, forming a thick felt between cap and capsule and then penetrates the interior. The hyphae are binucleate, septate and without clamps. At the surface of the sporogonium (Fig. 364, 8, Sp) they form a felt which is relatively loose in the Brazilian I. Hookeriarum (Moller, 1895). In I. javensis (Gaumann, 1922), the hyphae are imbedded in a gel forming a small fruc- tification like a drop of slime on top of the sporogonium (Fig. 364, 7, Sp). The hyphae are slightly sinuate, being quite parallel to each other in the Fig. 363. — Iola javanensis. 1. Section of young hymenium. 2. Older stage, showing the beginning of the formation of probasidia. ( X 375; after Gaumann, 1922.) extramatrical part in Fig. 363. Their ends become clavate, the two nuclei approach and fuse (Fig. 364, 2 and 3). The zygote nucleus remains a short time in a resting state, then passes over into the prophase. It migrates to the tip of the probasidium and begins synapsis. Meanwhile a parallel branch is formed below the primary probasidium, the dicaryon of the uppermost hyphal cell, the subterminal cell, migrates to the top of the cell and divides conjugately. One-half the daughter nuclei slip into the branch which again swells to a probasidium and pushes aside the primary probasidium. The other half remain in the hyphal cell where the formation of new probasidia is repeated (Fig. 364, 3 to 5), finally resulting in the structure shown in Fig. 364, 1 ; thus the whole development of probasidia rests in the dicaryon of the subterminal cell. AURICULARIALES 545 While the younger probasidia continue developing, the older ones germinate to basidia which remain enucleate for a long time (Fig. 364, 5 and 6, B). When they have reached approximately three-fourths of their final length, the diploid nucleus migrates into them and divides nor- mally into four daughter nuclei which slip out into the basidiospores. In /. Hookeriarum, the sterigmata are of unequal length and elevate the Fig. 364. — Iola javanetisis. 1 to 6. Development of probasidia. 7. Spherical fructi- fication, Sp, on sporogonium of moss (natural size). Iola Hookeriarum. 3. Irregular fructification of diplont of moss (natural size). Cystobasidium Lasioboli. 9,10. Germina- tion of selerobasidia, Sc. Saccoblastia ovispora. 11, 12. Development of basidia. 13. Germination of basidiospores. ( X 150; after Giiumann, 1922; Lagerheim, 1898; and Moller, 1895.) spores above the hymenium, while in I. javensis the basidium projects above the gel which only extends to the tops of the probasidia. The basidiospore germinates with a uninucleate secondary spore; further stages of germination and the genesis of the dicaryon are unknown. Perhaps the probasidia, filled with reserve material for the formation of basidia, have an ecological function as well as their biological function 546 COMPARATIVE MORPHOLOGY OF FUNGI as zeugites. In the case of /. javensis of the damp mountain forests of West Java, after an hour in free air with a relative humidity of 70 per cent and a temperature of 26° C. in the shade, the fructifications collapse. Returned to a crystalizing dish saturated with moisture, they resume somewhat the former appearance in the course of a week. If the relative humidity in the forest does not drop below 90 per cent, that prevalent in the rainy season on the moss carpet between the under- growth, the conditions of life are fulfilled. If the stores of nutrients which on the advent of high humidity may be used for basidial formation are not collected in the probasidium during a relative drought, the whole life process is at a standstill and the first basidia do not appear until 4 to 7 days after the resumption of growth. Hence in this species, the probasidia are not in a position to carry the fungus over unfavorable conditions as we shall find in subsequent groups. The hyphae within the sporogonium alone remain intact. A second factor is air temperature. The lower limit for basidial formation lies at 15° C, the optimum between 18° and 26° with a maxi- mum at 30°. Measurements taken under natural conditions have shown that only in the late morning are these limits exceeded and that after sunset the temperature again falls below the minimum. New basidia may only be formed during a short time. Therefore it appears that the probasidia are storage organs in which reserves are accumulated and meiosis occurs, so that when temperature relations are favorable, basidia may be formed more rapidly. If the humidity is sufficient, and the temperature below 15°, only preparation occurs, while as soon as the temperature rises above this limit, the basidium is protruded above the gel. The function of protection is probably assumed by the gel, since fructifications containing a gel are usually very resistant to cold. In Cystobasidium, which lacks a gel, the zeugites develop as organs of protection. C. Lasioboli (Lagerheim, 1898) forms arachnoid covering on the fructifications of Lasiobolus. Occasionally the hyphae have clamp connections. On short branches they form probasidia whose walls are considerably thicker than those of the basidia which arise from it or than those of the hyphae (Fig. 364, 9 and 10, Sc). The basidio- spores germinate in nutrient solutions by "sprout" conidia. The pro- basidia of this species unite in themselves the ecological functions of resting organs and of protective organs. Since they are encysted they will be called sclerobasidia and are homologous with the teliospores of the Uredinales. In Saccoblastia, whose only carefully studied species is S. ovispora (Moller, 1895; Coker, 1920) found in Brazil and North Carolina on the bark of trees, the mycelium forms a delicate, almost transparent covering. On this there project somewhat thinner hyphae whose terminal cells, as in Iola, occasionally swell slightly (Fig. 364, 11, p), and form lateral, AURIC ULARI ALES 547 pyriform outgrowths, which bend down on account of their weight (Fig. 364, 11 and 12, A). During the development of the basidium, the content of this sac passes into it, whereupon the basidium is abjointed and forms basidiospores. As in Iola, the subterminal cell develops a new pro- basidium. The basidiospores develop, with or without previous septa- tion, to secondary spores or form a gelatinous mass of small conidia, surrounded by a viscid gel (Fig. 364, 13). A cytological study of this species is needed for the interpretation of this storage organ which is unknown in other groups of fungi. Septobasidium also lacks the gel, and shows an increasing differentia- tion of zeugites. It is chiefly a tropical genus, although a few species Fig. 365. — Septobasidium bogoriense. A. Section of outer growth zone of crust. B. Hyphae developing pillars. C. Section of mature crust, stimulated by particles of earth to new growth. (X 110; after Gaumann, 1922.) occur as far north as southern Canada. As far as they are known, they grow either saprophytically or epiphytically on the secretions of scale insects (Petch, 1911; Burt, 1916) and only with difficulty on the trunks and twigs of trees. The hyphae are hyaline when young, becoming yellowish to dark brown in age. The species of Septobasidium may be separated into two groups which would probably be given generic rank, were it not for such transi- tional forms as S. cirratum. In the more primitive group, the fructifica- tion is a loose, arachnoid, flocculent crust, with either unlimited growth at the margin, or restricted growth, resulting in reticulate or sinuously divided fructifications, giving the appearance of foliose lichens. The 548 COMPARATIVE MORPHOLOGY OF FUNGI basidia are formed in the uppermost portion of the crust from pyriform to spherical probasidia, which are either terminal on the ends of hyphae or irregularly borne on lateral branches of more or less coiled hyphae. In S. frustulosum, the probasidium becomes septate and functions as a basidium, as do the teliospores of the Coleosporiaceae in the next order (Burt, 1916). In S. pinicola on Pinus Strobus and P. monticola, the probasidia are apparently at the same stage of development as in Iola, since the walls are not thickened and the basidium develops within a short time (Snell, 1922). In S. retiforme and S. frustulosum, the probasi- dia are colored brown, but no statement is made as to the thickness of the wall. Fig. 366. — Septobasidium albidum. Group of conidia resembling Torula. (X400; after Patouillard, 1913.) Septobasidium pseudopedicellatum. 2. Section of upper portion of crust (X360). 3, 4. Germinating basidiospores. (X720; after Coker, 1920.) Septo- basidium pedicellatum. 5. Development and germination of probasidia. (X260; after Patouillard, 1892.) The more highly differentiated group of species produce a layer of tissue next the substrate, from which rise hyphal pillars which support the outer layer bearing the hymenium (Fig. 365). S. cirratum forms a transition from the primitive group, since the pillars are of variable diam- eter and composed of loosely intertwined hyphae. In many species of this group the wall of the probasidium is thickened, and in S. castaneum also slightly colored, hence the zeugites might be called sclerobasidia (Fig. 366, 2 and 5). The basidiospores germinate directly to secondary spores, rarely to mycelia. In S. pseudopedicellatum and S. retiforme, they divide into as many as eight daughter cells before germination (Fig. 366, 3 and 4). These cells produce elongate sprout cells (Coker, 1920 ; C. W. Dodge, unpublished observations). In S. retiforme the basidium falls from the probasidium AURICULARIALES 549 before spores are produced on the lateral sterigmata, reminding one of the conditions found in some smuts. In S. Michelianum (Kiihner, 1926) the uninucleate basidiospores germinate with a short sterigma which bears a secondary spore only slightly smaller than itself. This becomes three to six septate and produces one to two very small, ellipsoidal conidia from each cell. The binucleate basidiospores form a septum between the nuclei then germinate as above. The morphological significance lies in the increasing differentiation of the zeugites which, here for the first time in semiparasitic forms, attain the height of development of teliospores. Consequently Cystobasidium and Septobasidium form an important approach to the Uredinales. Conidial fructifications have only been observed in S. albidum from the East Indies (Patouillard, 1913). The hyphal tips are differentiated into hyaline, later colored oidia (Fig. 366, 1). Phleogenaceae. — As in the other families of the Auriculariales, this family begins with gymnocarpous forms, although here the higher Fig. 367. — Stilbum vulgare. 1. Fructification. 2 to 7. Development of basidia. Hoehneliomyces delectans. 8. First basidium appearing on conidial hyphae. C, conidium ; B, basidium. 9, 10. Macro- and microconidia, the latter catenulate. 11. Germination of basidiospore with short hyphae, producing catenulate microconidia. (1 X 33; 2 to 7 X 1,320; 8 to 11 X 330; after Juel, 1898, and Moller, 1895.) members are angiocarpous. The basidia arise irregularly within definite layers which correspond to the gleba of the angiocarpous Basidiomycetes. The basidia lack sterigmata. In Stilbum vulgare (Juel, 1898) the fructification is scarcely more than a well-developed coremium, with the erect hyphae held together by 550 COMPARATIVE MORPHOLOGY OF FUNGI a gel. The cells are binucleate, the terminal cells become pyriform, the dicaryon fuses, the diploid nucleus divides twice with more or less longitudinal spindles. The basidia are two celled. After the first division a single septum forms and one nucleus slips into the basidiospore while the other degenerates (Fig. 367, 2 to 7). Pilacrella Solani is rather better developed, the caps becoming fleshy discs while the fertile layer contains long sterile periphyses which extend above the basidia. Hoehneliomyces shows the step from gymnocarpous to angiocarpous development. H. delectans (Pilacrella delectans) on fallen leaves and o o o Fig. 368. — Hoehneliomyces delectans. 1. Head of fructification. 2. Fructification in artificial culture before formation of head. (1 X 46; 2 X 6; after Moller, 1895.) stems of Euterpe oleracea in Brazil (Moller, 1895), forms a small watery irregular knob of hyphae on the substrate. From this arises a hyaline stipe formed of parallel hyphae which grow out below in all directions, giving the stipe a hairy covering (Fig. 368, 1). At the base of the cap, the peripheral hyphae are much branched, growing outward, then bending toward each other like a calyx. The central hyphae of the stipe, within this calyx, develop basidia at their tips. The basidiospores are not A URICULARIALES 551 discharged but collect in a shining white knob, supported by the "calyx." They germinate easily in nutrient solution (Fig. 367, 9 to 11). Besides, a large number of microconidia may be formed, each of which is sur- rounded by a thin gel. They do not germinate beyond a slight swelling. The hyphae from germinating basidiospores form coremia (Fig. 368, 2), basidial formation is limited to the top of the coremium, and fructifica- tions result similar to those found in Nature. In the Javan Hoehnelio- myces javanicus (Weese, 1920) the "calyx" is better developed than in H. delectans with its hyphae adhering to form a definite peridium around the basidial head. Here we have an angiocarpous fructification. In Phleogena faginea (Pilacre faginea, P. Petersii), the highest member of the series (Fig. 369), development is entirely angiocarpous. This species is found in late fall and winter on Fagus, occasionally on Acer and Carpinus (Brefeld, 1888; Istvanffi, 1895; Shear and B. 0. Dodge, 1925). Fig. 369. — Phleogena faginea. Habit of fungus on beech bark. (Natural size; after Brefeld, 1888.) Its stipe consists of a bundle of parallel hyphae. In the fundament of the head, the hyphae radiate and branch repeatedly, the branches becom- ing very small. At a certain stage they begin to bend inwards at the top of the pileus, forming the so-called peridium (Fig. 370, 2 and 3). This process proceeds basipetally. Within this zone, there arise loose coremia of clamp-bearing hyphae whose tips are transformed into basidia. In contrast to Pilacrella and Hoehneliomyces, the whole fructification con- sists of uniform hyphae, the same hyphae which form the stipe, intertwine to form the peridium and later the basidial branches which fill the interior of the fructification (Fig. 370, 4). When the spores are mature, the basidia and basidial branches shrivel, leaving only a mass of spores. The peridium, thanks to the helical involutions of the hyphae, winters over and disintegrates in the spring with anemochoric spore dispersal. The spores are thick-walled, light yellow to dark brown, possessing thin germ pores. They germinate to coarse brown, clampless primary mycelia which cut off brown, uninu- cleate conidia similar to species of Rhinotrichum. These germinate to 552 COMPARATIVE MORPHOLOGY OF FUNGI delicate, pure white, secondary mycelia, which become binucleate by extensive clamp formation. In the basidium, after the first division of Fig. 370. — Phleogena faginea. 1. Mature fructification. 2. Section of young fructi- fication forming the peridium. 3. Section of peridium with basidia below. 4. Loosely intertwined hyphae with basidia. (1 X 10; 2 X 16; 4 X 500; after Brefeld, 1888.) the fusion nucleus, a wall is formed before the second division. Each of the four cells of the basidium produces a single uninucleate spore. CHAPTER XXXIII UREDINALES The Uredinales, frequently called Uredineae or rusts, form a parasitic branch of the Auriculariales; as in the latter, the zeugite develops to a special organ which is encysted and acts as a resting spore in the higher forms. They differ from the Auriculariales, however, by the higher differentiation of these resting spores, by the varied types of other spore forms and by the lack of fructifications. They include three thousand species which are exclusively parasitic on cormophytes. Saprophtyic forms or forms cultivatable on artificial media, are still unknown. The mycelium consists of regularly septate, ramose hyphae, whose cells, particularly when young, contain numerous orange-colored drops of oil. Normally it grows intercellularly and sends allantoid, seldom branched or knotted, haustoria into the host cells which are not killed but only robbed of part of their substance. In many species, the myce- lium is limited to a small area near the place of infection; these species are annual; in others, outside of the tropics, it penetrates the whole host or a large part of it, overwinters in the perennial parts and grows again in the following spring. The mycelium of these species is perennial; it produces many kinds of malformations, sparse growth of the whole plant, enlargement or reduction of leaf surface, suppression or stunting of the floral parts, witches' brooms, etc. On Urtica parviflora, the hypertrophies which are produced by Puccinia Caricis accumulate in such large quantities that in central Asia they are eaten by the natives. In one case, in the Javan Goplana mirabilis on the leaves of Meliosma, extramatrical mycelium has been demonstrated. The cells of the hyphae are uninucleate in some portions of the life cycle, in others wholly binu- cleate; the haustoria are at times four nucleate. Occasionally clamp connections appear on the hyphae, as in the Auriculariaceae (Voss, 1903). There are five spore forms: pycnospores, aeciospores, urediniospores, teliospores and basidiospores. We shall discuss them in the order they usually appear in nature. The first spore forms visible in spring are the pycnospores (also known as pycnidiospores, or spermatia). They arise exclusively in uninucleate mycelium and in certain sori, pycnia (pycnidia or sper- mogonia). These lie either between the epidermis and cuticle, and are then more or less flat (Fig. 371, 2), or they are hypodermic, and are then often sunk into the host tissue as spherical or perithecial-like structures. 553 554 COMPARATIVE MORPHOLOGY OF FUNGI They develop as follows: The hyphae, which penetrate to the sur- faces from the intercellular spaces intertwine to form a thin pseudoparen- chymatous stroma. On its surface the hyphae grow perpendicularly to the surfaces of the leaves or radially, toward a common center, and form a layer of slender parallel hyphae (Fig. 371, 3) which generally have terminal, somewhat annular, colored thickenings. Above this ring, a young oval pycnospore develops. Meanwhile the nucleus has divided, one daughter nucleus migrates through the structure into the young spore which is separated above the thickening Fig. 371. — 1. Gymnosporangium clavariaeforme. Section of a pycnium on leaf of Crataegus ( X 345). 2. Phragmidium violaceum. Pycnium on Rubus with ruptured cuticle (X440). 3. Cronartium ribicola portion of pycnium (X 1,160). P, paraphyses; Ep, epidermis; C, cuticle. (After Blackman, 1904, and Colley, 1918.) by a septum and which then falls off. The other remains behind in the basal cell and divides repeatedly, forming many successive spores. The periphery of the whole sorus is surrounded by a ring of periphyses (in systematic works often called paraphyses) which have arisen by the elongation of the outer cells of the stroma. They intertwine in a dome over the fertile tissue and later by their pressure, rupture the epidermis. In the primitive Pucciniastreae, the periphyses are absent, the cuticle or epidermis of the host being the only covering of the sorus. At first this is often penetrated by a small pore through which the pycnospores (spermatia) are extruded, Later the whole cuticle or epidermis may UREDINALES 555 rupture, laying bare the sorus (Hunter, 1926). In Calyptospora Goepper- tiana, the pycnia are formed normally but the pycnospores regularly abort. In Gallowaya pinicola (B. O. Dodge, 1925) on Pinus virginiana, vestigial pycnia (spermogonia) are formed but they fail to rupture the overlying tissue or to form pycnospores (spermatia). Pycnospores are ovoid or spherical, very small (2 to 4^u) or, if bacilli- form, up to 1.6 by 9ju; their membrane is hyaline and smooth; their content poor in cytoplasm and reserve materials; the nucleus is comparatively large, sometimes occupying two-thirds of the cell volume. They accumu- late as a slimy mass in the cavity formed by the periphyses and are repeatedly extruded; in some species, as Cronartium ribicola, Endophyl- Fig. 372. — Types of aecia. 1. Caeoma of Phragmidium Rubi. P, paraphyses. 2. Aecidium of Uromyces Erythronii. Per, peridium. (1 X 400; 2 X 300; after Sappin- Trouffy, 1896.) lum Sempervivi and Puccinia obtegens (P. suaveolens) , they have a sweetish odor, in Gymnoconia Rosae, an offensive odor. Their further develop- ment is unknown. In some species, e.g., Phragmidium violaceum, they appear to degenerate early (Blackman, 1904); in others, as Cronartium ribicola, they appear to be normal (Colley, 1918). In any case, they seldom germinate and when they do form a short germ tube, it is not capable of producing infection. Simultaneously with the pycnospores or shortly thereafter, a second spore form, the aeciospores, usually develops in special sori, the aecia, on the uninucleate mycelium. These belong to two types: the caeoma, which is usually placed directly under the cuticle or epidermis, is broad and flat, naked or covered by periphyses (in the Uredinales, usually called paraphyses, Fig. 372, 1). After its formation it is able to spread laterally and is consequently indefinite in form. In the higher type, the aecidium (or cup type) is placed in the host tissue, several cell layers deep; it is spherical or ellipsoidal and always covered by pseudoperidium, also 556 COMPARATIVE MORPHOLOGY OF FUNGI called peridium for short. A further development in breadth is unknown in them ; in many cases, however, no sharp difference between caeoma and aecidium can be drawn, for there also appear in groups with well- developed peridia, species with peridia rudimentary or almost lacking. The development of the caeoma will be first described, e.g., Phrag- midium violaceum (Blackman, 1904; Welsford, 1915), P. speciosum (Christman, 1905), P. disciflorum (P. subcorticium) (Mme. Moreau, 1914) Gymnoconia Peckiana (Christman, 1905; Olive, 1908; Kursanov, 1910), Melampsora Rostrupi (Blackman and Eraser, 1906), M. Lini (Fromme, Fig. 373. — Phragmidium disciflorum. 1, 2. Development of caeoma. St. Z., sterile cells; F.Z., fertile cells. (1 X 535; 2 X 670; after Moreau, 1914.) 1912) and M. reticulata (Lindfors, 1924). The first indication of the fundament consists in an accumulation of intercellular hyphae between the epidermis and mesophyll. The cells of the hyphal knot next the epidermis elongate perpendicularly to it and lie close together, forming a subepidermal palisade layer. Each divides into a small sterile cell above and a large fertile cell below (Fig. 373). Where there is enough room, e.g., in the spaces between the epidermal cells, the fertile cell repeats this division, so that a chain of as many as four sterile cells may result; in Melampsora Lini there are usually two, and in Melampsora Rostrupi many sterile cells. The nucleus of the sterile cell remains small, degener- ates and disappears. This is followed by the gradual degeneration of the sterile cells themselves. Meanwhile, proceeding from the middle toward the margin, the walls between two fertile cells dissolve, the protoplasts fuse and a large, binu- UREDINALES 557 cleate, fusion cell is formed (Fig. 374, 1 to 3). Under exceptional cir- cumstances more than two fertile cells fuse, producing a multinucleate fusion cell. Since both fertile cells in Fig. 374, 1 to 3, are equal in form and position, the plasmogamy is isogamous. There also appear in the same sporus many deviations from this isogamous type. Thus cells of different ages may copulate, e.g., one of these may have cut off the sterile Fig. 374. — Phragmidium disciflorum. Development of aeciospores. 1 to 3. Fusion of basal cells. 4. Fusion of superimposed cells. 5, 6. Development of aeciospores. (X 1,130; after Moreau, 1914.) cell before the other; their position may be different (one somewhat higher than the other); and, finally, the septum may be only incompletely dissolved so that there may be only a pore through which the nucleus of one cell passes into that of the other. Where these forms appear singly, they may have been caused as pathological processes or as arti- facts by the uneven penetration of the fixative; in other forms, e.g., Phrag- midium violaceum in which they appear normally, their heterogamous nature may not be contested. Furthermore, frequently instead of the septum between two basal cells, the septum between one basal cell and the underlying hyphal cell is dissolved (Fig. 374, 4) or the wall between a basal cell and a cell of the neighboring mycelium or, finally, the wall between any two mycelial cells is dissolved. Thus plasmogamy takes place autogamously or pseudogamously. 558 COMPARATIVE MORPHOLOGY OF FUNGI Sp. ~~z~.z. if-sp. m The fusion cell elongates in the direction of the epidermis; its dicaryon passes to the tip and divides. The fusion cell then divides, as in the earlier cells, into a small apical and large basal cell (Fig. 374, 5, iz and bz). The basal cell elongates and repeats the above process so that a chain of binucle- ate cells arises; occasionally a basal cell may fork and form several, similar, parallel chains; perhaps in the multinucleate cells, the binucleate condition may again be attained. By the increasing pressure of the growing chain, the remains of the sterile cells are pressed together into a formless mass. These binucleate cells thus cut off, are called initial cells or aeciospore mother cells. After their ; 2w.Z.; nuclei have completed a conjugate mitosis, each divides by septal formation into a large terminal and small basal cell. The larger cell rounds up, the walls become sculptured and thickened and it is called an aeciospore (Fig. 374; 6, sp). The smaller intercalary cell (Fig. 374, 6, zw. z.) disintegrates and disappears, usually before the maturity of the sorus; biologically it fulfills the function of a dis- junctor, since by its degeneration, the aeciospores are loosened from the chain for further dispersal. Under favorable conditions, one finds in the young sorus a crushed sterile cell above and a free aecio- spore below (Fig. 375), then aeciospores with inter- calary cells, aeciospore mother cells and, at the base, binucleate basal cells in full activity. Finally the 375—Cronar- epidermis is ruptured by the pressure of the sorus Hum ribicoia. Section an(j the aeciospores escape into the free air. Sp^ci^oies^Zw^z'., In the aecidium, the fundament of the sorus is a intercalary cells; M. knot of plectenchy ma which is sunk several layers of cells; aB!z,SPbasad° cell, cells deep into the host tissue, in contrast to the (x 560; after Colley, position of the caeoma. In Puccinia Pruni-spinosae, the hyphae of the upper half of the knot grow further into the host tissue . The cells of the knot are isodiametric and about equal in size. At the margin, a peridium of 5 to 6 layers of thick-walled cells is formed. Further differentiation of the knot varies and may be classi- fied under four types, represented by Puccinia Mariae-Wilsoni (P. claytoniata) , Uredinopsis americana (U. mirabilis), Puccinia Violae and Endophyllum Sempervivi. In the Puccinia Mariae-Wilsoni type, (Fromme, 1914), to which con- form P. Poarum, Uromyces Poae (Blackman and Fraser, 1906), Cronartium -Sp. -HZ i-az. Fig. UREDINALES 559 ribicola (Colley, 1918), C. Comptoniae, C. pyriforme (Adams, 1919), Uromyces Caladii (Christman, 1905; Fromme, 1914), Puccinia Caricis and P. Pruni-spinosae (Kursanov, 1922), the hyphae of the knot are arranged Fig. 376. — Uromyces Poae. 1. Young aecidium. Fertile cells above and sterile degeneration cells below. 2. Immature aecidium with peridium, Per, and immature aeciospores, Sp. ( X 415; after Blackman and Fraser, 1906.) in a more or less palisade-like structure and are usually perpendicular to the plane of the epidermis, in a few species pointed toward the middle of the top. The terminal cells (in P. Pruni-spinosae, a few intercalary cells) 560 COMPARATIVE MORPHOLOGY OF FUNGI swell greatly, form a loose pseudoparenchyma poor in cytoplasm, and begin to degenerate slowly (Fig. 376, 1). This swelling and degeneration of the cells proceeds basipetally, until the pseudoparenchyma includes two-thirds to three-fourths of the knot and only 4 to 5 of the basal cells of the hyphae remain. These are filled with cytoplasm and are apparently richly nourished at the expense of the disintegrating terminal cells. Between each cell of a hypha and a cell of a neighboring hypha, follows a fusion of protoplasts, as in the caeoma, by the solution of the separating wall at first in the center, later in the periphery of the sorus. Usually only one cell of a hypha takes part in plasmogamy; but all are potentially capable, since the fusion cells lie scattered irregularly (i.e., at unequal heights) over the basal tissue and it is impossible to predict which cells are active. In addition, two cells lying one above the other may copulate with the same hypha. The further development of the fusion cells, the cutting off of the initial cells and their differentiation into aeciospores and intercalary cells, takes place in the same manner as in the caeoma. The growing spore chains push the pseudoparen- chyma in front of them and press against the epidermal layer of the host tissues. The type of Uredinopsis americana, to which belong Thekopsora Vacciniorum (Pucciniastrum Myrtilli) (Adams, 1919) and Gijmnosporan- gium juniperinum (Kursanov, 1922), resembles Puccinia Pruni-spinosae in the differentiation of the hyphal knot. As in the latter, the intercalary cells swell up; over the degenerated, gelatinous pseudo- parenchyma there lies another layer of compact vegetative tissue which separates the pseudoparenchyma from the host tissue. The third type, which includes Puccinia Violae (Fromme, 1914; Mme. Moreau, 1914; Kursanov, 1922), P. Falcariae (Dittschlag, 1910) and P. graminis (Kursanov, 1922) resembles P. Mariae-Wilsoni except that in this type the degeneration of the hyphae proceeds so far that there remains only a single layer of potential sexual cells. This cell layer corresponds in appearance to the palisade layer of the caeoma, only it lies inside the hyphal knot instead of on its top. Just as in the palisade cells of the caeoma, these sexual cells occasionally cut off some sterile cells, a thing not yet observed in P. Mariae Wilsoni. In the fourth type, to which, for example, belong Endophyllum Semper- vivi (Hoffmann, 1912) and Puccinia Eatoniae (Fromme, 1914) develop- ment is still simpler. Here, on the whole, no special sexual cells are formed, but plasmogamy takes place between any two mycelial cells in the basal region of the plectenchymatic knot, where the fusion cells elongate radially and cut off chains of initial cells as basal cells. In certain cases, it has been demonstrated that at the base of the aecia plasmogamy rarely takes place; in certain strains of Endophyllum Euphorbiae-sijlvaticae (Mme. Moreau, 1914), of E. Centranthi-rubri UREDINALES 561 (Poirault, 1913, 1915) and of Puccinia Pruni-spinosae (Kursanov, 1914), a layer of palisade cells is normally formed at the base of the aecia. This layer occasionally may cut off a few sterile cells. Although these are still uninucleate, they proceed without apparent cause to differentiate aeciospore mother cells which appear entirely similar to the binucleate ones and, like these, divide into aeciospores and intercalary spores. The aeciospores are naturally uninucleate, i.e., the whole course of development proceeds parthenogenetically. The reverse condition has been demonstrated for another strain of Endophyllum Euphorbia- silvaticae (Sapin-Trouffy, 1896; M. and Mme. Moreau, 1918, 1919). In it the whole mycelium is binucleate; consequently plasmogamy at the base of the aecia is omitted and development proceeds apogamously, as will be described later. The developmental history of the aecidium agrees with that of the caeoma only in so far as plasmogamy generally precedes the formation of the initial cells. The aecidium is distinguished from the caeoma by its pseudoperidium, which arises as follows: The uppermost aeciospores of a chain occasionally lose their spore character, as is the case in the buffer cells of Albugo; they increase in size in all directions, and adhere laterally to similarly deformed spores to form a peridium of a single layer of cells (Fig. 376, 2). As the maturation of the aecidia takes place from the center to the margin, new cells are always added laterally to this cover. When this transforma- tion has reached the periphery, it proceeds basipetally in the outer chains. In these outermost cells, not only the uppermost cells are deformed as peridial cells but the whole of the outermost chains is used for vegetative purposes. The basal cells of these chains proceed with the cutting off the initial cells, thus adding new cells to the pseudoperidium from beneath and enabling it to keep up with the growth of the central spore chains. The pseudoperidium here retains a firm texture as a result of the peculiar development of the intercalary cells. In these outermost chains, therefore, they are not separated directly beneath the aeciospores but obliquely toward the outer side. In this manner, they no longer function as disjunctors and the metamorphosed aeciospores adhere to each other as in the middle of a dome. In most forms, these peripheral intercalary cells degenerate early. In Pvccinia graminis and Gymnosporangium juniperinum, on the other hand, they increase in Fig. 377. — Puccinia gram- inis. Peripheral portion of aecidium. Section of the basal cell, B.z., and the lower portion of the peridium, Per., with intercalary cells, Zw.Z. (X 500; after Kur- sanov, 1914.) 562 COMPARATIVE MORPHOLOGY OF FUNGI size as the young peridium and press together to form a layer (Fig. 377) surrounding the pseudoperidium at its base at least and separating it laterally from the plectenchymatic knot (Kursanov, 1914; Fromme, 1914). The degree of thickening of the peridial cells depends entirely on climatic influences; thus in dry habitats and xerophytic leaf structure, thick- walled peridial cells with narrow lumina are preponderant; in damp habitats and in hygrophil leaf structures, thin-walled cells with broad lumina prevail (Mayus, 1903; Iwanoff, 1907). Moreover, the thickening in each species is characteristic. At the maturity of the aecidia, the top of the peridium with the host tissue above it is ruptured, the torn edges are bent outwards and thereby create the typical cup form (Fig. 372, 2). In Gymnosporangium, they project far over the host tissue and are curiously split into shreds (Roestelia type). The number of aeciospores in a sorus is very large; Fromme (1914) estimates more than 8000 for Puccinia Eatoniae, Buller (1924) 11,000 for Puccinia graminis. A bush of Berberis with 200 infected leaves produces about a billion spores. The aeciospores are very uniform in size, oval or slightly polyhedric, unicellular as the pycnospores but much larger, 15 to 40/z in diameter. Their content is colored orange-yellow, usually by an oily substance. Their membrane is usually thin and colorless, more seldom thick and brown, generally covered with fine or coarse warts or alveoles. They generally contain several germ pores which are usually only visible at germination when the membrane swells up in their vicinity. The aeciospores, at least in Gymnosporangium myricatum, are dissemi- nated by a peculiar elongation, reminiscent of the Entomophthoreae, dis- charged from the cup (B. O. Dodge, 1924) and then spread mainly by the wind. Immediately after maturity, they are capable of germination; usually they soon lose this power and seldom winter over. Germination occurs usually by a germ tube which penetrates a stoma of the new host and there develops a binucleate mycelium. According to the choice of host plants, two biological types may be distinguished. To one type belong those where the new host is one of the same species as the one which bore the aecium; e.g., in Phragmidium disciflorum the uninucleate aecial mycelium develops on Rosa; its aeciospores infect other individuals of the same species of Rosa. The Uredinales which belong to this type are called autoecious. In numerous other species, the germ tubes of the aeciospores show a biologically variable relationship, e.g., in Cronar- tium ribicola the uninucleate mycelium grows on the white pines, among others Pinus Strobus and P. cembra. The germ tubes of the aeciospores cannot infect P. Strobus but only species of Ribes, e.g., R. nigrum. The binucleate mycelium which develops from the aeciospores possesses, therefore, other physiological needs and lives on an entirely different UREDINALES 563 plant usually far removed systematically from the host with the aecial uninucleate mycelium. Uredinales of this type, which for the completion of their life cycle must successively infect two different host species, are called heteroecious. In some genera the method of germination of aeciospores is vari- able. In Endophyllum Sempervivi, they form germ tubes as usual when covered with water; in damp air, they germinate with another form of fructification, as basidia and basidiospores. The basidiospores are again able to infect individuals of Sempervivum, while infection by the usual germ tubes has not succeeded. Similarly, the aeciospores of Gymno- conia Peckiana (G. inter stitialis) on Rubus, especially late in the season, germinate occasionally with basidia instead of with germ tubes (Kunkel, 1920). Also in Kunkelia nitens on Rubus, germination normally takes place with basidia and basidiospores; in certain strains of Gymnoconia Peckiana, a caeoma of the Gymnoconia type (tube germination) and one of Kunkelia type (basidiospore germination) appear on the same mycelium ; indeed, within the same caeoma both spore types may appear (B. O. Dodge, 1923). On the binucleate mycelium which arises from the aeciospores germinating with a germ tube, aecia may again arise in some forms, e.g., in the above mentioned species: Puccinia Senecionis, Uromyces Hedysari-obscuri and Phragmidium disciflorum. The cytological proc- esses which take place in them have been discussed by Kursanov (1916) in Uromyces Scrophulariae on Scrophularia nodosa and U. Behenis on Silene Cucubalus (S. inflata). After infection by aeciospores had been completed, both uni- and binucleate mycelium was observed in the host plants; the binucleate mycelium has apparently resulted from the uninu- cleate mycelium by a pseudogamous plasmogamy. Both types of mycelium intermingle; nevertheless the pycnia are formed by uninucleate hyphae. In the hyphal knots one also finds binucleate hyphae, but the basal cells of the pycnospores are entirely uninucleate. The aecia are laid down at the same time as the pycnia. In the primordial knots uninu- cleate hyphae sometimes predominate, at other times binucleate. The binucleate hyphae proceed apogamously to the direct formation of aeciospore mother cells; between the uninucleate hyphae an isogamous sexual act takes place, and aeciospore mother cells are formed in the normal manner. Somewhat later, at the same point of infection which has already borne pycnia and aecia, a telium is laid down exclusively by binucleate hyphae whose end cells change in a normal manner to the teliospore mother cells. If one again infects the host with aeciospores formed in the first generation, one obtains a second generation of the fungus normally binucleate but nevertheless forming aecia (and later telia, but never pycnia) in a normal manner. The teliospores are identical with those 564 COMPARATIVE MORPHOLOGY OF FUNGI formed by the first generation. The aeciospore mother cells arise apog- amously, as was already partially the case in the first generation. This production of aecia and telia may be repeated for any number of genera- tions by a new sowing of aeciospores from the present generation. If one uses as the infective material, teliospores which have arisen in any generation, meiosis takes place in the basidia, as we shall see later, and the hyphae which penetrate the host are then uninucleate. These forms, in which the binucleate mycelium produced by the aeciospores again forms aecia apogamously, are an exception. Gener- ally the binucleate mycelium proceeds to the formation of a third spore form, the urediniospores. As the aeciospores, these are formed in special sori, uredinia, either covered by a "peridium" (or buffer tissue) or exposed. As an example of the covered type, we may cite Cronartium (Colley, 1918), Pucciniastrum (Ludwig and Rees, 1918; Colley, 1918; Kursanov, 1922; B. O. Dodge, 1923; and Moss, 1926), Hyalopsora, Uredinopsis, Milesina, Melampsorella and Thekopsora (Moss, 1926). As in the forma- tion of a caeoma, the hyphae intertwine to a flat intramatrical knot (Fig. 378). The upper cells, the spore initials, elongate and cut off a chain of three cells, the upper of which becomes the peridial cell P, the middle the disjunctor (not found in Cronartium) and the lower, the sporogenous cell which divides into the urediniospore Sp and the stalk cell St, which may degenerate during maturation of the spores as the intercalary cells of the aecia. Subsequent sporogenous cells are budded out from the basal cell. As in the aecidia, the peridial cells adhere laterally with neighboring cells to form a peridium one cell thick. The disjunctive cell degenerates, freeing the spores from the peridium. In Chrysomyxa (Melampsoropsis) the peridium is two cells thick but loose, weakly developed and evanescent, apparently vestigial since the second cell of the chain fails to function as a disjunctor. In Melamp- sora, the peridium consists of an evanscent layer of very thin-walled cells (Kursanov, 1915). The second type of uredinium, in which the urediniospores arise singly on short stipes without forming a peridium, includes the majority of the known rust genera. An intramatrical hyphal knot is formed here also ; each of the hyphal ends at the top of the knot, as the basal cells in the chain type, cuts off an initial cell which divides into a large apical cell, the future spore, and a smaller basal cell, the stipe cell. These, however, do not continue division but grow repeatedly laterally, as do the subter- minal cells of Iota and Eocronartium, and occasionally differentiate at their ends new initial cells which again divide into spores and stipe cells. Therefore the urediniospores lie beside each other in one plane (Fig. 379, 1). These two types, however, are not sharply distinct. Thus in Melampsorella both types have been reported. UREDINALES 565 Fig. 378. — Cronartium ribicola. Development of uredinium 1. Fundament, of sorus and stoma. 2. Older stage. 3. Mature sorus. P, peridial cell; Sp, young urediniospore; St, stalk cell; B, basal cell; A, multinucleate basal cell before the formation of the uredinio- spore mother cell, C; D, spore and stalk cell just formed from urediniospore mother cell; U, mature urediniospore; E, crushed epidermal cells. (X 330; after Colley, 1918.) Fig. 379. — Phragmidium Rubi. 1. Periphery of uredinium. P, paraphyses. Puc- cinia glumarum. 2. Uredinial mycelium in host tissue. (1 X 565; 2 X 830; after Sappin- Trouffy, 1896, and Lindfors, 1924.) 566 COMPARATIVE MORPHOLOGY OF FUNGI In the structure of the uredinium, there exists as great variety as in the covered type. In some genera, as in Puccinia, Uromyces, Phrag- midium and Triphragmium, they are surrounded by a margin of peri- physes or intermingled in the interior with paraphyses; and in Hemileia the stipes are joined together into a fascicle which emerges from the stoma bearing at its tip a small head of urediniospores. Both types of uredinia have one thing in common, that their spores arise (as the aeciospores) as daughter cells of an initial cell which divides into the future spore and the stipe cell. Thus their development is entirely homologous to that of the aeciospores, but since their mycelium is binucleate after Fig. 380. — Phragmidium Potentillae-canadensis. Development of the primary uredin- ium. 1. Fertile cells, F.Z., have cut off sterile cells, St.Z. 2. Fusion. 3. Formation of spore mother cell, I.Z., from basal cell, B.Z. 4. First nuclear division in the spore mother cell. 5. The spore mother cell has divided into a spore, Sp, and stalk cell, St.Z. 6 to 8. Lateral budding of the basal cell to a new spore mother cell. 9. Two mature urediniospores from the same basal cell. (After Christman, 1907.) the aecial stage, there is no plasmogamy before the formation of the initial cells. Forms in which the aecium closely resembles the uredinium are sometimes said to lack the aecium and the first sorus, except pycnia, is then called the primary uredinium, while the later uredinia, resulting from its spores, are called secondary uredinia. As far as these forms have been investigated, plasmogamy and further development occurs as in a caeoma (Figs. 380, 381), e.g., in such forms as Triphragmium Ulmariae (Christman, 1907; Olive, 1908; Kursanov, 1922; Lindfors, 1924), Phrag- midium Potentillae-canadensis (Olive, 1908), Uromyces Alchemillae, Puccinia obtegens (Kursanov, 1922) and probably also in Kuehneola albida UREDINALES 567 (Strelin, 1912). The close agreement which has been found in this respect between the manner of formation of spore and of peridium of the aecidia and uredinia is suggestive. In Uromyces Glycerrhizae, plas- mogamy appears to occur somewhere on the mycelium, as the hyphae which form the uredinium are already binucleate (Olive, 1913). These primary uredinia which have arisen on the uninucleate mycelium often differ in their appearance from the secondary ones formed later on the binucleate mycelium, e.g., they are distinguished by a greater size and a consequent greater deformation of the host or by a somewhat different color. Because of the close morphological relationship, it is often impossible to draw a sharp line between aecia and primary uredinia; thus the first sorus of Phragmidium violaceum is designated by some authors as an aecium (caeoma) and by others as a primary uredinium. Fig. 381.- -Triphragmium Ulmariae. Types of cell fusion in the primary uredinium. (X 1,720; after Lindfors, 1924.) The difficulties are in part due to the fact that urediniospores some- times greatly resemble the aeciospores. They are 15 to 40 /z in diameter, unicellular, ovoid to cuneate, and generally finely echinulate or verrucoses, the membrane is generally fairly thick, hyaline to yellow brown, and pierced by several equatorial germ pores which are filled with a substance of variable composition. The number and position of the germ pores furnish important systematic characters. The urediniospores are easily separated from their stipes and are disseminated by winds, as are the aeciospores. Immediately after their maturity they are capable of germination, but lose this ability after a few months. True overwinter- ing of urediniospores is known with certainty in only a few cases, as in Uredinopsis Struthiopteridis and Kuehneola albida. In continental climates, they may have the opposite task of serving as resting spores during a drought. In all these cases, they possess a very strong brown wall, a persistent stipe and are called amphispores. Germination may take place within very wide limits of temperature, but the ability to infect lies within narrow limits, i.e., in the neighborhood of the optimum for germination. At germination one or more germ tubes penetrate the stomata of the new host and there again develop a 568 COMPARATIVE MORPHOLOGY OF FUNGI binucleate and, occasionally secondarily, a multinucleate mycelium (Fig. 379, 2). At the germination of the urediniospores there is no change in host. On this binucleate mycelium there may arise uredinia with ure- diniospores which develop a new mycelium, which again forms uredinia, so that several generations of uredinia with uredinial mycelium follow one another within a single growing period. In the binucleate mycelium, the urediniospores play the same role of rapid propagation as the conidia on the haploid mycelium. After a definite length of time telia (sori of teliospores) appears on the binucleate mycelium. The exact moment of their appearance depends upon the condition of nutrition of the host and generally cor- responds with the end of the growing season; it can be retarded or hastened by the environment (Iwanoff, 1907;Morgenthaler, 1910;Gassner, 1916). The teliospores are the homologs of the probasidia and sclero- basidia of the Auriculariales: the dicaryon fuses in them to a single diploid nucleus which gradually prepares for meiosis. In contrast to the urediniospores, which arise during the diplophase, the teliospores terminate this diplophase. In addition to these normal forms, in which the telia arise on the binucleate mycelium, telia (in forms which lack the aecia and uredinia) may be formed directly on the uninucleate mycelium. In this respect five groups may be distinguished. In the first group, to which belong Uromyces scutellatus, U. laevis, Puccinia Fergussoni, P. Rossiana, Chryso- myxa Abietis (Kursanov, 1922), Uromyces alpestris (Tranzschel, 1910) and Galloway a pinicola (B. O. Dodge, 1925), the telia closely resemble the aecia; thus in U. alpestris they are formed in the interior of aecidia which do not open as such, and in U. scutellatus on Euphorbia the remains of the aecidial fundaments are indicated by peridial cells in the young telia. In their development, they correspond to aecia, e.g., those of the type of Puccinia Violae: the thick hyphal knot is differentiated into an upper sterile and lower fertile zone. Between two palisade cells or between two vegetative cells or between a palisade cell and a vegetative cell, plasmogamy occurs and the fusion cells develop to short, branched hyphae on whose ends are formed the teliospores. Similarly, the telia of Puccina Anemones {P. fusca) on Anemone nemorosa develop exactly as the aecia of Ochropsora Ariae on the same host (Lindfors, 1924). In a second group including, among others, Puccinia Malvacearum (Mme. Moreau, 1914; Werth and Ludwigs, 1912), P. transformans (Olive, 1908), P. Buxi (Mme. Moreau, 1914) and probably also P. Liliacearum (Maire, 1899), differentiation occurs as in a caeoma: on the top of the hyphal knot there are formed palisade cells which copulate with each other or with hyphal cells. In a third group, e.g., Uromyces Ficariae (in which the uredinium is acking) there is, as in Endophyllum Sempervivi, no definite palisade forma- UREDINALES 569 tion and plasmogamy takes place, as may occasionally happen in Puccinia malvacearum (Lindfors, 1924), at the base of the hyphal knot between two neighboring hyphal cells (Mme. Moreau, 1914) or even before the forma- tion of the telia, between two ordinary mycelial cells (Blackman and Fraser, 1906). In a fourth group, e.g., Uromyces Scillarum (Blackman and Fraser, 1906; Mme. Moreau, 1914), Puccinia Adoxae (Blackman and Fraser, 1906) and P. Aegopodii (Kursanov, 1922), plasmogamy takes place between two vegetative cells long before the formation of the telia. In the fifth group, finally, to which belongs Uromyces Rudbeckiae (Olive, 1911), plasmogamy is entirely lacking and the life cycle is apomic- tic in the uninucleate phase, as in Endophyllum Euphorbiae-silvaticae and some strains of Caeoma nitens. As teliospores of all five forms of fructification in the Uredinales have undergone very great differentiation in form and appearance, they offer very important characters for systematic groupings within the order. In them are four types which correspond to the families: Coleosporiaceae, Melampsoraceae, Cronartiaceae and Pucciniaceae. Coleosporiaceae. — In the Javan Goplana mirabilis on leaves of Meliosma, the sorus is extramatrical on the underside of the leaf, where it Pig. 382.- — 1. Goplana mirabilis. Hymenium. 2. Uredinopsis filicina. Zeugite, z, in spongy mesophyll. (1 X 320; 2 X 410; after Sydow, 1915, and E. Fischer, 1904.) looks macroscopically like a simple species of Septobasidium. The terminal cells of the extramatrical mycelium change as in the latter to a basidium; the subterminal cells develep laterally, as in Iola, to new basidia so that finally every hypha bears a small cluster of basidia (Fig. 382, 1). The peripheral cells of the sorus remain sterile and are transformed into periphyses. In Coleosporium Sonchi-arvensis (Sapin-Trouffy, 1896), C. Solidaginis (Holden and Harper 1902) and C. Campanulae (Juel, 1898), the binucleate, intercellular hyphae grow out of the interior of the host tissue toward the epidermis and come together beneath it to form a palisade layer (Fig. 383, 1). The terminal cell of each hypha 570 COMPARATIVE MORPHOLOGY OF FUNGI swells greatly and the dicaryon fuses, forming a single diploid nucleus. The zeugites elongate, forming the basidia. Because of the mutual pressure under the epidermis, they are flattened next each other and form a compact layer which is imbedded in a gel secreted by the membranes. In some species the basidia are thickened at the tip. This is primarily a biological adaptation, since the tips must rupture the epidermis by their pressure. After a time the basidia divide, as in Auricularia, into Fig. 383. — 1. Coleosporium Sonchi-arvensis. Hymenium. 2. Thekopsora areolata. Tclium. 3. Melampsora Helioscopiae. Telium. (1 X 270; 2, 3 X 340; after Sappin- Trouffy, 1896.) four cells, each cutting off a basidiospore and raising it above the ruptured epidermis on a long sterigma. In Gallowaya pinicola (B. O. Dodge, 1925) there is very little inter- twining of hyphae as a preliminary to the formation of the telial sorus. The hyphae grow out through the mesophyll and form a palisade of chains of four or five uninucleated cells. The terminal cells form the peridium as in the covered type of aecidium or primary covered uredi- nium. Soon after the epidermis is ruptured cell fusions occur between URE DIN ALES 571 the second or third cells from the outer ends of the chains, the separating walls completely disappearing. At the same time the buffer cells above collapse, like the disjunctive cells in the uredinium. The fusion cell divides immediately, the upper cell taking most of the cytoplasm, leaving the lower cell vacuolate. This upper cell then forms a short chain of binucleate cells which occupy the space below the peridium. Caryogamy begins in the terminal cell of these chains and proceeds slowly basipetally. The now uninucleate zeugite elongates and forms the typical four-celled basidium of the Auricularia type. After the basidiospores have been shed, the basidium collapses and the cell below elongates and forms a basidium. This process may continue until all the binucleate cells are used up, but age of the sorus and mechanical difficulties in raising the lower basidia high enough to secure complete dissemination of basidio- spores, usually results in the failure of the lowest cells to function properly. Here we have the diploid phase and the binucleate mycelium reduced to its lowest possible amount, without even the differentiation of telio- spores as such, consequently this species in some ways seems more primi- tive than Septobasidiwn and might be placed in Auricularia, except for the catenulate basidia. Similarly the so-called teliospores of Coleo- sporium are rather to be regarded as thick-walled basidia. The sorus consists exclusively of fertile basidia, while in Auricularia there are sterile paraphyses. Similarly the sorus should be regarded as basidial hymen- ium, not telium. In order not to confuse their terminology, however, systematists have used teliospore for structures which appear in the same position as true teliospores do in other rusts. These "teliospores" germinate "internally," directly to basidia. From the standpoint of comparative morphology, it must be emphasized that the Coleosporiaceae lack teliospores. Melampsoraceae. — As the Coleosporiaceae correspond to the Auricu- lariaceae, this family exhibits the developmental tendency of the Septo- basidiaceae. The zeugites increase in independence and become special storage organs in which the nutrients are prepared for the moment most favorable to basidial formation. The basidia agree extensively in their habits with Septobasidium, and are without stipes, lateral or terminal on hyphae; only they are formed (as is the character of the rusts) endoparasitically, exclusively within the host instead of upon its surface. In Uredinopsis (Faull, 1928), the teliospores arise in scattered groups just below the epidermis, occasionally a few in the mesophyll. They have a thin, hyaline, smooth membrane and are spherical or elongate, septate and capable of germination early the following spring (Fig. 382, 2). In Melampsorella, they are similar but are formed within the epider- mal cells and, in case several are laid down in the same cell and the space is not sufficient, they are flattened sidewise. They develop on new leaves 572 COMPARATIVE MORPHOLOGY OF FUNGI in the spring and germinate immediately with an apical basidium which ruptures the wall of the host cell and produces its spores outside the epidermis. In Milesina they develop on overwintered fronds and ger- minate at once. While in Melampsorella and Milesina the zeugites, because they are not encysted, should not be designated as teliospores in the true sense of the word, in Thekopsora, Pucciniastrum and Melampsora they have a firm membrane and become hypnospores. Besides, they do not arise individually scattered over the host tissue but are collected in more definite sori as true telia. In Thekopsora, they occur in the epidermal cells, usually several in one cell, almost completely filling it and by mutual pressure adhering in a plate (Fig. 383, 2). They divide by vertical or somewhat oblique walls into two to four daughter cells, each of which sends out a basidium. Pucciniastrum behaves similarly, its telia instead of being intracellular are intercellular under the epidermis. In Melamp- sora (Fig. 383, 3) the teliospores are joined laterally into a hypodermal or subcuticular crust; in them, however, the longitudinal division into daughter cells is absent. Faull (1928) summarizes developmental tendencies within the family as follows : Uredinopsis, Milesina and Hyalopsora are restricted to Abies and ferns, while the others are found on Abies, Larix or Picea and angiosperms, although in the latter case none are known on recent families such as Orchidaceae and Compositae. The characteristic yellow pigment of rusts is lacking in Uredinopsis and Milesina, being present in the other genera. The pycnia are comparatively large and deep seated in Uredinop- sis, Milesina and Hyalopsora and small and superficial in the others, becoming quite abortive in Calyptospora. The uredinium is quite con- stant but absent in Calyptospora. It is the largest in Uredinopsis, its peridium being simple in Uredinopsis, Milesina, Hyalopsora and Melamp- sorella and showing specialization in Pucciniastrum, Thekopsora and Melampsoridium. The telia are diffuse especially in Uredinopsis, less so in Milesina, Hyalopsora and Melampsorella, tending to become com- pact in Pucciniastrum, Thecopsora, Melampsoridium and Calyptospora. They are subepidermal in Uredinopsis, Pucciniastrum and Melampsori- dium, intraepidermal in the other genera; they are occasionally sub- epidermal in Milesina. The teliospores are irregular in form and number in Milesina and Hyalopsora. Cronartiaceae. — Here the teliospores are morphologically at approxi- mately the same stage of development as the Melampsoraceae. Several spores are cut off catenulately on the hypha, and the whole spore mass of the sorus clings together into a columnar spore body. In Cronartium ribicola the telia so extensively agree with the earlier described uredinia in the young stages, e.g., in the formation of the hyphal knot, peridium and sporiferous basal cells, that in this stage it is not possible to dis- UREDINALES 573 tinguish them. The initial cells change entirely into teliospores instead of dividing into spores and intercalary cells. They remain connected with one another and, by the increase of new cells on the lower side, form a lengthening column which finally ruptures the peridium and passes out through the epidermis (Fig. 384, 1). The teliospores are thin-walled, apically thickened and capable of immediate germination at maturity (Fig. 384, 2 to 7). Fig. 384. — Cronaritium ribicola. Short column of teliospores with teliospores already germinated in the upper portion. 2. Mature teliospore. 3. Beginning of germination. 4. Basidium. 5. Tip of basidium with basidiospore. 6, 7. Germination of basidispores. (1 X 115; 2 to 7 X 565; after Colley, 1918.) The telia of Chrysomyxa (Fig. 385) are similar in their structure but lack the peridium; in Chrysomyxa Abietis, however, the development of the teliospores is somewhat more complicated. Each of the fusion cells, which here, as in Uromyces scutellatus and Gallowaya pinicola, result from the fusion of two palisade cells, elongates much and divides into an apical "sporoid cell," which subsequently swells and thickens its wall, and into a basal cell, which remains slender and thin walled. The sporoid cell may divide by septa into two or three chambers and winter over in this condition. In spring each chamber forms a projection, into which 574 COMPARATIVE MORPHOLOGY OF FUNGI Fig. 385. — Chrysomyxa Rhododendri. Telium. a, catenulate teliospores (zeugites) ; p, basidium; e, epidermis of host; m, mycelium. (After Bary, 1884.) -ZeuSexualcelle-*Aeciospores-»BinucIeate-^TeIio8pores-^Basidia-*Ba8idiQ3pores. mycelium mycelium Diagram XXXIII. In this diagram it is noteworthy that haplont and diplont, as in Olpidium, possess individual thalli. In the life cycle of Uromyces Betae an alternation of generations proceeds with change of nuclear phase. The gametophyte consists of the uninucleate mycelium which arises from basidiospores and forms pycnia and aecia. The sporophyte consists of binucleate mycelium arising from aeciospores and forming first uredin- iospores and then teliospores. As both gametophyte and sporophyte in Uromyces Betae live on the same host, this alternation of generations can only be discerned cytologically. In the heteroecious forms, it coin- cides with alternation of hosts; thus, as has been shown above, Cronartium thrives in the haploid portion on Pinus and in the diploid portion on Ribes. Gametophyte and sporophyte here differ physiologically and are specialized on hosts systematically far apart. UREDINALES 583 Furthermore, it is noteworthy that normally not an aecial but a uredinial mycelium arises from aeciospores. Similarly from teliospores, only basidia and later aecia may be formed. The gametophyte, therefore, consists only of a short generation, that from the basidiospore to the aecium, i.e., it is unable to propagate itself. The only haploid fructifications which arise on the haploid mycelium, pycnospores, are generally not functional. In the heteroecious forms, therefore, the change of host of the gameto- phyte is obligatory; the gametophyte can only develop further if the aeciospores are able to reach the alternating host. It is different with the sporophytes. Here binucleate mycelium with urediniospores may always arise from the urediniospores as long as climatic conditions or the development of the host plant allows, so that an indefinite number of generations of uredinial mycelium and urediniospores follow one another. As the urediniospores, at germination, always infect the individuals of the same species of host as that on which they have arisen, the sporophyte is able to multiply indefinitely (as inOlpidium Viciae, by the zoosporangia). Consequently in the heteroecious species, the change of host is only facultative ; only if the sporophyte is forced by environment to form telio- spores is it obligatory to change host, as the basidiospores can only infect individuals of the gametophytic host. From the point of view of change of nuclear phase, this innate unlimited repetition leads to an increased duration of the sporophyte which subsequently predominates over the gametophyte. Forms which correspond to this scheme of development, in which the gametophyte forms pycnia and aecia and the sporophyte uredinio-, telio- and basidiospores, are called "eu-" forms (with complete life cycles) as Eu-puccinia or Eu-uromyces. In systematic literature, these spore forms are indicated by the symbols 0, I, II, III, where 0 indicates pycnia which are often facultative in appearance, I aecia, II uredinia and III telia. The basidia are not specially mentioned in this case as they always appear at the germination of the teliospore. Of the cyto- logically investigated forms, Cronartium ribicola, Puccinia graminis, Phragmidium violaceum and Puccinia Violae belong to this type. Besides these Eu-forms, a great number of species are known in which one or another of the spore forms is absent and the life cycle is "incom- plete." These other types of cycle are given special names: the four most important, -opsis, endo-, brachy- and micro- types, will be discussed here. In the -opsis forms, e.g., in Gymnosporangium and in Puccinia Falcariae, the urediniospores are lacking, in other species the pycnia also. The life cycle corresponds entirely with that of the eu- forms, only the expan- sion of the sporophyte, because of the repetition of urediniospores, is absent. In some earlier mentioned species, as Puccinia Senecionis and Uromyces Hedysari-obscuri, this gap is filled by the apogamous repetition 584 COMPARATIVE MORPHOLOGY OF FUNGI of aecial formation. The eu- and -opsis forms are called long-cycled forms, the other (endo-, brachy- and micro- forms) are called short-cycled forms. In the endo- type (0, I) both urediniospores and teliospores are lacking, e.g., Endophyllum Sempervivi on Sempervivum. The uninucleate mycelium penetrates the whole leaf parenchyma and winters over in the host. It first forms pycnia, then aecia. Plasmogamy occurs in the aecia, as was earlier shown, with consequent dicaryons which fuse in the aeciospores. These germinate (normally) with basidia whose spores again infect Sempervivum leaves. In the endo- type accordingly, the aeciospores have taken over, caryologically and biologically, the func- tion of teliospores. The life cycle may be indicated as follows: iPycnium— »Pycniospores PC R Uninucleate— »»Aeciuijn— *Sexual cells— ^Aeciospores— >-Basidia— *Basidiospores mycelium Diagram XXXIV. The gametophyte is formed as in the eu- forms, while the sporophyte has lost its individuality : it is limited to the aeciospores, on whose germi- nation meiosis takes place. Its height of development places it at the same stage as the diplonts of the Phycomycetes. In contrast to the endo- forms, the brachy- and micro- forms are distinguished by the lack of aecia, the micro- forms by the further lack of uredinia. As far as the brachy- forms (0, II, III) have been investi- gated, a typical sexual act occurs in the uredinium which takes the place of the aecium in the life cycle. In Triphragmium Ulmariae the basidio- spores germinate to a uninucleate mycelium. On this are formed pycnia and large primary uredinia of irregular shape. In the latter, sexual acts occur, the spores of the primary uredinium again infect plants of Ulmaria and develop there to binucleate mycelia which form small, rounded, secondary uredinia and later telia. Its life cycle proceeds according to the following scheme: Basidiospores /Pycnium — tPycniospores / P / Primary Uhinucteat£H*Primary-»Sexual cells-^TJrediniospores->Brnuc AJrcdmiospores / C R eate*-»Teliospores— +-Basidia mycelium Uredinium mycelium Diagram XXXV. It is essentially correct even to pycnia, often absent as in the eu- forms, but the primary uredinia are substituted for aecia. UREDINALES 585 In the micro- type (0, III), finally, the life cycle becomes still simpler by the absence of the uredinia. In Puccinia Malvacearum, the basidio- spore develops a uninucleate mycelium which produces the telia where plasmogamy occurs. The fusion cells develop to short, branched, binu- cleate hyphae, each of whch forms a teliospore at its tip. This can germinate immediately to a basidium with basidiospores, which infect new hosts and again develop uninucleate mycelia with telia. In con- trast to the long-cycled forms, this species is able to complete its life cycle several times within one season. These micro- forms, whose telio- spores are capable of immediate germination, are sometimes placed in a special group called lepto- forms. Wintering over occurs by the delayed germination of teliospores. In other micro- forms, as Puccinia Veroni- carum, two types of teliospores are formed (p. 576). The life cycle of the micro- type takes place according to the following scheme (the pycnia which are absent in P. Malvacearum are here added) : ^jrPycnium— »Pycni<)8pores P C . R Uninucleate— »Teliuni— *Sexual cells— »Binucleate— ►Teliospores— »Basidia—»Basidiosporea mycelium mycelium . Diagram XXXVI. In Uromyces Scillarum, the scheme is modified so that plasmogamy occurs somewhere on the mycelium. This scheme is the same in principle as that assumed for the Septobasidiaceae. Still simpler is Gallowaya pinicola, where the teliospores are not formed as such, but each cell of the short binucleate chain resulting from plasmogamy divides directly after caryogamy to form a phragmobasidium. The vestigial pycnia are the only structures which distinguish it in principle from the simpler Auriculariaceae, since not even a resting organ, such as the probasidium, is formed. Vestigial pycnium Uninucleate^-»-Telium— >SexuaI cells— >Short chain of->Basidia— ►Basidiospores mycelium binucleate cells Diagram XXXVII. In these different developmental types, the following courses exist: 1. The plasmogamy is shifted in time and place. It occurs in the aecia of the eu-, -opsis and endo- forms (in Uromyces Scrophulariae, also somewhat on the mycelium) before the development of pycnia, in the uredinia of the brachy- forms, and in the telia or somewhere on the mycelium in the micro- forms. Characteristically, it occurs between two slightly differentiated hyphae or hyphal tips, in the former hetero- gamously by the migration of one nucleus to the other cell, in the latter 586 COMPARATIVE MORPHOLOGY OF FUNGI isogamously by the dissolution of the separating septum. It leads to the formation of a dicaryon which is adapted to multiple conjugate divisions. 2. In all forms the gonotocont (which characterizes the Uredinales as Basidiomycetes) is developed as a basidium which throughout the whole order has a stereotyped form (except for variation in length of sterigmata). In contrast to this fixity in form and function, it is very variable in place of occurrence. It can (in the Coleosporiaceae and Ochropsora) be formed directly on the mycelium; or it can (in the other three groups) germinate from the most bizarre, encysted or thin-walled teliospores; or it can develop from aeciospores which have arisen either in aecidium or caeoma. Throughout all these variations, it remains unaltered. 3. The sequence of the five spore forms is controlled by internal factors; it is irreversible. In the life cycle, one spore form or another may be degenerate or disappear entirely but there is no species known, parthenogenetic or apogamous, in which the sequence is changed. This innate regularity is based in part on the change in nuclear phase, in part on the great age of the Uredinales. The only stable moment in the life cycle of the Uredinales depends on the fact that meiosis takes place in the same organ; on the other hand, the place of origin of the basidium and the place of the sexual act are variable. Furthermore, the gonotoconts are fixed in form (even to the basidium). The haploconidia (basidiospores and pycnospores) and the diploconidia (aeciospores and urediniospores) are fixed also. The zeugites (telio- spores), on the other hand, are plastic. Up to the present, in as far as we have discussed the bare fact of the ontogeny and morphology, the Uredinales agree with each other; there is, however, a complete anarchy in regard to the significance of all these forms and types of cycles. How have they arisen and how are they related? The answer to this question is difficult, for the Uredinales belong to the oldest known fungi and they have survived to our time, isolated as "living fossils." There exist today some very primitive genera but they are, for the most part, exotic and hence have not been investigated cytologically. Thus this answer cannot be given without considering at the same time the phylogeny of the Uredinales, their systematic division and the origin of their biological specialization. Concerning the phylogeny of the rusts there are two concepts, that of Bary (1884) which derives the Uredinales from the Ascomycetes and that of Brefeld (1889) which connects them to the Zygomycetes. Many mycologists today, as Blackman (1904), Lotsy (1907), Dittschlag (1910), Kursanov (1910, 1922), Maire (1911), Fromme (1912), Mme. Moreau (1914), Gwynne-Vaughan (1922), Lindfors (1924) and, in part, Killian (1920) follow Bary's opinion; they consider the Uredinales as the most primitive Basidiomycetes and place them at the beginning of this class. UREDINALES 587 Their point of view rests mainly on structure of the male sexual organ, which has survived as the pycnium. This appears very similar to the " spermogonium" of the Ascomycetes, e.g., Poly stigma; furthermore, the formation of a sweet solution and the odor which is detectible by man may be considered as entomophily. Thus the pycnospores correspond extensively in form and size to the spermatia of the lichens, they possess, as these, large nuclei and very small amounts of cytoplasm and reserve materials. Also, up to the present, they have not been germinated at least to the stage of infection of the host. The survival of the corresponding female organs would then be sought in the aecia. The ascomycetous ancestors had simple unicellular oogonia with unicellular trichogynes. The oogonia were joined together in groups and were fertilized by the spermatia arising in the spermato- gonia. During the degeneration of sexuality, the spermatial fertiliza- tion disappeared and in its place two female oogonia copulated with each other. The survivors of these gametangia are the present palisade cells which may be regarded as a sorus of reduced female organs. The survivors of the trichogynes remain as sterile cells cut off at the top of the palisade cells; they have lost their function and have become buffer cells whose function is passive, i.e., their dissolution gives the space necessary for the development of the spores. Mme. Moreau (1914) has sought for a different significance for the aecia. She proceeds from the hypothesis of Dangeard of gametophores in the Ascomycetes. The present aecia were preceded by pre-aecia in which chains of female gametes ("pre-aecidiospores") were formed upon the basal cells ("gametophores"). Likewise, a series of male sexual cells were cut off in the pycnia. The male and female sexual cells passed into the open and copulated. Because of the degeneration of sexuality, the plasmogamy followed within the female gametophoric sori between two female gametes. The differentiation of gametes undergoes no interrup- tion from this, only they are henceforth binucleate, behave no longer as gametes but divide into aeciospore and stipe cell. These conceptions (assuming that the phragmobasidium is originally a form of basidium) offer the advantage that they create in the Uredinales the sought-for link between the Ascomycetes and the Basidiomycetes; the latter had developed from the former through the rust series to the saprophytic forms. Other explanations, however, are possible. Thus, it is questionable whether the pycniospores are functionless spermatia, and accordingly under all conditions incapable of infection, since they are usually regularly and completely formed, even when in the micro- forms the other functional spore forms are suppressed. Here it is reason- able to suppose that for their further development they need the action of digestive juices of animals (Jaczewski, 1910). Even if they were func- tionless one could say more simply, that as diploconidia (urediniospores) 588 COMPARATIVE MORPHOLOGY OF FUNGI multiplied, the haploconidia became insignificant, except in Gallowaya, where they are vestigial although the haplont is dominant. If the pycno- spores were spermatia it would be inconceivable why they should arise principally on the upper side of the leaf while the aecia which they should fertilize arise on the lower side, or that, e.g., in Cronartium ribicola, they precede the aecia by at least one year (Colley, 1918; Adams, 1921). Furthermore in the Ascomycetes the functionless male sexual organs dis- appear before the female, hence it would be difficult to understand why their descendants would be unaltered and still form male sexual cells, capable of "germination'' to a limited degree, while the female sexual organs, which continue to fulfill their function, are deformed beyond recognition. Furthermore in the development of the aecia, the homologizing of the sterile cells at the top of the palisade with the trichogyne, is not satisfactory. Further, certain theoretical considerations contradict the direct derivation of the Uredinales from the Ascomycetes. In the ancestors among the Ascomycetes, it must have been a question of very primi- tive forms, e.g., Silurian, in which the ascus was eight spored and still plastic. From this, in the course of time, the phragmobasidium of the Uredinales at present has developed so far that none of its variants may be referred to the ascus as an ancestral form. Vice versa, one must assume that the sexual organs which early became functionless were able to hold their own during this long course of develop- ment and even, in certain cases, to form sexual cells still capable of "germination." Such a conception is fundamentally improbable, for it is shown in all series of the Ascomycetes, particularly, that the sexual organs are especially liable to reduction, gradually become modified, degenerate and disappear entirely. In these changing forms, however, the gonotoconts, the asci, remain constant. From the Protascineae up to the highest Euascomycetes, they remain essentially the same in form and biological value, thus characterizing the Ascomycetes as a homogeneous group. If, however, one wishes to derive the Uredinales directly from the Ascomycetes, their development must have proceeded in the opposite manner. If the otherwise stable ascus has changed directly into a conidiophore, which does not resemble it even in spore number, while the otherwise variable sexual organs retained their ability to function and even to form sexual cells capable of germination, it is the first example of such an interchange in the phylogenetic law of con- tinuity. This direct derivation of the Uredinales from the Ascomycetes, as significant as it was in its time, finds no support today. B. O. Dodge (1924, 1925, 1926) develops an interesting modification of the hypothesis of the relationship of the Basidiomycetes to the red algae, which meets most of the objections raised against that hypothesis. Just as the Ascomycetous line is characterized by the gradual degenera- UREDINALES 589 tion and disappearance of the male organs and by the assumption of their function by vegetative fusions, in the Basidiomycetous line, the female organs disappear first leaving the male organs, no longer functional, as vestigial structures whose presence is still physiologically important1 even after their cells have lost the corresponding female organs with which to copulate. The so-called sexual cells, gametes and sexual fusions are purely secondary, the fusions occurring between cells which are no more homologous to sexual organs, spermatia and oogonia, of any possible ancestral form than are the anastomoses of hyphae of the -f- and — strains of a heterothallic Coprinus. The presence of strains of rusts with a typical two-celled basidium, which is regularly associated with absence of spermogonia and the production of uninucleate spores, suggests that the presence of spermogonia may influence cell fusions in which they do not themselves take part, although a few cases have been observed where uninucleated spores have been produced in the presence of spermogonia. There is something in the inheritance of the rusts that determines when and where these cell fusions shall take place, as well as the nature of the cells fusing. The five great orders in the Florideae are distinguished mainly on the basis of the form and disposition of the carpogonial branches and auxiliary cells, and on the nature of the cell fusions which follow as secondary events. The gonimoblasts or ooblastema filaments, sporophytic outgrowths from the fertilized egg, in many genera are also involved in these secondary fusions preliminary to the develop- ment of the carpospores. It is to these secondary cell fusions in which the auxiliary cells of the red alga take the leading part, that we must look for the homologues of the fusing cells of the rust. There being no organ such as the egg apparatus in the rusts, the spermogonia, although they are so well developed in many species, can not carry out their primary male sexual function. Nevertheless there may be a series of activities in the growth of the rust linked with or influenced by the very inheritance which manifests itself morphologically in the shape of spermogonia. The fusions between the ooblastema filaments and auxiliary cells, and the other cell fusions in the red algae may very well be determined by the stimulus resulting from the presence of some of that element of maleness normally derived from the spermatium during fertilization. In the absence of the sexual fusions certain auxiliary cell fusions would not occur. Femaleness in the red algae outwardly expresses itself primarily in the organization of the carpogonial branch bearing the egg cell and its trichogyne. Auxiliary cells are secondary manifestations or accompanying phenomena. In a dioecious alga one should not expect to find auxiliary cells borne on the male plant. Femaleness in Caeoma nitens, i.e., the power to develop an egg apparatus, has been lost. Auxiliary cells represented by the cells in the sorus primordium are the secondary expressions. These cells are capable of fusing, usually in pairs, under a certain stimulus. 1 Unpublished experiments described in a letter from J. H. Craigie confirm this statement fully in Puccinia Helianthi, where the transfer of pycniospores from one pycnium to another appears necessary to secure normal development of aecia and binucleate aeciospores. 590 COMPARATIVE MORPHOLOGY OF FUNGI Maleness in the red algae is expressed in the form of antheridia producing spermatia. These bodies function primarily in fecundation and, in certain groups, secondarily in the cell fusions subsequent to fertilization. In the rusts maleness has persisted as shown by the development of spermogonia with their spermatia which are primarily functionless in the absence of an egg apparatus. This condition is associated with the occurrence of accessory cell fusions culmi- nating, in Gymnoconia, in nuclear fusions in the teliospore. A long-cycled rust becomes short cycled without losing the power to develop the basidium, which may be formed without previous caryogamy, in which case there is no necessity for meiosis. Therefore the number of cells in a phragmo- basidium need not always be four. The presence of some male element exer- cising its secondary function indicates maturity, and plasmogamy will occur, while inhibition of such a development is shown by the absence of plasmogamy. The Brefeld school (Brefeld, 1889; Tavel, 1892; Christman, 1907; Olive, 1908, 1911; in part E. Fischer, 1912) proceeds from the hypothesis discussed on page 421, that the basidium is a conidiophore which has become constant in form and spore number. Thus it connects the Ure- dinales and the Auriculariaceae with the Zygomycetes and attempts to elucidate this by a comparison between Chaetocladium and Endophyllum. The zygospores of Chaetocladium and the aeciospores of Endophyllum are both the direct product of a sexual act and both germinate normally with a conidiophore, which in Chaetocladium is indefinite and in Endo- phyllum is fixed as a basidium. The remaining spore forms were developed succesively de novo. This conception offers the advantage that it draws a direct parallel for the plasmogamy occurring between two basal cells and for the fusion cell itself: functionally the fusion cell is a zygospore formed by the copulation of gametangia which have become uninucleate. The difficulty is that it requires the basidium to be a stabilized conidio- phore which, as has been shown on page 421, is contradicted by important cytological considerations. Therefore, between the organization of the Zygomycetes and of the Uredinales, there lies such a broad gulf that this conception would be untenable. A third solution of the problem consists in the connecting of the Ure- dinales to other Basidiomycetes, particularly the Auriculariaceae. This idea was first expressed by Moller (1895) and further developed by Jahnchen (1923) and Neuhoff (1924). As a starting point one might consider Auriculariaceous forms, as Eocronartium muscicola, which possess micro- and macroconidia. The microconidia, cut off singly on unicellular sterigmata, are the ancestors of the pycniospores. The macroconidia arose singly from a mother cell which divided into a spore and a stipe cell, something as the initial cells of Phragmidium Potentillae-canadensis at the present time. With the transition to endoparasitism and the increasing difficulty to rupture the tissue of the host, the sporophores collect into sori. U RE DIN ALES 591 Since plasmogamy took place originally, as in the Polyporales and the Agaricales, anywhere between two hyphal cells, its shifting in the life cycle of the rusts and the remaining cases of pseudogamy are explained. Because of their endoparasitism, the hyphae became limited to the narrow intercellular spaces where they generally found no mate. Hence it is not remarkable that plasmogamy took place (at first preferably and in time exclusively) where for the first time in the life cycle numerous parallel hyphae were pressed together, i.e., in the primary uredinia of the ancestral forms. From these developed the more highly specialized aecia. This derivation is based on the fact that the uredinium possessed both the single-spored type (in which the stipe cells have only one purport) and the chain type, which led directly to the aecia. It is also supported by the fact that in certain heteroecious forms, as Puccinia Sydowiana (P. Vilfae), P. perdermiospora and P. Seymouriana, the aeciospores show peculiarities of structure so similar to those of the urediniospores that Arthur assumes a genetic connection between the aecial mycelium and the uredinial mycelium on other hosts, which he has demonstrated by cultural experiments. According to this, the eu- type would have arisen from the brachy- type. In connection with this localized pseudogamy the different groups of copulating hyphae may be explained; the types of Puccinia Mariae- Wilsoni, P. Violae and Endophyllum Sempervivi, etc., are only special cases produced by the structure of their sorus. Where the separating wall is incompletely dissolved or only a pore is formed, plasmogamy is heterogamous; where the dissolution of the wall proceeds further and extends almost along the whole wall, the nuclear migrations become feeble and plasmogamy is isogamous according to the present terminology ; these differences are not fundamental but only quantitative. The abscission of sterile cells may be explained on this basis, as Mme. Moreau does. Copulation took place only after the basal cells had already cut off some spores, and had continued their activity as diploconidia. From these points of view, one may represent the phylogenetic development of the Uredinales hypothetically in the following manner (Dietel, 1903, 1904, 1909, 1912, 1915, 1918; Faull, 1928): The primitive forms derived from the Auriculariaceae had lived on ferns in the Silurian. When the conifers appeared, its gametophyte could also live upon these. Subsequently the greater part of the cycle was shifted to the conifers upon which it developed greater dependence. They retained the gametophyte host and successively seized as suitable hosts those which, in the course of geological time, they encountered among the developing angiosperms. From a morphological viewpoint, they are characterized by the develop- ment of special zeugites which in the lower forms are formed at any point in the mycelium but in the higher forms arise in special sori and are trans- formed into teliospores. In the Coleosporiaceae and Melampsoraceae, 592 COMPARATIVE MORPHOLOGY OF FUNGI with the exception of Melampsora (to be considered later), they live in the haplophase exclusively on conifers, in the diplophase in different ferns and angiosperms. The zeugites gradually lost their significance and hence were no longer retained in the families branching off the main line. The primary cause may be that, as today in Hyalopsora and Uredinopsis, the urediniospores are able to winter over; thus meiosis was in the course of time fixed at their germination in the spring, i.e., the formation of the basidia was shifted forward to the overwintering urediniospores which thus assumed the role of zeugites and thereby attained new morphological develop- mental impulses. At first there developed the Cronartiaceae whose urediniospores and teliospores are similar and whose teliospores contribute toward propaga- tion. They retained the conifers as their gametophyte hosts. Thus there proceeded a special permanent development from forms with the single-spore type of urediniospores, all the more so as their branching off went hand in hand with a period of mutation in respect to physiological requirements. That such physiological mutations can occur is supported by the example of Cronartium asclepiadeum whose sporophytes can infect both Vincetoxicum, Paeonia and Pedicularis (which appear in the north temperate zone, the home of the gametophyte host, the pine, and hence may be regarded as the true hosts) and various exotic angiosperms, Verbenaceae, Balsaminaceae, Loasaceae, Tropaeola- ceae and Solanaceae, which it met for the first time in the course of experiments (Klebahn, 1914, 1916). A relaxation of extreme speciali- zation must already have been encountered in Melampsora, the only genus of these three families which changed its gametophyte host by migrating either to the sporophyte host, i.e., becoming autoecious, or to other angiosperms, Amentiferae, Saxifragaceae, Monocotyledoneae, etc. Besides the consideration set forth here, basidial formation is deferred to specially formed urediniospores from which arise the stipitate teliospores of the Pucciniaceae, no longer joined into crusts. Thus the Pucciniaceae are apparently of recent date. Since the Amentiferae are not parasitized, they must have been formed later than these. The oldest forms were plurivorous (omnivorous) and attained a full development at the time when the earth was being covered with a mass of new angiosperm families. The purely autoecious forms attained a prolific development in the tropics and the south temperate zones especially on Leguminosae, and in the north temperate zone chiefly on Rosaceae. There they have divided into a whole series of morpholog- ically distinct genera of which, on Leguminosae, we have mentioned Uromycladium and Ravenelia and on Rosaceae Phragmidium, Ochropsora, Triphragmium, Kuehneola and Gymnoconia. Also the partially heteroeci- ous Gymnosporangium has possibly arisen from this group by a second UREDINALES 593 shifting of the gametophyte from Rosaceae to conifers. Their teliospores usually resemble those of Phragmidium. The remaining mixed genera which contain both autoecious and heteroecious species, particularly Uromyces and Puccinia, in contrast to the Coleosporiaceae, Melampsoraceae and Cronartiaceae, are distin- guished in their change of host by a great stability in their sporophyte which chiefly inhabits the Glumiflorae, while their gametophytes have been spread to more than 50 families of angiosperms and again have become largely specialized to specific hosts. From these species, by a reduction of the life cycles, have arisen numerous micro- and endo- forms (E. Fischer, 1904, 1910; Dietel, 1918). In the micro- forms, meiosis came about in the long-cycled species as a result of a simplification of the life cycle where all spore forms up to the teliospore and eventually the pycnia were suppressed. In other cases there must have taken place a shifting of place of teliospore formation; thus the telia discussed on page 568 of Puccinia Fergussoni on Viola do not coincide with the structure of telia but with the aecia of the corresponding eu- form, Puccinia Violae, and in Uromyces scutellatus, U. laevis and U. alpestris on Euphorbia (mentioned on p. 568). Altogether one obtains the impression that the sorus was originally developed as an aecium, later became indefinite and was merged with the telia. These forms appear chiefly in tropical, alpine and polar regions. The development in the endo- forms has proceeded a step further; here also caryogamy has been advanced into the aecium, occurring in aeciospores rather than teliospores. While in the micro- form, Uromyces alpestris, teliospores are formed within the sori, originally considered to be aecia, where caryogamy takes place, in the endo- form, Endophyllum Euphorbiae-silvaticae on Euphorbia, the original tendency of the sori to form aeciospores preponderates and caryogamy takes place there. According to this conception the endo- forms are the end members of a series of developments which, by shifting of teliospore formation in certain micro- forms, became introduced into the aecium. Both Endo- phyllum (with aecidia) and Kunkelia (with caeomata) may thus be con- sidered, not as natural monophyletic genera, but as biological groups similar to the brachy- and hemi- groups. As an initial impulse for these modifications, we may consider a migration of the mother species into warmer regions. Thus the ancestral form on Rubus, Gymnoconia Peckiana, is found in the colder regions of North America, while its apparent derivative, the endo- form Kunkelia nitens, also on Rubus, is found in the warmer regions of the South and West. Besides, the number of endo- forms known from the tropics is continually increasing. In con- nection with this degeneration have again arisen forms in the Pucciniaceae quite similar to the primitive forms and consequently were considered primitive by many authors (E. Fischer, 1912; Groves, 1913). 594 COMPARATIVE MORPHOLOGY OF FUNGI As in the other orders, the probable relationships between the families and genera have been schematically represented below. In conclusion there may be briefly cited from the four families some interesting, pathologically important species, whose nomenclature, because of the various estimates of their biological importance, is always in a state of flux. The gametophytes of the Coleosporiaceae, Melamp- soraceae and Cronartiaceae occasionally produce pandemic diseases of conifers. Their aecidia are designated as blister rust, and earlier, when their heteroecism was unknown, were grouped together in the single genus Peridermium. In the gametophyte, the species of Coleosporium live on UREDINALES PUCCINI ACEAE Rayenelia Hemileia Uromycladium Puccinia Gymnosporangium PhragmidiumNy Triphragmium Kuehneola Gymnoconia Zaghouania Cystopsora Endophyllum Kunkelia CRONARTIACEAE Cronartium Chrysomyxza MELAMPSORACEAE Calyptospora Thecopsora Pucciniastrum Melampsoridium Melampsorella Hyalopsora Mileeina UredinopBis COLEOSPORIACEAE Coleosporium Goplana Gallowaya Diagram XXXVIII. pine needles; their sporophytes are specialized on different angiosperms as that of C. Sonchi on Sonchus. C. Senecionis and C. Campanulae, besides growing on their normal sporophyte hosts (Senecio and Campanula respectively) , also attack representatives of exotic families. In Chrysomyxa the micro- form, C. Abietis lives on fir needles, in the gametophyte; the heteroecious eu- form, C. Rhododendri lives on Rhododendron in the sporophyte. Cronartium ribicola, the white pine blister rust, has its gametophyte on the bark of Pinus Strobus and other white pines, the sporophyte on Ribes. C. asclepiadeum causes blister rust of the pine, while its sporophyte is plurivorous (p. 592). Melampsora pinitorqua causes a disease of pines (gametophyte on Populus) and Melampsorella UREDINALES 595 elatina (M. Caryophyllacearum) , the witches' broom of the white fir (sporophyte principally on Stellaria and Cerastium). Among the autoecious species of Pucciniaceae are Uromyces Betae, the beet rust, U. appendiculatus (£/. Phaseoli), the bean rust, Hemileia vastatrix, the coffee rust, and Phragmidium disciflorum and its relatives, the rosaceous rusts; among the heteroecious forms are Puccinia, Pruni- spinosae, the plum rust (gametophyte on Ranunculaceae), Puccinia graminis, the highly specialized black rust of cereals and other grasses (gametophyte on Berberis vulgaris and its relatives), P. dispersa, the brown rust of rye (gametophyte on Borraginaceae), P. triticina, the brown rust of wheat (gametophyte on Thalictrum), P. glumarum, the yellow rust of cereals (gametophyte unknown), P. Lolu (P.) coronifera, the crown rust of oats (gametophyte on Rhamnus) and Gymnosporangium Sabinae, G. globosum and G. Blasdaleanum, the rust of apples and pears (sporophyte on Juniperus or Libocedrus). CHAPTER XXXIV USTILAGINALES The Ustilaginales, or smuts, include several hundred species which parasitize higher plants, develop their thick-walled spores (smut spores) in definite organs and impart to these organs a burnt or charred appear- ance. In contrast to the Uredinales, they are saprophytic in a portion of the life cycle, and some of them may complete the whole cycle in artificial culture. Their mycelium consists of slender, hyaline hyphae whose cells, corresponding to the cytological life cycle, in some species are uni-, in others binucleate; occasionally, as in the higher Basidiomycetes, they can become multinucleate (Fig. 397, 1). In some forms, as in the corn smut Ustilago Zeae (U. Maydis) and in Entyloma and Doassansia, they grow only in the region of initial infection (i.e., in all the growing parts of the plants, even the roots) where they form their smut sori. In most other forms they penetrate the whole plant or single sprouts and much later form sori in leaves or fruits. Ustilago Tritici, the flag smut of wheat, and U. nuda, the flag smut of barley, infect flowers; the mycelium winters in the seeds, grows behind the growing point the following year and, at the end of the growing season, it forms a sorus in the ear. In most other cereal smuts, as Tilletia Tritici, bunt of wheat, U. Avenae, the flag smut of oats, U. levis, the covered smut of oats, U. Hordei, the covered smut of barley, U. Crameri, the millet smut, and Tuburcinia occulta (Urocystis occulta), the stem smut of rye, the infection takes place in spring in the young seedlings, the mycelium grows up the stem behind the growing point and forms the sorus : in T. Tritici and U. Crameri in the ovary; in U. Hordei in the ears; in U. Avenae and U. levis in the panicle; in Tuburcinia occulta mainly in the stem and leaves. In Cintractia Caricis and Tuburcinia Trientalis the mycelium is perennial in the rhizome and the shoots. In the former, it forms the sorus in the ovary, in the latter in the stems and leaves. The hyphae are mostly intercellular; in some species, as in the Uredin- ales, for the sake of nourishment they penetrate the host cells with capitate or racemoid haustoria and thereby cause direct injury to the plant. Thus the specimens of Trientalis infected by Tuburcinia are recognizable by the pathological thickening of their stems and the smaller size and lighter color of their leaves. In Entyloma Nymphaeae the haus- toria arise as special branches of the intercellular hyphae and swell 596 USTILAGINALES 597 into multinucleate appressoria, as in the Erysiphaceae, before the penetration of the host cell (Lutman, 1910). In many other forms, e.g., in most of the cereal smuts, the hyphae are only intercellular parasites, form no haustoria and take their food directly by osmosis. Even in these, however, the decomposition products of the hyphae seem to cause injury to the host, e.g., in Tilletia Tritici a retardation of growth and increased susceptibility toward Puccinia glumarum (Lang, 1917). In still others, e.g., U. Zeae, the hyphae grow intracellularly, penetrate the individual host cells and cause death. Conidia are formed on the host in some genera, as Entyloma and in Tuburcinia Trientahs (Woronin, 1881) and Ustilago Vuijckii (Seyfert, 1927). The hyphae form thick, white mats of simple unbranched coni- diophores on the lower sides of the leaves between the epidermal cells or on the filaments which creep around on the epidermis. The conidio- phore repeatedly cut off hyaline pyriform conidia which germinate with germ tubes or, under unfavorable conditions, with secondary conidia. In most other genera only the smut spore is known. It develops in certain organs of the host and only on its appearance may the infected plants be recognized as such. In many species, the host is not further deformed by the formation of a sorus. The tissue in which spore formation proceeds is resorbed; thus wheat kernels infected by Tilletia Tritici are recognizable by a slight swelling, a darker color, and a greater spreading of the glumes. Because of the presence of trimethylamine in the smut spores, their intense odor is like that of herring brine. Other species cause characteristic hypertrophies; thus the ovule of Polygonum Hydropiper attacked by Sphacelotheca Hydropiperis is turned into a spore "capsule" which often extends far above the unaltered perianth and, at maturity of the spore, bursts open in valves. In Melandryum the female flowers are induced to form staminate filaments by Ustilago violacea which, as U. Scabiosae, forms its sorus only in the anthers. These filaments are colonized by the fungus and destroyed. In U. Zeae, the parenchyma of the host is stimulated to form gelatinous growths up to the size of a child's head (smut tumors), which are again dissolved by the fungus. In eastern Asia the natives eat as vegetables beet-like stems of Zizania latifolia deformed by Ustilago esculenta (Hori, 1907); and in Polygonum chinense of Java the stem is stimulated by Ustilago Treubii to growths which occasionally appear like Cantharellus and form in their interior a peculiar capillitium which apparently participates in the dis- semination of spores. The number of the spores formed in such a sorus is very large ; in Tilletia Tritici, it averages four million spores per smutted kernel; according to Buller (1909) even twelve million. The smut spores, as the teliospores of the Uredinales, arise exclusively on binucleate mycelia. Before their formation the hyphae branch very much and form thick tissues of extremely slender, small cells which, as a 598 COMPARATIVE MORPHOLOGY OF FUNGI result of the swelling of their membranes, lie imbedded in a gelatinous sheath. In Ustilago Tragopogonis-pratensis (Rawitscher, 1912) and in U. Heu fieri (Sartoris, 1924), they divide into short unicellular sections which become moniliform and loosen themselves from the cell chain. They are irregularly angular (Fig. 397, 8 and 9), subsequently round off and change to thick-walled spores whereby the dissolved membranes are resorbed. In Entyloma Nymphaeae (Lutman, 1910) the sporogenous hyphae form numerous short side-branches, each of which develops a terminal spore (Fig. 394, 4 to 8). In Neovossia, at least in N. Moliniae, the proximal part of the sporiferous branch becomes thickened and remains as an appendage of the mature spores (Fig. 401, 3 to 5). In Fig. 394. — Entyloma Glauci. 1. Sorus of smut spores. Entyloma Nymphaeae. 2. Section of haustorium. The old appressorium has thickened its wall. 3. Young appressorium with nuclei entering. 4 to 8. Development of smut spores. (1 X 500; 2, 4 to 8 X 1,600; 3 X 860; after Dangeard, 1892, and Lutman, 1910.) Cintractia, the spores are successively cut off from a columella-like stroma which covers the ovary; they are progressively pushed outward and at maturity increase very much in circumference, adhere more or less securely and flatten into irregular polyhedra. In most forms the mycelium is entirely used up by spore formation and dissolved by the swelling; in Cintractia an unused part remains within the spore mass. The smut spores are hyaline and binucleate when young; in the course of development the dicaryon fuses to a single diploid nucleus (Fig. 394, 4 to 8). The mature spore wall consists of a thin endospore and a brown or violaceous, often characteristically sculptured exospore. In many genera of the Ustilaginaceae, Sphacelotheca, Ustilago (Fig. 395) and Cintractia (Fig. 397, 6) and of the Tilletiaceae, in Tilletia (Fig. 399), Neo- USTILAGINALES 599 vossia (Fig. 401) and Entyloma (Fig. 394, 8) and in the Graphiolaceae, the spores arise singly and form a dusty mass at maturity. In Entyloma, they remain in the interior of the host, joined into small, light-colored nests which germinate in situ. In Sphacelotheca the spore fundaments are only changed to real spores in the middle layers of the sorus; toward the outside and the interior their formation is incomplete ; they remain color- less, adhere in a tissue and form a five- to ten-celled hyaline sheath which covers the true spores on both sides. In other genera, among the Ustilaginaceae, Tolyposporium, Theca- phora, Testicularia and in the Tilletiaceae, Tuburcinia and Doassansia, several or more spores are joined into a spore ball. In Tolyposporium, Thecaphora and Tuburcinia (Fig. 400, 4 to 6), all spores are fertile. In Fig. 402, 4, Doassansia (Fig. 403, 4 and 5, 9 to 11) the outer spores degen- erate, lose their nuclei and contents and remain hyaline. In Testicularia the spore ball consists of an outer fertile layer, surrounding an inner ball of pseudoparenchyma. In Tuburcinia, the spore ball results from repeated division of one or more cells from the same hypha; in Doassansia, the whole hyphal tissue of an intercellular space or breathing pore becomes changed to a large ball resembling a seed, whose outer cells form an almost complete sheath, which, after the decay of the host tissue, makes it possible for the ball to float on the surface of water. The smut spores are generally disseminated by wind or insects; more seldom, as in Doassansia, is the whole ball borne by water. They are mostly capable of germination without a rest period but retain the ability to infect for several years. Germination takes place in water, more freely in dilute nutrient solutions; the exospore bursts open and a germ tube whose wall is a continuation of the endospore protrudes. Germ pores are known in only a few forms, e.g., Ustilago Tritici. The further course of germination is used to separate the Ustilaginaceae and the Tilletiaceae. Ustilaginaceae. — Typical examples are Ustilago Scabiosae (Harper, 1898), U. Tragopogojiis-pratensis (Dangeard, 1892; Federley, 1904; Rawitscher, 1912), U. violacea (Dangeard, 1892; Harper, 1898; Werth and Ludwigs, 1912), U. Zeae (Rawitscher, 1912), Sphacelotheca Hydropip- eris (Brefeld, 1895), U. Heufleri on Erythronium americanum (Sartoris, 1924) and Testicularia Cyperi (Edgerton and Tims, 1926). When the germ tube (promycelium) has attained about one-third its final length, the diploid nucleus migrates into it (Fig. 395); when the promycelium is fully developed, it divides meiotically, forming three septa. In rarer cases the nucleus remains in the spore and divides there; in this case one daughter nucleus migrates to the promycelium, divides and a septum is formed between the promycelial nuclei. The distal promycelial cell may divide again, producing a three-celled promycelium. In contrast to the basidium of the Auricularia type, the promycelial nuclei do not slip out into the basidiospores but remain in the promycelium. By lateral 600 COMPARATIVE MORPHOLOGY OF FUNGI and terminal growth, these spores develop indefinitely into easily dissoci- able sprout mycelia (Fig. 395, 4, 8 and 9), with slightly ellipsoidal, uni- nuclear cells, which continue budding until food is exhausted. In U. violacea and Testicularia Cyperi, the whole promycelium may be loosened from the smut spore and, lying free in the nutrient solution, may sprout further. When the food is exhausted, the sprout cells form long fine filaments on the surface so that in some forms, as U. zeae (Fig. 396, 2 and 3), a white pellicle results (Brefeld, 1895). From a %'i \k& '■^^ definite moment, i.e., at a certain ic] ';■/ \ |<2h F&A oxygen tension of the medium (Bauch, 1922), the sprout cells copulate either directly or through copulation tubes (Fig. 395, 10 and 11). Descendants of the same promycelial cell, at least in Ustilago violacea, do not copulate with each other. The four tetracyte nuclei are sexually differentiated in pairs. Appar- ently each nucleus impresses on its cell a definite sexual character, thus causing the formation of copulation tubes (Kniep, 1919). In the form of U. violacea on Dianthus deltoides, there appear secondary sexual characters which distinguish the sprout mycelia of both sexes by the physiological peculiarities of their behavior toward albu- moses, peptones and disodium phosphate (Bauch, 1922). The sprout cells, which become bi- nucleate, bud further with con- jugate division of their nuclei until they reach a suitable host, within which they form germ tubes and develop to binucleate mycelia which in turn form sori in the "predestined" organs. U. Zeae and U. Vuijckii form an important exception to this scheme. Here the sprout cells do not copulate, hence the hyphae within the host are uninucleate and plasmogamy first takes place in the sorus (Rawitscher, 1912, denied by Seyfert, 1927). The gelatinous denticulate portions Fig. 395. — Ustilago Scabiosae. 1 to 4. Germ- ination of smut spores. Ustilago violacea. 5 to 7. Germination of smut spores. 8, 9. Sprout mycelium. 10, 11. Copulation of sprout cells. (1 to 7, 10, 11 X 1,000; 8, 9 X 1,500; after Harper, 1898.) USTILAGINALES 601 of a sporogenous hypha lie beside each other in pairs (Fig. 396, 4 to 9), the separating walls dissolve and nuclei migrate toward the middle, while both sides become thinner and emptier; generally they can still divide into two daughter cells. They then round off, thicken their walls and, with the fusion of the dicaryon, are transformed to smut spores. These figures of germination in Figs. 395 and 396 are of the Ustilago Scabiosae type and are extensively modified in many other forms of the Ustilaginaceae. In U. domestica (Fig. 397, 11), on Rumex domesticus, and U. Holostei (Fig. 397, 10), sprout cells are formed only on two pro- mycelial cells, where many are present in whorls. In U. domestica they Fig. 396. — Ustilago Zeae. 1. Germinating smut spore. Promycelium, P, developing a sprout mycelium. 2. Sprout mycelium. 3. Hypha with sprout cells. 4. Uninucleate hyphae from a lesion on corn. 5, 6. Uninucleate hyphal cells. 7 to 9. Copulation. 10. Young spore. 11. Mature uninucleate spores. (1 to 3 X 300; 4 to 11 X 660; after Brcfeld, 1895, and Rawitscher, 1912.) copulate as soon as they have fallen away; in U. Holostei the upper ones grow downwards clinging close to the promycelium, the lower ones grow upwards and copulate without falling off. Only the binucleate sprout cells fall away and germinate to sprout mycelia (Brefeld, 1895). From analogy to U. violacea, we must assume that the promycelial cells are sexually differentiated. In Cintractia Montagnei on Rhynchospora, the promycelium is four celled (Fig. 397, 6 and 7), the lower cell generally remaining in the spore (Rawitscher, 1922). Immediately after the formation of septa, or almost simultaneously, each pair of neighboring cells copulates either by resorp- tion of the wall or by copulation tubes; the content of one cell does not 602 COMPARATIVE MORPHOLOGY OF FUNGI migrate into the other but the copulation tubes take up the contents of both cells and develop to sprout mycelia. In other species, as U. nuda (Rawitscher, 1922), U. Tritici (Lang, 1910; Paravicini, 1917) and U. Hordei (Hils, 1912), the promycelium, under suitable conditions of growth, i.e., in presence of high oxygen tension, may develop mostly to unbranched hyphae instead of sprout mycelium. Occasionally these hyphae can again change to sprout mycelium. Between two more or less neighboring hyphal cells or between two hyphae of different promycelia, there appear copulation tubes through which the content of one cell wanders over into that of the other. Fig. 397. — Ustilago levis. 1. Portion of intercellular hypha. Ustilago nuda. 2 to 5. Germinating and copulating promycelia. Cintractia Montagnei. 6, 7. Germinating and copulating promycelia. Ustilago Tragopogonis pratensis. 8. Young binucleate spore fundaments. 9. Mature uninucleate spores. Ustilago Holostei. 10. Germination of smut spore with fusing sporidia. Ustilago domestica. 11. Germination of smut spore in nutrient solution. Ustilago Panici-frumentacei. 12. Submersed germination of smut spore. 13. Germination of smut spore in air. (1 X 860; 2 to 9 X 660; 10 to 13 X 240; after Lutman, 1910; Rawitscher, 1912, 1922; and Brefeld, 1895.) In U. bromivora (Bauch, 1925), as in Cintractia Montagnei, copulation may occur between two promycelial cells through copulation tubes or, as in U. violacea, between two ordinary sprout cells; in certain strains the sprout cells, as in the promycelial cells of U. nuda, develop first to long copulation tubes which only fuse at the tip. U. bromivora shows an interesting retrogression in the form of its promycelium. Besides the normal four-celled promycelium, there may also develop from a smut spore, two two-celled or one two-celled and two one-celled or one one- celled and one three-celled promycelium. The number four of the pro- mycelial cells generally remains constant, while the promycelium has entirely lost its characteristic form. USTILAGINALES 603 This degeneration goes still further in U. Panici-frumentacei; where the promycelium is no longer four-celled but only two-celled. The distal cell is generally elongated and germinates to a sprout mycelium (Fig. 397, 12 and 13). In still other species, e.g., Thecaphora deformans on Leguminosae, in U. Vaillantii on Scilla, etc., and U. longissima on Glyceria, no true pro- mycelium is formed. In Thecaphora deformans, the smut spores germi- nate in nutritive solutions to much-branched mycelia which cut off sprout cells (one apiece?) on dichotomous tips. These fall away easily and develop to new mycelia. On germination of the smut spores of U. Vail- lantii in water, there emerge slender, uninucleate, germ tubes which \J Fig. 398. — Ustilago Vaillantii. 1 to 6. (X 1,300.) Ustilago longissima, var. macrospora 7 to 11. Germination of smut spores (X 1,100). (After Paravicini, 1917, and Bauch, 1923.) grow further. Their fate is unknown. On germination in nutritive solutions the germ tube remains very short and cuts off one or more sprout cells which generally fall away (Fig. 398, 2 to 4). The nucleus divides in three and forms two septa. The three-celled sprout mycelium cuts off at its septa further sprout cells which again become three-celled, etc. In older cultures, copulation takes place (Fig. 398, 5 and 6) either by copulation tubes or between different sprouts or by partial and temporary solution of the wall between two cells of the same sprout. The binucleate cells develop to slender hyphae (Paravicini, 1917). In U. longissima the germ tube develops to a multicellular, uninucleate mycelium which is easily broken up and proceeds to sprouting. The sprouts are again 604 COMPARATIVE MORPHOLOGY OF FUNGI indefinite in length and cell numbers. Under suitable conditions, copu- lation takes place through copulation tubes, whereupon their cells become binucleate and grow further by sprouting (Brefeld, 1883; Para- vicini, 1917; Bauch, 1923). In the variety macrospora, meiosis occurs in the smut spore; the first sprout cell contains two nuclei of different sexual tendencies which generally are separated by a septum (Fig. 398, 9). The sprout cells arising from these are uninucleate (Fig. 398, 10 and 11) and copulate normally later (Bauch, 1923). Tilletiaceae. — In Tilletia Tritici (Dastur, 1921; Rawitscher, 1922) meiosis takes place in the smut spore, as in U. longissima var. macrospora, and proceeds very rapidly, but not quite simultaneously. Generally there are three steps of division, forming eight daughter nuclei in the smut spore (Fig. 399, 1 to 7). Frequently some nuclei divide still further, whereby are formed from ten to six- teen nuclei. The nuclei first lie to- gether in a sphere in the center of the cell and migrate into the pro- mycelium which has been formed in the meantime. This is aseptate and on germination in damp earth is, very short; in a nutrient solution, it develops to a long thread whose base emits its protoplasm into the grow- ing tip and remains empty (Fig. 399, 8); thereupon the empty parts are successively separated by septa. When the promycelium reaches the surface, a number of acicular sporidia corresponding to the nuclear number are cut off at the tip. Each spor- Fig. 399.— Tilletia Tritici. Germination idium contains a nucleus which sub- of smut spores. (i, 6, 7, io x 660; 2 to sequently is separated by a septum 5 X 1,000; 8, 9 X 500; after Rawitscher, /T?. onf. ft> -ittu-i iu *-ii 1922, andParavicini, 1917.) (FlS- 399> 9)- While they still are attached to the promycelium or after they have fallen away, they copulate by tubes and the nucleus and cytoplasm of one migrates into the other. The sporidia which have become binucleate develop by conjugate division of their nuclei to slender mycelia which cut off large, thin-walled, binucleate, falcate conidia (Fig. 399, 10). These may again develop mycelia which finally penetrate into the delicate tissue of the seedling. The remaining forms of the Tilletiaceae correspond with the above picture of germination. In Tuburcinia Trientalis (Fig. 400, 7 to 11), the terminal cells of the promycelium fall away from the germ tube and USTILAGINALES 605 Fig. 400. — Tuburcinia Trientalis. 1. Section through an infected leaf. The conidio- phores force their way between the epidermal cells. 2. Conidia germinating to secondary spores, c, in damp air. 3. Conidia germinating in water at the end of six hours. 4. Section through a stem, showing spore balls, Sp. 5, 6. Development of a spore ball. 7. Germi- nating spore ball. 8. Normal promycelium. 9. Basidial cells with four or eight basidio- spores which have separated from the promycelium. 10. Later stage with copulation completed. 11. Sporidia germinating with secondary and tertiary spores. (1, 2, 5, 6 X 215; 3, 7, 8, 11 X 345; 4 X 60; 9, 10 X 415; after Woronin, 1881.) 606 COMPARATIVE MORPHOLOGY OF FUNGI the spore which collapses (Woronin, 1881). In Neovossia, from 30 to 50 or more sporidia are formed (Fig. 401, 4 and 5); they never fuse but Fig. 401. — Neovossia Moliniae. 1. Tuft of hyphae with filamentous conidia. 2. Fila- mentous conidia germinating to falcate conidia. 3. Young smut spores. 4, 5. Germina- tion of smut spores. (1, 2 X 270; 3 X 330; 4, 5 X 240; after Brefeld, 1895.) develop to very slender mycelia which, in case the germination occurs in water, pour out their content into falcate conidia or, if the germination Fig. 402. — Tuburcinia Ranunculi. 1 to 3. Development of a spore ball with fertile and sterile cells. 5 to 9. Germination of smut spores. Tuburcinia Violae. 10. Binucleate sporidia. (1 to 3 X 860; 4 X 230; 5 to 9 X 450; 10 X 660; after Lutman, 1910; Kniep, 1921; and Rawitscher, 1922.) takes place in nutrient solution, develop branched mycelia which, according to cultural conditions, form acicular or falcate conidia (Brefeld, USTILAGINALES 607 1895). In Tuburcinia Ranunculi (Urocystis Anemones) on Ranun- culus (Fig. 402, 5 to 9) there are four daughter nuclei, eight in Tubur- cinia Violae. The promycelium of the former divides into a whorl of three to four branches, in the latter into eight, which separate by septa. In case only three branches are formed, the fourth nucleus remains in the promycelium. Each two branches form two short outgrowths which come together in horseshoe-shaped copulation tubes. In individuals Fig. 403. — Doassansia Sagittariae. 1. Portion of a germinating spore ball. 2. Germi- nation of smut spore and sprouting of conidia. 3. Sprouting of sporidia in nutrient solu- tion. Doassansia Alismatis. 4. Development of a smut sorus. 5. Germinating spore ball. Doassansia punctiformis. 6 to 8. Germination, copulation and formation of sprout cells. Doassansia deformans. 9, 10. Development of a spore ball. Doassansia Martianof- fiana. 11. Young spore ball. (1 X 100; 2, 4 X 500; 3, 6 to 8 X 245; 5 X 200; 9, 10 X 860; 11 X 440; after Setchell, 1892; Dangeard, 1892; Brefeld, 1895; Lutman, 1909; and Rawitscher, 1922.) with three branches, the third branch copulates with the promycelium. In this manner there are formed from the four and eight uninucleate sporidia two and four binucleate sporidia (Kniep, 1921; Rawitscher, 1922). The binucleate sporidia develop to long, narrow hyphae, where the protoplasm and nuclei migrate toward the tip and are abjointed from time to time at the base; gradually in aqueous cultures, development ceases as a result of inanition. In special nutritive solutions after a few 608 COMPARATIVE MORPHOLOGY OF FUNGI weeks in T. Ranunculi there appear many little flakes of ramose hyphae. They gradually become gray brown and, on forming smut spores, dark brown. In Entyloma, germination is similar to Tuburcinia, only in case copu- lation still occurs on the promycelium, copulation tubes are formed at the tips rather than at the base of the sporidia. In Doassansia, finally, there are, as in Ustilago, two types of develop- ment: D. punctiformis on Butomus umbellatus, and D. Alismatis (Fig. 403, 6 to 8) behave as Ustilago Scabiosae, i.e., copulation takes place between each pair of sporidia (Brefeld, 1895). In D. Sagittariae the sporidia germinate without copulation to uninucleate sprout mycelia (Fig. 403, 2 to 3) which after infecting the host continue as uninucleate mycelia. Copulation occurs, as in U. Zeae, on the formation of the smut spores (Rawitscher, 1922; Seyfert, 1927). Tuburcinia primulicola, known only from a short note by Wilson (1915), is exceptional. Its mycelium consists of uninucleate cells which winter in the host. It develops in the inflorescence and forms large masses of uninucleate conidia on the calyx. These fall off, lie on the corolla and copulate by tubes. The nucleus of one conidium migrates into the other. These binucleate cells germinate on the flowers to binucleate mycelia on which the smut spores appear later. Graphiolaceae. — For a long time this family was shifted between the Phacidiales, Pyrenomycetes, Myxomycetes, imperfects and Ustila- ginales, and has only recently been shown as undoubtedly related to the Ustilaginales (E. Fischer, 1883, 1920, 1922; Killian, 1924). The best- known representative, Graphiola Phoenicis, grows on the fronds of Phoenix dactylifera. Its fructifications appear on both the upper and lower sides of the pinnae, seldom on the midrib and form round or elongate, black tuberosities, approximately 1.5 mm. thick and Yi mm. high, whose walls are composed of a sclerenchymatous exterior and a thin inner peridium. At maturity, a yellow fascicle of sporogenous hyphae and capillitium breaks from the middle of the tuberosity. This fascicle towers like a column above the peridial crater. In contrast to the uninucleate cells of the vegetative hyphae, each of the cells of the sporo- genous hyphae contains a dicaryon of unknown origin. These cells sprout laterally in basipetal sequence to three to six spore initials, divide into two daughter cells which round off and gradually, with the fusion of the dicaryon, develop to thick-walled smut spores (gemmae). In germination the diploid nucleus divides into four daughter nuclei, one of which remains in the smut spore while the other three migrate into the germ tube and become separated from each other by septa. Under favorable conditions of nourishment, the germ tube may sprout. Shropshiria Chusqueae (Stevens, 1927) on Chusquea simpliciflora has been referred to this family by its author. In this genus the cups USTILAGINALES 609 are sunken in a sclerotium, with their tops and spore masses projecting slightly above the surface. Unfortunately the life cycle has not been studied. In the Ustilaginales, three types of life cycles may be distinguished. The first type includes Ustilago Zeae, Doassansia Sagittariae and Graphiola Phoenics; it is related to the micro- forms of the Uredinales and to Schizo- saccharomyces octosporus of the yeasts. The structure of the peridial walls of the Graphiolaceae also suggests a further development of the aecidium of a micro- form of the Uredinales. This type of life cycle is shown in the following diagram: 1 F C R^ I Uninud£at5.nrycelium-*Smut sppres-+Promycelium-»-Uninucleate sprout mycelium Diagram XXXIX. The second type includes Ustilago violacea and the majority of the smuts. It possesses no analog in the Uredinales; among the yeasts it corresponds to the Saccharomycodes Ludwigii type, mutatis mutandis: 1 :eliu Binacleate myce*ium-7»Smut spores — ►Promycelium^Uninucleate sprout mycelium->Binucleate sprout mycelium Diagram XL. The third type is only known in Tuburcinia primulicola. It also has no analog among the Uredinales: p c R . Uninucleate mycelium— pi 1-4. — , 1922a, Note on two remarkable Ascomycetes, Proc. Amer. Acad. Arts Sci., 57 : 425-434, 1 pi — , 1924, Contribution towards a monograph of the Laboulbeniaceae III, Mem. Amer. Acad. Arts Sci., 14: 313-414, pi 1-12. 1926, IV, Ibid., 15: 431-580, pi I-24. Theissen, F., 1909, Xylariaceae austrobrasilienses, Ann. 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Deutsch. Akad. Naturf. Halle, 52: 313-376, pi. 17-23. — , 1890, Die Pilze, [Schenk] Handb. d. Botanik, 4: 271-755. INDEX Illustrations are indicated by bold -face numbers, generic and specific names by italics. Abies, 572 Abjoint, 3 Absidia, 95, 100, 113 glauca Hagem, host, 97 Lichtheimii Lendner, 94 Orchidis (Vuillemin) Hageni, 109 Acacia bonariensis Gill., 215 Acaulium, 175 albonigrescens Sopp, 183 nigrum Sopp, 9 Acer compestris L., 314 platanoides L., 314 Pseudoplatanus L., 374 Acervulales, 615 Acervulus, 8 Acetabula, 345 leucomelas (Pers.) Boudier, 131 Achlya, 54, 64 americana Humphrey, 68 aplanes Maurizio, 64 debaryana Humphrey, 68 decor ata Petersen, 66 polyandra Hildebrand, 69 racemosa (Hildebrand) Pringsheim 69 radiosa Maurizio, 66 Achorion, 170 Achroomyces Tiliae (Lasch) Hoehnel, Ada omnivora (Shear) C. W. Dodge, Acompsomyces, 371 Acrospermaceae, 296 Acrosporus, 414 Adelphogamy, 13, 14 Aecidium, 558 Aeciospore, 562 Aecium, 555 Aesculus Hippocastanum L., 268 Agaricaceae, 457-460 Agaricales, 451-466 Agaricus campestris [L.] Fr., 411 melleus Vahl, 403 tabularis Peck, 407 Agropyron repens Beauv., 223 Agyrieae, 317 Aipim, 241 Akermannia, 116 Albugineae, 76, 77, 84-88 Albugo, 73, 74, 76-80, 84 Bliti (Biv.) O. Kuntze, 85, 87, 89 Candida (Pers.) 0. Kuntze, 77, 86, 87, 89 I pomoeae-panduranae (Schw.) Swingle, 86, 89 Lepigoni (Bary) O. Kuntze, 87 Portulacae (DC.) O. Kuntze, 77, 85, 89 Tragopogonis (Pers.) S. F. Gray, 86, 89 Aleuria asterigma Vuillemin, 338 sylvestris Boudier, 346 tectoria (Cooke) Boudier, 344 Aleurodiscus ammphus (Pers.) Rabenh., 441 polygonius (Pers.) Hoehnel and Litsch., 399 sparsus (Berk.) Hoehnel and Litsch., 441 Alina Jasmini Raciborski, 207 65, Alisma, 47 Allomyces arbuscula Butler, 57, 58, 59 f. dichotoma (Coker and Grant) Kanouse, 58 541 Alnus, 163, 165 443 incana Medic, 163 Alternaria, 221 Alternation of generations, 2 Alyxia buxifolia R. Br., 302 Amanita, 460 bisporigera Atk., 454 muscaria (L. ex Fr.) Qu61et, 453 rubescens (Scop, ex Fr.) Quelet, 411 Amanitopsis, 459, 460 Amauroascus verrucosus (Eidam) Schroe- ter, 167, 168 Ambrosia artemisifolia L., 20 Amerosporeae, 617 Amoebochytrium rhizidioides Zopf, 45, 46 671 672 COMPARATIVE MORPHOLOGY OF FUNGI Amorphomyces, 367, 374, 375, 377 Falagriae Thaxter, 366, 368 Amphigynous antheridium, 82 Amphimixis, 11, 14 Amphisphaeriaceae, 264-267 Amphispore, 567 Amphithecium, 316 Amphoromorpha blattina Thaxter, 390 Anaptychia ciliaris (L.) Massal., 352, 361 Ancylistaceae, 59-63 Ancylistes, 51 Closterii Pfitzer, 62, 63 Androgynous, 66 Androphore, 336 Andropogon, 244 Androsace Chamaejasme Willd., 23 Anellaria separata (L. ex Fr.) Karsten, 399, 407 Anemone nemorosa L., 568 Angelica, 222 Angiocarpous, 410 Anhellia, 215 Anisomyxa, 24 Annulus, inferior, 452 superior, 453 Antheridium, 127 amphigynous, 82 androgynous, 66 definition, 12 paragynous, 82 Anthostoma, 281 Anthurus borealis Burt, 507 Sanctae-Catharinae E. Fischer, 507 Aphanoascus cinnabarinus Zukal, 170, 171 Aphanomyces, 64 euteiches Drechsler, 69 laevis Bary, 68, 69 Aphelidiopsis, 34 Aphelidium, 34 Aphragmium, subg. of Pythium, 74, 88 Apiognomonia erythrostoma (Pers. ex Fr.) Hoehnel, 276 veneta (Sacc. and Speg.) Hoehnel, 274 Apioporthe anomala (Peck) Hoehnel, 283 obscura (Peck) Wehmeyer, 283 phomospora (Cooke and Ellis) Weh- meyer, 283 Apiosporium salicinum (Pers.) Schroeter, 265 Apiurn graveolens L., 160 Aplanes, 51, 66 Braunii Bary, 30, 66 Apodachlya, 54 pyrifera Zopf, 70 Apogamy, 13, 14 Apomixis, 13, 14 Appressorium, 5 Araiospora, 51 pulchra Thaxter, 72 spinosa (Cornu) Thaxter, 71 Arcangeliella caudata Zeller and C. W. Dodge, 467, 487 Stephensii (Berk.) C. W. Dodge, 487 violacea (Massee and Rodway) C. W. Dodge, 487 Archicarp, definition, 12 Archimycetes, 15, 17-29 Armilla, 453 Armillaria, 459 mellea (Vahl ex Fr.) Quelet, 6, 403, 407, 411, 454, 459 host, 145 mucida (Schrad. ex Fr.) Quelet, 397, 399 Armillariella mellea (Vahl ex Fr.) Patou- illard, 459 Artemisia campestris L., 222 Arthrorhynchus, 375 Cyclopodiae Thaxter, 374, 388 Artocreas poroniaeforme Berk. and Broome, 438 Aschion, subg. Tuber, 357 Ascobolaceae, 338, 343 Ascobolus carbonarius Karsten, 338, 339, 340 citrinus Schweizer, 338, 341 denudatus Fr., 338 furfuraceus Pers., 338 glaber Pers., 341, 342 immersus Pers., 136, 341 macrosporus Crouan, 338 magnificus B. O. Dodge, 338, 339 stercorarius [Bull.] Rehm, 337, 341 vinosus Berk., 338 Winteri Rehm, 341 Ascochyta Pisi Libert, 269 Ascocorticium, 330 Ascodesmis nigricans Tieghem, 336, 337 Ascogenous hyp ha, 129 Ascogonium, 12, 127 Ascoidea rubescens Brefeld, 146, 147 Ascomycetes, 127-395 Ascophanus carneus (Pers.) Boudier, 341, 342 ochraceus (Crouan) Boudier, 342 INDEX 673 Ascopolyporus polychrous Moller, 243 polyporoides Moller, 243, 244 villosus Moller, 243 Ascospore, 10 Ascotricha chartarum Berk., 259 Ascus, 10 Aseroe arachnoidea E. Fischer, 507, 508, 509 rubra La Bill., 508, 509, 510 Aspergillaceae, 170-186 Aspergillopsis, 176 Aspergillus Fischeri Wehmer, 182 flavus Link, 175, 182 fumigatus Fres., 175, 182, 1S3 herbariorum [Wigg.] E. Fischer, 175, 181, 182, 183 nidulans (Eidam) Winter, 176, 180, 183, 184 niger Tieghem, 175 Oryzae (Ahlb.) Cohn, 174, 175, 179 repens (Corda) Sacc, 182 Wentii Wehmer, 174, 179 Asterina Usterii Maire, 207, 305 Asterineae, 304 Asterinella Puiggarii (Speg.) Theissen, 303 Asterocystis radicis Wildemann, 19 Aster odon, 445 Asterostroma, 445 Astraeus hygrometricus (Pers.) Morgan, 475 stellatus [Scop.] E. Fischer, 475 Atichia glomerulosa (Ach.) Flot., 158 Atichaceae, 158 Atta, 460 Auricularia, 414 auricula- J udae (L. ex Fr.) Schroet., 541, 543 Auriculariaceae, 540-543 Auriculariales, 540-552 Auriculariopsis, 441 Autoecious, 562 Autogamy, 13, 14 Automixis, 13, 14 Autophagy, 12 Azygospore, 109 B Baeomyces rufus (Hudson) Rebent., 352 roseus Pers., 352 Bagnisiella australis Speg., 215 Bagnisiopsis peribebuyensis (Speg.) Theissen and Sydovv, 216 Balansia ambiens Moller, 245, 246 Claviceps Speg., 246, 247 diadema Moller, 245, 246 Hypoxylon (Peck) Atk., 245 redundans Moller, 245, 246 BalladynaGardeniae Rac, 206, 207 Balsamia, 355 Setchelli (E. Fischer) Gaumann, 355 Bambusa Blumeana R. and Sch., 244 Barclayella flagellifera (Ellis and Ever- hart) Sacc, 284 Basidioboleae, 117-120 Basidiobolus, 93 lacertae Eidam, 117 myxophilus R. E. Fr., 118 ranarum Eidam, 117, 118, 119, 120 Basidiomycetes, 396-613 Basidiophora, 77, 80 entospora Roze and Cornu, 78, 89 Basidiospore, 10, 417 Basidium, 10, 412 Battarrea, 480 Berberis vulgaris L., 595 Beta maritima L., 24 vulgaris L., 24 Betula alba L., 163, 283, 284 lutea Michaux, 197 Binucleate phase, 15 Blakeslea, 113 trispora Thaxter, 102 Blastocladia globosa Kanouse, 58 gracilis Kanouse, 58 Pringsheimii Reinsch, 57, 58, 59 prolifera Minden, 58 ramosa Thaxter, 58 rostrata Minden, 58 Strang ulata Barrett, 58 tenuis Kanouse, 58 Blastospora, 575 Smilacis Dietel, 578 Blemmatogen, 452 Blumenavia rhacodes Moller, 502, 503 Bolbitius, 463 Boletaceae, 464 Boletinus cavipes (Opat.) Kalchbrenner, 464 Boletus, 238 flavus With, ex S. F. Gray, 464 parasiticus [Bull.] Fr., 464 Zelleri Murrill, 464 674 COMPARATIVE MORPHOLOGY OF FUNGI Botryorhiza, 575 Hippocrateae Whetzel and Olive, 576 Botryosphaeria Bakeriana Rehm, 217 inflata Cooke and Massee, 216, 217 mascarensis (Mont.) Sacc, 217 Quercuum (Schw.) Sacc., 217 Ribis (Fr.) Gross, and Dugg., 217, 218 Saubinetii (Mont.) Niessl, 237 Viburni Cooke, 216, 217 Botrytis, 237 argillacea Cooke, 436 cinerea Pers., 325 Boudiera Claussenii Hennings, 336 Bovista nigrescens Pers., 472 Brachybasidiaceae, 433, 434 Brachybasidium Pinangae (Rac.) Gau- mann, 433, 434 Brachymeiosis, 133 Brachypodium sylvaticum Beauv., 251 Bremia, 73, 77, 80 Lactucae Regel., 90 Bromus inermis Leyss., 223 Broomeia congregata Berk., 474 Bulbil, 5, 407 Bulgaria inquinans [Pers.] Fr., 319 polymorpha (Oeder) Wettstein, 319 Bulgariaceae, 319-320 Butomus umbellatus L., 608 C Caeoma, 556 nitens (Schw.) Trelease, 569 C alamagrostis epigeios Roth, 251 Caldesiella, 443 Caliciopsis, 264, 326 Calicium pallidum Pers., 326 Calocera cornea [Batsch] Fr., 535, 538 flammea [Schaeffer] Bonorden non Fr., 538 viscosa [Pers.] Fr., 403, 535, 536, 538 Calonectria erubescens (Rob.) Sacc, 237 graminicola (Berk, and Broomed Wollenw., 237 nivalis Schaffnit, 237 Colostoma cinnabarinum Desvaux, 478 lutescens (Schw.) Burnap, 478 Wallisii (E. Fischer) C. W. Dodge, 478 Calvatia coelata (Bull, ex Fr.) Morgan, 474 maxima [Schaeff.] Morgan, 474 Calyptospora, 572 Goeppertiana Kuehn, 555 Camarophyllus borealis (Peck) Murrill, 456 virgineus (Wulfen ex Fr.) Fayod, 457 Cantharellaceae, 533, 534 Cantharellales, 529-534 Cantharellus aurantiacus Wulfen ex Fr., 457 cibarius Fr., 413, 533, 534 cinereus [Pers.] Fr. 533, 534 tubaeformis [Bull.] Fr., 533, 534 umbonatus [Gmelin] Fr., 442 Cantharomyces, 386 Capnodium meridionalis Arnaud, 267 salicinum [Pers.] Mont., 265 Carabidae, 118 Carlia Hippocastani (Jaap) Hoehnel, 268 Carpinus Betulus L., 165 Caryogamy, 1 Cassia nictitans L., 579 Castanopsis argentea (Bl.) A. DC, 205 Catothecium, 307 Cauloglossum transversarium (Bosc) Fr., 495 Celastrus scandens L., 197 Celidiaceae, 317 Cell walls, 3 Cenangium Abietis (Pers ex Schw.) Duby, 318 Centrum, 201 Cephalideae, 113 Cephalosporium, 236 Ceracea Lagerheimii Pat., 535, 536 Ceraiomyces Dahlii Thaxter, 388 Cer atomy ces mirabilis Thaxter, 365 rostratus Thaxter, 365 Ceratomycetaceae, 365-367 Ceratostoma brevirostre (Fr.) Sacc, 263 Ceratostomataceae, 262, 263 Ceratostomella echinella Ellis and Ever- hart, 262 fimbriata (Ellis and Halsted) Elliott, 262 pilifera (Fr.) Fuckel, 262 Cercis canadensis L., 280 Cercosphaerclla, sect. Mycosphaerella, 267 Cercospora, 267 cerasella Sacc, 269 microsora Sacc, 269 Ceriomyces citrinus (Boudier) Sacc, 449 Zelleri Murrill, 464 INDEX 675 Chaetocladieae, 113 Chaetocladium, 97, 113 Brefeldii Tieghem and Lemonnier 106, 107 var. macrosporum Burgeff, 95, 96 Jonesii (Berk, and Broome) Fres., 106, 107 Chaetomidium, 259, 260 Chaetomium Boulangeri Lindfors, 259 cuniculorum Boulanger non Fuckel, 259 globosam Kunze, 257 Kunzeanum Zopf, 257 var. chlorinum Mich., 258 spirale Zopf, 258 Zopfii Boulanger, 259 Chaetophora, 45 Chaetostylum Fresenii Tieghem and Lemonnier, 106, 107 Chamonixia caespitosa Rolland, 491 Chenopodium, 50 Chevalieria ctenotricha (Pat. and Hariot) Arnaud, 219 Chevalieropsis ctenotricha (Pat. and Hariot) Arnaud, 219 Chiastobasidium, 413 Chitonomyces, 364 cerviculatus Thaxter, 384 introversus Thaxter, 384 japanensis Thaxter, 384 longirostratus Thaxter, 384 oedipus Thaxter, 384 Chlamydospore, 8, 109 Choanephora, 102, 113 Cucurbitarum (Berk, and Ravenel) Thaxter, 101 Choiromyces, 359 Chrysomyxa, 564 Abietis (Wallroth) Unger, 568, 573, 574, 594 Rhododendri (DC.) Bary, 574, 594 Chusquea simpliciflora Munro, 608 Chytridiales, 33-50, 90 Chytridineae, 33 Chytridium olla A. Br., 40 Cicinnobolus Cesatii Bary, 195 Cintractia, 598 Caricis (Pers.) Magnus, 596 Montagnei (Tulasne) Magnus, 601, 602 Circinella conica Moreau, 100 minor Lendner, 100 Cistus, 187 Citromyces, 175, 176 caeruleus Sopp, 178 purpurescens Sopp, 178 Citrus, 265 Cladochytrium Alismatis Busgen, 47 tenue Nowakowski, 46 Cladodcrris, 458, 459 Cladonia gracilis (L.) Willd., 352 Cladophora, 90, 94 Cladophoraceae, 33 Cladosporium, 221 Clamp, connection, 401-403 Clathraceae, 497-511 Clathrella chrysomycelina (Moller) E. Fischer, 503, 504 Clathrus cancellatus [Tournefort] L. ex Lam. and DC, 498, 499, 500, 501, 502 columnatus Bosc, 498, 501 ruber Micheli ex Pers., 498 Clavaria amethystina [Battarra] Pers. ex Fr., 442 aurea Schaeffer ex Fr., 442 cinerea Bull. ex. Fr., 532 cristata [Holmsk.] Pers. ex Fr., 532 falcata Pers. ex Fr., 532 formosa Pers. ex Fr., 442 fragilis [Holmsk.] Fr., 442 grisea [Pers.] Fr., 532 pistillaris [L.] Fr., 442 rugosa [Bull.] Fr., 532 Clavariaceae, 441, 442 Clavariopsis, 523 prolifera Pat., 523 Claviceps balansioides Moller, 246, 248 lutea Moller, 248 purpurea (Fr.) Tulasne, 5, 247, 248, 249, 250 ranunculoides Moller, 248 Wilsonii Cooke, 252 Clavulina cinerea (Bull, ex Fr.) Schroeter, 532, 533 cristata (Holmsk. ex Fr.) Schroeter, 532 rugosa (Bull, ex Fr.) Schroeter, 532 Clavulinaceae, 532 Cleistocarpous perithecium, 134 Clitocybe aur.antiaca (Wulfen ex Fr.) Studer, 457 cerussata (Fr. Quelet, 457 expallens (Pers. ex Fr.) Quelet, 403 laccata (Scopoli ex Fr.) Quelet, 457 monadelpha Morgan, 459 paradoxus Cost, and Duf., 458 676 COMPARATIVE MORPHOLOGY OF FUNGI Clitopilus noveboracensis Peck, 457 Closterium, 62 Clypeus, 294 Coccoideae, 294 Coccomyces hiemalis Higgins, 312, 314 lutescens Higgins, 314 prunophorae Higgins, 314 Codiaceae, 91 Coenocytic, 3 Coenozygote, 31 Coleosporiaceae, 569-571 Coleosporium Campanulae (Pers.) Lev., 569, 594 Pulsatillae (Steud.) Lev., 580 Senecionis (Pers.) Fr., 594 Solidaginis (Schw.) Thiimen, 569 Sonchi-arvensis (Pers.) Lev. in Berk., 569, 570 Collema crispum (L.) Wigg., 350 pulposum (Bernh.) Ach., 351 Collybia conigena (Pers.) Quelet, 396 eurhiza (Berk.) Hoehnel, 458 tuberosa (Bull, ex Fr.) Quelet, 457 velutipes (Curt, ex Fr.) Quelet, 457, 458 Colus Garciae M oiler, 505 Completoria complens Lohde, 121 Compso?nyces, 375 verticillatus Thaxter, 375 Conidiobolus, 94 utriculosus Brefeld, 120, 121 villosus Martin, 121 Conidiophore, 8 Conidium, 8 Coniocybe pallida (Pers.) Fr., 326 Coniophora cerebella Pers., 403, 406, 437 Coniothecium, 266 Conjugales, 93 Coprinaceae, 461-463 Coprinus atramentarius [Bull.] Fr., 461, 462 comatus [Battarra] Fr., 461, 463 ephemerus [Bull.] Fr., 461, 463 fimetarius [L.] Fr., 397, 399, 400, 401, 418 lagopus Fr., 399, 463 micaceus (Bull, ex Fr.) Fr., 399 narcoticus [Batsch] Fr., 399, 403 niveus [Pers.] Fr., 399, 463 nycthemerus [Bull.] Fr., 407 papillatus [Batsch] Fr., 399 radians (Desm.) Fr., 399 Rostrupianus Hansen, 399 Coprinus stercorarius [Bull.] Fr., 399, 461, 463 sterquilinus [Mich.] Fr., 399, 414, 461, 462 Cora pavonia Fr., 439, 440 Corallomyces Iatrophae Moller, 241 Cordyceps capitata [Holmsk.] Link, 189 militaris [L.] Link, 253, 254 norvegica Sopp, 253 ophioglossoides (Ehrh.) Link, 253 rhynchoticola Moller, 253 thyrsoides Moller, 254, 255 Volkiana Moller, 255 Core, 201 Coremiales, 615 Coremium, 8 Coreomyces Corisae Thaxter, 365 curvatus Thaxter, 366 Cornus alternifolia L. f ., 203 stolonifera Michaux, 194 Corticiaceae, 434-440 Corticium alutaceum (Schrad.) Bres., 437 bombycinum (Sommerf.) Bres., 397, 398, 403, 419, 437 botryosum Bres., 436 centrifugum (Lev.) Bres., 437 comedens (Nees) Fr., 433 coronilla Hoehnel, 438 effuscatum Cooke and Ellis, 438 javanicum Zimm., 436 Koleroga (Cooke) Hoehnel, 436 lacteum Fr., 437 niveocremeum Hoehnel and Litsch., 438 polygonium [Pers.] Fr., 399 radiosum Fr., 437, 438 roseo-pallens Burt, 404, 438 sahnonicolor Berk, and Broome, 436 Sambuci Pers., 396 seriale Fr., 408 serum (Pers.) Fr., 396, 400 Stevensii Burt, 436, 437 subgiganteum Berk., 438 terrestre (Kniep) Gaumann, 397 vagum Berk, and Curtis, 436 varians Kniep, 396, 402 Cortina, 452 Cortinarius, 459 largus [Buxbaum] Fr., 459 Corylus, 233 americana Walt., 163, 197 Avellana L., 198 INDEX 677 Coryne Cylichnium (Tulasne) Boudier, 319 prasinula Karsten, 319 sarcoides (Jacquin ex Fr.) Tulasne, 319 Corynelia, 264 Coryneliaceae, 264 Coryneum disciforme Nees ex Fr., 284 Corypha australis R. Br., 221 Crataegus monogyna Jacquin, 297 Oxyacantha L., 297 Craterellus clavatus (Pers. ex Fr.) Fr., 442 cornucopioides (L. ex Fr.) Pers., 533, 534 lutescens (Pers. ex Fr.) Fr., 533, 534 pistillaris Fr., 442 Craterocolla, 523 Crepis, 161 Cronartiaceae, 572-575 Cronartium, 564 asclepiadeum Fr., 592, 594 Comptoniae Arthur, 559 pyriforme (Peck) Hedgcock and Long, 559 ribicola Fischer de Waldheim, 554, 555, 558, 559, 562, 565, 572, 573, 580, 583, 594 Cruciate basidium, 415 Crucibulum vulgare Tulasne, 482, 483, 484 Cryptococcus, 149 Cryptomyces Pteridis (Rebent. ex Fr.) Rehm, 308, 309, 310, 311, 312 Crjrptomycetaceae, 308 Cryptoporus volvatus (Peck) Hubbard, 447 Cryptosphaeria, 281 Cryptospora, 284, 285 Cryptosporella, 284, 285 Cryptosporium, 285 Cryptovalsa, 280 Nitschkei Fuckel, 280 sparsa Ellis and Everhart, 280 Ctenomyces serratus Eidam, 169, 170 Cubonia brachyasca (Marchal) Sacc, 339 Cucumis, 113 Cucurbitaria Berberidis (Pers). S. F. Gray, 263 Labumi (Pers. ex Fr.) Cesati and Notaris, 263 Cucurbitariaceae, 263, 264 Cudonia lutea (Peck) Sacc, 327, 328 Cunninghamella, 113 Bertholletiae Stad., 101 echinulata Thaxter, 101 Cyathus fascicularis Schw., 482 hirsutus Schaeff., 467 olla [Batsch] Pers., 482 striatus [Hudson] Willd., 467, 484 Cyclomyces, 448 Cyclops, 14 Cycloschizon Alyxiae (Massee) Arnaud, 302 Cylindrocarpon candidum (Willk.) Wollenw., 237 Mali (All.) Wollenw., 237 Cylindrocystis Brebissonii Meneghini, 36 Cyphellaceae, 440, 441 Cystidium, 412 Cystobasidium Lasioboli Lagerheim, 545, 546 Cystopsora, 580 Cystosorus, 29 Cytidia, 440, 441 Cytospora, 285 Cyttaria Darwini Berk., 320 Gunnii Berk., 320 Harioti E. Fischer, 320 Hookeri Berk., 320 Cyttariaceae, 320 D Dacryomitra, 538 glossoides (Pers. ex Fr.) Brefeld, 535 Dacryomyces, deliquescens [Bull.] Duby, 535, 536, 537, 538 longisporus Brefeld, 538 ovisporus Brefeld, 537, 538 Dacryomycetaceae, 536-539 Dacryomycetales, 535-539 Daedalea quercina [L.] Pers. ex Fr., 448 unicolor [Bull.] Fr., 403, 409 Daldinia exsurgens (Mont.) Rehm, 287 Dangeardia mamillata Schroder, 40 Dasyscypha calycina (Schum. ex Fr.) Fuckel, 322 Willkommii Hartig, 322 Debaryomyces, 149 globosus Klocker, 151, 152 Kloeckerii Guill., 148, 151, 152 tyrocola Konokotina, 152 Delacroixia coronata Costantin, 121 Delastria rosea Tulasne, 362 Delicatula integrella (Pers. ex Fr.) Fayod, 458 Delitschia, 261 678 COMPARATIVE MORPHOLOGY OF FUNGI Dematieae, 617 Demaiium, 149 pullulans Bary, 269 Dematophora, 262 Dendrocalamus flagellifer Munro, 244 Dendrogaster cambodgensis Pat., 489 candidus (Harkness) Zeller and C. W. Dodge, 488 globosus (Harkness) Zeller and C. W. Dodge, 490 utriculatus (Harkness) Zeller and C. W. Dodge, 490 Dendrophysis, 441 Dermateaceae, 318 Dermatea carpinea (Pers.) Rehm, 318 Cerasi (Pers.) Notaris, 318 cinnamomea (Pers. ex Sacc.) Rehm, 318 Dermatella dissepta (Tulasne in Schlech- tendal) Sacc., 318 Dermopeltinaceae, 308 Deuterogamy, 12 Deuteromycetes, 11 Dianthus deltoides L., 600 Diaphoromyces Lispini Thaxter, 383 marginatus Thaxter, 383 Diaporthaceae, 281-286 Diaporthe Berlesiana Sacc. and Roume- guere, 282 leiphaemia (Fr.) Sacc, 282 obscura (Peck) Sacc, 283 oxyspora (Peck) Sacc, 282 perniciosa Marchal, 283 syngenesia (Fr.) Fuckel, 282 Wibbei Nitschke, var. Comptoniae (Ellis and Everhart) Wehmeyer, 284 Diatrypaceae, 277-281 Diatrype disciformis (Hoffm.) Fr., 278, 279 stigma (Hoffm.) Notaris, 278 tremellephora Ellis, 278 Diatrypella betulina Peck, 281 Frostii Peck, 281 quercina (Pers.) Nitschke, 281 Dichomyces biformis Thaxter, 372, 373 Diblepharis, 56 Dicaryon, 14 Dichaenaceae, 296 Dichonema sericeum (Sw.) Mont., 440 Dichotomosiphon, 91 Diclinous, 66 Dictyolaceae, 442 Dictyolus bryophilus (Pers. ex Fr.) Quelet, 442 glaucus (Batsch ex Fr.) Quelet, 442 ? umbonatus (Gmelin ex Fr.) Gaumann, 442 Dictyonema sericeum (Sw.) Berk., 440 Dictyophora indusiata (Ventenat ex Pers.) E. Fischer, 514, 616 phalloidea Desvaux, 516 Dictyuchus, 64, 66 monosporus Leitgeb, 66 Dicyma, 259 Didymella applanata (Niessl) Sacc, 221 cladophila (Niessl) Sacc, 221 moravica Petrak, 221 proximella (Karsten) Sacc, 221 Rehmii (J. Kunze) Sacc, 221 Didymosporeae, 617 Dielsiella Alyxiae (Massee) Theissen and Sydow, 302 Dilophia graminis (Fuckel) Sacc, 270 Dilophospora graminis Desm., 270 Dimeromyces, 385 adventitiosus Thaxter, 377 africanus Thaxter, 377 rhizosporus Thaxter, 388 Dimerosporium Veronicae (Libert) Arnaud, 305 Dimorphism, sexual, 11 Diospyros macrophylla Bl., 178 Diplanetism, 51 Diplocystis, 474 Diplont, 1 Diplophlyctis intestina (Schenk) Schroe- ter, 37, 38 Dipodascaceae, 137-139 Dipodascus albidus Lagerheim, 137, 138, 139 Discina, 345 Discula Platani (Peck) Sacc, 274, 276, 276 Disculina, 285 Dispira americana Thaxter, 109 Distichomyces, 378 Ditangium, 523, 525 Cerasi (Schum.) Gaumann, 524 Doassansia, 596, 599 Alismatis (Nees) Cornu, 607, 608 deformans Setchell, 607 Martianoffiana (Thiimen) Schroeter, 607 \ INDEX 679 Doassansia, punctiformis (Niessl) Schroeter, 607, 608 Sagittariae (Westendorp) Fisch, 607, 608, 609 Dothideaceae, 291-294 Dothideae, 291-293 Dothideales, 291-295 Dothidella Derridis (Hennings) Theissen, 293 Ulmi (Duval ex Fr.) Winter, 291 Dothiora, 215 Dothiorella, 218 Draparnaldia glomerata (Vaucher) Agardh, 41 Drepanopeziza Ribis Klebahn, 321 E Ecchyna faginea Fr., 551 Petersii (Berk, and Curtis) Boudier, 551 Echinochloa, 246 Echinodontium iinctorium Ellis and Ever- hart, 445 Echinophallus Lauterbachii Hennings, 514, 515 Ectrogella Bacillariacearum Zopf, 60 Dicksonii (Wright) Scherffel, 60 Licmophorae Scherffel, 59, 60 monostoma, Scherffel, 60 Egg, 11 Eichhornia crassipes Solms-Laubach, 431 speciosa Kunth, 431 Eichleriella spinulosa (Berk, and Curtis) Burt, 523 Elaphomyces, as host, 253 cervinus (L. ex S. F. Gray) Schelch- tendal, 188 granulatus [Alb. and Schw.] Fr., 188 muricatus Fr., 189; as host, 253 variegatus Vittadini, 189 Elaphomycetaceae, 188-189 Elaphomyceteae, 188 Elasmomyces krjukowensis (Bucholtz) Sacc. and D. Sacc, 487 Empusa Fresenii Nowakowski, 122 Grylli (Fres.) Thaxter, 123 Muscae Cohn, 121 Enarthiromyces indicus Thaxter, 374 Endogonaceae, 113-117 Endogone fasciculata Thaxter, 114, 116 incrassata Thaxter, 115 lactiflua Berk., 114, 116, 116 Endogone Ludwigii Bucholtz, 116 macrocarpa Tulasne, 116 malleola Harkness, 114 microcarpa Tulasne, 116 pisiformis Link, 116 reniformis Bres., 114 sphagnophila Atkinson, 116 Endogonella borneensis Hoehnel, 116 Endomyces capsularis (Schionn.) Guill., 143 decipiens (Tulasne) Reess, 142, 145 fibuliger Lindner, 141, 142, 143 Hordei Saito, 142 javanensis Klocker, 143 Lindneri Saito, 142, 143 Magnusii Ludw., 143, 144 Endomycetaceae, 139-148 Endomycetales, 137-158 Endophyllum, 575 Centranthi-rubri Poir., 560 Euphorbiae-silvaticae (DC.) Winter, 560, 561, 569, 581, 593 Sempervivi (Alb. and Schw.) Bary, 555, 558, 560, 563, 568, 581, 584 Valerianae-tuberosae R. Maire, 582 Endoptychum agaricoides Czernaiev, 494 Endosporella Diopsidis Thaxter, 390 Endothia gyrosa (Schw.) Fr., 286 parasitica (Murrill) Anderson, 135, 285, 286 singularis (H. and P. Sydow) Shear and Stevens, 286 Englerula Macarangae Hennings, 211 Englerulaceae, 211 Entoloma flavifolium Peck, 457 Entomopeziza Mespili (DC.) Hoehnel, 322 Soraueri Klebahn, 322 Entomophthora americana (Thaxter) Sacc, 123, 124 Culicis (A. Braun) Fres., 123, 124 Delpiniana Cavara, 123, 124 echinospora (Thaxter) Sacc, 124, 125 Fresenii (Nowakowski) Riddle, 122 geometralis (Thaxter) Sacc, 123, 124 Grylli Fres., 122, 123 Muscae (Cohn) Fres., 121, 122 occidentalis (Thaxter) Sacc, 124 radicans Brefeld, 123 rhizospora (Thaxter) Sacc, 125 Sciarae (Olive) Gaumann, 123, 124 sepulchralis (Thaxter) Sacc, 124, 125 sphaerosperma Fres., 123, 124 680 COMPARATIVE MORPHOLOGY OF FUNGI Entomophthoraceae, 117-125 Entomophthoreae, 120-125 Enlomosporium Mespili (DC.) Sacc, 322 Entonaema liquescens Moller, 228 mesenterica Moller, 228 Entophlyclis bulligera (Zopf) A. Fischer, 40 Cienkowskianum (Zopf) A. Fischer, 40 Entyloma, 596, 597, 599, 608 Glauci Dangeard, 598 Nympheae (D. D. Cunn.) Setchell, 596, 598 Eocronartium muscicola (Pers. ex Fr.) Fitzpatrick, 541, 542 Epibasidium, 415 Epichloe Bambusae Patouillard, 244 typhina (Pers. ex Fr.) Tulasne, 244 Epilobium, 23 Epiplasm, 131 Epithecium, 316 Epiihele Typhae (Pers. ex Fr.) Pat., 437 Eremascus albus Eidam, 140, 141 fertilis Stoppel, 139, 140, 141 Ergot, 248 Erysiphaceae, 192-204 Erysiphe, 200, 201, 202 Cichoracearum DC, 132, 195, 197, 198 communis Wallroth, 197, 200 graminis DC, 194, 197 Martii Lev., 198, 200 Polygoni DC ex S. F. Gray, 193, 197, 198, 200 Erythronium americanum Ker., 599 Euascomycetes, 166-395 Eucantharomyces, 386 Eucarpy, 7 Euglena, 41, 42 Eumycetes, 15 Euphorbia, 568 Eurychasma Dicksonii (Wright) Magnus, 60 Eurytheca, 215 Eusclerotinia, 322 Eusynchytrium (subgenus), 20 Euterpe oleracea Martius, 550 Eutuber, 357 Eutypa Acharii Tulasne, 277 lata (Pers.) Tulasne, 277 spinosa (Pers.) Tulasne, 277 tumida (Ellis and Everhart) Weh- meyer, 281 Eu-ustilago, 610 Exciple, 316 Exciplulaceae, 615, 617 Exidia, 523 repanda Fr., 524 saccharina Fr., var. foliacea (Brefeld) Bres., 524 Exidiopsis ciliata Moller, 521 cffiusa Brefeld, 521 Exoascus, 164 Betulae Fuckel, 163 Crataegi (Fuckel) Sadebeck, 163 Exobasidiaceae, 530-532 Exobasidium, 435 discoideum Ellis, 413, 532 Rhododendri Cramer, 413, 532 Vaccinii (Fuckel) Woronin, 530, 531 F Fabraea Fragariae Klebahn, 316, 322 maculata (Lev.) Atkinson, 322 Ranunculi (Fr.) Karsten, 322 Fairy ring, 407 Favolus europaeus [DC] Fr., 448 Fertilization, 11 Ficus Carica L., 270 Fimetaria fiynicola (Roberge) Griffiths and Seaver, 258 merdaria (Fr.) Gaumann, 258 Fislulina hepatica [Schaeffer] Fr., 403, 449 Fistulinaceae, 449, 450 Fomes annosus (Fr.) Cooke, 446 applanatus (Pers. ex Fr.) Gillet, 411 fomentarius (L. ex Fr.) Gillet, 447 igniarius (L. ex Fr.) Gillet, 411, 447 officinalis (Vill. ex Fr.) Lloyd, 447 Ribis (Schum. ex Fr.) Cooke, 447 Fraxinus americana L., 197 Fructification, 7 Fumago salicina (Pers.) Tulasne, 265 Fungi Imperfecti, 614-618 Furrowing, 3 Fusarium candidum (Link) Sacc, 237 didymum Hart., 235, 236 discolor Appel and Wollenw., 235, 236 gibbosum Appel and Wollenw., 235, 236 Mali Allescher, 237 nivale Cesati, 237 orthoceras Appel and Wollenw., 233 Solani (Mart.) Appel and Wollenw., 235, 236 INDEX 681 Fusarium subulatum Appel and Wollenw., 235, 236 Willkommii Lind, 235, 236 Fusicladium dendriticum (Wallroth) Fuckel, 269, 270 Fusicoccum, 285 veronense, Massalongo, 274 G Galactinia saniosa (Schrad. ex Fr.) Sacc, 345 succosa (Berk.) Sacc, 131 Galium rubioides L., 312 Gallacea Scleroderma (Cooke) Lloyd, 491 Gallowaya pinicola Arthur, 555, 568, 570, 585 Gametangial copulation, 12 in Phy corny cetes, 31 Gametangium, 11 Gamete, 11 Gametophyte, 2 Gardenia, 206 Gasteromy cetes, 467-519 Gautieria graveolens Vittadini, 490 Parksiana Zeller and C. W. Dodge, 490 plumbea Zeller and C. W. Dodge, 491 Rodwayi (Massee) Zeller and C. W. Dodge, 490 Geaster coronatus [Schaeffer] Schroeter, 476, 478 fimbriatus Fr., 467 hygrometricus Pers., 475 marchicus Hennings, 476 velutinus Morgan, 475 Gemma, 3, 8 Genabea fragilis Tulasne, 361 Genea cerebriformis (Harkness) Gilkey, 360, 361 Gardnerii Gilkey, 361 Harknessii Gilky, 361 Thwaitesii (Berk, and Broome) Petch, 359, 360 Vallisumbrosae Bucholtz, 360, 361 Generations, alternation of, 2 Geoglossaceae, 325-329 Geoglossum difforme Fr., 326 glabrum Pers., 327 glutinosum Pers., 326 Geolegnia, 66 Geopora, 346 Geopyxis Catinus (Holmsk. ex Fr.) Sacc, 130, 131 Geranium maculatum L., 193 Robertianum L., 298 Gibberella Saubinetii (Dur. and Mont.) Sacc, 233, 237 Gigantochloa apus Kurz, 244 Glaziella, 114, 116, 117 aurantiaca (Berk, and Curtis) Cooke, 114, 116 vesiculosa Berk., 116 Gleba, 408, 467 Gloeocystidium, 412 clavuligerum Hoehnel and Litsch., 437 polygonium (Pers.) Hoehnel and Litsch., 399 Gloeoglossum difforme (Fr.) Durand, 326 glutinosum (Pers.) Durand, 326, 327 Gloeosporium fructigenum Berk., 277 nervisequum (Fuckel) Sacc, 274, 275 Platani (Lev.) Oudemans, 274 Ribis (Libert) Mont, and Desm., 321 venetum Speg., 215 Gloeotulasnella, 431 Glomerella cingulata (Stoneman) Spauld- ing and Schrenk, 277 rufomaculans (Berk.) Spaulding and Schrenk, 277 Glyceria, 603 fluitans R. Br., 252 Gnomonia erythrostoma (Pers.) Auerswald, 276 leptostyla (Fr.) Cesati and Notaris, 276 veneta (Sacc and Speg.) Klebahn, 274, 275, 276 Gnomoniaceae, 274-277 Godfrinia conica (Scop, ex Fr.) Maire, 456 Gomphidius, 456 Gonapodya, 54 polymorpha Thaxter, 58 siliquiformis (Reinsch) Thaxter, 57, 58 Gonotocont, 1 Goplana mirabilis Rac, 553, 569 Gossypium, 113 Grandinia crustosa [Pers.] Fr., 443 Graphiola Phoenicis (Mougeot) Poit., 608, 609 Graphiolaceae, 608-609 Graphis scripta (L.) Ach., 297 Graphium, 259 Guadua Tagoara Kunth, 243 682 COMPARATIVE MORPHOLOGY OF FUNGI Guepinia, 538 femsjoeniana Olsen, 635 Guignardia Aesculi (Peck) Stewart, 270 Bidwellii (Ell.) Viala and Ravaz, 269 Guillermondia, 152 Gymnoascaceae, 168-170 Gymnoascus candidus Eidam, 169 Reessii Baranetzky, 168, 169 setosus Eidam, 169 uncinatus Eidam, 169 Gymnocarpous, 410 Gymnoconia, 577 interstitialis (Schlecht.) Lagerheim, 563 Peckiana (Howe) Trotter, 556, 563, 578, 593 Rosae (Barclay) Liro, 555 Gymnomyces Gardneri Zeller and C. W. Dodge, 485 Stillingeri (Lloyd) Zeller and C. W. Dodge, 485 Gymnosporangium, 575, 576, 577, 583 Blasdaleanum (Dietel and Holway) Kern, 595 clavariaeforme (Jacquin) DC., 554, 581 globosum Farlow, 595 juniperinum [L.] Martius, 560, 561 myricatum (Schw.) Fromme, 562 Sabinae (Dickson) Winter, 595 Gynophore, 336 Gyrinidae, 364 Gyrinus, 375 Gyrocephalus, 523 Gyromitra curtipes Fr., 349 esculenta (Pers. ex Fr.) Fr., 348 infula (Schaeffer ex Fr.) Quelet, 347, 348 Gyrophana lacrymans (Wulfen ex Fr.) Pat., 443 H Hainesia Lythri (Desm.) Hoehnel, 322 Haplomyces, 386 Haplont, 1 Haplosporangium, 94, 113 bisporale Thaxter, 107 Harpochytrium Hedenii Wille, 40 Hyalothecae Lagerheim, 39 Haustorium, 5 Helicobasidium orthobasidion (Moller) Pat., 540 purpureum (Tulasne) Pat., 540 Helminthosporium, 221 Helotiaceae, 322-325 Helvella crispa [Scopoli] Fr., 347 elastica Bull, ex Fr., 347 Ephippium Lev., 347 infula Schaeffer ex Fr., 348 lacunosa Afzel ex Fr., 347 Helvellaceae, 346-350 Hemiangiocarpous, 410 Hemiascomycetes, 137-165 Hemigaster candidus Juel, 466 Hemihysteriaceae, 301 Hemileia, 566, 577 vastatrix Berk, and Broome, 578, 595 Hemisphaeriales, 298-307 Hemi-ustilago, 610 Hendersonia foliorum Fuckel, 270 Heracleum, 161 Hericium caput-ursi (Fr.) Banker, 445 coralloides (Scopoli ex Fr.) Pers., 445 Herpomyces, 374 Periplanetae Thaxter, 375 Heterobasidiae, 418 Heterobasidion annosum (Fr.) Brefeld, 446 Heterochaete Sanctae-Catharinae Moller, 521 Heteroecious, 563 Heterogamy, 11 Heterothaliism, 11, 108, 227, 399 Hevea, 89, 238, 287 Hibiscus, 113 Hieracium, 268 Hirsutella varians (Boul.) Pat., 435, 436 Histiomycetes, 616 Hoehneliomyces delectans (Moller) Weese, 549, 550, 551 javanicus Weese, 551 Holocarpy, 7 Holocoryne, sect. Clavaria, 442 Hologamy, 12, 14 Homobasidiae, 418 Homothallism, 11 Horde um, 223 Hormotheca Robertiani (Fr.) Hoehnel, 298 Humaria anceps Rehm, var. aurantiaca Delitsch, 344 carbonigena (Berk.) Sacc, 344 convexula (Pers. ex Fr.) Quelet, 135 gramdata (Bull, ex Fr.) Quelet, 344, 345 Roumegueri (Karsten) Sacc, 344 INDEX 683 Humaria rutilans (Fr.) Sacc, 344 theleboloides (Alb. and Schw. ex Fr.) Rehm, 344 Humulus, 197 Hutchinsia, 23 Hyalodidymeae, 617 Hyalopsora, 564, 572 Hyaloria Pilacre M oiler, 627 Hyaloriaceae, 526, 527 Hyalosporeae, 617 Hydnangiaceae, 485-488 Hydnangium carneum Wallroth, 487 citrinum (Harkness) Zeller and C. W. Dodge, 485 Fitzpatrickii Zeller and C. W. Dodge, 485 pusillum Harkness, 486 sociale (Harkness) Zeller and C. W. Dodge, 486 Stephensii Berk, and Broome, 487 Hydnellum, 445 Hydnobolites, 354 Hydnochaete, 442 Hydnocystis Thwaitesii Berk. and Broome, 359 Hydnodon, 445 Hydnopsis, 443 Hydnotrya, 354, 355 Tulasnei Berk, and Broom?, 355 Hydnum coralloides Scopoli ex Fr., 445 omnivorum Shear, 443 repandum L. ex Fr., 533, 534 Hygrocybe conica (Scopoli ex Fr.) Karsten, 456 constans Lange, 456 miniata (Fr.) Karsten, 446 nigrescens (Quelet) Kuhner, 456 nitida (Berk, and Curtis) Murrill, 456 Hygrophoraceae, 456, 457 Hygrophorus agathosmus Fr., 456 borealis Peck, 456 conicus [Scopoli] Fr., 201, 456 constans Lange, 456 Karstenii Sacc. and Cuboni, 456 Langei C. W. Dodge, 456 miniatus Fr., 451, 456 nigrescens Quelet, 456 nitidus Berk, and Curtis, 456 olivaceoalbus Fr., 456 virgineus [Wulfen] Fr., 457 Hymenium, 10 Hymenochaete, 438 noxia Berk., 439 tenuis Peck, 437 Hymenogaster Barnardi Rodway, 488 Behrii Harkness, 488 caerulescens Soehner, 491 fragilis Zeller and C. W. Dodge, 488 globosus Harkness, 490 lilacinus Tulasne, 488 luleus Vittadini, 488 populetorum Tulasne, 488 Rehsteineri Bucholtz, 489, 491 tener Berk., 488, 489 verrucosus Bucholtz, 491 violaceus Massee and Rodway, 487 Hymenogasteraceae, 488-491 Hypericum, 23 Hyphal bodies, 121 Hyphales, 615 Hyphopodia, 206 capitate, 209 mucronate, 209 Hypholoma, 459, 460 perplexum, Peck, 397 sublateritium (Schaeffer ex Fr.) Quelet, 411 Hyphomycetes, 614, 616 Hypobasidium, 415 Hypochnus, 434 isabellinus Fr., 436 ochroleucus Noack, apud Sacc, 436 subtilis Harper non Schroeter, 437 Hypocrea alutacea [Pers. ex Fr.] Tulasne, 240 citrina [Pers.] Fr., 239 cornu-damae, Pat., 240 delicatula Tulasne, 238, 239 parmelioides Mont., 239 pezizoidea M oiler, 240 poronioidea M oiler, 240 rufa [Pers.] Fr., 239 Hypocreales, 225-256 Hypocrella cavernosa Moller, 243 Gaertneriana Moller, 243 verruculosa Moller, 243 Hypocreopsis lichenoides (Tode ex Fr.) Seaver, 239 parmeloiodes (Mont.) Thaxter, 239 riccioidea (Bolton) Karsten, 239 Rhododendri Thaxter, 239 Hypoderma, 296 deformans Weir, 297 684 COMPARATIVE MORPHOLOGY OF FUNGI Hypodermataceae, 296 H ypodermatella, 296 Laricis Tubeuf, 297 sulcigena (Link) Tubeuf, 297 Hypogyny, 66 Hypomyces, 237 aurantius (Pers. ex Fr.) Tulasne, 238 chrysospermus (Bull, ex Fr.) Tulasne, 238 ochraceus [Pers.] Tulasne, 238 rosellus (Alb. and Schw. ex Fr.) Tulasne, 238 Hypostomaceae, 612 Hypostomum Flichianum Vuill., 612 Hypostroma, 293 Hypothecium, 316 Hypoxylon coccineum Bull, ex Tulasne, 287 fuscum (Pers. ex Fr.) Fr., 287 unitum (Fr.) Nitschke, 287 Hysterangiaceae, 491-497 Hysterangium clathroides Vittadini, 492, 493 Fischeri Zeller and C. W. Dodge, 496 fuscum Harkness, 495 Gardneri Fischer, 495 inflatum Rodway, 492 nephritictim Berk., 492 stoloniferum Tulasne, var. americanum Fitzpatrick, 493 Hysteriaceae, 296 Hysteriales, 296-297 Hysterogaster fusisporum (Massee and Rodway) Zeller and C. W. Dodge, 488 luteus (Vitt.) Zeller and C. W. Dodge, 488 Hysterostomella discoidea (Rac.) Arnaud, 301, 302 Hysterothecium, 296 Icmadophila aeruginosa (Scopoli) Trev., 352 ericetorum (L.) Zahlbr., 352 Idiomyces, 375 Ilex aquifolium L., 233 Ilytheomyces, 384 Imperfect form, 10 fungi, 614-618 Indigofera arrecta Hochst. ex Rich., 88 Inocybe, 459 Inoperculatae, 317 Iola Hookeriarum Moller, 544, 545 javanensis Pat., 544, 545 Irenina obesa (Speg.) Stevens, 208 Iris pseudacorus L., 46 Irpex, 443 Isaria, 177, 252 farinosa [Holmsk.] Fr., 253 Isoachlya, 69 paradoxa (Coker) Kauffman, 69 Isogamy, 11 Isokonteae, origin of Chytridiales from, 34 Ithyphallus impudicus [L.] Fr., 514 tenuis E. Fischer, 513 Ixocomus flavus (With.) Quelet, 464 J aczewskia, 492 Jaraia Salicis Nemec, 59 Jatropha Aipi Moller, 240 K Kainomyces Isomali Thaxter, 372 Kalchbrennera corallocephala (Welwitsch and Currey) Kalchbr., 505, 507 Tuckii Berk., 505 Kames, 187 Kernel, 201 Kneiffia, 443 Aegerita (Hoffm.) Herter, 437 coronilla (Hoehnel) Gaumann, 438 corticalis (Bull, ex Fr.), Bres., 530 gigantea (Fr.) Bres., 396 Konradia bambusina Rac, 242 Kordyana Polliae Gaumann, 530, 531 Kuehneola, 577 albida (Kiihn) P. Magnus, 566, 567, 578 Kunkelia, 575, 593 nitens (Schw.) Arthur, 563, 593 Kusanoopsis guianensis Stevens and Weedon, 212, 213 Laboulbenia chaetophora Thaxter, 370, 375, 376 elongata Thaxter, 373, 392 Gyrinidarum Thaxter, 370, 375, 376 INDEX 685 Laboulbeniaceae, 367-377 Laboubeniales, 364-395 Laburnum, 263 Laccaria laccata (Scopoli ex Fr.) Berk. and Broome, 457 Laccophilus, 364 Lachnea abundans Karsten, 338, 344 cretea (Cooke) Philips, 338 scutellata (L. ex Fr.) Gillet, 343, 344 stercorea (Pers.) Gillet, 343 Lachnocladium, 442 Lactariaceae, 460 Lactarius deliciosus [L.] Fr., 461 host, 227 rufus [Scopoli] Fr., 460 sanguifluus Fr., 461 Lagenidium americanum Atk., 62 pygmaeum Zopf, 62 Rabenhorstii Zopf, 62 Lamella, 454 Lanomyces tjibodensis Gaumann, 205 Larix, 572 Lasiobolus, 545 brachyascus Marchal, 339 pulcherrimus (Crouan) Schroeter, 338, 342 Latex organs, 408 Laudatea caespitosa Johow, 440 Laurus, 265 Ledum palustre L., 322, 324 Lemanea, 223 Lembosia Bromeliacearum Rehm, 304 Lemna, host of Reessia, 20 Lentinus, 458 Lenzites abietina [Bull.] Fr., 403, 406, 448 sepiaria [Wulfen] Fr., 409, 448 Leontodon, 23 Leotia gelatinosa Hill, 328 lubrica [Scopoli] Pers., 328 Lepidium, 88 Lepiota, 459, 460 meleagris (Sow.) Quelet, 406 rhacodes (Vitt.) Quelet, 403 Leptolegnia, 64 Leptomitaceae, 70-73 Leptomitus, 54 lacteus (Roth) Agardh, 70 Leptopeltinaceae, 308 Leptosphaeria acuta (Mougeot and Nestler) Karsten, 135, 222 avenaria Weber, 223 caespitosa Niessl, 222 Leptosphaeria doliolum (Pers.) Cesati and Notaris, 222 herpotrichoides Notaris, 222 Lemaneae (Cohn and Wor.) Sacc, 223 salebrosa (Preuss) Winter, 222 Leptostroma, 297 Leptostromataceae, 615, 617 Leptothyrium Juglandis Libert, 276 macrothecium Fuckel, 322 Lespedeza cytisoides Bentham in Miq., 23 Leucogaster araneosus Zeller and C. W. Dodge, 470 citrinus (Harkness) Zeller and C. W. Dodge, 470 foveolatus (Harkness) Zeller and C. W. Dodge, 470 fioccosus Hesse, 470 luteomaculatus Zeller and C. W. Dodge, 470 odoratus (Harkness) Zeller and C. W. Dodge, 470 rubescens Zeller and C. W. Dodge, 470 Leucopaxillus paradoxus (Cost, and Duf.) Boursier, 458 Leucophlebs, 467, 615 Leucostoma Persoonii (Nitschke) Weh- meyer, 285 subclypeata (Cooke and Peck) Weh- meyer, 285 Leveillelleae, 393 Leveillula taurica (Lev.) Arnaud, 193, 195, 196, 197, 202 Ligniera, 25 Limacella, 459 Limacinia Citri (Briosi and Pass.) Sacc, 265 spongiosa Arnaud, 265, 267 Limacium agathosmum (Fr.) Schroeter, 456 Karsteni (Sacc. and Cuboni) Kuehner, 456 olivaceoalbum (Fr.) Schroeter, 456 Livistona australis Mart., 221 Lophodermium hysterioides [Pers.] Sacc, 297 laricinum Duby, 297 macrosporum (Hartig) Rehm, 297 nervisequum (DC.) Rehm, 297 pinastri (Schrad.) Chev., 296, 297 Loranthomyces, 307 Lotus corniculatus L., 50 Lycogalopsis Solmsii E. Fischer, 486 686 COMPARATIVE MORPHOLOGY OF FUNGI Lycoperdaceae, 472-479 Lycoperdon depressum Bon., 467, 473 excipuliforme Scopoli ex Pers., 467 gemmatum Batsch ex Fr., 473, 474 pyriforme Schaeffer ex Pers., 403 Lysimachia nummularia L., 22 Lysurus borealis (Burt) Hennings, 507 Mokusin (L. ex Pers.) Fr., 505, 506 M Maccagna camica Mattirolo, 487 tasmanica (Kalchbr.) Zeller and C. W. Dodge, 487 Macowanites, 488 Macrochytrium botrydioides Minden, 45 Macrophoma, 218 Macropodia, 346 Macrosporium, 221 Magnusia nitida Sacc, 173 Magnusiella, subg. Taphrina, 163, 164 Mamianella, 284 Manihot, 241 Marasmius oreades (Bolton) Fr., 458 perniciosus Stahel, 458 plicatus Wakker, 458 Sacchari Wakker, 458 Marssonina Fragariae Sacc, 322 Juglandis (Libert) Sacc, 276 Matruchotia varians Boul., 436 Maurodothis Alyxiae (Massee) Sacc. and Sydow, 302 Mazzantia Gallii (Fr.) Mont., 284 Medeolaria Farlowi Thaxter, 330 Medicago saliva L., 49 Megalonectria, 238 verrucosa M oiler, 238 Meiosis, 11 Melampsora, 572 Helioscopiae Winter, 570 Lini (Ehrenb.) Lev., 536 pinitorqua Rostrup, 594 reticulata Blytt, 556 Rostrupi Wagner, 556 Melampsoraceae, 571-572 Melampsorella, 564, 571, 572 Caryophyllacearum (Link) Schroeter, 595 elatina Arthur, 595 Melampsoropsis, 564 Melampyrum, 198 Melanconiales, 614 Melanconis stilbostoma (Fr.) Tulasne, 282, 283 Melanconium bicolor Nees ex Fr., 283 Melandryum, 597 Melanogaster variegatus (Vitt.) Tulasne, 469 Melanops Quercuum (Schw.) Rehm, 217 Melanospora, 225 bulbillifera (Berl.) Gaumann, 226 destruens (Shear) Shear and B. O. Dodge, 226 erythraea Moller, 226 globosa Berlese, 226 Mangini Vincens, 226 marchica Lindau, 226 parasitica Tulasne, 226 Zobelii (Corda) Fuckel, 226 Meliola Camelliae (Catt.) Sacc, 207 corallina Mont., 208 Evodiae Pat., 208 obesa Speg., 208 Penzigii Sacc, 207 Meliosma, 553, 569 Mellilotus, 197 Meria Laricis Vuill., 612 Meristogenous pycnia, 8 Merogamy, 11, 14 Merostachys speciosa Spr., 242, 243 Meridius domesticus Falck, 443 lachrymans [Wulfen] Schum. ex Fr., 403, 404, 405, 443, 444 pinastri (Fr.) Burt, 443 rubellus Peck, 444 tremellosus Schrader ex Fr., 444 Mesocarpus, 62 Mesochytrium (subgenus), 20 Mesophellia arenaria Berk., 189 castanea Lloyd, 188, 189 sabulosa (Cooke and Massee) Lloyd, 189 Mesophellieae, 188-189 Mesospore, 575 M etasporangium, sect. Pythium, 75, 88 Metula, 176 Michenera Artocreas Berk, and Curtis, 438 Microglossum viride (Pers ex Fr.) Gillet, 327 Micromyces, 24 Microsphaera, 202, 203 Alni (Walk.) Winter, 203 var. Lonicerae (Schlecht. ex Fr.) Salmon, 203 alphitoides Gr. and Maublanc, 204 INDEX 687 Microsporum, 170 Microthyriaceae, 303-307 Microthyrieae, 304 Milesina, 564, 572 Milium effusum L., 251 Mindeniella spinospora Kanouse, 58 Mitremyces lutescens Schw., 478 Wallisii Fischer, 478 Mitrula paludosa Fr., 327 phalloides [Bull.] Chev., 327 Mollisiaceae, 321, 322 Monadineae, origin of Chytridiales from, 34 Monascus Barkeri Dangeard, 172 purpureus Went, 172 Monilia, 149, 323, 324 Candida Bonorden, 4 sitophila (Mont.) Sacc., 226 Monoblepharidaceae, 54-56 Monoblepharis brachyandra Lagerheim, 55, 56 insignis Thaxter, 55, 56 macrandra (Lagerheim) Woronin, 55, 56 var. longicollis Lagerheim, 56 polymorpha Cornu, 56 sphaerica Cornu, 55, 56 Monochytrium Stevensianum Griggs, 20 Montagnellaceae, 295 Morchella esculenta [L.] Pers. ex. Fr., 348, 349, 350 rimosipes DC. ex Fr., 348, 349 Morpho, host, 252 Mortierella, 94, 98, 113 Bainieri Costantin, 95, 113 reticulata Tieghem and Lemonnier, 95 Roslafmskii Brefeld, 98 Mortierelleae, 98 Moschornyces, 368, 375 insignis Thaxter, 388 Mucedineae, 617 Mucor, 100, 101, 113 corymbifer Cohn, 94 erectus Bainier, 108 flavus Bainier, 94 javanicus Wehmer, 94 Mucedo L., 8, 94, 102, 108, 109, 112 pusillus Lindt, 94 racemosus Fresenius, 94, 95 Rammannianus Moller, 94 sphaerosporus Hagem, 94, 97 strictus Hagem, 94 Mucor, sylvaticus Hagem, 94 tenuis Bainier, 108 Mucoreae, 113 Mucronella, 443 Munkielleae, 301 Muscardine, 253 Mutinies bambusinus (Zoll.) E. Fischer, 513 caninus (Hudson ex Pers.) Fr., 511, 512, 513 Muelleri E. Fischer, 512 Mycelium, 3 Mycena codoniceps Cooke, 457 galericulata (Scopoli ex Fr.) Qu61et, 458 pterigena (Fr.) Quelet, 457 sanguinolenta (Alb. and Schw. ex Fr.) Quelet, 457 subalcalina Atk., 457 Mycobacterium tuberculosis (Koch) Leh- mann and Neumann, 175 Mycobonia, 437 Mycocitrus aurantium Moller, 241, 242 Mycoderma, 149 Mycogalopsis retinospora Gjurasin, 331 Mycogone, 237 puccinioides (Preuss) Sacc, 238 rosea Link, 238 Mycomalus bambusinus Moller, 243 Mycosphaerella Bolleana Higgins, 270 cerasella Aderhold, 269 Fragariae (Tulasne) Lindau, 268 Hieracii (Sacc. and Briard) Jaap, 268 Hippocastani (Jaap) Klebahn, 268 millegrana (Cooke) Schroeter, 269 nigerristigma Higgins, 270 pinodes (Berk, and Bloxam) Stone, 269 punctiformis (Pers. ex Fr.) Schroeter, 268 sentina (Fr.) Schroeter, 268 tabifica (Prilleux and Delacroix) Johns, 269 Mycosphaerellaceae, 267 Myosotis, 23 Myriangiaceae, 212-214 Myriangiales, 212-224 Myriangium Duriaei Mont, and Berk., 213, 214 Pritzelianum Hennings, 214 Thwaitesii Petch, 214 Myrica asplenifolia L., 284 Myrioblepharis, 56, 90 688 COMPARATIVE MORPHOLOGY OF FUNGI Myrmecocystis cerebrijormis Harkness, 360 V allisumbrosae (Bucholtz) E. Fischer, 360 Myxochytridiales, 17 Myxoderma, 459 Myxomycetes, 15 Myxosporium valsoideum (Sacc.) Alles- cher, 274 Myzocytium, 60 proliferum Schenk, 61 vermicolum (Zopf) A. Fischer, 61 N Nadsonia, 149 elongata Konokotina, 152 fulvescens (Nadson and Konokotina) Sydow, 152 Nectria cinnabarina (Tode) Fr., 234, 237 Coryli Fuckel, 233 curcurbitula Fr., 237 ditissima Tulasne, 234 galligena Bres., 236, 237 inaurata Berk, and Broome, 233, 234 Ipomoeae Halst, 233, 236 oropensoides Rehm, 234, 235 Peziza [Tode] Fr., 235 Ribis (Tode ex Fr.) Oudemans, 236 sinopica Fr., 233, 234, 235 Nectrioideae, 617 Nematospora, 149 Nematosporangium, subg. Pythium, 75, 88 Neobarclaya flagellifera (Ellis and Ever- hart) Sacc, 284 Neocosmospora, 226 vasinfecta E. F. Smith, 227 Neovossia, 598, 599 Moliniae (Thiimen )Korn., 598, 606 Nerium, 265 Neurophyllum clavatum (Pers. ex Fr.) Pat., 442, 456 pistillaris (Fr.) Pat., 442 Neurospora, 226 crassa Shear and B. O. Dodge, 227 erythraea (M oiler) Shear and B. O. Dodge, 226, 227 sitophila (Mont.) Shear and B. O. Dodge, 226, 227 tetrasperma Shear and B. O. Dodge, 227 Nidularia farcta (Roth ex Pers.) Fr., 467 globosa Ehrhart ex Sprengel, 467 pisiformis (Roth) Tulasne, 467, 482, 483, 485 Nidulariaceae, 482-485 Nitschkia cupularis (Pers. ex Fr.) Karsten, 264 Nolhofagus Cunninghami Oersted, 320 Nowakowskiella ramosa Butler, 46, 47 "Nucleus," 201 Nummularia Bulliardi Tulasne, 286 Nyctalis asterophora Fr., 457 lycoperdoides [Bull.] Schroeter, 457 parasitica [Bull.] Fr., 457 Nycteromyces streblidinus Thaxter, 385, 386 O Ochropsora, 580 Ariae (Fuckel) Sydow, 568 Octaviania, 486 Odontia crustosa Pers. ex Quelet, 443 Oedocephalum, 438, 614 Oedogonium, 40, 90 Oidiopsis, 197 taurica Lev., 193 Oidium, 7 Oidium, 197 quercinum Thiimen, 204 Tuckeri Berk., 204 Olpidiaceae, 17-20 Olpidiaster radicis (Wildeman) Pascher, 19 Olpidiopsis Saprolegniae (Cornu) A. Fischer, 26 Olpidium Brassicae (Woronin) Dan- geard, 19 Salicomiae Nemec, 19 Viciae Kusano, 18 Olyra, 246 Omphalia chrysophylla (Fr.) Karsten, 457 integrella (Pers. ex Fr.) Quelet, 458 Onobrychis sativa Lam., 325 Onygena equina [Willd.] Pers. ex S. F. Gray, 186, 187 Onygenaceae, 186, 187 Oogonium, 12 Oomyces javanicus Hoehnel, 242 monocarpus Moller, 242, 245 Oomycetes, 51-91 phylogeny, 53 INDEX 689 Oosphere, 52, 68, 69 Oospora, 226 Oospore, 52 Operculatae, 317 Ophiobolus cariceti (Berk, and Broome) Sacc, 276 graminis Sacc, 276 herpotrichus (Ft.) Sacc, 276 Ophiodotis Henningsiana Moller, 244, 245 raphidospora Rehm, 244, 245 Orbilia rubella (Pers.) Karsten, 524 Orthosporangium, sect. Pythium, 75, 88 Ostropaceae, 296 Otidea aurantia (Pers. ex S. F. Gray) Massee, 334 Ovulariopsis, 197 Ozonium omnivorum Shear, 443 Pachyphloeus, 356 luteus (Hesse) E. Fischer, 357 melanoxanthus (Berk.) Tulasne, 357 Paeonia, 592 Panaeolus, 459 campanulatus (L. ex Fr.) Quelet, 399, 400, 407 fimicola (Buxbaum ex Fr.) Quelet, 400 separatus (L. ex Fr.) Bigeard, 399 Pandorina morum (Mull.) Bory, 40 Panicum, 246 Crus-ardeae (Willd. ex Nees), 248 Papaya, 88 Papulaspora, 226, 338 Paragynous, 82 Paraphysis, 134 Paraphysoid, 216 Paraplectenchyma, 5 Parasitella simplex Bainier, 97 Parathecium, 316 P armarium scabrum Hassk., 4S6 Parmelia Acetabulum (Necker) Duby, 352 physodes (L.) Ach., 239 tiliacea (Hoffm.) Ach., 352 Parmularia discoidea Raciborski, 301 Parmulineae, 301 Parodiellina manaosensis (Hennings) Arnaud, 218 Parodiopsis megalospora (Sacc and Berlese) Arnaud, 210 melioloides (Winter) Maublanc, 209 Parodiopsis Perae Arnaud, 209 Stevensii Arnaud, 210 Parthenogamy, 13, 14 Parthenogenesis, 13, 14 Paspalum, 248 Passiflora alata Dryander in Aiton, 498 Patellariaceae, 317 Patellinia Fragariae Stevens and Per., 322 Paxillaceae, 463, 464 Paxillus rhodoxanthus (Schw.) Peck, 463 Peckiella, 226 lateritia (Fr.) Maire, 227 Thiryana (Maire) Sacc and Sydow, 227 Pedicularis, 592 Pedogamy, 13, 14 Pellicle, 453 Pellicularia Koleroga Cooke, 436 Peloronectria vinosa Moller, 241 Penicilliopsis brasiliensis Moller, 177, 178, 179 clavariaejormis Solms-Laubach, 177, 178, 182, 183 Penicillium Camemberti Thom, 175 candidum Link, 179 claviforme Bainier, 176 crustaceum [L.] Fr., 8, 176, 177, 179, 184, 185 digitatum Sacc, 175 glaucum Link, 179 italicum Wehmer, 175 olivaceum Wehmer, 175 Roqueforti Thom, 175 silvaticum (Wehmer) Biourge, 176 vermiculatum Dangeard, 180, 181, 183 Peniophora Aegerita [Hoffmann] Hoehncl and Litsch., 437 Candida (Pers. ex Fr.) Lyman, 437 chaetophora Hoehnel and Litsch., 437, 438 chordalis Hoehnel and Litsch., 437, 438 coronilla Hoehnel in Hoehnel and Litsch., 438 corticalis (Bull, ex Fr.) Cooke, 530 gigantea (Fr.) Massee, 396 Habgallae (Berk, and Broome) Cooke, 438 quercina [Pers.] Cooke, 530 Sambuci (Pers.) Burt, 396, 400, 401, 402, 437 Penisetum, 245 690 COMPARATIVE MORPHOLOGY OF FUNGI Perfect form, 10 Pericystis alvei Betts, 146 apis Maassen, 146 Peridium, 408, 46^ Periphysis, 134 Perisporiaceae, 204-211 Perisporiales, 192-211 Perithecium, 134 Perittogamy, 420 Peronospora, 73, 74, 77, 80, 84 Alsinearum Casp., 83 Brassicae Gaumann, 90 cannabina Otth, 90 effusa (Grev.) Rabenhorst, 83 Ficariae (Nees) Tulasne, 83, 84 parasitica (Pers.) Fr., 83 Schachtii Fuckel, 90 Schleideni Unger, 90 Spinaciae Laub., 90 vemalis Gaumann, 83 Peronosporaceae, 73-91 Peronosporeae, 77-80, 83, 84, 89, 90 Pestalotia flagellifera Ellis and Everhart, 284 palmarum Cooke, 614 versicolor Speg., 614, 615 Peucedanum, 161 Peyritschielliaceae, 377-388 Peziza asterigma (Vuill) Sacc. and Trav- erso, 338 Catinus Holmsk. ex Fr., 131 domiciliana Cooke, 345 leucomelas Pers., 131 repanda Wahlenberg, 338 sylvestris (Boudier) Seaver, 346 tectoria Cooke, 344 theleboloides Alb. and Schw. ex Fr., 344 vesiculosa Bull, ex Fr., 131 Pezizella Lythri (Desm.) Shear and B. O. Dodge, 322 Phacidiaceae, 308 Phacidiales, 308-314 Phacidiella discolor (Mout. and Sacc.) Potebnia, 314 Phacidiostromataceae, 308 Phacidium repandum [Alb. and Schw.] Fr., 312 Phaeodidymeae, 617 Phaeosporeae, 617 Phalaris arundinacea L., 252 Phallaceae, 511-518 Phallogaster saccatus Morgan, 496 Phallus impudicus L. ex Pers., 406, 514, 515 tenuis (E. Fischer) Lloyd, 513, 514 Phaseolus lunatus L., 89 Phellodon, 445 Phialide, 175 Philipsielleae, 317 Philocopra coeruleotecta Rehm in Sax, 260 curvicolla (Winter) Sacc, 135 zygospora (Speg.) Sacc, 261 Phlebia merismoides Fr., 443 Phleogena faginea (Fr.) Link, 551, 552 Phleogenaceae, 549-552 Phleospora, 267 Phlycitidium brevipes (Atk.) Minden, 36 Phoenix dactylifera L., 608 Pholiota, 459, 460 praecox (Pers. ex Fr.) Quelet, 397 Phoma apiicola Klebahn, 617 Betae (Oudemans) Rostrup, 269 conidiogena Schnegg, 8 Phomopsis, 282 Phragmidium, 566, 576 disciflorum (Tode) James, 556, 557, 562, 563, 595 Potentillae-canadensis Dietel, 566, 590 Rubi (Pers.) Winter, 555, 565 speciosum (Fr.) Cooke, 556 subcorticium (Schrank) Winter, 556 violaceum (Schultz) Winter, 554, 555, 556, 557, 567, 577, 583 Phragmites communis Trinius, 252 Phragmobasidium, 414 Phragmosporeae, 617 Phycomyces, 100, 113 nitens [Agardh] Kunze, 109, 111, 112 Phycomycetes, 30-126 Phyllachora graminis (Pers.) Fuckel, 294 Phyllachoraceae, 294, 295 Phyllachoreae, 294 Phyllactinia, 193, 204 corylea (Pers.) Karsten, 132, 194, 198, 199, 200, 203 suffulta (Rebentisch) Sacc, 132 Phyllobieae, origin of Chytridiales from, 34 Phyllosticta tabifica Prillieux et Delacroix, 269 Phymatosphaeria, 213 Phymatotrichum omnivorum (Shear) Dug- gar, 443 INDEX 691 Physcia pulverulenta (Schreber) Nyl., 315, 352, 361 Physoderma maculare Wallroth, 47 Zeae-Maydis Shaw, 48 Phytophlhora, 73, 74, 76, 80, 84, 88 Arecae (Colem.) Peth., 74, 82, 89 Cactorum (Leb. and Cohn) Schroeter, 82, 89 erythroseptica Pethybridge, 82, 83, 88, 89 Faberi Delacroix and Maublanc, 89 Fagi Hartig, 82, 89 infestans (Mont.) Bary, 80, 82, 89 Nicotinanae Breda de Haan, 82 omnivora Bary, 89 parasitica Dastur, 82, 90 Phaseoli Thaxter, 82, 89 Syringae Klebahn, 74, 82, 89 Picea, 572 Engelmanni Engelmann, 442 Pichia membratiifaciens Hansen, 148, 149, 153 Piersonia bispora Gilkey, 357, 359 Pilacre faginca (Fr.) Berk, and Broome, 551 Pe.te.rsii Berk, and Curtis, 551 Pilacrella delectans Moller, 550 Solani Cohn and Schroeter, 550 Pilaira anomala (Cesati) Schroeter, 98 Pilobolus anomala Cesati, 98 crystallinus (Wigger) Tode ex Fr., 99, 100 microsporus (Klein) Brefeld, 100 oedipus Mont., 100 roridns (Bolton) Pers ex Fr., 98 Pinus cembra L., 562 'monticola Douglas ex Lambert, 442, 548 pollen of, 36, 62 Strobus L., 548, 562 virginiana Miller, 555 Pionotes, 235 Piptocephalis, 113 Freseniana Bary, 95, 104 Piscidia erythrina L., 259 Pisolithus, 472 Pistillaria, 441 Pisum sativum L., 198 Placodium, 279 Plantago lancoelata L., 24 Plasmodiophora Brassicae Woronin, 24 Plasmogamy, 1 Plasmopara, 73, 77, 80, 84 alpina (Johansen) Blytt, 83, 89 densa (Rabenhorst) Schroeter, 83, 89 nivea (TJnger) Schroeter, 89 pygmaea (Unger) Schroeter, 80, 89 viticola (Berk, and Curtis) Berlese and Toni, 79, 84, 89 Platanus, 274 Platygloea caroliniana Coker, 541 Lagerstroemiae Coker, 541 nigricans (Fr.) Schroeter, 541 Plectascales, 166-191 Plectenchyma, 5 Plectodiscella Pyri Woronikhin, 214, 215 veneta Burkholder, 215 Plectodiscellaceae, 215 Plectospira, 64 myriandra Drechsler, 68, 69 Pleonectria berclinensis Sacc, 237 Ribis (Rabenh) Karsten, 237 Pleolpidium inflatum Butler, 29 irregulars Butler, 20 Pleosphaera Citri (Briosi and Passerini) Arnaud, 265 Pleospora gramineum Diedicke, 221 herbarum (Pers. ex Fr.) Rabenh., 135, 220 Hyacinthi Sorauer, 220 scirpicola (DC.) Fuckel, 135 Pleurage anserina (Cesati in Rabenh.) O. Kuntze, 261 Brassicae (Klotzsch) O. Kuntze, 261 coeruleotecta (Rehm in Sax) Giiumann, 260 curvicolla (Winter) O. Kuntze, 135 curvula (Bary) O. Kuntze, 134 fimiseda (Cesati and Notaris) Griffiths, 134 hirsuta (Dangeard) Gaumann, 258 macrospora (Auerswald) O. Kuntze, 258 minuta (Fuckel) O. Kuntze, 134 zygospora (Speg.) O. Kuntze, 261 Pleurosporous, 414 Plicaria Adae Sadler, 344 ampliata (Pers.) Rehm, 338 repanda (Wahlenberg) Rehm, 338 saniosa (Schrad ex Fr.) Rehm, 345 succosa (Berk.) Rehm, 131, 345 Pluteus admirabilis Peck, 457 Poa pratensis L., 194, 223 692 COMPARATIVE MORPHOLOGY OF FUNGI Podaxis carcinomalis (L. ex Pers.) Desvaux 495 Podaxon carcinomale (L. ex. Pers.) Fr., 495 Podocarpus, 264 Podosphaera, 202 leucotricha (Ellis and Everhart) Sal- mon, 204 Oxyacanthae (DC.) Bary, 203 Podospora anserina (Cesati in Rabenh.) Winter, 261 Brassicae (Klotzsch) Winter, 261 curvula (Bary) Winter, 134 fimiseda (Cesati and Notaris) Winter, 134, 135 hirsuta Dangeard, 258 minuta Winter, 134 Podostroma alutaceum (Pers.) Atk., 240 cornu-damae (Pat.) C. W. Dodge, 240 Polyandromyces Coptosomalis Thaxter, 385, 386 Polyascomyces, 377 Polyenergid, 3 Polyete lardaria, 123 Polygonum chinense L., 597 Hydropiper L., 597 Polymorphism, 9, 127 Polyphagus Euglenae Nowakowski, 42, 43,44 Polypodium longissimum Blume, 301 Polyporaceae, 445-449 Polyporales, 429-450 Polyporus basilapidioides (Mc Alpine) Lloyd, 447 Berkele.yi Fr., 447 betulinus [Bull.] Fr., 447 confluens Fr., 447 frondosus [Schrank] Fr., 447 Goetzii Hennings in Lloyd, 447 Mylittae Cooke and Massee, 447 officinalis [Vill.] Fr., 447 pes-caprae Pers. ex Fr., 447 rhinocerotis Cooke, 447 Ribis [Schum.] Fr., 447 sacer Fr., 447 Sapurema M oiler, 447 squamosus [Hudson] Fr., 409, 411, 447 sulphur eus [Bull.] Fr., 447 Tuberasler Jacquin ex Fr., 447 umbellatus Fr., 447 Polysaccum, 188, 472 Polystictus pargamenus Fr., 447 versicolor (L. ex Fr.) 447 Polystigma rubrum (Pers. ex Fr.) DC, 229, 230, 231, 232 Polystomellaceae, 301-303 Polystomelleae, 301 Populus, 163, 165, 198, 233 Poria, 443 vaporaria (Pers. ex Fr.) Cooke, 445 Poronia punctata [L.] Fr., 288, 290 Porothelium, 443 Potentilla, 23, 163 Probasidium, 415 Prosenchyma, 5 Prosoplectenchyma, 5 Protoachlya paradoxa (Coker) Coker, 69 Protoblem, 452 Protohydnum cartilagineum M oiler, 526 lividum Bres., var. piceicola Kuehner, 526 Protohymenium, 411 Protomerulius brasiliensis Moller, 525, 526 Farlowii Burt, 526 Protomyces inundatus Dangeard, 160 macrosporus Unger, 159, 160 pachydermus Thtimen, 159, 160 Protomycetaceae, 159-161 Protospore, 23 Protozoa, origin of Chytridiales from, 34 Protubera Maracuja Moller, 497, 498 Pro-Ustilago, 610 Prunus domestica L., 229 insititia L., 229 Padus L., 322 pensylvanica L. f., 270 spinosa L., 229 Psalliota, 459, 460 campestris (L. ex Fr.) Quelet, 411 tabularis (Peck) Lloyd, 407 Psathyra gyroflexa (Fr.) Quelet, 466 Psathyrella, 460 Pseudobalsamia magnata (Harkness) Gil- key, 355, 356 Setchelli E. Fischer, 355 Pseudogenea calif ornica E. Fischer, 361 Pseudogamy, 13, 14 Pseudolpidiopsis Oedogoniorum (Wilde- man) Scherffel, 39 Schenkiana (Zopf) Minden, 38 Pseudolpidium Saprolegniae (A. Braun) A. Fischer, 27 Pseudomixis, 13, 14 Pseudoparaphysis, 216 INDEX 693 Pseudoparenchyma, 5 Pseudoperithecium, 365 Pseudopeziza Medicaginis (Libert) Sacc, 322 Ribis Klebahn, 321 tracheiphila Miiller-Thurgau, 322 Trifolii (Bernh.) Fuckel, 322 Pseudophyses, 440 Pseudopycnidiales, 615 Pseudosphaeriaceae, 219-223 Pseudotsuga taxifolia (Lam. apud Poir.) Britton, 442 Pseudovalsa lanciformis (Ft.) Cesati and Notaris, 284 Psophocarpus tetragonolobus DC, 23 Psoralea Mutisii Kunth, 24 Psorica, 264 Pteris, 308 aquilina L., 431 Pterula, 442 Puccinia, 566, 575 Adoxae Hedw., 569 Aegopodii (Schum.) Mart., 569 Anemones Pers., 568 Buxi DC, 568 Caricis (Schum.) Reb., 553, 559 claytoniata (Schvv.) Sydow, 558 coronifera Klebahn, 595 dispersa Eriksson and Hennings, 595 Eatoniae Arthur, 560, 562 Falcariae (Pers.) Fuekel, 560, 583 Fergussoni Berk, and Broome, 568, 593 fusca (Pers.) Winter, 568 glumarum (Schm.) Eriksson and Hen- nings, 565, 595, 597 graminis Pers., 560, 561, 562, 576, 581, 583, 595 Helianthi Schw., 581, 589 Liliacearum Duby, 568 Lolii Niels, 595 Malvacearum Mont., 568, 569, 578, 581, 585 Mariae-Wilsoni G. W. Clinton in Peck, 558, 591 obtegens (Link) Tulasne, 555, 566 peridermiospora (Ellis and Tracy) Arthur, 591 Poarum Niels., 558 Podophylli Schw., 577, 582 Pruni-spinosae Pers., 558, 559, 561, 595 Rossiana (Sacc.) Lagerheim, 568 Puccinia, Senecionis Libert, 563, 583 Seymouriana Arthur, 591 suaveolens (Pers.) Rostrup, 555 Sydowiana Dietel, 591 transformans Ellis and Everhart, 568 triticina Eriksson, 595 Veronicarum DC, 575, 585 f. fragilipes Korn, 576 f. persistans Korn, 576 Vilfae Arthur and Holway, 591 Violae (Schum.) DC, 558, 560, 583, 593 Pucciniaceae, 575-582 Pucciniastrum, 564, 572 Myrtilli (Schum.) Arthur, 560 Pueraria Thunbergiana Bentham, 23 Pustularia vesiculosa (Bull, ex Fr.) Fuckel, 131, 337, 344 Pycnidiales, 615 Pycnidiospore, 8 Pycnidium, 8 Pycnium, 8, 554 Pycnochytrium (subgenus), 20 Pycnospore, 8, 555 Pycnothecium, 301 Pyrenophora trichostoma (Fr.) Sacc, 219, 220 Pyronema, 422 confluens (Pers.) Tulasne, 128, 129, 130, 332, 333, 334, 335, 336 var. inigneum Brown, 335 domesticum (Sow.) Sacc, 334 Pyrrhosorus marinus Juel, 29 Pythieae, 74-76, 81-83, 88, 89 Pythiogeton, 79, 80, 88 transversum Minden, 80 utriforme Minden, 89 Pythiomorpha, 88 gonapodioides Petersen, 79, 89 Pythiopsis, 54, 64 Pythium, 20, 51, 73, 74, 78, 79, 88, 90 aphanidermatum (Edson) Fitzpatrick, 88 debaryanum Hesse, 79, 81, 88 diacarpum Butler, 75, 80, 88 gracile Schenk, 74, 75, 88 Indigoferae Butler, 30, 75, 88 intermedium Bary, 75, 76, 80, 88, 90 monospermum Pringsheim, 88 palmivorum Butler, 75, 81, 88 proliferum Bary, 75, 76, 80, 81, 88 ultimum Trow, 79, 81 694 COMPARATIVE MORPHOLOGY OF FUNGI Pythium vexans Bary, 81 Pyxidiophora, 238 Q Quaternaria Persoonii Tulasne, 280 R Radulaceae, 442-445 Radulum, 443 Ramaria, sect. Clavaria, 442 Ramularia, 267 Hieracii (Baumler) Jaap, 269 Tulasnei Sacc, 268 Ramularisphaerella, sect. Mycosphaerella, 267 Ranunculus, 23 acris L., 198, 200 cassubicus L., 322 Ravenelia, 579 appendiculata Lagerheim and Dietel, 579 cassiaecola Atkinson, 579 Reessia amoeboides Fisch, 20 Resupinate fructification, 408 Rhachomyces, 375 velatus Thaxter, 372 Rhacophyllus lilacinus Berk, 464, 465 Rhipidium europaeum (Cornu) Minden, 70, 71, 72 Rhizidiomyces apophysatus Zopf, 36, 37 Rhizidium bulligerum Zopf, 40 Cienkowskianum Zopf, 40 Rhizina undulata Fr., 329, 330 Rhizinaceae, 330-332 Rhizoctonia Crocorum (Pers.) DC. ex Fr., 540 Solani Kiihn, 436 violacea Tulasne, 540 Rhizoid, 5 Rhizomorph, 5, 407 Rhizomyces crispatus Thaxter, 373, 375 ctenophorus Thaxter, 388 Rhizophidiurn Dicksonii Wright, 60 pollinis (A. Braun) Zopf, 36 Rhizophlyctis Braunii (Zopf) A. Fischer, 41 Rhizopogon Briardi Boudier, 469 diplophloeus Zeller and C. W. Dodge, 469 pannosus Zeller and C. W. Dodge, 469 Rhizopogon luteolus Fr. and Nordholm, 469 rubescens Tulasne, 468, 469 violaceus Cooke and Massee, 491 Rhizopogonaceae, 468-470 Rhizopus, 95, 100, 113 nigricans Ehrenberg, 95, 96, 109 Orizae Went and Geerligs, 94 Rhododendron, ferrugineum L., 324, 532 hirsutum L., 324 Rhodopaxillus nudus (Bull, ex Fr.) Maire, 459 Rhopalogaster transver sarins (Bosc) Johnston, 492, 495 Rhynchophoromyces rostralus Thaxter, 365, 377 Rhynchospora, 601 Rhyparobius, 339 Pelletieri (Crouan) Rehm, 342 Rhytisma acerinum [Pers.] Fr., 308, 312, 313 Ribes, 197 aureum Pursh, 321 nigrum L., 562 rubrum L., 321 Rickia, admirabilis Thaxter, 378, 380 biseriata Thaxter, 381, 382 circumdata Thaxter, 380, 381 Coelostomalis Thaxter, 382, 383 coptengalis Thaxter, 380, 381, 382 dichotoma Thaxter, 378, 379, 381, 382 Discopomae Thaxter, 378 elegans Thaxter, 378 encymonalis Thaxter, 379, 380 inclusa Thaxter, 380, 382 introversa Thaxter, 379, 382 macrandra Thaxter, 378, 381 pallida Thaxter, 378, 379 papuana Thaxter, 379, 382 rostellata Thaxter, 380, 381 rostrata Thaxter, 382 Sylvestri Speg., 378, 382 Ring, inferior, 452 movable, 452 superior, 453 Roesleria pallida (Pers.) Sacc, 326 Roestelia, 562 Rosa, 562 Rosellinia necatrix (Hartig) Berlese, 262 quercina Hartig, 262 Rozella septigena Cornu, 28, 29 Rosenscheldia, 222, 295 INDEX 695 Rozites, 459, 460 gongylopohora M oiler, 460 Rub us, 563 Ruhlandiella berolinensis Hennings, 331 hesperia Setchell, 331 Rumex domesticus Hartm., 601 scutatus L., 50 Russula, 461; host, 238 citrina Gillet, 411 S Saccardia, 215 Saccardiaceae, 215 Saccharomyces cerevisiae Hansen, 149, 153, 154, 155 Chevalieri Guill., 154 ellipsoideus Hansen, 153 Mangini Guill., 154 minor Engel, 153 Pastorianus Hansen, 149, 153 Saccharomycetaceae, 148-158 Saccharomyceteae, 148 Saccharomycodes Ludwigii Hansen, 148, 154, 155 Saccoblastia ovispora Moller, 545, 546 Saccobolus violascens Boudier, 342 Saccomyces Dangeardii Serbinov, 40, 41 Salicornia herbacea L., 19 Salix, 233 Caprea L., 270 discolor Muhl., 194 purpurea L., 59 Sanicula Menziesii Hook, and Arn., 50 Saprolegnia, 36, 54, 63 ; host, 26, 27 atiisospora Bary, 69 dioica Bary, 69 ferax (Gruith) Thuret, 69 hypogyna Pringsheim, 66 mixta Bary, 7, 66, 69 monoica Pringsheim, 66, 67, 68, 69 Thureti Bary, 69 torulosa Bary, 64 Saprolegniaceae, 63-69 Sarcodon, 445 Sarcosphaera, 346 Saxifraga aizoides L., 23 moschata Wulff., 23 stellaris L., 23 Scabiosa Succisa L., 23 Scarabaeidae, 118 Schizophyllum commune Fr., 399, 407, 409, 458, 459 Schizosaccharomyces asporus Eykmann, 150 mellacei Jorg., 150 octosporus Beijerinck, 149, 150 Pombe Lindner, 150 Schizosaccharomyceteae, 148-150 Schizothyriaceae, 308 Schneepia discoidea (Rac.) Rac. in Theissen and Sydow, 301 Schwanniomyces occidentalis Klocker, 153 Scilla, 603 Scirrhieae, 294 Sclerobasidium, 415 Sclerocystis, 114, 116, 117 Dussii (Pat.) Hoehnel, 116 Scleroderma Bovista Fr., 470, 471 Geaster Fr., 470 vulgar e Hornemann, 470 Sclerodermataceae, 470-472 Sclerospora, 77, 80, 84 graminicola (Sacc.) Schroeter, 83, 89 philippinensis Weston, 77 Sclerotinia baccarum (Schroeter) Rehm, 322 • cinerea (Bonorden) Schroeter, 324, 325 fructigena (Pers.) Schroeter, 323 Fuckeliana (Bary) Fuckel, 325 heteroica Woronin and Navashin, 322 laxa Aderhold and Ruhland, 323 Ledi Navashin, 322, 324 Libertiana Fuckel, 325 Linhartiana Prillieux and Delacroix, 322 Padi Woronin, 322 Rhododendri E. Fischer, 324 sclerotiorum (Libert) Schroeter, 325 Trifoliorum Eriksson, 325 Urnula (Weinmann) Rehm, 322, 323 Vaccinii Woronin, 322 Sclerotiopsis concava (Desm.) Shear and B. O. Dodge, 322 Sclerotium, 5 Sclerotium Clavus DC., 248 Scolecite, 127 Scrophularia nodosa L., 563 Sebacina ciliata (Moller) C. W. Dodge, 521 gloeocystidiata Kuehner, 412, 521 incrustans (Pers. ex Fr.) Tulasne, 521 696 COMPARATIVE MORPHOLOGY OF FUNGI Sebacina minor (Moller) Pat., 520, 521 papillata (Moller) Pat., 520 uvida (Fr.) Bres., 521 Secale cereale L., 223 Secale cornutum, 248 Secotium acuminatum Mont., 494 agaricoides (Czernaiev) Holl6s, 494 erythrocephalum Tulasne, 493, 494 Gueinzii Kunze, 494 krjukoivense Bucholtz, 487 Novae-Zealandiae Cunningham, 493 Sempervivum, 563 Sepedonium, 237 chrysospermum [Bull.] Fr., 238 Septobasidiaceae, 543-549 Septobasidium albidum Pat., 548 bogoriense Pat., 547 castaneum Burt, 548 cirratum Burt, 547 frustulosum (Berk, and Curtis) Pat., 548 Michelianum (Cesati) Pat., 549 pedicellatum Pat., 548 pinicola Snell, 548 pseudopedicellatum Burt, 548 retiforme (Berk, and Curtis) Pat., 548 Septocladia dichotoma Coker and Grant, 58 Septoria, 10, 267 aesculicola (Fr.) Sacc., 268 Agropyri Ellis and Everhart, 223 Bromi Sacc, 223 nodorum Berk., 223 Passerinii Sacc, 223 pyricola Desm., 268 Secalis Prillieux and Delacroix, 223 Tritici Desm., 223 Septorisphaerella, sect. Mycosphaerella, 267 Sepultaria, 346 Seta, 316 Setaria, 246, 248 Crus-ardeae Kunth, 248 Sexual dimorphism, 11 Sexuality, 11 Shiraia bambusicola Hennings, 241 Shropshiria Chusqueae Stevens, 608 Silene Cucubalus Wibel, 563 inflata Sm., 563 Silphidae, 118 Simblum rubescens Gerard, 505 sphaerocephalum Schlecht., 505 Siphonales, 90 Siphonomycetes, 30 Sirobasidiaceae, 527-528 Sirobasidium albidum Lagerheim and Pat., 528 Brefeldianum Moller, 527, 528 Solarium Dulcamara L., 20 nigrum L., 20 tuberosum L., 20 Solenia, 441 Solorina saccata (L.) Acharius, 352 Sonchus oleraceus L., 198 Sordaria fimicola (Roberge) Cesati and Notaris, 258 macrospora Auerswald, 258 merdaria (Fr.) Winter, 258 Sordariaceae, 257-262 Sorodiscus, 25 Sorolpidium, 24 Sorosphaera, 25 Sparassis crispa [Wulfen] Fr., 442 radicata Weir, 442 ramosa [Schaeffer] Schroeter, 442 spathulata Fr., 442 Spathularia velutipes Cooke and Farlow, 327, 328, 329 Sperm, 11 Sphacelia segetum Lev., 248 Sphacelotheca, 598, 599 Hydropiperis (Schum.) Bary, 597, 599 Sphaeriaceae, 262 Sphaeriales, 257-290 Sphaerita, 20 Sphaerioideae, 617 Sphaerobolaceae, 480-482 tSphaerobolus iowensis Walker, 482 stellatus Tode ex Fr., 480, 481, 482 Sphaerocreas, 114 Sphaeroderma bulbilliferum Berlese, 226 Sphaerognomonia, 284 Sphaeronema corneum Cooke and Ellis, 322 fimbriatum (Ellis and Halsted) Sacc, 262 Sphaeropsidales, 614 Sphaerosoma echinulatum Seaver, 330 fragile Hesse, 330 fuscesens Klotzsch, 330, 331 Janczewskianum Rouppert, 330 Sphaerosporangium, subg. Pythium, 75, 88 INDEX 697 Sphaerostilbe, 238 repens Berk, and Broome, 238 Sphaerotheca, 200, 201, 202 Castagnei Lev., 196 Humuli (DC.) Burrill, 196, 197, 198, 199, 204 v&r.fuliginea (Schlecht.) Salmon, 198 mors-uvae (Schw.) Berk, and Curtis, 193, 197, 198, 204 pannosa (Wallroth) Lev., 197, 204 Sphaerozone ostiolatum (Tulasne) Setchell, 330 Sphaerulina intermixta (Berk. and Broome) Sacc, 269, 270 Trifolii Rostrup, 270 Sphyridium byssoides Th. Fr., 352 Spicaria, 226 Spirogyra, 36, 39 Spongospora subterranea (Wallroth) Lagerheim, 24, 25 Sporangiocyst, 29 Sporangiole, 105 Sporangiophore, 7 Sporangiospore, 7 Sporangium, 7 Spore, 7 Sporodinia, 100, 107, 113 grandis Link, 100, 109, 110, 111 Sporodochium, 8 Sporonema Platani Baumler, 274, 275, 276 quercicola Massalongo, 322 Sporophlyctis rostrata Serbinov, 41 Sporophyte, 2 Sporormia intermedia Auerswald, 258 leporina Niessl, 258 megalospora Auerswald, 261 Sporotrichum, 237, 259 Sprout cell, 3 Steccherinum, 445 Stephanospora carotaecolor (Berk, and Broome) Pat., 487 Stereocaulon paschale (L.) Hoffm., 352 Stereum fasciatum (Schw.) Fr., 438, 445 frustulosum [Pers.] Fr., 439 hirsutum [Willd.] Fr., 403, 438 purpureum Pers. ex Fr. 439 Sterigma, 175 Sterigmatocystis, subg. Aspergillus, 175 Stichobasidium, 413 Stictidaceae, 308 Stigmatea Robertiani Fr., 298, 299, 300 Stigmateaceae, 298-301 Stigmatocyst, 209 Siigmatomyces Baeri (Knoch) Peyritsch, 369, 370-373, 377 Sarcophagae Thaxter, 370, 372 Stigmatopodium, 209 Stilbeae, 617 Stilbonectria, 238 Stilbum vulgar e (Tode) Juel, 549 Stomatopodia, 207 Slrobilomyces, 464 Stroma, 8 Stromatinia, 322 Strophariax, 459, 460 Stylospores, 8 Stypella minor M oiler, 520 papillata M oiler, 520 Stypinella, 540 Stysanus, 177 thyrsoides Sopp, 9 Succisa pratensis Moench, 23 Suspensor, 109 Symphyogenous pycnium, 8 Syncaryon, 14 Syncephalastrum, 113 cinereum Bainier, 103 racemosum Cohn, 103 Syncephalis, 94, 98, 103, 113 aurantiaca Vuill., 104 nodosa Tieghem, 109 Synchytrium, 20 aecidioides (Peck) Lagerheim, 24 aequatoriense (Sydow) Gaumann, 23 aureum Schroeter, 23 decipiens Farlow, 23 endobioticum (Schilb.) Percival, 20, 21 Psophocarpi (Rac.) Gaumann, 23 Puerariae Miyake, 23 Saxifragae Rytz, 23 Succisae Bary and Woronin, 23 Taraxaci Bary and Woronin, 23 vulcanicum (Rac.) Gaumann, 23 Syncoryne, sect. Clavaria, 442 Synnematomycetes, 616 Syringa, 203 Systremma, Ulmi (Duval ex Fr.) Theis- sen and Sydow, 291, 292, 293 Taphridium, 160 rhaeticum Volk., 161 Umbelliferarum (Rostrup) Lagerheim and Juel, 161 698 COMPARATIVE MORPHOLOGY OF FUNGI Taphrina, Alni-incanae (Ki'ihn) Magnus, 163 aurea (Pers.) Fr., 163, 165 Betulae (Fuckel) Johansen, 163 bullata (Berk, and Broome) Tulasne, 162, 163 Carpini Rostrup, 163, 165 Cerasi (Fuckel) Sadebeck, 165 Coryli Nish., 163 Crataegi Fuckel, 163 deformans (Berk.) Tulasne, 161, 162, 163, 165 epiphylla Sadebeck, 163, 164 Insititiae (Sadebeck) Johansen, 163, 165 Polentillae (Farlow) Johansen, 163, 164, 165 Pruni (Fuckel) Tulasne, 163, 164, 165 Tosquinetii (Westendorp) Magnus, 165 Taphrinaceae, 161-165 Taphrinales, 159-165 Taraxacum, 23 officinale Weber in Wigg., 159 Tarichium, 125 Teichospora meridionalis Arnaud, 266, 267 salicina (Pers.) Arnaud, 265, 266 Teichosporella, 267 Teleblem, 452 Terfez, 187 Terfezia Leonis Tulasne, 187 Terfeziaceae, 187 Testicularia, 599 Cyperi Klotzsch, 599, 600 Tetracyte, 1 Tetramyxa, 25 Tettigomyces acuminatus Thaxter, 380, 388 africanus Thaxter, 386, 387, 388 chaetophilus Thaxter, 386, 387, 388 gracilis Thaxter, 386, 387 Gryllolalpae Thaxter, 386, 387 intermedins Thaxter, 386, 387 vulgaris Thaxter, 386, 387 Thalictrum alpinum L., 89 Thallus, 2, 3 Thamnidium,, 113 chaetocladioides Brefeld, 107 elegans Link, 105, 106 Thamnomyces Chamissonis Ehrenberg, 288, 289 Thaxteriola nigromarginata Thaxter, 390 Thecaphora, 599 deformans Durieu and Mont., 603 Theocotheus Pelletieri (Crouan) Boudier, 342 Thekopsora, 564, 572 areolata (Fr.) Magnus, 570 Vacciniorum Karsten, 560 Thelebolus stercorals Tode ex Fr., 342, 343 Zukalii Heimerl, 339 Thelephora anthocephala [Bull.] Fr., 533 palmata [Scopoli] Fr., 533 perdrix Hartig, 439 Theobroma Cacao L., 458 Thielavia basicola Zopf, 173, 174 Thraustotheca, 64 clavata (Bary) Humphrey, 52, 65 Thyriothecium, 305 Tilia, 268 cordata Mill., 269 Tilletia, 598 Tritici (Bjerk.) Winter, 419, 596, 597, 604 Tilletiaceae, 604-608 T olyposporium, 599 Tomentella fiava Brefeld, 436 Torula, 149 Torulaspora Delbrueckii Lindner, 152 Rosei Guill., 152, 153 Trabutieae, 294 Trametes, 447 Pini (Brot.) Fr., 447 radiciperda Hartig, 446 Tremella compacta Moller, 522, 523 fuciformis Berk., 522 lutescens Pers., 523, 524, 525 meserderica Retzius ex Fr., 524, 525 Tremellaceae, 520-526 Tremellales, 520-528 Tremellodendron, 523 Tremellodon cartilagineum (Moller) Pat., 526 crystallinum [Miiller], 526 gelatinosum [Scopoli ex Fr.] Pers., 526 527 Trenomyces circinans Thaxter, 385, 386 388 histophthorus Chatton and Picard, 385 388 Laembothrii Thaxter, 385 Lipeuri Thaxter, 385 Trentepohlia, 297 Trichocoma paradoxa Junghuhn, 187 INDEX 699 Trichocomaceae, 187 Trichoderma viride Pers. ex S. F. Gray, 239 Trichoglossum hirsutum (Pers. ex Fr.) Boudier, 327, 328 velutipes (Peck) Durand, 327 Trichogyne, 127 Tricholoma Georgii (Clusius ex Fr.) Quelet, 459 nudum (Bull, ex Fr.) Quelet, 400, 459 Trichothyriaceae, 307 Trichothyrium fimbriatum Speg., 306 Trichophyton, 170 Trientalis, 596 Trifolium, 50, 197 Triphragmium, 566 Ulmariae (Schum.) Link, 566, 567, 578, 584 Tripospora, 264 Triticum, 223 Tryblidiaceae, 308 Tubaria, 459, 460 Tuber, 356 aestivum Micheli ex Vittadini, 354 brumale Vittadini, var. melanosporum (Vittadini) E. Fischer, 354 dryophilum Tulasne, 354 excavatum Vittadini, 357 rufum Pico, 358 Tuberales, 354-363 Tubercularia, 236 vulgaris Tode ex Schw., 237 Tubercularieae, 617 Tuburcinia occulta (Wallroth) Liro, 596 primulicola (Magnus) Rostrup, 608, 609 Ranunculi (Libert) Liro, 606, 607, 608 Trientalis Berk, and Broome, 596, 597, 604, 605 Violae (Sow.) Liro, 606, 608 Tulasnella anceps Bres. and Sydow, 431 cystidiophora Hoehnel and Litsch., 431 deliquescens Juel, 431, 432 grisea (Rac.) Juel, 431 helicospora Raunkaier, 431 hyalina Hoehnel and Litsch., 431 thelephorea Juel, 431, 432 traumatica Bourdot and Galzin, 431 Tulasnellaceae, 431-433 Tulostoma, 414 brumale Pers., 479 mammosum [Micheli] Fr., 479 squamosum [Gmelin] Pers., 479 Tulostomataceae, 479-480 Turbinate cell, 45 Typhula Betae Rostrup, 441 Candida Fr., 441 erythropus [Bolton] Fr., 401 variabilis Riess, 441 Typhulochaeta, 203 U Ulocolla, 523 foliacea Brefeld, 524 Uncinula, 202, 203, 204 Aceris (DC.) Sacc, 203 necator (Schw.) Burrill, 204 Salicis (DC.) Winter, 194, 197, 198 Sengokui Salmon, 203 Uredinales, 553-595 Uredineae, 553 Uredinium, 564 secondary, 566 Uredinopsis, 564, 571, 572 americana Sydow, 558 filicina Magnus, 569 mirabilis (Peck) Magnus, 558 Struthiopteridis Storm., 567 Uredo aecidioides Peck, 24 Urocystis Anemones (Pers.) Kniep non Winter, 607 occulta (Wallroth) Rabenhorst, 596 Violae (Sow.) Fischer-Waldeheim, 606 Uromyces, 566, 575 Alchemillae (Pers.) Fuckel, 566 alpestris Transhel, 568, 593 appendicidatus (Pers.) Link, 595 Behenis (DC.) Unger, 563 Betae (Pers.) Lev., 582, 595 Caladii (Schw.) Farlow, 559 Erythronii (DC.) Passerini, 555 Ficariae (Schum.) Lev., 568 Glycerrhizae (Rabenhorst) P. Magnus, 567 Hedysari-obscuri (DC.) Carestia and Piccone, 563, 583 laevis Kohn., 568, 593 Phaseoli (Pers.) Winter, 595 Poae Rabenhorst, 558, 559 Rudbeckiae Arthur, 569 Scillarum (Grev.) Winter, 569, 585 Scrophulariae (DC.) Fuckel, 563, 585 scutellatus (Schr.) Lev., 568, 593 striatus Schroeter, 576 700 COMPARATIVE MORPHOLOGY OF FUNGI Uromycladium bisporum McAlpine, 579 maritimum McAlpine, 578, 579 simplex McAlpine, 578, 579 Tepperianum (Sacc.) McAlpine, 579 Urophlyctis alfalfae (Lagerheim) Magnus, 49 pluriannulatus (Berk, and Curtis) Farlow, 50 Potteri Bartlett, 50 pulposa (Wallroth) Schroeter, 50 Ruebsamenii Magnus, 50 Trifolii (Passerini) Magnus, 50 Urtica, 222 dioica L., 222 parviflora Roxb., 553 Usnea barbata (L.) Weber, 361 Ustilaginaceae, 599-604 Ustilaginales, 596-613 U stilaginoidea, 244 Oryzae (Pat.) Brefeld, 248 Setariae Brefeld, 248 Ustilago, 598 A venae (Pers.) Jensen, 596 bromivora (Tulasne) Fischer Waldheim 602 Crameri Korn. in Fuckel, 596 domestica Brefeld, 601, 602 esculenta Hennings, 597 Heufieri Fuckel, 598, 599 Holostei Bary, 601, 602 Hordei (Pers.) Kellerman and Swingle, 596, 602 levis (Kellerman and Swingle) Magnus,- 596, 602 longissima (Sow.) Tulasne, 603 var. macrospora Dav., 603, 604 Maydis Corda, 596 nuda (Jensen) Kellerman and Swingle, 596, 602 Panici-frumentacei Brefeld, 602, 603 Scabiosae (Sow.) Winter, 597, 599, 600, 601 Tragopoqonis pratensis (Pers.) Rous- sel, 598, 602 Treubii Solms-Laubach, 597 Tritici (Pers.) Rostrup, 596, 599, 602 Vaillantii Tulasne, 603 violacea (Pers.) Fuckel, 597, 599, 600, 602, 609 vixens, Cooke, 248 Vuijckii Oudemans and Beijerinck, 597, 600 Ustilago Zeae (Beckmann) Unger, 596, 597, 599, 600, 601, 609 Ustulina vulgaris Tulasne, 286 zonata (Lev.) Sacc, 287 Vaccinium Myrtillus L., 324 uliginosum L., 322, 324 varingaefolium Miq., 242 Vitis-idaea L., 322, 530, 531 Valeriana, 23 Valsa, 285 leucostoma (Pers.) Fr., 285 subclypeata Cooke and Peck, 285 Valsaria, 281, 285 Vulsella, 285 Vaucheria, 90 Veil, inner, 452 partial, 452 universal, 452 Veluticeps, 437 Venae, externae, 356 internae, 356 Venturia inaequalis (Cooke) Winter, 269, 270, 271, 272, 273 Verpa bohemica (Krombholz) Schroeter, 348 Verticillium 237, 259 agaricinum (Link) Corda, 238 Vicia unijuga A. Braun, 18 Vincetoxicum, 592 Viola, 23, 593 Volkartia, 160 Volutella scopula Boulanger, 616 Volva, 452 Volvaria, 460 Volvoboletus, 464 Vuilleminia comedens (Nees ex Fr.) Maire, 433 Vuilleminiaceae, 433 W Willia anomala Hansen, 149, 150 saturnus Klocker, 149, 154 Woronina polycystis Cornu, 27, 28, 29 Woronin's hypha, 127 Xanthoria parietina (L.) Th. Fr., 352 Xenomyces, 116 INDEX 701 Xylaria allantoidea (Berk.) Berk., 288 anisopleura Mont., 288 arbuscula Sacc, 288 carpophila [Pers.] Fr., 288 Hypoxylon [L.] Grev., 289 obovata Berk., 288 polymorpha [Pers.] Grev., 288 tentaculata Rav., 288 trachelina (Lev.) Cooke, 288 Xylariaceae, 286-289 Xylocrea piriformis M oiler, 228 Zaghouania, 580 Phillyreae Pat., 578 Zeugite, 15 Zizania latifolia Turcz. apud Stapf, 597 Zodiomyces vorticellarius Thaxter, 366, 367, 368 Zoospore, 7 Zygomycetes, 92-126 Zygophore, 109 Zygorhizidium Willei Loewenthal, 36. 37 Z ygorhynchus, 100, 113 Dangeardi Moreau, 111 Moelleri Vuill., 109 Zygosaccharomyces Barkeri Sacc. and Sydow, 150, 151 Chevalieri Guill., 161, 152, 154 Nadsonii Guill., 152 Pastori Guill., 152 Priorianus Klocker, 148, 150, 151 Zygospore, 109 Zygote, 1 Zygotonium, 24