SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES JOHN S. KARLING Columbia Univertity Oi X = §1 ^_ — l = I =0 i • -. m i J" l ** : ° I a i □ : m ]0 O THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES Including a Complete Host Index and Bibliography BY JOHN S. KARLING ( 'olumbia University First Edition t PUBLISHED BY THE AUTHOR NEW YORK CITY 1942 COPYRIGHT, 1943, BY THE AUTHOR. ALL RIGHTS RESERVED. THIS BOOK, OR PARTS THEREOF, MAY NOT BE REPRODUCED IN ANY FORM WITHOUT PERMISSION OF THE AUTHOR. Dedicated to the Memories of SCHENK, CORNU, AND ZOPF For their Contributions to the Knowledge of the Lower Fungi PREFACE Tins shall volume on the simple, holocarpic, bi- flagellate Phycomycetes is the second in a series of lectures presented to graduate and research stu- dents o£ mycology at Columbia University on the origin, development, phytogeny, and evolution of the lower organisms. These simple Phycomycetes, with the exception of the Lagenidiaceae, were formerly included in tin- Chytridiales by most mycologists, hut with the recognition in recent decades that the Dumber, position, and relative lengths of the flagella are of fundamental phylogenetic significance, the viewpoint has gradually developed that these species cannot be incorporated in the same order with the posteriorly uniflagellate chytrids. On the basis of present-day evidence, the author concurs with this belief and is accordingly presenting these biflagel- late species apart from the chytrids. Many of these simple fungi exhibit distinct oomycetous characters and tendencies and should perhaps be included di- rectly in existing or new families of the Phycomy- cetes, while the life cycles of other species suggest .1 relationship or at least a parallelism in develop- ment with the Plasmodiophorales and Proteomyxa. It is thus impossible at present to include all of them in one family or order and very difficult to assign them to a definite position in a natural system of classification. For this reason they are treated sepa- rately and are referred to here as a heterogeneous collection of simple, holocarpic. biflagellate Phyco- niyeetes. This long title is obviously inadequate and can also be extended to include other Phycomycetes not discussed here, the tballi of which may some- times be holocarpic. A more adequate and briefer title is not available, although the descriptive name Holobiflagellomycetes is suggested. The use of the term "simple" is not to be interpreted as meaning th.it these fungi ;ire primitive and have given rise directly to the higher Oomycetes and Zygomycetes. Nor does the author wish to convey the impression that by discussing these diverse fungi under one title that In- considers them as constituting a natural phy- logenetic series. Whether or not they comprise sev- eral distinct families is obviously open to question. The family Wbroninaceae, for example, includes several dissimilar genera and is very doubtful. Should the type species Woroni na polycystis prove to be a member of tin- Plasmodiophorales. as set ins quite likely at present, tin former family name would no longer be tenable. The author has none- theless grouped the genera in five families, realiz- ing fully that the grounds for doing so are woefully inadequate. Mycologists will doubtless disagree with this arrangement, but in our state of meager knowl- edge concerning many of the genera and species, classification into families is not SO important at present, in the author's opinion, as making available to research students all known facts and data. These fungi have been the subject of study for al- most a century, but no serious attempt has been made to summarize the widely scattered data in zoological and botanical journals. Fischer ('92), Schroeter ('97), and Mindcn ('11) discussed rather fully the species known at the turn of the century, but since that time most textbooks of mycology have given scant attention to them. During the past two dec- ades several new genera and species have been dis- covered, and additional intensive studies on long known species have modified our concepts of host range, sexuality, relationships, etc., within the group. In light of these discoveries and the fact that these simple holocarpic fungi are so significant from the standpoints of phylogeny and evolution of flu- higher Phycomycetes. the author believes that a separate and complete treatment of them is very es- sential and worthwhile, particularly in stimulating research. A full discussion of the doubtful and ex- eluded species is also presented with the purpose of making these data available to researcli workers. Although the author agrees with the view that Ach- lyogeton, so far as it is now known, should be ex- eluded because of its reported posteriorly uniflagel- late zoospores, he nevertheless believes it may pos- sibly prove to be a valid member of the group. In the text which follows very few technical terms are used. A glossary is accordingly unneces- sary and has been omitted. Separate bibliographies are provided at the end of each chapter to expedite reference to the literature on particular subjects, genera, and species. A host index of plant and ani- mal genera and species, together with an inclusive bibliography, is presented in the final chapter. Due to war conditions, many of the recent European and Asiatic journals have not been available, so that this index and bibliography may not be complete. The illustrations of numerous authors in America and other parts of the world have been freely used by the author. Grateful thanks for this courtesy is here- by expressed to them. These contributors are too numerous for individual mention, but full credit for their drawings is given in the descriptions of the plates. Columbia University Ni:w Yobs t !m October, mm.' CONTENTS Preface CHAPTER I Introduction Bibliography 3 CHAPTER II 4 Woroninaceae Woronina Pyrrhosorus 1 »> Ro/.ellopsis CHAPTER III Ectrogellaceae Ectrogella 17 Eurychasma 22 Eurychasmidium Aphanomycopsis CHAPTER IV 0-1 Olpidiopsidaceae Olpidiopsis 31 Development of thalli and zoosporangia 33 Resting spore development and sex differentiation 38 Cellular relations between host and parasite 40 Parasites of Sa prolcyiiiu ** Parasites of Aehlya i5 Parasites of Aphanomycet "*' Parasites of I'ifthiiim *' Parasites of algae *° Parasites of cryptogams and insects ,- Pseudolpidium Pseudosphaerita Blastulidiopsis 58 Pythiella 58 vii >7559 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES CHAPTER V Sirolpidiaceae 63 Sirolpidium 63 Pontisma 63 Petersenia 66 CHAPTER VI Lagenidiaceae 70 Lagenidium 71 Lagenidiopsis 71 Mvzocytium 83 Lagena 90 Doubtful genera 92 Resticularia 92 Excluded genera 94 Achlyogeton 9-i Protascus 96 Mitochytridium 98 Rhizomyxa 98 CHAPTER VII Phvlogeny and relationships 100 Woroninaceae 100 Woronina 100 Pyrrhosorus 101 Rozellopsis 101 Ectrogellaceae 102 Sirolpidiaceae 10-i Olpidiopsidaceae 10-1 Lagenidiaceae 105 CHAPTER VIII Hosts and Bibliography 108 Plant hosts 108 Fungi 108 Olpidiaceae 108 Saprolegniaceae 108 Pvthiaceae Ill Mucoraceae Ill CONTEN Cfi .... Ill A1SM , ' Ill Myxophyceae Occillatoriaceae ... in Scytonemaceae ... Heterokontae Tribonemaceae ... Ill Crvptomonadaceae • , ... Ill Euglenaceae Dinoflagellata Peridiniaceae Diatoms Bacillariaceae Chlorophyceae Chlamydomonadaceae Zygnemaceae ...•■•• Desmidaceae ... 115 Chaetophoraceae . , . ... 115 Oedoeoniaceae ... 115 Cladophoraceae ., ... HO BrvonMuaceae ,., 1K5 \ aiuhenaceae . . . 1K5 Cnaraceae . . IK! Phaeophyceae ... 1K5 Ectocarpaceae , , , .... 116 RluxlophviTiU' „ 1K5 C eramiaceae 117 Rhodymemaceae 117 Rhodophyllidiaceae Liverworts . . . 117 Ricciaceae . . . 117 NI ■ :. ; " : ' ... in rnnli;ntihi'«l species ... 117 Gymnosperms ... 117 PmaCeaC ' . . 118 Angiosperms iig Gramineae 118 Solanaceae ... 118 Caryophyllaceae 118 Animal Hosts 1 18 Infusoria 118 Rotatoria 118 Nematode i)i,,ura ■■■'.; no Coleoptera Crustaceae THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES Species Index l-° Subject Index 121 Author Index 122 /■?'- Chapter I Introduction LIBRARY The ruNGi presented herewith as tin- simple, holo- carpic, biflagellate Phycomycetes comprise a hetero- geneous collection of approximately eighty species which .ire characterised by relatively small or re- duced, holocarpic thalli and biflagellate zoospores. Although tlu>e characters are common to all mem- bers of the group, present day evidence does not fully warrant the inclusion (if these species in one coherent family or order. The simple species were formerly included by most mycologists in the family Woroninaceae and placed among the Chytridiales, while the elongate, more mycelioid members were incorporated in the Lagenidiaceae and regarded as closely related to the Saprohgniaeeae and Py- thiaceae. Inasmuch as the Chytridiales are char- acterised by posteriorly uniflagellate zoospores, the members of the Woroninaceae can no longer be in- eluded in this order as it is now reeognized. For this reason these biflagellate species as well as the I agenidiaceae are described apart from the cby- trids. As will become evident helow, they do not constitute a well-defined order or family and it is accordingly impossible to give the group as a whole a distinctive name. They arc thus presented as sim- ple, holocarpic, hiflagellate Phycomycetes. The ma- jority of them arc Oomycete-like and appear to he either simple and primitive or reduced and degen- erate Oomycetes, hut since some species are re- ported to he isogamous. like the Zygomycetes, they must for the time being he listed under the more general term Phycomycetes. Further study of known species and the discovery of new ones will doubtless invalidate many of the present day concepts con- cerning their phylogeny and relationships, and it is not improbable that they may eventually be in- eluded in existing families and orders of the Oomy- cetes and Zygomycetes. Whether or not the known genera and species comprise several distinct and clearly defined fami- lies is not at all certain at the present time. The critical developmental stages of many species are unknown, and the limits of the genera are not sharply defined. Nevertheless as an aid iii classifica- tion and an expedient of reference, they have been grouped into rive families on the hasis of thallus structure and method of sexual reproduction. The structure of the vegetative thallus alone is obviously of questionable diagnostic value, hut in species where resting spores and sexual reproduction are unknown, it is the only hasis of distinction for the present. The order in which the families are pre seated does not always indicate degree of com- plexity, phylogenetic relationship, and evolution. The provisional family Woroninaceae is presented first because of its plasmodium-like thallus and other structural similarities it has in common with the Plasmodiophorales, hut the second family, Bctrogellaceae, s h o w s distinct saprolegniaceous characteristics by its diplanctic zoospores. How closely this family is related to the Saprolgcnialcs cannot he ascertained at present, because so little is known about its resting spores or the occurrence of sexuality. The Olpidiopsidaceae should perhaps be placed next to the Lagenidiaceae because of its pre- dominantly heterogamous type of sexual reproduc- tion. The Sirolpidiaceae, however, is placed in this relative position because its thallus has a tendency to become elongate, filamentous, mycelioid and frag- mented like that of some species of Lagenidium and Mysocytium. On the other hand, its thallus may sometimes be reduced and distinctly olpidioid. The occurrence of such thalli and the fact that nothing is known about the type of sexual reproduction makes the position of this family next to the Lageni- diaceae very problematical. The Lagenidiaceae ap- pears to be the most complex as far as thallus struc- ture and method of sexual reproduction are con- cerned and is accordingly presented as the highest family in the evolutionary series. In most species tin thallus is elongate and often distinctly mvee- lioid, but it may also be reduced, unicellular, and olpidioid. However, the resting spores or oospores are usually developed in partially or fairly well differentiated oogonia as in the higher Oomycetes. The simpler, olpidioid species were discovered shortly before the middle of the last century. Al- though they had probably been observed earlier. Nageli ('44) was among the first to describe and il- lustrate them as globular bodies in the mycelium of water molds, but he mistook them for a part of the normal life cycle of the host. Cienkowski ('.55) like- wise misinterpreted the parasites which he found in Achlfia prolifera as a third type of sporangia de- veloped by this host, hut in the same year the para- sitic nature of these intrainatrical bodies was clearly recognized by Alexander Braun. The species which he described in Saprolegnia fcra.r is now believed to relate to 0/ pidiopsis Saprolegniae. He named this parasite Chytridium Saprolegniae and placed it in his sub-genus Olpidium of the Chytridiaceae. Thus. at an early stage these (Jlpiiliupxix parasites became associated with the ehytrids in myeologieal litera- ture, and this fact together with their striking simi- larity of thallus structure .and type of development to that of the olpidioid ehytrids arc probably the chief reasons why most mycologists up to the pres- ent time have included them in the Chytridiales. Despite Braun's excellent study Pringsheim ('60) was still doubtful about the nature oi these parasites and believed that they might possibly be the anthcri THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES dia of Saprolegnia. However, an intensive study by Cornu in 1872 settled forever the question of whether they are parasites or relate to the life cycle of the host. He proved conclusively their parasitic nature and established the genera Olpidiopsis and Woronina for the biflagellate species which occur in Achhia, Aphanomyces, and Saprolegnia. Like Braun he included these parasites in the Chytridiales. Cornu observed that the resting spores were usually accompanied by one or more attached, thin-walled, empty vesicles which he assumed to be male cells or antheridia. In 1878 Reinsch observed the passage of the protoplasm of the small cell into the larger one, and since that time the resting spores have been generally regarded as zygotic in origin. Cornu and Reinsch observations were followed by the early studies of Fischer which contributed much to our knowledge of the developmental phases of these fungi. His observations and conclusions were never- theless incorrect and confusing in several respects, and it was not until 1892 that he corrected some of his errors. Subsequent students of these olpidioid parasites, including Zopf ('84.), Schroeter ('86, '97), Petersen ('09, '10), Minden ('11), and others, con- tinued to include them in the Myxochytridiales, al- though Lotsy ('07) and Vuillemin ('08) emphasized that the so-called chytrids with biflagellate zoo- spores have a different origin from those with uni- flagellate zoospores and should be sharply separated from the latter. These differences were clearly rec- ognized by Scherffel in 1925, who for the first time removed Olpidiopsis and similar genera from the Chytridiales and placed them at the bottom of a Saprolegniales-Peronosporales series. Seherffel's in- terpretation has been followed by a few mycologists, particularly Weston ('35, '41) and Sparrow ('35, '42). In the meantime, while data about the simple olpidioid parasites were accumulating, extensive studies had been made on the more complex, elon- gate and mycelioid species at the other end of the series. In the group now known as the Lagenidiaceae the genera Mysocytium and Lagenidium were dis- covered and created by Schenk in 1858 and 1859. Because of their elongate thalli and the fact that the zoospores may be formed in a thin, extramatrical vesicle, these species were first regarded as members of the genus Pythium by Schenk, Pringsheim ('58, '60), and Walz ('70), although it was not then known that the zoospores are biflagellate. These workers figured and described the zoospores as uni- flagellate, but the subsequent studies of Zopf ('78, '79, '84, '87) proved the presence of two flagella as well as the fact that sexual reproduction in many of the species is heterogamous. These discoveries coupled with the association of Mysocytium and Lagenidium species with Pythium in mycological literature emphasized their relationship to the higher filamentous Oomycetes, and the Lagenidia- ceae were accordingly never included directly in the Chytridiales. Most mycologists have subsequently incorporated this family with the Saprolegniales. Since the time of Zopf several unicellular, olpidioid species of Myzocytium and Lagenidium have been discovered, the thalli of which are strikingly similar to those of Olpidiopsis, so that the gap between the Olpidiopsidaceae and the elongate mycelioid mem- bers of the Lagenidiaceae has been bridged as far as thallus structure is concerned. These simple Phycomycetes are fairly common in nature and almost world wide in distribution. So far they have been reported from Europe, Asia, and North America, and when more extensive studies are made they will doubtless be found to occur in Africa and Australia also. They are ubiquitous in host range and occur in diatoms, blue green, green, brown, and red algae, fungi, liverworts, mosses, gvmnosperms. and angiosperms. Among animal hosts they have been reported in infusoria, rotifers, nematodes, weevils, mosquitoes, copepods and crustaceans. They are predominantly aquatic and may occur in marine as well as fresh water. Most species of the families Ectrogellaceae and Sirolpi- diaceae parasitize marine algae. The majority of species are parasitic and eventually kill their hosts, while others are weakly parasitic or saprophytic. Obligate parasitism has been reported for a few spe- cies. They may cause marked reactions in their hosts which involve increased cell division and enlarge- ment and lead to gall formation. Other species merely kill and absorb most of the contents of the host cells. Only one species appears to be of eco- nomic significance. Lagena radicicola in conjunction with other fungi causes a root disease of wheat, barley, rye, and corn which is characterized by stunted curved roots and a reduction in the root system as a whole. The stems of infected plants are considerably shorter than those of normal indi- viduals, while the leaves may become pale-green and lighter in color and under certain conditions show "browning symptoms." Since several of these species do not appear to be closely related, differences in types of development are to be expected, and it is impossible to give an introductory account which will apply to all fami- lies and genera. In the family Woroninaceae, as it is here interpreted, the vegetative assimilative thal- lus has been described as a plasmodium which un- dergoes cleavage at maturity. The segments thus formed may develop either into zoosporangia or resting spores. The former may be united in a spo- rangiosorus or lie free, and give rise to zoospores which are discharged to the outside and reinfect the host. The resting spores whenever formed usually appear as the fungus culture becomes older and more mature. In W. polycystis they are usually ag- gregated in compact cystosori as in some genera of the Plasmodiophorales, while in other species they lie loose and free. Like the sporangia, they form zoospores in germination. Neither zoosporangia nor resting spores have been observed in Pyrrhosorus. The spore mother cells which comprise the sorus divide three times to form eight free, thin-walled INTRODUCTION 8 spores, and these are Boon transformed directly into ■oospores, without going through a dormant period. In the polysporangiate species of Hoaellopsia 1 1 » » - segments "I the plasmodium form either zoospo rangia or resting spores, but unlike in Woronina they become separated by septa which the host cell forms. As a result, neither sporangia nor resting spores are united in sporangio- and cystosori, re- spectively. In the monosporangiate species of tins genus ele.iv age of the thallus apparently does not oc- cur, since each infection is reported to give rise to one (oosporangium or resting spore. In .ill species nt the Woroninaceae, however, the zoospores encyst temporarily on the surface of the host and form dur- ing germination a penetration tube through which the Spore content passes into the host cell as a naked protoplast. Nevertheless, marked differences in type of development occur in this provisional family which clearly indicate that the generic and family concepts arc inadequate. The resting spores in all three genera appear to he asexual, since no fusion of gametes has been observed during their forma- tion. In the second family. Ectrogellaceae. no plasmo- dium occurs, and each zoospore gives rise to one (oosporangium or resting spore. The zoospores of this family, however, exhibit true diplanetism like those of Achilla and other genera of the Saproleg- niales. Resting spores are known in only two spe- cies of this family. In K. perforans they are asexual or possibly parthenogenetie. while in /•.'. Licomo- phorar they have been reported to be zygotic by Scherffel i '25 ). hut the evidence of sexuality in this species is not conclusive. The family Olpidiopsid- aceae includes approximately thirty species which have the same type of vegetative development as those of the Ectrogellaceae. In some species of Olpidiopsis the zoospores exhibit what has been de- scribed as partial and primitive diplanetism, while in 0. Oedogon'iOTum and Pythiella vernalis they are typically diplanetic. Well defined sexuality occurs in a large number of members of this family. At the close of the vegetative period in Olpidiopsis fusion between thalli of unequal, and rarely of equal, size occurs which results in the formation of a thick- walled zygote. These thalli are generally described as OOgOnia and antheridia on the basis of relative size, but they are not markedly differentiated as gametangia or gametes. Nonetheless, the evolution and differentiation of such gametangia and heterog amy are foreshadowed in Olpidiopsis. The degree of sexuality varies considerably in this genus. Some species are wholly sexual or parthenogenetie while others are partially so and form only a few zygotes. In Pythiella an egg cell or oosphere with a trace of periplasm is formed in the oogonium— apparently an advance in heterogamy toward the Pytkium type. So far as is now known, the development of the thal- lus in the Sirolpidiaceae is similar to that of the Ectrogellaceae and Oljiidiopsidaee.ie with the ex- ception that it may become more elongate and fila- mentous and undergo segmentation. The segments thus formed may separate and are transformed di- rectly into olpidioid zoosporangia. The occurrence of resting spores is unknown or at least very doubt- ful in this family, and no evidence of sexuality has been reported. In the family I.agcnidiaceae the content of the zoospore does not enter the host as a naked ainoe boid body, but the tip of the germ tube elongates, enlarges, and eventually develops into the mature thallus. In tin- majority of species the thallus is elongate, septate, and may become distinctly my - eclioid. Reduced unicellular, olpidiod thalli. how- ever, are not uncommon. In some species the seg- ments of the thallus may separate as in the Sirolpi- diaceae. The segments are transformed either into zoosporangia or gametangia and both types of re- productive structures may be intermingled in the same thallus. The zoospores may be fully developed in the zoosporangia and swim directly away after emerging or are only partly formed in sporangia and undergo further development in an extramatrical vesicle. In other species the content of the sporan- gium emerges to the outside as a naked protoplasmic mass and undergoes cleavage into zoospores in much the same manner as in Pythium. The presence of a vesicular membrane around the protoplasmic mass and the zoospores which are subsequently formed has been reported in a number of species hut appears to be lacking in others. In some species the zoospores encyst in a mass at the mouth of the exit tube and exhibit marked diplanetism. Sexual reproduction in this family is predominantly heterogamous. but in Lagenidium sacculoides, Lagena radieicola, a n d Resticularia nodosa it is reported to be isogamous. The segments of elongate thalli as well as entire re- duced unicellular thalli which function as game- tangia are only slightly or not at all differentiated as sexual organs. The female gamctangium or oogonium, however, is usually larger, more vesicu- lar, and frequently barrel-shaped, while tin' 80- called antheridium is usually elongate and tubular. Differentiation of an egg cell and periplasm in the female gamctangium has not been conclusively dem- onstrated, but the ooplasm may contract and aggre gate toward the conjugation tube or pore during plasmogamy. The zygote which results from fusion lies free in the oogonium and is generally referred to in the literature as an oospore. In some species the antheridium is lacking, and the resting spores are funned parthenogenetically. BIBLIOGRAPHY : INTRODUCTION Braun, A. 1855a. Her K'gl. Preuss. Akad. Wiss. is;,:,: :is:,. . 1855b. Abh. K'gl. Akad. Wiss. 1855: 61. Cienkowski, I., 1865. Mot. Zeit. 13: 801. Cornu, M. 1H7.». Ann. Sci. Nat. .-> ser. 15: 113. Fischer, A. 1880. Hot. Zeit. :is: 689. . 188S.Jahrb. Wiss. Bot. 13: 286. . . 1892. Rabenhorst's Krypffl. I. t::i7. Lotsy, .1. 1'. mo?. Vortrage iiber Botanische Stammen- geschichte I. Jena. 4 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES Minden, M. 1911. Krypt'fl. Mark Brandenburg 5: 262. Nageli, C. 1844. Zeits'chr. Wiss. Bot. no. 1, 3: 22. Petersen, H. E. 1909. Bot. Tidsskr. 29. . 1910. Ann. Mycol. 8: 539. Pringsheim, N. 1858. Jahrb. Wiss. Bot. 1: 384. . 1860. Ibid. 2: 205. Reinsch, P. 1878. Ibid. 11: 283. Scbenk, A. 1858. Uber das Vorkommen Contractiler Zel- len ira Pflanzenreich. Wurzburg. . 1859. Verh. Phys. Med. Gesell. Wurzburg 9: 27. Scherffel, A. 1925. Arch. Protistk. 52: 38. Schroeter, J. 1886. Cohn's Krypt'fl. Schlesiens 3: 195. . 1897. Engler und Prantl, Die Naturpflanzf. I, 1: 85. Sparrow, F. K. 1935. Proc. 6th Intern. Bot. Congress 11: 182. . 1942. Mycologia 34: 113. Vuillemin, P. 1908. Prog, rei Bot. 2: 1. Walz, J. 1870. Bot. Zeit. 28: 556. Weston, W. H. 1935. Proc. 6th Intern. Bot. Congress 1: 266. . 1941. Symposium on Hydrobiology, p. 130. Univ. of Wisconsin Press. Zopf, W. 1878. Verh. Bot. Verein. Brandenburg 20: 77. . 1879. Hedwigia 18: 94. . 1884. Nova Acta Ksl. Leop.-Carol. Dcut. Akad. Nat. 47: 143. . 1887. Abh. Naturf. Gesell. Halle 17: 97. Chapter II Woroninaceae Minden, 1911. Krypt. Fl. Mark Brandenburg 5: 224. This family was proposed by Minden for all simple holocarpic species, exclusive of the Lagenidiaeeae, which had been reported to have biflagellate zoo- spores, and as such it included Olpidiopsis, Pseudol- pidium, JVoronina, and Rozella. Minden placed this family in the Chytridiales, and together with the Olpidiaeeae and Synchytriaceae it comprised the so- called Myxochytridiales of Fischer. In creating the Woroninaceae, Minden ignored Petersen's ('09) earlier-named family Pseudolpidiaeeae which was proposed for Olpidiopsis and Pseudolpidium. Since Minden's time numerous other genera have been added to the Woroninaceae, and this family has been rather generally regarded as a convenient dumping ground in the Chytridiales for fungi of this type with biflagellate zoospores, although Petersen and Scherffel in particular emphasized the similarity and relationships of such fungi to the Lagenidiales and Saprolegniales. Sparrow ('42) discarded the family name Woroninaceae entirely, presumably be- cause he believed that the genus JVoronina, after which the family takes its name, belongs in the Plas- modiophorales. While the data at hand favor the view that JV. polycystis, at least, is a member of this order, further intensive study of JVoronina is needed before this question can be settled. Until this rela- tionship is established, the present author is tempo- rarily retaining the Woroninaceae in a restricted sense for Woronina, Pi/rrhosorus and Rosellopsis. By this interpretation it is not, however, to be re- garded as a well established and unquestionable family of closely related genera, but still as a con- venient catch-all for species which are reported to have a plasmodial vegetative stage but which at pres- ent cannot be definitely included in the Plasmodio- phorales. In Woronina, Pyrrhosorus, and the septi- genous species of Rozellopsis the plasmodium is re- ported to undergo segmentation into a number of closely aggregated or loose and separate spores, spore mother cells, sporangia, or resting spores, and the suggestion is obvious that such species may pos- sibly be transition forms between the Plasmodio- phorales and the non-plasmodial, non-soric genera. However, our knowledge relative to both groups is plate 1 Woronina polycystis Figs. 1, 2. Biflagellate zoospores. Fischer, '82. Figs. 3, 4. Anteriorly biflagellate zoospores. Cook and Nicholson, '33. Figs. 5, 6. Early infection stages. Fischer, I.e. Fig. 7. Same. Cook and Nicholson, I.e. Figs. 8-10. Amoeboid changes in shape and position of young parasite in host cell. Fischer, I.e. Figs. 11, 12, 13, 15. Successive stages in development of the parasite and its cleavage into a sporangiosorus. Note local hypertrophy and septation of host hypha. Fischer, I.e. Fig. 14. Vacuolate thallus undergoing centrifugal cleav- age. Fischer, I.e. Fig. 16. Sporangiosorus. Cornu, '72. Figs. 17-20. Maturation, cleavage, and emission of zoo- spores from a sporangium. Fischer, I.e. Fig. 21. Small empty sporangiosorus. Cornu, I.e. Fig. 22. Cleavage of thallus into a cystosorus. Fischer, I.e. Fig. 23. Mature cystosorus. Cornu, I.e. Fig. 24. Septate, locally hypertrophied hypha of Sapro- legnia with five cystosori of various sizes and shapes and two empty sporangiosori. Fischer, I.e. Fig. 25. Elongate, irregular cystosorus. Cook and Nicholson, I.e. Fig. 26. Variously-shaped resting spores from a cys- tosorus. Fischer, I.e. Figs. 27, 28. Thick-walled resting spores. Cook and Nicholson, I.e. Fig. 29. Germination of cystosorus. Resting spores swelling and vesieulating to become zoosporangia. Fischer, I.e. Fig. 30. Germination of resting spores. Cook and Nicholson, I.e. WORONINACEAE PLATE 1 Woronina polycystis THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES so incomplete at present that this suggested rela- tionship is largely hypothetical. WORONINA Cornu, 1872. Ann. Sci. Nat. 5 ser. 15: 176. (PLATES 1 AND 2) Thallus intramatrical, plasmodial, naked but im- miscible with the host protoplasm; cleaving into segments which become zoosporangia or resting spores. Zoosporangia and resting spores united in compact sporangiosori and cystosori respectively, or lying loose and free of each other. Zoosporangia usually spherical, oval or ellipsoid with a short exit papilla or an elongate cylindrical and basally in- flated exit tube. Zoospore pyriform or somewhat kidney-shaped with one to several refractive gran- ules, heterocont (?): emerging singly and fully formed; occasionally liberated within the host cell; swimming directly away in a comparatively slow and even manner. Resting spores spherical, oval, irregular and polygonal, with a smooth, spiny or sculptured outer wall; producing one or several zoo- spores directly in germination. This genus has been fully discussed by the writer ('42) in relation to the phylogeny and relationships of the Plasmodiophorales. It includes at present five species most of which are incompletely known and very doubtful, and in light of present-day knowledge Woronina appears to be scarcely more than a dump- ing ground for species with a plasmodial stage which cannot be incorporated with certainty at present in the Plasmodiophorales or Proteomyxa. The type species, W. polycystis, has a life cycle almost iden- tical to that of Octomyxa of the Plasmodiophoraeeae, while W. glomerata resembles species of the zoo- sporic Myxozoidia or Proteomyxa by its animal type of nutrition. As a consequence these two species have been included in the Plasmodiophorales (Spar- row, '42) and the Proteomyxa (Zopf, '94; Seherffel, '25) respectively. The other species, W. aggregata, W. elegans, and W. asterina, are so imperfectly known that it is impossible to determine their tax- onomic and generic distinctions. Woronina must ac- cordingly be interpreted for the time being as a in- coherent and questionable group of species. It is nonetheless phylogenetically significant, because it includes organisms which appear to be transitional forms between the Proteomyxa, Plasmodiophorales, and simple, holocarpic biflagellate oomycete-like fungi. Numerous undiscovered Woronina-like spe- cies doubtless exist, the discovery of which may pos- sibly bridge the present-day gaps. Sparrow ('42) disposed of Woronina directly by including it in the Plasmodiophorales without pre- senting additional evidence of its relationship to this order, but this disposition merely overlooks and does not clear up the problems involved. Woronina polycysiis will probably prove to be a plasmodio- phoraceous species closely related to Octomyxa Achlyae, and in that event some of the remaining species must be segregated in another genus. Woro- nina glomerata may well be a member of the Proteo- myxa as Zopf and Seherffel contended, but further study is necessary to settle this point. Inasmuch as these two species differ in certain re- spects their development will be described sepa- rately. In W. polycysiis the contents of the zoospore enters the host hypha as a naked protoplasmic mass (PL 1, figs. 6-10), undergoes amoeboid changes in shape, develops into a plasmodium-like thallus as it feeds on the host protoplasm, and causes local hyper- trophy (figs. 11, 12). At maturity the thallus cleaves into segments (figs. 13, 14) which develop into zoosporangia (figs. 15, 16) and form a typical sporangiosorus. As in Octomyxa, the peripheral zoosporangia are usually independent with a single exit papillae, while the deeper lying ones may be confluent with a common papilla for zoospore emission. Each sporangium pro- duces a number of biflagellate zoospores (figs. 18, 19) which reinfect the host hyphae. As the culture becomes older, the mature thalli cleave into small segments which become the resting spores. These remain closely attached and form compact cystosori of various sizes and shapes (figs. 23—25). As in Ligniera and Polymyxa, the cystosori may be elon- gate, irregular, flattened, oval and almost spherical, and include a few to numerous polygonal spores, each of which produces one zoospore in germination. As to the structure of the zoospores there is, how- ever, considerable disagreement among students of this species. Fischer described and figured them as ellipsoid (fig. 1) with a slight indentation at one side and two slightly unequal flagella. The shorter flagellum arises from the anterior end and extends forward in swimming, while the longer one is in- serted laterally and projects backward. It must be noted, however, that Fischer's description was not applied directly to W. polycystis but related to the zoospores of Rozella, Olpidiopsis, and IVoronina as a group. Cook and Nicholson ('33), on the other hand, described the zoospore as spherical (fig. 3, 4) with two anterior flagella which lash back and forth in breast-stroke fashion in swimming. These work- ers were non-committal about the relative lengths of the flagella, but most of the figures show them to be equal in length. One of their figures (fig. 3), how- ever, shows flagella of unequal length. If the zoo- spores are anteriorly biflagellate, as Nicholson and Cook contended, and heterocont as Fischer reported, they do not differ fundamentally from those of the Plasmodiophorales. In view of the wide differences in observation it is not altogether improbable that what is now called W. polycystis may relate to more than one organism or species. Further critical stud- ies of this species are therefore highly essential. So far schizogony has not been reported in W. polycystis, and nothing is known about the type of nuclear divisions in the vegetative thallus. This parasite has never been studied critically from fixed w ORONINACBAE and stained material, and it is not improbable thai future investigation may reveal the occurrence 01 schizogony and "promitotic" divisions. It should be noted iii tiiis connection, however, that the walls of the sporangia and resting spores of W. polycystis give 'l delinite cellulose reaction, while those of the Plasmodiophorales do not. Furthermore, in germi- nation tin- content of the EOOSpore enters the host through ;i penetration tube (tins. 5 7) leaving the empty ease on the outside of the host eell .is ill Olpidiopsis, Rosellopsis, etc. In the Plasmodio- phorales the zoospores are reported to enter directly. The latter difference may not he important, hut the presence of cellulose is fundamentally significant, according to present-day student of phylogeny. Woronma glomerata parasitizes species of Vau- cheria and causes septation of the filaments without hypertrophy (PI. 2. fig. 1). It forms sporangio- and cystosori, hut the resting spores and sporangia are not closely aggregated and compact as in W. poly- ci/stis hut may lie loose and free of each other (figs. <>. 10. l.'i). Motile zoospores were observed by To- kunaga who described them as biflagellate, hut noth- ing further is known about the number, position and relative length of the flagella. The zoospores appar- ently enter the host directly and divide, according to Zopf ( '94, p. 54). The daughter cells soon become amoeboid and after a while may divide also (fig. 2). The amoebae feed directly on the host protoplasm and engulf starch grains, chlorophyll granules, etc., whereby they may become quite green in color. This engulfed food is held in sharply-defined yaeuoles (fig. I), according to Scherffel. and later as the cleavage segments of the plasmodium are trans- formed into zoosporangia or resting spores the ex- traneous waste material is extruded to the outside (fig. 5) like in typical proteomyxean species. As a consequence, the groups of sporangia and spores are usually accompanied by masses of dark brown waste material i figs. 1. 5. Oi. 10). The amoebae may unite by fine cytoplasmic strands or pscudopods and form a reticulate plas- modium which often completely fills the delimited portions of the host filament. The amoebae may separate again, which suggests that they do not lose their entity as cells in the large plasmodium but in- stead remain distinct and form a pseudoplasiiindiiini suggestive of that in the Aerasieae. This, howcyer. remains to be shown. Zopf nevertheless reported that the large plasmodium cleaves into segments or "Theilplasmodien" at maturity, each of which forms a group of zoosporangia or resting spores. This di- vision of amoebae and plasinodia is somewhat sug- gestive of schizogony in the Plasmodiophorales. The resting spores, unlike those of II'. polycystis and the Plasmodiophorales, function as zoospo- rangia in germination and produce numerous zoo- spores. The content of the spore undergoes cleavage i tiir--. ii. 12) into zoospore initials, while the endo spore expands out through the germ pore and forms a globular vesicle which then develops a cylindrical exit tube of variable length ( fig. 13A). Occasionally. Vesicles of two adjacent spores fuse and form a coin moil one (figs. I 3 H, C). After the \esiele and exit tube have been formed, the zoospores in the resting Spore pass through these structures to the outside of the host. The hyaline vesicle in this species is some what similar in appearance to the thin-walled, hya- line zoosporangia which are developed on the sur- face of germinating resting spores of many chytrid species, but whether they are to be regarded as such or as inflated bases of exit tubes is not certain. As noted above. Zopf and Scherffel regarded IV. glomerata as an organism with a fungus-like life cycle and an animal type of nutrition, and they ac- cordingly believed that it should be placed in the family (iymnococcaceac among the Proteomyxa. W. POLYCYSTIS Cornu, I.e., pi, 7, figs. t-19. II'. polycystis var. scalariformis. Petersen, Hilo. Ann* Mycol. 8:557. Sporangosori oval, ellipsoid, somewhat irregular or elongate, 30 X 100 p., 60 X 476 p, often in linear rows, lying in successively delimited septate seg- ments of the host hyphae. Zoosporangia occasionally single, usually in small or large groups, hyaline, smooth, spherical, 12— 20 ju, oval, ellipsoid or polyg- onal with a short exit tube, or papilla. Zoospores hyaline with one small granule or globule, elongate, 2 X 4 /«.. or spherical 3.5—4 /*.. Cystosori spherical, ellipsoid, barrel-shaped, cylindrical or irregular. 42-140 ju, 50 X 308 /x, dark brown, covered on the surface with numerous cone-shaped and pointed pro- jections which relate to the outer cysts or spores. In- dividual cysts or resting spores thick-walled, spheri- cal or polygonal, 4-8.(5 p in diameter, usually com- pactly united; producing one (?) zoospore in germi- nation. Parasitic in the vegetative filaments, zoospo- rangia, zoospores, antheridia and oogonia of Sapro- legnia monoica and S. thureti in Germany (Fischer, '82; Minden, 11); Achlya polyandra, A. racemosa, Achhia sp.. Saprolegnia spiralis and Saprolegnia monoica in France (Cornu, I.e.; Dangeard, '90); Achlya racemosa in Russia (Sorokin. '83, 'Nil;) Saprolegnia sp., in Switzerland (Maurizio, !••">); Saprolegnia ferax, Saprolegnia sp., Achlya tic Bary- ana, Achilla sp.. in England ( Hartog. '90 J Smith and R.iiusbottoiu. 17; Cook and Nicholson, '.'(3; Spar- row. ':i(i ) ; Saprolegnia sp., and Achilla sp.. in Den- mark ( Petersen. 'Oil, '10), and Achlya sp.. in New York, L. S. A. (Sparrow. '32, '33), causing septa- tion and marked hypertrophy of the infected fila- ments. Until recently most workers regarded the para site which Pringsheim ('60) described in Achhia dioica as W. polycyttit, but Couch ('Jill) has shown that it relates to another species. Pringsheim clla dioica, with posteriorly uniflagellate zoospores. Cook ('32) reported that W. polycystis iiarasitiz.es Oedogonium crassusculum var. idiosporium in Eng land. This is the only account so far of its occurrence in hosts other than the water molds. The plasmodi.i THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES and sporangiosori of Cook's fungus may possibly belong to either W. glomerata or W. aggregata, or a new species. According to Fischer ('92) W. poly- ci/stis is limited to species of Saprolegnia and will not infect Achlya, but subsequent workers have not confirmed his observations. So far no intensive cross inoculation experiments have been made. The valid- ity of Peterson's forma scalariformis is open to seri- ous question. As noted elsewhere, Fischer, Zopf, Cook and Nicholson described the mature vegetative thallus as a plasmodium, but they did not prove conclusively whether it arises from a single infection or by fusion of several amoebae within the host cell. Minden be- lieved that in cases of multiple infection fusion of several protoplasts is not an improbable occurrence. According to Fischer the thallus may exhibit many of the characteristics of a plasmodium, undergoing amoeboid changes in shape which are accompanied by slow and weak wave-like streaming of its dense protoplasm. As to its mode of feeding, Zopf main- tained that it engulfs the protoplasm of its host di- rectly. Cook and Nicholson reported that it feeds on glycogen and the oil globules of its host, because they were able to demonstrate by microchemical tests the presence of the same substances in both the host and parasite. They, furthermore, maintained that the mature plasmodium or young sorus becomes surrounded by a cellulose wall as it segments into sporangia and spore rudiments ; yet none of their figures show the presence of such a wall. W. GLOMERATA (Cornu) Fischer, 1892. Rabenhorst's Kryptog. Fl. I, 4:64. Chi/trkiium glomeratum Cornu, I.e., p. 187, pi. 7, figs. 20-2-2. * Zoosporangia occasionally single, more often in small groups or loose aggregates which measure 50-96 fi X 70-300 /* ; individual zoosporangia hya- line, smooth, oval or spherical, 10-33 /x, with a single broad flask-shaped exit tube which may or may not project beyond the surface of the host. Zoospores hyaline, oval, 2-2.6 ju, somewhat kidney-shaped or ellipsoid, 2.4 X 3.6 ft., with numerous small gran- ules ; position and relative lengths of flagella un- known. Resting spores in groups like the zoospo- rangia, hyaline, spherical or ellipsoid, 12-24 /*, with a granular content, thin endospore, and thick exo- spore which has a net-like sculptured surface simi- lar to that of Tilletia Iritici; functioning as a zoo- sporangium in germinating and producing numer- ous zoospores. Parasitic in J'aucheria sessilis, J', terrestris and Vaucheria sp., in France (Cornu, I.e.), Germany (Zopf, '94), Hungary (Scherffel, '25), Bulgaria (Valkanov, '31) and Japan (Tokunaga, '33), caus- ing septation but no hypertrophy of the infected host filaments. W. AGGREGATA Zopf, 1894. Physiol. Morph. Nied. Organismen 4:(i0. Zoosporangia, 10 to 20 in number, grouped in round grape-like clusters or sori, hyaline, smooth and spherical with a tubular cylindrical exit tube. Zoospores and resting spores unknown. Parasitic in Mougeotia sp., in Germany. This species has the same type of development as TV. glomerata, according to Zopf, but differs pri- marily by the arrangement of the zoosporangia >n the sorus and the presence of non-inflated exit tubes. Zopf also observed a similar JT'oron/tta-like organ- ism in the mycelium of I'ilobolus, but he did not iden- tify it. DOUBTFUL SPECIES W. ELEGANS (Perroncito) Fischer, I.e., p. 66. Chytridmrn elegans Perroncito, 1888. Centralbl. Bakt. Parasitk. 4: 295. Sporangesori single, spherical to star-shaped, 6-1 10 fj., rosy red in color and made up of 8-20 spo- rangia. Zoosporangia smooth, spherical, 20-30 (t., egg-shaped or pyriform with several 4-5 /j, X 5-100/j. cylindrical exit tubes which bore through the cuticle of the host. Zoospores oval, somewhat elongated, 2-4 jx. X 4-5 fi, with two long flagella and numerous minute red granules ; position and relative lengths of flagella unknown. Cystosori and resting spores unknown. Parasitic in Philodina rosetta in Italy. plate 2 Woronina glomerata Fig. 1. Septate filament of Vaucheria terrestris with six cystosori. Zopf, '94. Fig. 2. Septate portion of a V. sessilis filament with numerous amoebae, some united by fine protoplasmic strands and containing chlorophyll granules. Zopf, I.e. Fig. 3. Same, five hours later. Amoebae have separated, begun to retract their pseudopods, and are rounding up. Extraneous chlorophyll granules have been extruded. Zopf, I.e. Fig. 4. Two amoebae with extraneous material in food vacuoles, Scherffel, '25. Fig. 5. Sporangiosorus of four sporangia, one of which has emitted its zoospores. Extruded waste material lying nearby. Scherffel, I.e. Fig. 6. Large sporangiosorus. Zopf, I.e. Fig. 7. Two large sporangiosori. Tokunaga, '33. Fig. 8. Single sporangium undergoing cleavage. Zopf, I.e. Fig. 9. Zoospores emerging from zoosporangia. Note inflated exit tubes. Zopf, I.e. Fig. 10. Cystosorus of loosely united and separate rest- ing spores. Zopf, I.e. Fig. 11. Enlarged view of resting spore with sculptured exospore. Zopf, I.e. Fig. 12. Early germination stage. Zopf, I.e. Fig. 13. Group of germinated resting spores with long exit tubes. In two of the pairs the superficial zoospo- rangia or indospores have fused to form a common vesicle. Zopf, I.e. Fig. 14. Resting spore of II'. asterina. Tokunaga, I.e. WOIIONIN.MKAK PLATE 2 10 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES This species is at present a doubtful member of the genus, since the cystosori and resting spores are unknown. It differs i'rom the other species by the presence of thick greatly elongate exit tubes on the zoosporangia. W. ASTERINA Tokunaga, 1933. Trans. Saporo Nat. Hist. Soc. 13:26. PI. 2, figs. 15, 16. Zoosporangia 1 to 20 in number, arranged in sin- gle or double rows in delimited segments of host hvphae which measure 18-30X96-216^; indi- vidual zoosporangia, hyaline, smooth, spherical, 12-19 ,u, opening by a small papilla. Zoospores hya- line, spherical or ovoid, 3-4. /x; position and relative lengths of flagella unknown. Resting spores loosely aggregated in single or double rows, or lying free; hyaline, spherical, 12-22^, with large, broadly conical or pyramidal spines ; germination unknown. Parasitic in Achlya americana in Japan, causing septation by no hypertrophy of the host hyphae. The validity of this species as a member of JVoro- nina is highly questionable and the present writer is inclined to exclude it. The resting spores and spo- rangia are only loosely aggregated and often lie free in the segments of the host hyphae, and they may have arisen from separate individual thalli as in spe- cies of Olpidiopsis. Furthermore, the resting spores (fig. 14), are strikingly similar in structure and ap- pearance to those of 0. fusiformis (0. minor.). Un- like species of Olpidiopsis, however, TV. asterina does not cause hypertrophy of the host hyphae. but whether or not this character is specific remains to be seen. PYRRHOSORUS similar to those of many of the simple holocarpic biflagellate isocont Oomycete-like fungi, and off- hand it might be regarded as a transition form be- tween this group and the Plasmodiophorales. How- ever, to interpret it as such does not seem fully war- ranted at present, since the complete life cycle of P. marinus apparently is not known. For the time being, Pyrrhosorus is included in the Woroninaceae as this family is herewith interpreted. P. MARINUS Juel, I.e., p. 14, figs. 1-29. Plasmodium or thallus partly or completely filling host cell and extending into adjacent cells. Spore- mother cells spherical, 8 yu, with numerous ref rin- gent orange globules. Zoospores pyriform, 2.5 X 4.5 fx, with an orange pigment spot; flagella op- positely directed in swimming. Saprophytic in dead branches of C ystoclonium purpurascens in Sweden. The life cycle of P. marinus is as follows: In the early developmental stages it consists of small glob- ular thallus lying within the host cell (fig. 2). Such thalli may often be associated in pairs (fig. 3) or groups, and Juel accordingly considered it possible that they may later coalesce and form a large Plas- modium. The uninucleate thallus grows in size as its nucleus enlarges (fig. 4) and apparently divides. Mitoses in the plasmodium have not been observed, and Juel was uncertain as to the manner of origin of the multinucleate stages. A later stage is shown in figure 5 of a plasmodium witli four large nuclei. The developing plasmodia apparently have the ability to dissolve intervening cell walls (fig. 5) and may eventually occupy several cells. Although they may be distinctly amoeboid in shape with numerous blunt Juel, 1901. Bih. Kgl. Svensk. Vet.-Akad. Hand. 26, afd. Ill, No. 14: 14. (plate 3) Thallus intramatrical, plasmodial, naked when young but apparently immiscible with the host pro- toplasm; becoming invested with a wall at maturity and segmenting into spore-mother cells which ag- gregate to form a sorus. Spore-mother cells divid- ing three times to form octads of naked spores which soon become transformed into laterally biflagellate, isocont zoospores. Zoosporangia and resting spores lacking (?) or unknown. This genus was created for an orange-colored fungus which Juel found parasitizing a red alga, C ystoclonium purpurascens, in Sweden. As has been pointed out by the writer ('42) in his book on the Plasmodiophorales, it has many characteristics in common with these organisms, but differs by its lat- erally biflagellate isocont zoospores, naked spore- mother cells and spores; lack of zoosporangia and resting spores; and by its saprophytic habit of life. As is shown in figure 1 its zoospores are strikingly plate 3 Pyrrhosorus marinus (All figures after Juel) Fig. 1. laterally biflagellate isocont zoospores with an orange colored eye spot. Fig. 2. Uninucleate thallus. Fig. 3. Paired young thalli. Fig. 4. Uninucleate thallus with enlarged primary nu- cleus. Fig. 5. Four-nucleate thallus passing through cell wall. Fig. 6. Multinucleate thallus. Fig. 7. Multinucleate amoeboid thallus. Fig. 8. Cleavage into spore-mother colls. Fig. 9. Sorus of spore-mother cells. Fig. 10. Isolated spore-mother ceil. Fig. 11. A sorus, the spore-mother colls of which have divided into groups of four daughter cells. Fig. 12. Spindle-shaped spore-mother cells (?) in a branched thallus. Fig. 13. Spindle-shaped spore-mother colls and acces- sory sterile colls in an elongate host cell. Fig. 14. Sorus with spore-mother and sterile cells. Fig. l.r>. Nuclei of spore-mother cells dividing. Fig. l(i to 19. Mitosis and cytokinesis of spore-mother cells. w 0RON1NACEAE 1 I I'l.ATK 3 • • • V » :• & ■ • in \ ■ 16 + * ' *• * m &i pa*/1 » « ; 15 • ■ ■ J 17 a in -^^ 18 19 * • . I'\ rrhosorus 12 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES pseudopod-like extensions and vacuoles (figs. 6, 7) it is not certain from Juel's account that they move about and migrate from cell to cell as in Plasmodio- phora, etc. No evidence of schizogony was observed by Juel, but Winge interpreted some of the uninu- cleate stages as probable meronts. The mature plasmodium is multinucleate, vacuo- late, and usually irregular in shape (figs. 6-8), and just before sporulating forms an enveloping mem- brane like Sorolpidium. Plasmodia which are exten- sively drawn out and occupy several host cells may accordingly appear lobed, irregular, and tubular (fig. 12) after the wall has formed. Following this stage the protoplasm divides into uninucleate seg- ments. In this process no distinct cleavage furrows have been observed. The plasmodium appears to be- come highly vacuolate (fig. 8) during this process, and the cytoplasm accumulates around the nuclei and forms stellate protoplasmic islands which re- semble somewhat the sporonts of Tetramyxa. These segments soon become almost spherical or spindle- shaped (fig. 12), and Juel thought that the latter type of cells are formed in plasmodia which are highly vacuolate and scarce in cytoplasm. In addi- tion to these two kinds of segments, irregular elon- gate, oval and smaller ones may be formed, appar- ently as the result of unequal cleavage, which finally degenerate. The spherical, 8 /x in diameter, and spindle- shaped segments are uninucleate, naked, and never develop a distinct wall. They aggregate to form a definite sorus (fig. 9) and each cell soon divides into octads of spores as in Octomyxa, which led Juel to call them spore-mother cells. In this process of spore formation the nuclei divide mitotically (figs. 15-18) and each mitosis is followed by cell division. Defi- nite chromosomes (2 to 5) are formed on a sharply- defined spindle during mitosis, and there is no evi- dence of "promitosis," according to Juel's figures. Each of the eight naked spores soon becomes trans- formed directly into zoospores without developing thick walls and becoming dormant. The zoospores apparently infect the host cells and develop into the small thalli shown in figures 2 and 3. ROZELLOPSIS Karling, 1942. Aracr. Jour. Bot. 29: 33. My- cologia 34 : 205. which extend through the host wall; usually filling the host sporangia or the hypertrophied portions of the hyphae completely; sporangium wall tightly pressed against, seemingly fused with, and usually indistinguishable from that of the host. Zoospores slightly variable in size and shape, with one to sev- eral minute globules, heterocont, shorter flagellum usually extending forward and the longer one back- ward in swimming; zoospores swirling in the spo- rangium before emerging and swimming away ; con- tent of zoospore flowing into host cell through an in- fection tube in germination, leaving the empty zoo- spore case attached to host cell. Resting spores un- known in monosporangiate species ; solitary in septi- genous polysporangiate species, lying free within host cell and separate from host wall, variable in size, brown and spiny; protoplasm coarsely granu- lar, including a large vacuole or globule of hyaline material; germination unknown. This genus was created for the Rozella-like spe- cies with biflagellate heterocont zoospores which have been described from time to time. As such it is perhaps scarcely more than a provisional dumping ground for imperfectly known species of this type. It was proposed primarily to include Pleolpidium inflatum Butler ('07) and a similar parasite which Miss Waterhouse ('40) found in Phytophthora. Whether or not the species which Fischer described as R. septigena and R. simulant belong here is ob- viously open to question. He figured and described the zoospores as biflagellate and heterocont, but it is particularly noted in this connection that his de- scription does not apply specifically to these spe- cies. It relates instead to the zoospores of Woronina, Olpidiopsis and Rozella collectively. Inasmuch as many of Fischer's observations of other similar para- sites have proven inaccurate, it is not altogether im- probable that he may have been mistaken about the number, relative lengths, and position of the flagella. On the other hand, it is equally probable that he had at hand a different fungus from the one described by Cornu as R. septigena. This is suggested by To- kunaga's ('33) confirmation of Fischer's report of biflagellate heterocont zoospores in R. simulant, which is identical to R. septigena except in host range. For this reason Fischer's R. septigena has been separated from Cornu's species of the same name and placed temporarily with R. simulans in Rozellopsis. This genus accordingly includes two in- completely known aseptigenous monosporangiate, and two doubtful septigenous, polysporangiate spe- ( PLATE 1) Thallus, intramatrical, more or less indistinguish- able from but apparently immiscible with the host protoplasm; becoming invested witli a wall at ma- turity and forming one sporangium ; or cleaving (?) into several segments which become separated by host walls, mature in basipetal succession, and de- velop into sporangia or resting spores. Sporangia terminal or intercalary in host hyphae, variable in size and shape, with one to several exit papillae cies. So far as is now known Rozcllopsis has the same type of development as Rozella. In monosporangiate species the thallus develops into one sporangium or resting spore, whereas in the septigenous members the thallus is reported to segment into several por- tions, each of which develops into a sporangium or a spore. Germination of the zoospores, infection, and entrance of the parasite have not been observed in R. inflata, so that the following description of the processes is based on R. uaterhouseii and R. septi- WOHOMN \< KAK 13 gena. According to Fischer and Miss Waterhouse the aoospores come to real on the host hyphae and develop germ tubes of variable lengths (tigs. S 7, 16 which penetrate the host wall. The contents flow into the fungus hyphae through this tube and soon become obscured by and almost completely lost to sight in the host protoplasm. Although it is not visi- ble as a clearly-defined body its presence is never- theless evident by the increased density and opacity of the host protoplasm in the region of infection. Fischer reported that the young thallus of A'. septi- gena loses all individuality as it mixes with the host protoplasm and develops into a plasmodium. hut his account is not based on observations of fixed and stained material. It is not improbable that the para- site remains naked until very late in development, hut it is apparently immiscible with the host proto- plasm. If it is amoeboid in shape with numerous fine pseudopods it may well infiltrate the interstices of the host protoplasm and appear to be fused or mixed with the latter. This, however, remains to be deter- mined by intensive cytologic a] study of fixed and stained material. As the parasite increases in size and attains vege- tative maturity, numerous small vacuoles usually appear in the cytoplasm of the hypertrophied por- tions of the host hyphae (figs. 9, 16), but it is not always certain whether these vacuoles relate to the cytoplasm of the parasite or the host. However. since they seem to fuse later and form the large central vacuole of the parasite's sporangium (fig. 10) they probably relate to the parasite. Such vacu- oles may move about and undergo marked changes in shape from time to time (fig. <)). According to Butler, the vacuolate stage is not very marked in R. inflate. At this stage one or more dome-shaped exit papillae are usually present which project through the host wall (figs. 9, 10). Their presence is prob- ably an indication that the parasite has reached vegetative maturity and been transformed into an incipient sporangium. The formation of the spo- rangium wall has never been observed, but it has been described in the literature as indistinguishable from and seemingly fused with that of the host. However, by plasmolytic experiments Miss Water- house demonstrated that R. waterhouseii has a dis- tinct membrane of its own which may be readily separated from the host wall. Whether or not it is composed largely of cellulose had not been deter- mined. Cytokinesis is probably accomplished by centri- fugal cleavage furrows which progress from the border of the central vacuole to the periphery, al- though it has not yet been clearly demonstrated. Ac- cording to Miss Waterhouse, the risible changes in the protoplasm preparatory to sporogenesis .ire quite characteristic. Tin- central vacuole may disappear, leaving the protoplasm quite clear and homogeneous except for a few dark granules in tin- center. Shortly thereafter the protoplasm takes on the appearance as if it had undergone cleavage into zoospore initials, but this phase persists only for a short time. The protoplasm becomes optically clear again, and after a period of about half an hour tin- exit papillae ores with one or two refractive globules at the ends. R. waterhouseii Figs. 5-7. Infection of hyphal tip of Phytophthora cryp- togea. Fig. 8. Early stage of hypertrophy. Fig. 9. Later stage. Sporangium of parasite delimited by cross septa, multivacuolate with one exit papilla. Fig. 10. Still later stage in which the vacuoles have fused to form a large central one. Fig. 11. Sporangium with zoospore initials. Fig. 12. Zoospores swarming in the sporangium and emerging through the exit orifice. Figs. 13, 14. Heterocont motile, and encysted zoospores. R. septigena Fig. 15. Heterocont zoospores with one refractive glob- ule. Shorter flagellum at anterior end. Fig. 16. Multiple infection of Baprolegnia hyphal tip. Fig. 17. Hypertrophied and septate host hypha with several "Reihensporangien" in various stages of develop- ment. Figs. 18-21. Stages in development of the resting spores. 7?. simulans Fig. 22. Infected hypha of Achlya flagellata with spo- rangia in various stages of maturity. Fig. 23. Anteriorly biflagellate heterocont zoospores with a refractive globule. WOHOXl.V.ll I M PLATE 4. P>^ Rozellopsis 16 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES long with a few small refringent granules in the center or near the posterior end; flagella apparently laterally inserted (?) ; zoospores active for twenty- four hours or more, or rounding up and encysting. Resting spores unknown. Parasitic in Phytophthora cryptogea and P. megasperma, London, England, causing occasional hypertrophy of the host sporangia and supporting hyphae. Miss Waterhouse discovered this parasite in ma- terial collected from the Hogsmill River, a Surrey tributary of the Thames, and gave an excellent ac- count of its development and infection of the host. She succeeded in inoculating P. megasperma with it, but all attempts to infect Rhiphidiiim continum and R. americanum were unsuccessful. This species dif- fers from R. inflata by its pyriform zoospores and the fact that it causes only slight hypertrophy of the host. Because of its similarity in other respects to Butler's species, Miss Waterhouse, however, did not diagnose it as a new species. Septigenous Polysporangiate Species R. SEPTIGENA (Fischer) Karling, I.e., p. 34. Rozella septigena Fischer, 1883. .Tahrb. wiss. Bot. 13:331. PI. 14, fig. 19; pi. 15. (Not R. septigena Cornu, 181-2.) Sporangia up to 20 in a linear row in delimited segments of the host hyphae, of the same size and shape as the hyphal segments, with 1-2 apical or lateral exit papillae. Zoospores elongately pyriform, 4 ii X 6-8 /x, hyaline, with a minute central refrac- tive spot; shorter flagellum anteriorly attached, longer flagellum lateral. Resting spores solitary in segments of the hyphae or in short swollen side branches or "false oogonia," spherical, 20/*, with a hyaline endospore and spiny brown exospore, spines 2/i long; contents coarsely granular, including a large refractive globule; germination unknown. Parasitic in Saprolegnia monoica and »S'. thureti in Germany (Fischer, I.e.; Minden, I.e.) causing hypertrophy and septation of the host hyphae. Fischer's attempts to inoculate Achlya with this species failed, and he accordingly concluded that it is limited in host range to Saprolegnia. His results have not been confirmed experimentally. R. SIMULANS (Fischer) Karling, I.e., p. 34. Rozella simulans Fischer, I.e., p. 331 ; Minden, I.e., p. 371, fig. 11a; Tokunaga, 1933. Trans. Sapporo Nat. Hist. Soc. 13:25. PI. 3, figs. 13-14. Sporangia up to 15 in a linear row in delimited segments of the host hyphae, cylindrical, barrel- shaped, 25-90 ix X 60-250 /x, with 1-2 apical or lat- eral exit papillae. Zoospores elongate, ellipsoidal, 2.4 ii X 6 ix, hyaline, with a small refractive spot and two unequal flagella attached at the anterior end. Resting spores solitary in short swollen side branches or "false oogonia," of the same size, shape, content, and appearance as those of the previous species ; germination unknown. Parasitic in Achlya polyandra and A. racemosa in Germany (Fischer, I.e.; Minden, I.e.), Achlya sp., in Switzerland (Mauricio, '95), and A. flagellata in Japan (Tokunaga, I.e.), causing hypertrophy and septation of the host hyphae. According to Fischer, this species is similar to R. septigena and differs only by its limitation in host range to species of Achlya. Subsequent workers who reported its occurrence, however, did not make cross inoculations but accepted Fischer's observations without question. Inasmuch as Minden apparently did not determine the number, relative lengths, and position of the flagella of his fungus, it is just as probable that the resting spores which he figured relate to R. septigena as to the present species. Like- wise, it is not certain that Tokunaga's species is R. simulans, although the host reactions and sporangia are similar. He figured the zoospores as anteriorly biflagellate and narrow, while Fischer described them as large and exactly similar to those of R. sep- tigena with the short flagellum anteriorly and the long one laterally attached. Consideration, however, must be given to the difficulty of determining the exact position of the flagella on active zoospores, and it is possible that these differences in observa- tions are due to this factor. If this species is identical to R. septigena, as Fischer maintained, and will in- fect only Achlya, it may possibly be a physiological race of the former species. bibliography: woroninaceae Cook, W. R. I. 1933. New Phytol. 31, 133. , and W. H. Nicholson. 1933. Ann. Bot. 47: 851. Couch, J. N. 1939. Jour. Elisha Mitchell Sci. Soc. Dangeard, P. A. 1890. Le Bot. 3:63. Hartog, M. M. 1890. Rept. 6th Meeting Brit. Assn. Adv. Sci. 1890:873. Karling, J. S. 1943. The Plasmodiophorales. New York. Maurizio, A. 1895. Jahrb. Nat. Gesell. Graiibundens. 38:9. McLarty, D. A. 1941. Bull. Torrey Bot. Club. 68:49, 75. Petersen, H. E. 1909. Bot. Ark. 39:5. . 1910. Ann. Mycol. 8:494. Pringsheim, N. 1860. Jahrb. Wiss. Bot. 3:305. Scherffel, A. 1935. Arch. Protistk. 53:1. Smith, A. L. and J. Ramsbottom. 1917. Trans. Brit. Mycol. Soc. 6:331. Sorokin, N. 1883. Arch. Bot. du Nord France. 3:1. . 1889. Rev. Mycol. 11:74, 81. Sparrow, F. K. 1933. Mycologia, 24:373. 1933, Ibid., 25:515. 1942, Ibid. 34: 113. . 1936. Jour. Linnean Society. London, Botany, 50: 425. Valkanov, A. 1931. Arch. Protistk. 73:361. Waterhouse, G. M. 1940. Trans. Brit. Mycol. Soc. 24:7. KOTHOiiKI.I. \( I'.AK Chapter III Ectrogellaceae Scherffel, 1925. Arch, IVotistk. 52: (i 17 Tin- family supercedes tin- Eurychasmaceae which Petersen created in 1905 for the genus Eurychasma. Because Petersen included hi* family in tin- Myxo- chytridiales, with whicb it has little in common ix- cept for its olpidioid holocarpic thalli, Scherffel re- garded the Eurychasmaceae as invalid. Although he placed Eurychasma and Ectrogella in the Saproleg- niaccae, he nevertheless suggested (p. <> ) that they might comprise a separate family, the Ectrogel- laeeae. which he described as a group of simple saprolegniaceous fungi the thalli of which are trans- formed holocarpically into single zoosporangia. Coker and Matthews ('•'!") incorporated Scherffel's family in the Saprolegniales and added the genus Aphanomycopsis which Scherffel had included in the Saprolegniaceae. A similar interpretation was made by Sparrow in 1983 and ]J)3<>. In his recent classification of the aquatic Phycomycetes he placed the Ectrogellaceae as the first and most primitive family of the Saprolegniales and added his in w genus Eurychasmidium to the group. Accord- ing to his classification, this family includes Kctro- gella, Eurychasma, Eurychasmidium, and Aphano- mycopsis. Whether Aphanomycopsis belongs here or in the I.agenidiaccae or Saprolegniaceae is open to serious question. As will become more evident he- low its thalli may he strikingly similar to those of parthenogenetic species of Lagenidium. On the other hand, it may also have the appearance of a species of Aphanomyces in which sporangia are not well differentiated. The suggested relationship of this family to the Saprolegniaceae is based largely on the similarity in method of zoosporogenesis. the presence of di- planetism, and in the structure and behavior of the zoospores, since evidence of sexual reproduction in the Ectrogellaceae is at present very imager and inconclusive. Resting spores are unknown in Eury- chasma, Eurychasmidium and in all species of Kctru- gella except E. Licmophorae and E. perforans. In Aphanomycopsis tiny appear to he formed parthe- nogenetically or merely by the contraction and en- cystment of the cell ( tent. In K. Licmophorae fusion of undifferentiated male and female thalli has been reported, hut the evidence presented is not conclusive. ECTROGELLA Zopf, 1884. Nova Acta KM. Leop.-Carol. Dent. Akad. Nat. 47 : 175. I'l. \TK S ) Thallus intramatrical, holocarpic, wall showing a more or less marked cellulose reaction when tested with chloro-iodide of zinc ; oval, elongate, cylindrical and vermiform; forcing the valves of the diatom host apart at maturity. Zoosporangia single or num- erous, hyaline, smooth, oval, egg-shaped, elongate. cylindrical, vermiform and slightly irregular, some- times becoming partially cxtramatrical at maturity, with one to several comparatively short, wide, taper ing exit tubes which project between the separated valves of the diatom cell. Zoospores variable in shape, hyaline, with one to several small refractive granules; usually hecoming active within the spo- rangium; diplanetic, primary swarmers anteriorly or laterally biflagellate and isocont. emerging singly and swimming directly away as in Saprolegnia; or aflagellate, gliding out and encysting in a group at the mouth of the exit tube as in Achlya; secondary swarmers oval, lemon-shaped, and pyriform, usually with a ventral furrow, laterally biflagellate with the flagella inserted nearer the anterior end ; the shorter active flagellum directed forward and the longer one backward in swimming. Resting spores hyaline, smooth, spherical or oval, thick-walled with one large or several smaller refractive glohules ; formed parthenogenetically or by the fusion (?) of the con- tents of a small male thallus or antheridium (?) with that of female thallus through a hroad conjuga- tion tube; germination unknown. This genus was first included in the Olpidiaceae, hut since the discovery that the zoospores are bi- flagellate and diplanetic it has been regarded, par- ticularly by Scherffel, Coker and Matthews, and Sparrow, as a primitive group of the Saprolegni- ales. As it is here constituted Ectrogella includes five species, some of which may possibly prove to he identical from future studies. All are parasites of diatoms and infect marine as well as freshwater spe- cies. The life history and development of Ectrogella Species arc shown in plate •"). The zoospores come to rest on the host cell and put forth a germ tube which soon penetrates the silicified wall of the host (fig. 1 ). The content of the spore then Hows into the host. leaving the empty zoospore ease and penetration tube behind. The young thallus is at first uninu- cleate, naked and amoeboid with numerous pseudo- pods ( fig. 2H ) hut becomes enveloped by a thin mem- brane or wall very shortly after entering Hie host cell. Multiple infection may frequently occur, so that as many as thirty young thalli may occasionally be found in a single cell. As the thalli develop the chlo- roplasts of the host begin to lose their normal color, disintegrate and break down. So far no direct en- gulfing of masses of host protoplasm or discrete bodies by the thallus has been observed. With in- 18 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES crease in size and maturity the wall of the thallus becomes well defined and conspicuous, while the pro- toplasm takes on a greyish-granular appearance like that of the Saprolegniaceae (figs. 1-2). Numer- ous small vacuoles are usually present during the early development stages (figs. 6, 7) but these gradually fuse into a large central one with an ir- regular outline (figs. 10, 19). As a result the re- mainder of the protoplasm is displaced towards the periphery of the sporangium where it forms a com- paratively thin, irregular, parietal layer. Simultane- ous with these changes and the transformation of the thallus into a zoosporangium the valves of the dia- tom cell are spread apart (fig. 18), and the exit tubes begin the push out. These vary greatly in number, diameter, and length, and in E. Licmophorae be- come thick-walled and inflated at the base, whereby they are able to separate the valves of the diatom. As a result of this spreading apart of the diatom shell and the growth of the exit tubes, the zoospo- rangium may become partially extramatrical, and in E. perforans and E. Licmophorae especially, it has much the same appearance and relation to the host as that of Eurychasma. The exit tubes and adjacent portions of the ma- ture sporangium wall give a marked cellulose reac- tion when treated with chloro-iodide of zinc, while the remainder of the wall reacts only slightly or not at all. Petersen (05) interpreted this difference as a matter of age and activity. Scherffel found that the empty zoospore cysts likewise give a marked cellulose reaction. Cleavage and zoosporongenesis occur in the same manner as in the Saprolegniaceae according to Scherffel. Furrows progress centrifugally from the border of the central vacuole (figs. 10, 19, 22) and thus delimit the zoospore initials. As these furrows progress numerous small refractive globules may appear at the inner periphery of the zoospore rudi- ments (fig. 23). When the cleavage furrows have reached and cut through the plasma membrane, the central vacuole disappears, and the whole sporan- gium takes on a coarsely granular appearance and the zoospore initials are no longer visible (fig. 11). This is known as the homogeneous granular stage of zoosporongenesis. It is doubtless the result of a re- hydration and swelling of the zoospore anJagen, as Harper ('99) described for Synchytrium, whereby the lines of demarkation become very faint or in- visible. After some time the outlines of the zoospores become visible again (fig. 11), and shortly there- after they begin to shake, wobble, and glide upon eacli other. These are the so-called primary swarm- ers which are oval to pyriform in shape and may be aflagellate or have two equal rudimentary flagella attached laterally (fig. 13), or at the anterior end (figs. 26, 30, 31). These primary swarmers may emerge and swim directly away as in Saprolegnia, or glide out and encyst at the mouth of the exit tubes as in Achhia (figs. 14,27,32). Scherffel regarded the method of cleavage and zoosporongenesis described above as typical of the Saprolegniaceae and not of the Chytridiales, and for this and other reasons he maintained that Ectro- gella is a member of the former family. As the pres- ent writer has pointed out previously ('37) cleavage in this genus is not fundamentally different from that described by Harper ('99, '14), Swingle ('03), Sehwarze ('22) and others for the Mycetozoa, Chy- tridiales, Ooomycetes and Zygomycetes in general. The point which Scherffel tried to emphasize is not plate 5 Ectrogella bacillariacearum (Figs. 2-5, 17, 18 after Zopf, '84; fig. 35 after Petersen, '09; remainder after Scherffel, '25.) Fig. 1. Early infection of Synedra cell. Fig. 2. Synedra cell with 21 small parasites. Fig. 3. Synedra cell with one elongate tubular parasite. Fig. 4. Surface view of infected Synedra cell. Fig. 5. Mature sporangium with central vacuoles. Figs. 6-9. Stages of growth and maturation of spo- rangium. Small vacuoles fusing to form central row of larger vacuoles. Fig. 10. Centrifugal cleavage. Fig. 11. Contracted granular stage following cleavage. Fig. 12. Reappearance of outlines of cleavage segments. Fig. 13. Primary zoospores with rudimentary flagella. Fig. 14. Synedra cell with encysted Ectrogella zoospores at mouth of exit papillae. Fig. 15. Empty cysts and secondary zoospores. Fig. lfi. Laterally biflagellate heterocont secondary zoospores. Figs. 17, 18. Empty zoosporangia with several exit pa- pillae. E. monostoma Fig. 19. Mature zoosporangia undergoing cleavage; exit papilla at A. Fig. 20. Empty cysts and cystospores at mouth of exit papilla. Fig. 21. Laterally biflagellate heterocont secondary zoo- spores with a large vacuole. E. Gomphonematis Figs. 22-25. Cleavage stages in a zoosporangium. Fig. 26. Anteriorly biflagellate primary zoospore. Fig. 27. Empty sporangium with two exit papillae. Zoo- spores encysted at one papillae, while those which emerged from other papilla swam away. E. Licmophorae Fig. 28. Portion of a Licmophora cell showing a naked amoeboid uninucleate thallus with pseudopods at left; two uninucleate thalli with walls near host nucleus in center; and a tetranucleate thallus at right. Fig. 29. Mature sporangium with cleavage segments. Figs. 30, 31. Anteriorly biflagellate primary zoospores. Fig. 32. Zoospores encysted at mouth of exit papillae. Fig. 33. Parthenogenetic resting spore (?) in rudimen- tary oogonium (?). Fig. 34. Antheridium (?) and oogonium (?) with oospore (?) connected by fusion canal (?). Fig. 35. Resting spore of E. perforans. ECTROOELLACEAE PLATE 5 19 Ectrogelln 20 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES that the method of cleavage is fundamentally dif- ferent in the Saprolegniaceae but primarily centri- fugal in direction, because of the presence of a large central vacuole which displaces the protoplasm in a comparatively thin layer at the periphery. Doubt- less when cleavage in Eurychasma and Ectrogella has been intensively studied from fixed and stained material the fundamental similarity of the process will become quite evident. The secondary zoospores emerge from the cysts after a short dormant period (figs. 15, 20, 27). In E. Gomphonematis the numerous small granules present in the primary swarmers fuse during the en- cysted stage and form a single large refractive glob- ule. These zoospores are oval and pyriform in shape with two unequal flagella inserted laterally or close to the anterior end. In motion the shorter flagelluni is directed forward, while the longer one is dragged along behind (figs. 16, 21). Unlike those of the uni- flagellate rhizidiaceous chytrids the zoospores swim more evenly and do not dart about in a zigzag path. Resting spores have so far been observed only in E. perforans (fig. 35) and E. Licmophorae (figs. 33, 34). In the former species no sexual fusion has been reported and the spores appear to be nothing more than spherical, thick-walled, encysted thalli or spo- rangia. In the latter species, however, Scherffel fig- ured a thick-walled spore lying in a thin envelope with a hyaline thin-walled, empty vesicle or com- panion cell attached to one side by a broad tube (fig. 34). He regarded the resting spore as a oospore in a rudimentary oogonium which has been formed by fusion of the protoplasts of an antheridium and egg cell through a broad conjugation canal. Scherffel did not observe actual fusion in E. Licmophorae, and figure 34 may relate to nothing more than an irregular thallus, the content of which contracted into a thick-walled resting spore in the larger of the two lobes, as is suggested by figure 33. Resting spore formation of this type is not uncommon in species of the lower simple fungi, i.e., Olpidium gregarium, Cantenaria Anguillulae, etc. The evidence of sexual reproduction in Ectrogella is thus very meager and inconclusive, and until further proof is found the presence of sexuality in this genus must be regarded as highly questionable. E. BACILLARIACEARUM Zopf, 1884, I.e., pi. 16, figs. 1-21. Cymbanche fockei Pfitzer (pro parte), 1869. Sitz'b. "Niederrh. Ges. Nat. Heilk. 26:2-21. Olpidium gilli de Wildeman, 1896. Ann. Soc. Beige Micro. 20:41; Gill, 1893. Jour. Hoy. Micro. Soc, 1893:1, pi. 1. Zoosporangia solitary or up to 30 in a cell, smooth, hyaline, oval, elongate, cylindrical, vermiform, 4-9 fi in diameter and up to 200 jx in length with 1 to 1 1 short exit tubes or papillae in single or opposite rows, which project between the separated valves of the diatom cell on the girdle side and stain in- tensely violet with chloro-iodide of zinc. Zoospores diplanetic ; primary zoospores pyriform, 2Xlft with a refractive spot at the anterior and numerous granules at the posterior end and two rudimentary (?) equally long, 4 /x, flagella inserted laterally in a slight indentation near the anterior end ; emerging fully formed and swimming directly away, later coming to rest and encysting; secondary zoospores, oval 2 X 4 /"■ ( ?) with a tapering anterior end, near which arise two unequal flagella, and one to several refractive granules near the posterior end. Resting spores unknown. Parasitic in Synedra lunalaris, Synedra sp. ; Gomphonema sp. and Pinnularia sp. in Germany (Zopf, I.e.); Synedra sp. and Gomphonema sp. in Belgium (de Wildeman, '90, '93, '94, '95); Pleuro- sigma attenuatum, Synedra sp., Pinnularia sp., Coc- conema lanceolatum and Nitzschia sigmoidea in England (Gill, '93; Smith and Ramsbottom, '17); Synedra ulna, Pinnularia sp., Gomphonema sp., and Meridion circulare, in Hungary (Scherffel, '25; Domjan, '35), and Pinnularia sp. in New York, U. S. A. (Sparrow, '33). This species was found in great abundance in Nitzschia sigmoidea by the au- thor during the summer of 1942 at Beaufort, North Carolina. This is the type species of the genus, and although it apparently occurs abundantly in nature it is still incompletely known. Petersen regarded it as a prob- able species of Pleotrachelus with numerous exit tubes arranged in rows. The question of whether or not the organism which Gill described relates in entirety to this spe- cies has been the subject of much discussion. As is indicated in the synonomy above de Wildeman be- lieved that the sporangia shown in figures 1-8 by Gill relate to a species of Olpidium since only a sin- gle elongate exit tube is present, while the thalli shown in figure 9 relate to E. bacillariacearum. Min- den recognized O. gilli as a valid species, but Scher- ffel was undecided about its validity. He maintained, however, that it as well as Van Heurck's fungus is not identical to Zopf 's or to any of his own species of Ectrogella, and believed that figure 9 of Gill may relate to E. bacillariacearum or Aphanomycopsis. Scherffel failed to observe Zopf's species in Pinnu- laria and Gomphonema, and he was accordingly of the opinion that Zopf's figure 23, plate 16, may re- late to Lagenidium brachystomum. Van Heurck ('99, p. 64, fig. 22) figured and de- scribed an endophytic parasite with a single elon- gate exit tube in Pleurosigma angulatum which is strikingly similar to Gill's organism. Van Heurck believed that his fungus may be identical to Gill's species. As Fischer ('92) pointed out. Pfitzer's Cym- banche fockei may perhaps relate in part to E. bacillariacearum. Zopf ('84, '85), however, regarded it a member of the Saprolegniaceae. It is also possi- ble that the thick-walled structure with an eccentric vacuole which Pfitzer described may be the resting spore of this species. Pfitzer described this spore as containing small starch grains like those found by Pringsheim in Saprolegnia, but these bodies are ob- BCTROQKLLACEAE 21 viously of a different nature than starch grains. The structures described for Focke as spores of diatoms, which Pfitzcr interpreted as a part of Ci/mbanche fockei. relate to a species of the Mwo/.ooidia. (ii/m- noccoccu* fockei, according to Zopf ('8 1-1). pp. 120. 126 | and Fischer. E. PERFORANS Petersen. 1905. Over. K'gl Dansk. Videos. Selsk. For. (">); Miii, ftg. VII, 1-H. Zoosporangia solitary or up to ."> ill a cell, smooth hyaline; wall staining light violet with chloro-iodide of sine; spherical 20-85/*, oval, elongate, 22 23// 26 10,.. sometimes slightly irregular, and be- coming partially extramatrical at maturity with 1 to S short, very broad, !>-12 /i X 8-10 /i. exit tubes. Zoospores hyaline with a refractive globule at the anterior end. emerging fully formed and swimming directly away, pyriform and somewhat curved with the two rlagella attached anteriorly (?) and op- positely directed in swimming, relative lengths of flagella unknown; motion during swimming uneven and twisting. Rest spores spherical, 14-19 /t, hya- line, smooth, thick-walled with one large or several smaller refractive globules; germination unknown. Parasitic in Licmophora Lyngbyei, Licmophora sp.. and Synedra ulna in Denmark (Petersen, I.e.; Sparrow. '.'iM; Licmophora abbreviate!, Striatella unipunctata and Verticella sp., in Mass., U. S. A. Sparrow. '3<>b). causing distortion of host cell and complete destruction of the host protoplasm. The author has recently ('42) observed this species in great abundance in /.. abbreviata and L. fiaf/etlata at Beaufort, North Carolina. This species appears to be a virulent parasite and may attain epidemic proportions in Licmophora, ac- cording to Sparrow ( '36b). In the shape of its spo- rangia with numerous broad exit tubes this species is strikingly similar to K. I.icmophorae, and Scher- ffel was accordingly of the opinion that the two spe- cies may prove to be identical. It is to be noted, how- ever, that the has,- of the exit tubes of E. perforans is not thickened and does not form a spreading ap- paratus as in K. I.icmophorae, nor do its zoospores encyst in a group at the mouth of the exit canals as far as is now known. It is primarily for these rea- sons that Sparrow ('84) regarded K. perforans as a distinct species. It is not improbable, however, that when intensive comparative studies have been made of both species and their range of variation worked out. they may prove to lie identical. Sparrow I '36 ) described the zoospores as possi- bly anteriorly birlagellate with both flagella op- positely directed in swimming. He was unable to de- termine the relative lengths of the rlagella. and it is not known whether the zoospores are iso- or hetero- cont. Sparrow found that as much as eighty-eight per cent of the Licmophora cells in a single mount may be parasitized by this species. The zoospores are callable of attacking other hosts as well, since species of I'orticella which ingest free swimming zoospores may in turn be attacked by the swallowed parasites and completely destroyed. No conclusive evidence of sexuality has been found in this speeies. Petersen found isolated thick- walled resting spores (fig. 85) in several instances. but these were not accompanied by empty antheridia or companion cells. Sparrow ('84), on the other hand, believed that the spores are surrounded by a thin envelope. In one instance he found an empty hemispherical cyst. :( /i in diameter, attached to a fully mature spore. However, no stages of fusion were observed. E. MONOSTOMA Scherffel, I.e.. p. 8, pi. 1. lifrs. 10-19. Zoosporangia solitary, elongate, tubular, some- what spindle-shaped, i-8 fi. in diameter, slightly swollen in the median region from which a single, short, 2-3 /x thick, cylindrical exit tube or papilla arises; exit tube and part of the sporangium wall staining intensively violet with chloro-iodide of zinc. Primary zoospores aflagellate, gliding out of the sporangium and encysting in a group at the mouth of the exit tube; individual cystospores spherical, 6-8 ix in diameter, wall showing a marked cellulose reaction; secondary swarmers, lemon- shaped, 8 it. long, with a ventral furrow, heterocont (?), shorter fiagellum directed forward and the longer one dragged along behind while in motion. Resting spores unknown. Parasitic in Sunedra ulna in Hungary; Pinnii- laria sp. in New York, U. S. A. (Sparrow, '33) and Sunedra sp. in England (Sparrow, '36a). According to Scherffel and Sparrow, this species differs from the other members of Ectrogella only by the presence of one short exit tube. Except for this character and the median bulge (fig. 19) its thallus and zoosporangia are identical to those of E. bacillariacearum which parasitize the same host. Obviously the presence of one or more exit tubes is not always a distinctive specific character. However, the secondary zoospores of E. monostoma appear to be considerably larger (8 /*. long) than those of E. bacillariacearum which Zopf reported to be only 2 to 3 fi. in diameter. Zoospore size is a more constant specific cell character, and if further observations confirm this difference the validity of E. monostoma will be established. E. GOMPHONEMATIS Scherffel, I.e.. p. !», pi. 1. Bgs. 20, 21. Zoosporangia solitary, oval, oblong, egg-shaped with 1 or usually 2 short exit tubes located at the ends. Zoospores diplanetic. primary zoospores egg- shaped and somewhat elongate. 3 /x long, with a lew highly refractive granules and the two equal flagella, slightly longer than the spore body, inserted almost at the apical end: swarming within the sporangia, later emerging singly and swimming away (?) or encysting in a group at the mouth of the exit tubes; granules fusing during encystment to form a large refractive globule as in some rhizidiaceous chytrids; germination of cysts, and structure of secondary zoospores unknown. Resting spores unknown. 22 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES Parasitic in Gomphonema micropus in Hungary. Except for the oval shape of its thallus and zoo- sporangia (figs. 22-25) this species does not appear to have any particularly outstanding characters. Scherffel believed that the primary zoospores (fig. 26) may encyst at once at the mouth of the exit tube (fig. 27A) as in E. bacillariacearum and in Achlya species or swim away as in Saprolegnia and encyst later. Until more is known about this organism its validity as a distinct species will remain doubtful. E. LICMOPHORAE Scherffel, I.e., p. 10, pi. 1, figs. 23-30. Zoosporangia solitary or up to 10 in a cell, spread- ing open the diatom shell and becoming partially extramatrical at maturity; oval, slightly elongate with 1 to 10 exit tubes which are inflated, thick- walled, and flask-shaped at the base and give the mature sporangium and irregular, somewhat stellate appearance. Zoospore diplanetic; primary swarm- ers pyriform, 3 /x long, with two equal, apically in- serted flagella which' are approximately twice as long as the spore body; swarming within the spo- rangium, emerging singly and encysting in a group at the mouth of the exit tube; individual cysts 3.5 ft in diameter; germination of cysts and structure of secondary swarmers unknown. Resting spores sin- gle, hyaline and spherical, 12/j., smooth and thick- walled; with several irregular refractive globules, lying in a spherical, 14 //, in diameter, cell or envel- ope which may be connected by a short broad canal or tube to an oval hyaline vesicle or companion cell ; germination unknown. Parasitic in Licmophora sp. in Hungary. As has been noted before, Scherffel regarded the resting spore as a fertilized egg in a rudimentary oogonium, and in this respect he believed that E. Licmophorae may be closely related to Aphanomy- copsis and Olpidiopsis. This species also shows con- siderable resemblance to Eurychasma dicksonii and E. perforans by its broad exit tubes and partially extramatrical zoosporangia. Whether or not it is dis- tinct from the latter species remains, however, to be seen. EURYCHASMA Magnus, 1905. Hedwigia .41 : 347. (plate 6) Thallus intramatrical when young but becoming partially extramatrical at maturity; oval, ellip- soid, pyriform, dome-shaped, angular or irregular; transformed completely into a zoosporangium ; wall of mature thallus well defined and showing a marked cellulose reaction when tested with chloro-iodide of zinc. Zoosporangia solitary in a cell, hyaline, smooth, oval ellipsoid, pyriform, angular or irregular with 1 to 3 broad exit papillae or short tubes which are usually completely extramatrical. Zoospores either (1), coming to rest and encysting in the sporangium, forming thus a network of polygonal cysts as in Dictyuchus, later emerging from the cysts into the central portion of the sporangium and then swim- ming out; or (2), swimming out at once and pausing for a few moments at the mouth of the exit papilla, then gliding away without encysting. Zoospores ellipsoid and pyriform, hyaline, containing several small granules ; heterocont with the two flagella at- tached near the anterior end. Resting spores un- known. This genus includes at present two incompletely known species which are parasitic in brown and red algae. Our knowledge of the genus is based almost entirely on E. dicksonii the life cycle of which is illustrated in Plate 6. Until the last decade the zoo- spores were described as posteriorly uniflagellate, although in 1925 Scherffel predicted that further study would show them to be biflagellate. Dan- geard's and Sparrow's studies in 1934 confirmed this prediction as is shown in figures 1 and 2. Ac- cording to Sparrow, the zoospore comes to rest and encysts on the host cell (fig. 3) and soon forms a germ tube which penetrates the host cell wall. The content of the zoospore passes into the host as a naked body leaving the spore case and penetration tube on the outside (fig. 4) as in Ectrogella, Py- thiella, Olpidiopsis, etc. Within the host cell the young parasite appears as a naked amoeboid proto- plast (fig. 6) with one to several pseudopod-like ex- tensions and resembles the early stages of Ectro- gella Licmophorae. According to Lowenthal, it as- sumes a position near the host nucleus (fig. 6), but whether or not this migration takes place by inde- pendent amoeboid movement has not been deter- mined. Lowenthal believed that it remains naked and surrounded by the host protoplasm until it is fairly large and multinucleate (fig. 7). In the early de- velopmental stages it is hardly to be distinguished from the host protoplasm in living material, but as it increases in size it becomes very vacuolate (figs. 8, 9), according to Sparrow. Petersen ('05) described four distinct and successive maturation stages which he believed are also characteristic of the Chytri- diales as a whole. At that time, however, it was gen- erally believed that Eurychasma belonged among the chytrids. Since doubt has been expressed about the sequence of these stages it is worthwhile to enu- merate them at this point: 1, Stade protoplasmique ordinare characterized by dense, almost avacuolate protoplasm and division of the nuclei; 2, Stade glob- uleux in which nuclear division and zoospore differ- entiation have been completed, and the sporangium is filled witli numerous closely appressed globules of an oleaginous nature; 3, Stade ecumeux char- acterized by an increase in size of the sporangium, highly vacuolate protoplasm with the nuclei lying in the peripheral region and the cytoplasmic bridges separating the vacuoles, and by the disappearance of the outlines of the zoospores; and 4, Stade a zoo- spores regulierement disposes contre la membrane in which the zoospores are regularly distributed BCTROOELL Ml M 28 around the inner periphery of the sporangium. In liirlit of what has since been discovered about zoo- Bporogenesis in Pythiella, Ectrogella, and other similar genera, it is very doubtful that numerous large vacuoles arc present in the /oosporangium after the loospores have been delimited, as Petersen reported for stade ecumeux. Before cleavage begins the vacuoles doubtless fuse to form one or more larger central ones (fig. 12) which apparently disap- pear when the centrifugal cleavage furrows reach the plasma membrane, as Scherffel and Couch have described for Ectrogella and Pythiella. It is. further- more, questionable that nuclear division lias been completed at the time of the stade globuleux. Peter- son's studies relate only to living material, and in SUch preparations it is impossible to determine when nuclear division is finished. Petersen's report that these stages are characteristic of the Chytridiales as a whole was denied by Scherffel who maintained that they are typical only of the Saprolegniaceae and their elose relatives. Both he and Lowenthal re- ported that the zoospores are delimited simultane- ously, hut this is probably incorrect. Cleavage is doubtless progressive as has been shown for other closely related genera. According to Petersen, the zoospores become very active within the sporangium, and after a while come to rest and encyst around the inner periphery. They thus form by mutual contact and pressure a periph- eral layer of polygonal cysts — the so-called "net- sporangium" stage (figs. 11. 11, 15). Sparrow, on the other hand, observed that the zoospores usually emerge at once and swim away ( Hg. 7) after a brief pause at the mouth of the exit tube. He found the "net-sporangium" stage only occasionally and con- cluded therefore that its occurrence may possibly be a reaction to adverse environmental conditions. Nevertheless, two types of zoospore behavior have been observed, one as in Saprolegnia and the other as in Diet yuchus. It differs from that of the latter genus, however, by the fact that the zoospores which emerge from the cysts do not pass through the spo- rangium wall but into the central cavity and then out through the exit tubes. Whether or not those which emerge directly and at once from the sporangium encyst after a period of motility as in Saprolegnia has not been determined. Petersen and Scherffel nonetheless regarded the zoospores of Eurychasma a^ diplanetic — the first motile stage occurring within the sporangium and the second on the outside. So far no one has figured or described the shape of the primary Bwanners within the sporangium, nor the number, relative lengths, and position of their flagella. The effect of Eurychasma on the host cell varies considerably as Rattray and subsequent workers have pointed out. In some instances the infected cells may not be greatly hypertrophied. while in other cases they may be several times their normal size. According to Sparrow, hypertrophy begins shortly after the entry of the parasite ( tigs. .'i. 1. 5). However, infected cells an- not stimulated by the parasite to divide; nor do the adjacent healthy cells enlarge or divide as far as is now known. Hyper trophy is thus confined to infected cells. The en Largement of the host cell does not keep pace with the growth of the parasite, since the latter eventu ally bursts out of the confining host wall and is often one-third to one-half cxtraniatrieal at maturity as is shown in figures 10, 11. 11. IK, and 1!). According to Lowenthal, destruction of the cell contents does not occur at once in I'l/laiella cells, since the nucleus and plastids may lu- clearly discerned even when the parasite almost completely fills the cell. The pyre- noids. however, disappear very shortly. Sparrow, on the other hand, reported that the plastids of Striaria soon become discolored and disintegrate, and the de- generated protoplasm which is not utilized by the parasite eventually forms a brownish-green layer around the mature parasite. Prior to the discovery that the zoospores of Eury- chasma are biflagellate, this genus was generally in- cluded in the family Olpidiaccae of the Chytridiales, although as early as 1905 Petersen had made it the type genus of a new family, F.urychasmaceae, which he placed near the Olpidiaceae. Scherffel ('25), however, merged Eurychasma with Ectrogella and included it in the Saprolegniaceae, although it was not then known that the zoospores are biflagellate. He did this on the grounds that the thallus bursts out of the host cell as in species of Ectrogella; that the appearance of the protoplasm and the stages of zoosporogenesis are similar in both genera, and on the belief that the zoospores are typically diplanetic. It is to be noted, however, that the "net-sporan- gium" stage has not been found in species of Ectro- gella. Furthermore, resting spores are unknown in Eurychasma, and since it is not improbable that they may be found to be quite different from those of Ectrogella, Eurychasma is retained here as a sepa- rate genus for the time being in the family Ectro- gellaceae. E. DICKSONII (Wright) Magnus, I.e.. tips. 1-3. Rhizophidium dicksonii Wright, 1879. Trans. Roy. Irish Acad. 26:369. PI. 3. Olpiditim dicksonii (Wright) var. Btriariae Wille, 1899. Vidensk, Selsk. Skr. Math. Nat Klasse 1. 3:3. PI. 3. Ectrogella dicksonii (Wright) Scherffel, Ifl.'j. Arch. Protist'k, 52 :i, 11. Zoosporangia solitary, hyaline, smooth, oval, ellip- soid, somewhat elongate. L'0-25 /j. X 10-80 /n, angu- lar and slightly irregular with 1-3 short, broad, cxtraniatrieal exit tubes or papillae. Zoospores oval, pyriform 3 X 5 /», with two unequal flagella in- serted near the anterior end. Resting spores mi known. Parasitic in Edocarpus granulosus, E. CTinttuS, Pylaiella littoralis and Striaria attenuata in Ire land I Wright. I.e.; Johnson. '09); Ectocarpus con- fervoides, E. crinitus and E. pusillus in Austria (Hauck, '78): E. sUiculosus in Scotland (Rattray, '81); Striaria attenuata var. fragilis and Pylaiella littoralis in Norway (Wille, '99; Lowenthal. '05); 24 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES P. littoralis, Stictyosiphon tortilis, Striaria atten- uata, Akinetospora sp., Ectocarpus sp., E. confer- voides, E. sandrianus, and Punctaria sp., in Den- mark and Greenland (Petersen, '05 ; Sparrow, '34) ; Stictyosiphon corbierei and Ectocarpus sp. in France (Pierre Dangeard, '34), causing marked hypertrophy and destruction of the infected cells. Magnus ('05) claimed to have seen it in marine algae at Kiel also as early as 1872. As is evident in the synonomy given above this type species of the genus has undergone numer- ous taxonomic changes. Wright, Hauck, Rattray, Fischer ('92) and Schroeter ('97) placed it in the genus Rhizophidium, but in '99 Wille transferred it to Olpidium because of the lack of a rhizoidal sys- tem. In 1905 Magnus called attention to the fact that the sporangia burst through the host cell and become partially extramatrical with one to several broad exit tubes or papillae, characters which are unlike those of Olpidium; and he accordingly created the new genus Eurychasma for Wright's species. Finally, in 1925, Scherffel transferred it to Ectro- gella. This species had doubtless been seen before its discovery by Wright and mistaken for a stage in the life cycle of its host. Wright and Rattray were of the opinion that the reproductive organs of certain marine algae described by Harvey (1862) and Kiit- zing (1855, 1861) relate to this species. Magnus, however, claimed that the latter workers had studied and figured Chytridium plumulae. E. SACCULUS Petersen, 1005, Overs. K'gl. Dansk. Videns. Selsk. Forh. (5):477, figs. VIII, 5, 8, 9. , Zoosporangia solitary, largely extramatrical, hya- line, smooth, irregular, elongate, 80—184 ji high, with one to three broad exit tubes; intramatrical portion lobed and irregular. Zoospores and resting spores unknown. Parasitic in Rhodymenia palmata and Halosac- cion ramentaccum in Greenland, causing marked hypertrophy and destruction of the infected cell. According to Petersen, this species differs from E. dichsonii by the lobed and irregular shape of the zoosporangia, particularly the intramatrical por- tion. Although he did not observe the zoospores, he believed that they may behave in the same fashion as those of the previous species. On the basis of present-day knowledge concerning Eurychasma it appears to be a very doubtful species, and further study may prove it to be identical to E. dichsonii. Scherffel, on the other hand, believed that it may be a species of Ectrogella. Whether or not Gran's ('00) Olpidium Lauderiae parasitic in Lauderia borcalis belongs in Eury- chasma or Ectrogella is a matter of dispute. Peter- sen (I.e., p. 469) regarded it as a questionable spe- cies of the former genus and renamed it E. Laud- eriae. Scherffel thought that it may prove to be a member of Ectrogella, and named it Ectrogella Lauderiae. EURYCHASMIDIUM Sparrow, 1936. Biol. Bull. 70: 241. (plate 7) Thalli intramatrical, solitary or numerous, unicel- lular, spherical, ellipsoid, irregular and lobed. Zoo- sporangia solitary or up to eight in a cell, variously- shaped with one or numerous exit tubes which may end flush with the surface of the host cell or extend beyond it. Zoospores diplanetic, encysting in polyg- onal cysts at the mouth of the exit tubes, emerging later and leaving the empty cysts behind ; relative lengths and position of flagella unknown. Resting spores unknown. Sparrow created this genus for the parasite of Ceramium which Magnus first discovered in 1872 and described as Chytridium (Olpidium) tumi- faciens. As is shown in Plate 7 it is very similar to plate 6 Eurychasma dichsonii (Figs. 1, 3-5, 8-11, 14-17 after Sparrow, '34; fig. 2 after Dangeard, '34; figs. 6, 7, 12, 13 after Lowenthal, '05; fig. 18 after Wright, '77.) Fig. 1. Fixed and stained biflagellate heterocont zoo- spores. Fig. 2. Biflagellate heterocont zoospores with a taper- ing anterior end near which the flagella are attached. Fig. 3. Early infection stage of Striaria cell. Fig. 4. Enlarged algal cell with zoospore case and in- fection tube attached. Fig. 5. Enlarged algal cell with small parasite within. Fig. 6. Naked young uninucleate amoeba-like parasite with several pseudopods lying in cytoplasm of a Pyiaielta littoralis cell; host nucleus at left. Fig. 7. Naked tetranucleate parasite in which only two nuclei are visible; lying in the vacuole of a gametangium of Pylaiella. Figs. 8-9. Distended host cells with vacuolate parasites; exit papillae beginning to form. Fig. 10. Partially extruded parasite which has ruptured the enveloping host wall. Fig. 11. Zoosporangium with a peripheral layer of zoo- spores. Fig. 12. Longitudinal section of parasite before cleav- age showing the protoplasm as a thin layer lining the sporangium. Fig. 13. Longitudinal section of sporangium after com- pletion of cleavage. Fig. 14. A "net-sporangium" in which all but two of the zoospores have evacuated their cysts. Fig. 15. Sporangium with two exit tubes and a periph- eral layer of encysted zoospores. Fig. 16. Portion of a "net-sporangium" showing emer- gence of zoospore from a cyst. Fig. 17. Sporangium showing direct discharge of zoo- spores without previous encystment. Fig. 18. Sporangia in cells of Ectocarpus granulosus. Fig. 19. Empty thallus of Eurychasma sacculus show- ing irregular sac-like character of intramatrical portion. Petersen, '05. ECTROOBLL Ml M 2 a PLATE (> • Kurvcliasina 26 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES Eurychasma in method of infection and develop- ment, but, according to Sparrow, it differs funda- mentally by the presence of comparatively narrow exit tubes, its completely intramatrical position in the host, the encystment of the zoospores outside the sporangium, and by a more pronounced effect on the host cell. However, differences in number, length and diameter of the exit tubes, effect on the host, partial or complete intramatrical development are questionable generic characters, and when Eury- chasmidium as well as Eurychasma are more fully known they may possibly prove to be identical. Sparrow reported that zoospore germination and infection of the host are similar to those of Eury- chasma and Ectrogella, although he did not actually observe these processes. In a few cases, however, he found empty zoospore cases and infection tubes at- tached to p'arasitized cells (fig. 6), which suggests that the contents of the spore enter the host cell as a naked body. Multiple infection apparently occurs fairly often, since as many as eight thalli may be found in a single cell (fig. 3). The well-established thalli are easily distinguishable in the host cell by the presence of numerous refractive globules in the protoplasm (figs. 5-9). As growth continues the chloroplasts begin to disintegrate and the remainder of the host protoplasm becomes quite vacuolate (figs. 6-7). Concomitant with these internal changes the host cell becomes distended and its wall greatly thickened (figs. 8-10). Infected cells do not divide, but healthy cells of adjacent nodes are stimulated to divide. There are thus formed in the vicinity of parasitized cells a number of curved stunted lateral branches (fig. 8, 9) which give a bushy appearance to the infected regions of the host plant. < The successive internal maturation changes in the parasite are identical to those described by Peter- sen for Eurychasma, including the characteristic "stade ecumeux." The final stages in zoospore for- mation and emergence have not been observed, so that it is not known whether the zoospores become flagellate and swarm within the sporangium or glide out without flagella. In either event, they come to rest and encyst in loose masses at the mouth of the exit tubes (fig. 10). The cystospores thus formed (fig. 11) are polygonal in shape, and after a period of quiescence the protoplasm of each cyst emerges and develops into a flagellate zoospore. Sparrow reported that the zoospores are biflagellate, but he did not illustrate them and say whether they are iso- or heterocont, nor show at what place the fla- gella are attached. As far as the writer is aware the zoospores of this genus have never been illus- trated. E. TUMIFACIENS (Magnus) Sparrow, I.e., figs. 14-21. PI. 1, fig. 1. Chytridwm (Olpidium) Pumifaciens Magnus, 1872a. Sitz'b. Gesell. Nat. Freunde Berlin, 1872:87. 1872b. Jahresb. Komm. Untersuch. Deut. Meere Kiel 2:61. PI. 1, figs. 1-16. 1873. Hedwigia, 12: 28. Olpidium tumifaciens (Magnus) Fischer, 1892. Raben- horst's Krypt. PI. 1, IV: 27. Pleotrachelus tumifaciens (Magnus) Petersen, 1905. I.e., p. 456. Zoosporangia, hyaline and smooth, spherical, 100-1 10 ^, ellipsoid, 110 X 200 n, irregular and lobed with 1 to 30 exit tubes. Zoospores hyaline with a single refractive globule, eliptical, 3 X 5 1^- Addi- tional details are given in the generic diagnosis above. Parasitic in Ceramium fiabellic/erum and E. acan- thonotum in Scotland (Magnus, I.e.) and England (Smith and Ramsbottom) ; a red alga in Belgium (de YVildeman '00) ; Ceramium sp. and C. diaphanum in the United States ( Murray, '03 ; Sparrow, I.e.) ; and Ceramium rubrum in Denmark (Petersen, I.e.). According to Magnus, this species was first ob- served by Cramer in 1855 (pi. 11, figs. 9, 11) at Naples, Italy, who mistook it for a monstrosity of C. flabelligerum (C. spiniferum). Sparrow believed that the organism which he observed at Wood's Hole is the same as Magnus' species, but there are some differences in the accounts of it given by the two authors. Magnus described the zoosporangia as soli- tary or numerous in a cell with one or two exit tubes which extend considerably beyond the algal cell, but he failed to observe any marked thickening of the host wall. Sparrow, on the other hand, reports that the wall is abnormally thickened, while the zoo- sporangia may possess as many as thirty exit tubes, through which the ellipsoid, biflagellate zoospores emerge. These differences may well be due to the limited observations of Magnus, but there is none- theless a possibility that Sparrow may have studied a different species. plate 7 Eurychasmidium tumifaciens (Figs. 1-4 after Magnus, '72; figs. 6-11 after Sparrow, '36.) Fig. 1. Young thalli in the apical hair cell of 0. flabel- ligerum. Fig. 2. Older tliallus in same type of cell. Fig. 3. Enlarged cell with eight spherical thalli. Fig. 4. An enlarged apical cell containing a mature tliallus with two broad exit tubes. Fig. 5. Early developmental stage of tliallus in Cera- mium diaphanum. Fig. 6. More mature tliallus with zoospore case and in- fection tube still attached to the enlarging host cell. Fig. 7. Tliallus surrounded by vacuolate host proto- plasm. Fig. 8. Tliallus completely filling host cell, the wall of which is greatly thickened. Fig. 9. Lobed irregular, vacuolate tliallus. Fig. 10. Empty sporangium with numerous short exit tubes; groups of cystospores near the exit tubes. Fig. 11. A group of polygonal cysts. BCTROOELL u i u PLATE 7 27 Eurvchasmidium 28 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES APHANOMYCOPSIS Scherffel, 1925. Arch. Protistk. 52: 11. (plate 8) Thallus intramatrical. holocarpic, filamentous and thread-like or irregularly tubular, simple or branched, continuous or septate; walls showing a marked cellulose reaction when tested with chloro- iodide of zinc; whole thallus or segments trans- formed directly into sporangia or oogonia (?). Zoo- sporangia elongate, filamentous and cylindrical or short and tubular with one to several straight, curved or irregular exit tubes which project considerably beyond the surface of the host. Zoospores diplanetic, emerging in succession without flagella and encyst- ing in a cluster at the mouth of the exit tube ; sec- ondary zoospores grape seed-shaped with a ventral furrow and conspicuous vacuole, isocont ( ?) or heterocont (?), active shorter flagellum directed forward in swimming with the longer one dragging behind; swimming movement relatively slow and even, not darting. Oogonia questionable. Resting spores or oospores (?) single or several in thallus or segments thereof; parthenogenetic (?), germina- tion unknown. Scherffel regarded this genus as closely related to Ectrogella monostoma and included it in the Saprolegniaceae near Aphanomyces because of its long thread-like zoosporangium and the formation of zoospores in single linear rows. He furthermore believed that the thalli of Aphanomycopsis with their incipient resting spores should be interpreted as rudimentary oogonia containing one or several egg cells which develop asexually or partheno- genetically, a viewpoint which was subsequently ac- cepted by Sparrow ('33) and Coker and Matthews ('37). The latter workers, however, included Aphanomycopsis in the family Ectrogellaceae, and later on Sparrow ('-12) followed this classification. Tokunaga ('33) on the other hand, placed it in the Lagenidiaceae. Scherffel pointed out that this genus differs from Aphanomyces by the lack of well differ- entiated zoosporangia and oogonia, but Tokunaga found the former structures to be strikingly like those of Lagenidium, as is shown in figures 15, 19, and 25. The segments which contain the resting spores are also similar in shape to the oogonia of some species of Lagenidium. The fact that the zoo- spores are diplanetic, encyst in clusters at the orifice of the exit tubes, and are heterocont after emerging from the cysts does not exclude this genus from the Lagenidiaceae since such characters are also to be found in L. Oedogonii and Lagenidium sp., Couch. Likewise, several species of the latter genus are parthenogenetic, but each so-called oogonium forms but one spore. On the bases of Tokunaga's studies, Aphanomycopsis is herewith included only tempo- rarily in the Ectrogellaceae. It is not altogether im- probable, however, that Tokunaga's fungus may be different from Scherffel's and Sparrow's species. Further studies are therefore essential to a better understanding of the identity and relationships of A phano m ycops is . Scherffel reported that the zoospores which emerge from the cysts are heterocont (fig. 2), but Tokunaga described and figured them as isocont (fig. 16) without indicating any specific flagellum orientation during motility. After coming to rest on the host the zoospores form a broad germ tube which makes a small round hole in the silicified wall and penetrates the diatom cell (figs. 4, 5). The penetra- tion tube continues to elongate, broadens, branches, and eventually develops into a full grown thallus, while the zoospore case and extramatrical portion of the tube remains attached on the outside (fig. 6). Scherffel and Sparrow reported only elongate, sim- ple (fig. 13) or branched (fig. 17) non-septate thalli, but West and West and Tokunaga found that the thallus may be divided into segments by one to sev- eral septa (figs. 7, 15, 19, 25) at maturity. One or more exit tubes are formed as the thallus develops, but they do not perforate the diatom cell like the penetration tube, according to Scherffel. In- stead, they pass out between the valves of the host when young and then develop thickened walls at the region of exit, whereby the valves of the diatom are pushed apart (figs. 13, 18). This so-called "Spreiz- apparat" was observed by Scherffel and Sparrow, but Tokunaga did not illustrate it in his figures of plate 8 Aphanomycopsis bacillariacearum (Figs. 1-6, 8-12, 14, 17, 18, 20-24 after Scherffel, '25; fig-. 7 after West, '09; fig. 13 after Sparrow, '33; figs. 15, 16, 19, 25 after Tokunaga, '33.) Fig. 1. Zoospore emerging from cyst. Fig. 2. Laterally biflagellate heterocont zoospore. Fig. 3. Optical cross section of same showing ventral groove and vacuole. Figs. 4, 5. Infection of host. Fig. 6. Empty zoospore case and infection tube on dia- tom cell. Fig. 7. Branched septate thallus with zoospores clus- tered at tip of exit tube. Figs. 8-11. Stages in cleavage and zoospore formation in exit canal. Fig. 12. Branched exit tube with zoospores which failed to emerge from main branch. Fig. 13. Two thalli with clusters of discharged zoo- spores, greatly enlarged. Fig. 14. A thallus with three exit tubes. Fig. 15. Branched septate thallus with several exit tubes. Fig. 16. Bean-shaped isocont zoospores. Figs. 17-19. Empty thalli. Note thickened basal portion of exit tube, the so-called "spreading apparatus." Fig. 20. Thallus with three young oospores (?), two of which occur in pairs. Figs. 21-23. Developmental phases of the latter two oospores or resting spores. Fig. 24. Large oval resting spore. Fig. 25. Two branched septate thalli with oospores in two expanded cells. BCTROGRLLACEAE PLATE 8 29 Aphanomycopsis 30 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES this fungus. At maturity the protoplasm undergoes cleavage in the filamentous thallus and exit tubes, and forms elongate cylindrical segments (figs. 8-11) which then pass out in succession in a linear row as in Aphanomyces, according to Seherffel, round up, and form a cluster of cystospores at the mouth of the exit tube (figs. 7, 13, 14, 15). The lack of a differ- entiated sporangium in Aphanomycopsis is one of the chief characters which separates this genus from Aphanomyces in Scherffel's opinion, but it may be noted in this connection that Tokunaga found the sporangia to be delimited by cross walls from the re- mainder of the thallus. So far no evidence of sexuality has been observed in Aphanomycopsis. Nevertheless, Seherffel re- garded the thalli which bear one to several resting spores as rudimentary oogonia, but the evidence for this viewpoint is not convincing. In the process of resting spore formation the protoplasm of the entire thallus or segments thereof contracts into one or more globular portions (fig. 20) which develop thick, smooth hyaline walls and become dormant (figs. 21-24). Whether these spores give rise di- rectly to zoospores or a germ tube in germination is not known. A. BACILLAR1ACEARUM Seherffel, I.e., p. 14. PI. 1, figs. 31-35; pi. 2, figs. 36-18. Thallus 8-10 /x in diameter, continuous or septate, not markedly constricted at septa; branches often inflated at the end. Zoosporangia filamentous and thread-like, or cylindrical, tubular, unbranched or irregularly branched and lobed, 4.8-16.8 /x X 150 /x. Exit tubes 4.8-7 /x X 150-240 /x, thickened and in- flated at base to form a so-called "spreading appara- tus" for separating the valves of the diatom cell. Zoospore cysts at mouth of exit tubes spherical, 6-8 /x. Zoospores 7-8 /x X 10-12 /x. Entire thallus functioning as a rudimentary oogonium (?) in con- tinuous specimen; oogonia (?) intermingled with sporangia in septate thalli, terminal or intercalary, cylindrical and medianly expanded, 15.6-26.6 xi in diameter, periplasm absent. Oospores (?) oval, 20 X 24 ii, spherical 14.4-20 /x, hyaline, smooth and thick-walled with a large eccentric globule and a bright lateral spot. For further details see generic description above. Parasitic in Pinnularia I'iridis, Epithemia turgida, Cymbella gastroides, and Nitsschia sigmoidea in Hungary (Seherffel, I.e.) Pinnularia sp., and Syne- dra sp., in New York and England (Sparrow, '33, '36), Surirella sp., and Navicula sp., in Japan (To- kunaga, '34). The parasite (fig. 7) which West and West de- scribed in Pleurotaenium ehrenberghii is very simi- lar and probably identical to A. bacillariacearum. Their contention that this is the same fungus which Archer ('60) described from the same host seems very doubtful. bibliography: ectrogellaceae Coker, W. C, and Welma D. Matthews. 1937. North Amer. Flora. 2, pt. 1:17. Dangeard, P. 1934. Ann Protist. 4:(i9. Domjan, A. 1935. Folio Cryptogam. 2:9. Fischer, E. 1893. Rabenhorst's Kryptog'fl. 1, IV:11. Focke. Physiol. Studien 2:43, pi. 6, figs. 24-30. Gran, H. 1900. Nyt. Mag. Naturvid. 38:123. Harper, R. A. 1899. Ann. Bot. 13:467. . 1914. Amer. Jour. Bot. 1:127. Harvey, W. H. 1862. Phycologia Australia 4. PI. 227, fig. 3. Hauck, F. 1878. Oesterr. Bot. Zeitschr. 28:321. Johnson, T. 1909. Sci. Proc. Royal Dublin Soc. 12:131. Karling, J. S. 1937. Mem. Torrey Botanical Club. 19:1. Kutzing, F. T. 1855. Tabulae Phycologicae V. Tab. 82. 1861. Ibid., X:2C. PI. 82. Lowenthal, W. 1905 Arch. Protistk. 5:225. Murray, G. 1903. Grevillea. 21:103. Rattray, J. 1884. Trans. Edinburgh Roy. Soc. 32:589. Schroeter, J. 1897. Engler und Prantl, Die Nat. Pflanzenf . I, 1 :64. Schwarze, C. E. 1922. Mycologia 14:143. Smith, A. L., and J. Ramsbottom, 1917. Trans. Brit. Myeol. Soc. 6:231. Sparrow, F. K. 1933. Mycologia, 25:513. 1942, Ibid., 34:115. . 1934. Dansk. Bot. Ark. 8, no. 6:1. . 1936a. Jour. Linn. Soc. London Bot. 50:417. . 1936b. Biol. Bull. 70:236. Swingle, D. B. 1903. U. S. Bureau PI. Ind. Bull. 37. Tokunaga, Y. 1934. Trans. Sappora Nat. Hist. Soc. 13:227. Van Heurck. 1899. Traite des Diatomees. Anvers. West, W., and G. S. West. 1906. Trans. Roy. Irish Acad. Sect. B, 33:77. Wildeman, E. 1890. Ann. Soc. Micro. Beige 14:1. 1893, Ibid., 17:33. 1894, Ibid., 18:149. 1895, Ibid., 19:59. Zopf, W. 1884. Encykl. der Naturwiss. 3:129. 0LPIDI0P8IDACEAE 3 1 Chapter IV Olpidiopsidaceae Sparrow. 1942. Mycologia 34: 11. "i. This family name appropriately replaces the Pseu- dolpidiaceae previously proposed by Petersen in 1909. Since Olpidiopsis was the first genus to be created for fungi of tliis type it is appropriate that the family take its name from this genus. Furthermore, there is considerable doubt about the validity of Pseudolpidium and should this genus prove to be synonymous with Olpidiopsis the name Pseudolpidiaceae would no longer be descriptive nor tenable. Petersen included two genera, Olpidiopsis and Pseudolpidium, in his family and placed it in the Lagenidiineae next to the family Lagenidiaceae. Sparrow likewise placed his Olpidiopsidaceae in tin Lagenidiales but extended the family to include Petersenia, Pythiella, and Pseudosphaerita as well as Olpidiopsis and Pseudolpidium. Whether or not Pseudosphaerita belongs in this family is open to serious question, because nothing is known about the presence of sexuality and the nature of tile resting spores in this genus. In the event it proves to be a valid genus of this family. Dangeard's Pseudo- sphaeritaceae may also be merged with the Olpidiop- sidaceae. However, if Dangeard's ('83) and Mitch- ell's ('28) reports that the thallus segments after each nuclear division are correct. Pseudosphaerita differs markedly from Olpidiopsis in method of de- velopment. The present writer is nevertheless in- cluding it here temporarily for want of a better group in which to place it. Blastulidiopsis is also in- cluded here provisionally for the same reason, al- though the development of the thallus by the en- largement, growth, and elongation of the intramatri- cal tip of tin- germ tube is more suggestive of rela- tionship with the Lagenidiaceae than the Olpidiop- sidaceae. Petersenia is excluded from this family because the thalli of all known species, except /'. andreii, are strikingly similar to those of Sirolpidium and Pontisma in the Sirolpidiaceae. According to Spar- row's account /'. andreii is apparently a species of Olpidiopsis and is accordingly transferred to this genus. The inclusion of Pythiella in the Olpidiop- sidaceae is likewise questionable. While its method of zoosporogenesia and behavior of the zoospores is similar to those of some Olpidiopsis species, the presence of periplasm in the so-called oogonium sug- gests a more direct relationship with the Pvthiaeeae. Furthermore, its walls give no positive cellulose re- action when tested with chloro-iodidc of zinc, a character which is considered to be of fundamental significance in phylogeny and relationship. As it is herewith described, the Olpidiopsidaceae includes three incompletely known genera. Pseudosphaerita, Blastulidiopsis and Pseudolpidium in addition to Olpidiopsis and Pythiella, genera which future stud- ies may or may not prove to be closely related. As such it includes species with markedly hetcrocont and isocont zoospores, and is accordingly not a very coherent family of closely related genera. The se- quence in which the genera are described below is no indication of their primitiveness or complexity. OLPIDIOPSIS Cornu, 1872. Ann. Sei. Nat. 5 ser. 15: 114. (plates 9 to 13) Pleocystidium Pisch. 1884. Sitz'b. I'liys. Med. Soc. Er- langen lfi: 60. Diplophysa Schroeter, issii. Cohn's Kryptog'fl. Schle- siens :S: 19.5. Olpidiopsis (Cornu) Fischer, ISO.'. Rabenhorst's Kryp- tog'fl. I, 4: 37. Pseudolpidium Fischer (pro parte) I.e., p. 33. PseudolpidiopsU Minden, 1911. Kryptog'fl. Mark Bran- denburg 5: .'.5.3. Thallus intramatrieal, appearing more or less naked but immiscible with the host protoplasm when young but soon becoming invested with a cellulose wall. Zoosporangia solitary or numerous, up to SO or more in a host cell, hyaline or greyish-granular. smooth or covered with non-cellulosic spines, knobs. or warts; spherical, oval, ellipsoid, fusiform, elon- gate, lobed, sac-like or irregular with one to several broad, tapering or cylindrical, straight, curved, coiled, short or elongate exit tubes which may end Hush witli the surface of the host cell or project be- yond it. Zoospores hyaline with numerous minute re- fractive granules, and in some species containing a contractile vacuole; oval, ellipsoid, elongate, .and slightly renif'orm. iso- or hetcrocont; flagella in- serted laterally near the anterior end or anterior! v. shorter flagellum extending forward and the longer one backward in swimming; emerging fully formed and swimming directly away or occasionally lying quiescent in a mass for a few moments at the mouth of the exit tube before becoming actively motile; diplanetic in one species, primary swarmers aflagel- latc and amoeboid, or flagellate, encysting to form Cystospores; movement of zoospores more or less even in swimming, not darting, interrupted by one to several rest periods during which the Hagella may be retracted. Resting spores parthenogenetic or sexual; spherical, oval, ellipsoid or elongate, hya- line, golden, yellowish-brown or brown with a smooth or knobby, warty, spiny, undulating and 32 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES wavy exospore; warts, spines and knobs non-cellu- losic ; content coarsely granular with one to several large or small refringent globules ; male or com- panion cells when present, single or numerous, oval, spherical, elongate or vermiform, hyaline, smooth or warty and spiny. Resting spores transformed di- rectly into zoosporangia in germination and liberat- ing zoospores through exit tubes. General Considerations As is shown in the synonomy above species of this genus have undergone the usual taxonomic vicissi- tudes and have been bandied about from one genus to another. Cornu created the genus Olpidiopsis in 1872 for five parasites which he found in various species of the Saprolegniales. In three of these para- sites he observed thick-walled resting spores to which were attached one or more smaller empty vesicles which he assumed to be male cells or anther- idia. Although Cornu did not specifically mention the presence of attached cells as the distinguishing generic character of Olpidiopsis, it subsequently came to be regarded as such. Reinseh ('78) later observed the passage of the protoplasm of the small cell into the larger thallus, and since that time the resting spores of Olpidiopsis have been generally believed to arise from fusions of unlike and sexually differentiated thalli. In a subsequent study of these parasites, Fischer ('80) failed to find empty male companion cells attached to what he believed to be the resting spores of 0. Saprolegniae. Accordingly. two years later ('82) he rejected the cellule adja- eeiite character as diagnostic for the genus, and re- dlagnosed and described Olpidiopsis as having asexual resting spores. Further studies in the mean- time, however, convinced Fischer that his earlier ob- servations were incorrect, and in 1892 he inter- preted the genus in the original sense and estab- lished a second genus, Pseudolpidium for the Olpidiopsis-\ike species with asexual resting spores. In this genus he included P. Saprolegniae and P. fusiforme, for which he described resting spores, and four additional doubtful species in which rest- ing spores were unknown. In the meantime Zopf ('84) and Fisch ('81) had described two similar parisites, 0. schenkiana and Pleocystidtum parasiticum, with uniflagellate zoo- spores and sexual resting spores in Spirogyra. Two years later Schroeter established a new genus, Di- plophysa, for Cornu's O. Saprolegniae and his own D. elliptica which parasitizes Mesocarpus sp. Fischer ('92), however, reduced Diplophysa and Pleocystidtum to synonyms of Olpidiopsis and di- vided Cornu's genus into two subgenera — Olpidiop- sis with biflagellate zoospores, and Pleocystidtum with uniflagellate zoospores. In the former he placed 0. Saprolegniae and 0. minor (0. fusiformis), while O. schenkiana and 0. parasitica were included in Pleocystidtum. The sporangia and resting spores of several additional algal parasites were described by de Wildeman in 1895, and in 1911 Minden estab- lished a new genus Pseudolpidiopsis (synonymous with Pleocystidium and Diplophysa), in the family Olpidiaceae for these species as well as 0. schen- kiana and 0. parasitica. Inasmuch as the number of flagella on the zoospores of de Wildeman's fungi were unknown, Minden was not justified in refer- ring these species to Pseudolpidiopsis. Since that time the zoospores of 0. schenkiana and its synonym 0. parasitica have been shown to be biflagellate and heterocont, so that Pseudolpidopsis also becomes a svnonym of Olpidiopsis. In the meantime, Butler ('07) added two additional species to the genus Pseudolpidium. Since the time of Fischer and Butler until quite recently very little critical study was made of Pseu- dolpidium, although several new Olpidiopsis and Pseudolpidium species were described, and these two genera have been distinguished respectively by the presence and absence of male cells on the rest- ing spores. In 1939, however, McLarty and Shanor independently discovered that the spiny structures which Fischer had interpreted as the resting spores of Pseudolpidium are nothing more than spiny evanescent zoosporangia, thus showing that Fisch- er's genus, based on the misinterpretation of these sporangia, is no longer valid. McLarty found in ad- dition that the majority of resting spores of 0. Ach- li/ae develop parthenogenetically without sexual fusion, which suggests further that other Pseudol- pidium species, i.e., P. Pythii, P. gracile, and P. stellatum, etc., with true resting spores lacking in attached male cells are only parthenogenetic mem- bers of Olpidiopsis. He ('41) accordingly amended the diagnosis of Cornu's genus to include such spe- cies and listed Pseudolpidium as a synonym. The present writer is following this diagnosis almost completely but retaining Pseudolpidium provision- ally as a dumping ground for the species in which no resting spores have yet been found, i.e., P. Glen- odinianum, P. Sphaeritae and P. deformans. The first two of these species will probably be included eventually in Olpidiopsis, but P. deformans, because of its amoeboid schizogonic thallus, appears to be- long to a different group of organisms. McLarty and Shanor furthermore demonstrated quite clearly from monozoospore infection experi- ments that the number, size and shape of the zoo- sporangia as well as the character of the spines, warts, and knobs on the resting spores are highly variable and of little diagnostic value in distinguish- ing closely-similar species. It is accordingly almost impossible to determine with certainty the identity of most of the Saprolegnia- and .ic/i/^a-inhabiting species which were only briefly and meagerly de- scribed prior to 1939 and 1941. Until all species have been as intensively studied as O. varians and O. Achlyae, an accurate diagnosis of this genus is well-nigh impossible, and for this reason the classi- fication given below is to be regarded as temporary. Particularly significant in diagnosis are the re- sults of Shanor's ('40) and Miss Whiffen's ('42) (il.rtmiii'Mh \< i v r 38 rable 1. showing the host range of Ave species of Olpidioptu. Numerals Indicate number of monospure Infections at- tempted; +■ and below numerals, success or failure to secure infection; and 11. the original hosi from which each parasite was isolated. From Shanor, 1940. Hosts >■ ~ ~- Parasites ? o > * -^ V- •- £ -^ '~ = C ^ ^ ^ '~ -~ ~ "^ e § « - ? c 2r g g .3 ; §i0-S2 2"S.a,e » 2 * ? ■-, - "8 I g> -S i £ « s i3 » "S. ~ a 3> § ». t - §s § g a E .§ ? -2 f r ~ * ^ "* " •; : * t ■ "1 .i IS < g- £ I- ■= •£. s = 5 i t 3 2 II 8 2 2 2 2 2 2 2 J J 2 2 2 2 2 2 2 2 2 2 + + 1- 1 1 4. 4 3 J " H 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 + + + L ~_ 1 — -' - 2 2 2 2 2 2 2 2 2 2 2 2 1 4 4 2 2 H 1 1 1 12 + + + + + + + + + 22222222222222234221 1 H 1 12 ++ + + + + + + 222 2 2 22222H42223222222222 Olpidioptit variant O. ftuiformit 0. Baprolegniat O. mcrassata (). luxuriant (O. Aphanomt/cit) cross inoculation experiments involving numerous host species of Saprolcgnia, Achlya, other related genera, and Pythium. As is shown in table 1, Shanor found that 0. ftuiformit and 0. variant are re- stricted in host range to a few species of Achlya, while 0. Aphanomycet (O. luxurious) is limited to Aphanomycet laevis. .Miss Whiffen, however, found a form of the latter species on ./. cladogamous which would not infect ./. laevis. Olpidiopsis Saproleg- niae and 0. mcrassata, on the other hand, are re- stricted to the same species of .Saprolegnia and to all hut one, I. eccentrica, of the same species of Itoachlya, according to Shanor. The number of in- fections attempted by Shanor. however, is small, and more extensive tests may possibly give different results. Furthermore, it is not evident from Shanor 's account that temperature, pH concentration, and other environmental conditions were controlled in his experiments. Such factors have proven to be very significant in infection and development of other fungus diseases, and it is quite probable that they operate in relation to Olpidiopsis also. Nonetheless, the obligate parasitism and limited host range of Olpidiopsis species which parasitize the Saproleg- niaceae have been clearly established. Shanor's re- sults are furthermore significant, because they sug- gest that species which were formerly believed to be distinct. 0. Aphanomycet and 0. luxuriant for example, may be identical. This is further substan- tiated by the observations that these species arc not as distinct morphologically as they were earlier reported to be. The data presented by McLarty and Shanor show Mry definitely that hasty observations and meager descriptions, of the kind so frequently made in the past, without exact identification of the host and in- tensive study of the range of morphological varia- tion, are practically worthless in the study of Olpi- diopsis. Further studies on these parasites of sapro- legniaceous hosts, if they are to be of value, must comply with the following criteria: 1, Exact identi- fication of the host from pure cultures ; 2, Mono- spore infections of a pure culture of the host to de- termine whether one or more parasite species are present in the original host culture; 3, Intensive study of monospore infection cultures of the para- site to determine the variations in size, shape, and echinulation or spininess of the sporangia, in the degree of sexuality present, and in the character of the outer resting spore wall; 1, Extensive inocula- tion of saprolegniaceous hosts to determine the host range. Development of Thalli and Zoosporangia The development and life cycle of Olpidiopsis species are as follows: The zoospore comes to rest on the host cell, develops a definite cellulose wall ( fig. 8) and forms a conspicuous germ tube through which the content of the spore passes into the host (figs. 9-11). leaving the empty case on the outside. Occasionally, the germ tube fails to penetrate the host and may elongate and branch to a marked de- gree. Figure 7 shows a spore which germinated in water outside of the host and formed a branched germ tube which is strikingly similar to the rhizoida] system of a young rhizidiacous ehytrid thallus. The newly-entered zoospores and young thalli are ap- parently naked but immiscible with the host proto- plasm. Even after ten hours following entrv into tin host McLarty was unable to demonstrate the 31 THE SIMPLE HOLOCARPIC BIFLAUELLATE PHYCOMVCETES presence of a structural cellulose wall by plasnio- lytic experiments and treatment with chloro-iodide of zinc. According to Scherffel and Diehl, the young parasite may change its shape and position and in- dependently undergo slight amoeboid movement, but McLarty maintained that in 0. Achylae, at least, such changes are caused by the rapid stream- ing of the host protoplasm in which the parasite is passively carried along (figs. 12-15). In 0. andreei (P. Ectocarpi) Jokl figured the young thallus as an amoeba with one to several long, more or less radi- ally oriented pseudopods (fig. 162) which migrates towards and engulfs the host nucleus. Fisch and Scherffel also have shown that the young thalli of 0. schenkiana {P. parasiticum) , and O. Oedogoni- orum respectively are often to be found in close as- sociation with the host nucleus (fig. 133) which sug- gests that the food supply may be more optimum in that region of the host cell. All present-day workers are agreed that no fusion of young thalli or newly-entered zoospores to form a plasmodium occurs in Olpidiopsis. The monospore infection experiments of McLarty and Shanor show conclusively that each zoospore gives rise to a single independent thallus or sporangium. By the time the thallus has attained mature size it is invested by a definite wall which in most species has been shown to give a marked positive cellulose reaction when tested with chloro-iodide of zinc. This wall is evi- dently formed by the parasite itself, but the knobs, warts, and spines which may later appear on it ap- parently have a different origin. As Fischer has shown, globules and masses of transformed host protoplasm accumulate at separate points around the periphery of the thallus wall (fig. 31) and are gradually transformed further into spines, warts, and other excrescences (fig. 32). These spines show no positive cellulose reaction when tested, which further suggests that they are different from the primary wall. Inasmuch as they are formed in this manner, it is to be expected that they will vary markedly in size, length, and shape. As is shown in figures 26 to 30 they may be lacking entirely or cover only a part of the sporangium (fig. 26) and vary from blunt knobs to broad or fine spines. Spininess of the sporangia can therefore no longer be regarded as a specific character. The protoplasmic changes which occur during the growth, development, maturation and cleavage of the thalli and zoosporangia have been intensively studied in living as well as fixed material of several Olpidiopsis species, particularly O. Saprolegnia, O. Aphanomycis, and O. Achlyae. Successive stages of these changes are illustrated in figures 16 to 25 of two sporangia of O. Achlyae. The young developing thallus usually includes numerous fatty refractive bodies, and as it grows in size, the latter increase in number and size and impart a granular and slightly yellowish gleam or refringent appearance to the protoplasm (fig. 16). With further development these globules gradually become broken up into bodies of smaller size and appear as oily droplets suspended in the more homogeneous protoplasm (fig. 17). At this stage of development small vacuoles ap- pear in the protoplasm (fig. 17), and as they become more distinct they begin to coalesce. The protoplasm at this stage appears granular and slightly brown in appearance, and when stained with Sudan III it be- comes brick-brown in color. Coalescence of the vacu- oles continues until one or more large central ones are formed (fig. 19). Within an hour following this stage the vacuoles begin to undergo changes in shape (fig. 20) which may continue for a few minutes to half an hour. Cleavage furrows then begin to form at the periphery of the vacuoles and travel centri- fugallv to the plasma membrane (fig. 21) and de- limit the initial zoospore segments (fig. 22). How- ever, in O. Achlyae the areas previously occupied by the vacuoles as such do not disappear as the cleav- age furrows cut through the plasma membrane as Schwartze ('22) described for 0. Saprolegniae. In- plate 9 Olpidiopsis A chlyae (All figures after McLarty, '41) Fig. 1. Slightly bean-shaped living zoospore with vacu- oles and refractive granules. Fig. 2. Fixed and stained zoospore with large nucleus. Slightly unequal flagella inserted beside a deep-staining body near the anterior end. Fig. 3. Amoeboid zoospore. Fig. 4. Zoospore retracting flagella before going into a temporary rest period. Figs. 5, 6. Zoospore at rest. Fig. 7. Zoospore germinated in water with a branched, rhizoid-like germ tube. Fig. 8. Zoospore at rest and encysted on surface of host hypha. Figs. 9-11. Successive infection stages. Figs. 12-15. Changes in shape of the newly-entered parasite due to the streaming of the host protoplasm. Fig. 16. Two incipient zoosporangia surrounded by a dense layer and radiating strands of the host protoplasm. Figs. 17-20. Successive maturating stages of two zoo- sporangia. Figs. 21-25. Cleavage and sporogenesis of lower spo- rangium shown in previous figures. Fig. 26. Smooth and partly-spiny zoosporangia. O. variant Figs. 27-30. Variations in the character of the sporan- gium wall. Shanor, '39. O. fusiformis Figs. 31, 32. Formation of spines on zoosporangia. Fischer, '82. 0. Vexans Figs. 33-37. Successive stages in the development of a thallus from fixed and stained material. Nuclear division simultaneous and completely synchronous. Barrett, '12. Fig. 38. Portion of a zoosporangium following cleavage. Vacuolar areas still present. Barrett, I.e. oi.lMDior.-in ICE \ i 88 PLATE 9 :r Olpidiopsis 36 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES stead, McLarty found that for about a minute fol- lowing the completion of cleavage the zoospores re- mained faintly visible flanking the irregular vacu- olar spaces (fig. 22). Then as the protoplasm be- comes more homogeneously granular and somewhat oleaginous in appearance again, the outlines of the zoospores disappear, and the vacuoles regain their even contours (fig. 23). This is the so-called homo- geneous stage following cleavage which has been de- scribed by most students of Olpidiopsis. Sporangia in the stage illustrated in figure 23 may undergo a prolonged rest period before liberating the zoo- spores. That the zoospore initials do not become eon- fluent during the homogeneous stage, as Butler (07) believed, is shown by MeLarty's plasmolytic experi- ments on sporangia in this stage. After a period of about three quarters of an hour the zoospore seg- ments become visible again (fig. 24), and shortly thereafter the vacuolate areas disappear suddenly and entirely. The zoospores soon assume their ma- ture shape and begin to swarm in the sporangium, and within a few minutes following this stage, the tip of the exit tube opens. The zoospores then emerge fully developed and swim directly away (fig. 25). Variations of the type of cleavage and zoospore behavior described above for 0. Achlyae have often been reported. In O. Saprolegniae and 0. Oedogo- niorum, for example, Coker ('23) and Scherffel ('25) noted that the whole content of the zoospo- rangium may occasionally emerge to the outside as a globular, naked, undifferentiated, protoplasmic mass and then undergo cleavage into zoospores as in Lagenidium and Pythitim. In 0. Pythii the zoo- spores swarm for a brief period at the mouth of the exit tube (fig. 1 14) and then come to rest in a cluster, 'according to Butler. After a few minutes motion is resumed, and the zoospores, which are by this time provided with two flagella, swim away. A similar be- havior for the zoospores of 0. schenkiana was re- ported by Scherffel (figs. 137, 138). This initial rest period at the mouth of the exit tube and the subse- quent ones which interrupt the active swimming stage have been interpreted by Butler, Barrett, Scherffel, and Diehl as evidence of primitive or rudi- mentary diplanetism. In coming to rest the zoo- spores may retract their flagella (fig. 4) and assume spherical or elongate shapes (figs. 5, 6) but they do not encyst. At least no empty vesicle is left behind as they form new flagella and swim away. In O. Oedogoniorum, on the other hand, Scherffel reported true diplanetism. The primary swarmers are later- ally biflagellate (fig. 153). The cystospores later germinate, and an empty vesicle is left behind as the secondary swarmer emerges. Whether or not the position of the flagella on the secondary swarmers differs from that of the primary swarmers is not known. The accounts and descriptions in the literature on the shape of the zoospores and relative lengths of the flagella vary considerably. Most investigators have described the zoospores as oval, elongate, and taper- ing at the anterior end or somewhat reniform with- out a marked ventral furrow and with two flagella of equal or almost equal length inserted in or near the anterior end. Other workers have reported them to be almost spherical, oval, pyriform and distinctly heterocont (figs. 103, 158). Accurate data on the exact location and relative lengths of the flagella are lacking in most species. However, since the zoo- spores swim fairly rapidly and undergo changes in shape it is difficult to determine with certainty the relative lengths of the flagella in living material. Markedly heterocont zoospores have been reported and figured for (). irregularis (Constantineanu, '01), 0. schenkiana (Scherffel, '25), and 0. Ricciae (du Plessis, '33), while in the remaining species they have been described as isocont or with flagella of plate 10 O. Achlyae Figs. 39-53. Successive stages of nuclear division. Mc- Larty, I.e. O. luxurious Fig. 54. Two young incipient zoosporangia and a larger female thallus with an attached male thallus in a swollen hyphal tip. Barrett, I.e. O. Achlyae (All drawings after McLarty, I.e.) Figs. 55-58. Successive stages in the development of a parthenogenetic and a sexual spore. Incipient spores in figure 55 surrounded by a hyaline, amorphous zone or layer. Fig. 59. Incipient spore from fixed and stained material showing centripetal development of spines at localized points. Fig. 60. Remanent of border of amorphous zone form- ing a membrane-like border around the tips of the spines. Figs. 61-67. Variations in the character of the exospore. O. vexans and other species Fig. 68. Young male and female thalli; nuclei dividing. Barrett, I.e. Figs. 69-76. Stages in nuclear division from female thallus. Barrett, I.e. Fig. 77. Gelatinization of intervening wall between the male and female thalli prior to plasmogamy. Barrett, I.e. Fig. 78. Later state in gelatinization. Nuclei in small male thallus dividing. Barrett, I.e. Fig. 79. Passage of male nuclei into female thallus. O. luxurious. Barrett, I.e. Figs. 80-82. Nuclear pairing and karyogamy. O. vcxaus. Barrett, I.e. Fig. 83. Mature resting spore with two attached male thalli which still contain their protoplasm. O. Achlyae. McLarty, I.e. Fig. 84. Resting spore with four attached empty male cells. Fig. 85. One empty male thallus between two resting spores. O. luxurious. Barrett, I.e. Drawn from photograph. Fig. 86. Small O. minor-like resting spore of O. various. Shanor, '39a. Fig. 87. Early germination stage. Male thallus enveloped by spiny exposure. O. variant. Shanor, I.e. OLPIDIOPSID ICGAI PLATE 10 0 $ o 39 V- ., ,, 42 38 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES "about" equal length. Whether or not the heterocont species should he segregated in a separate group on this basis is of questionable diagnostic value until the zoospores of all species have been intensively stud- ied. According to Couch ('41) one of the flagella of 0. Saprolegniae has a long distinct tail piece, while the other one possesses nine to eighteen lateral "tin- sel" cilia, 1.5 /a long, which may occur on one or both sides or follow a spiral course. The same type of flagella will probably be found to occur in all species of Olpidiopsis. During growth and development of the thalli the nuclei undergo simultaneous and synchronous divi- sion (figs. 34, 35, 37), according to Barrett and Mc- Larty. Nuclear division is typically indirect and not of the so-called promitotic type reported for the Plasmodiophorales, although the resting nuclei pos- sess a very large nucleole and little chromatin in the form of granules on a reticulum (fig. 39). Succes- sive division stages from thalli of 0. Achlyae are shown in figures 39 to 53. The fact that most of the stainable material is in the form of a globular nu- cleole which often appears to be vacuolate or made up of differentially stainable regions (figs. 41, 42) suggested to McLarty that the nucleole functions as a storehouse of chromatin. This is further substan- tiated, in his opinion, by the radial orientation of the chromatin network on the nucleole (figs. 40, 41) and the latter's gradual disappearance as the prophase changes progress. Barrett, on the other hand, found a well-defined dense chromatin reticulum in addition to a large nucleole in resting nuclei of the female thalli (figs. 58 to 60). McLarty interpreted the emergence of radially oriented chromatin threads as the beginning of the prophases (figs. 40, 41), and as these stages progress the chromatin becomes more evident as globular (fig. 43) or rod-shaped densely stained bodies (fig. 44). By this time the nucleole has usually disappeared. Concurrent with the emer- gence of chromosomes a deeply stainable centro- some-like body appears at one of the nuclear poles in O. Achlyae (fig. 43) and undergoes division (figs. 45, 46). The daughter bodies thus formed then gradually migrate around the nuclear membrane (fig. 47) to the opposite poles of the nucleus (figs. 48, 49, 50). Barrett, however, found no evidence of centrosomes in 0. vexans. No conspicuous astral rays have been found in association with these bodies in O. Achlyae, nor does the division spindle appear to arise from them as far as is now known. Accord- ing to Barrett, the latter originates from the chro- matin mass in the equator of the nucleus and gradu- ally grows towards the poles, but his figures of the process are not definite and clear. In profile views of the equatorial plate stages the chromosomes are often arranged in a broken ring (fig. 50) around the margin of the spindle, but usually they are closely crowded together and appear as a dark band. In polar views of this stage (fig. 51) McLarty found six chromosomes in O. Achlyae which is the same number reported by Barrett for O. vexans. No evi- dence of meiosis has been found in these divisions in the thalli and zoosporangia. The halves of the chro- mosomes separate in the metaphases and migrate (fig. 52) to the poles as two compact deeply stained masses (fig. 53), which may often be connected by a slender chromatin filament (figs. 53, 76). The nu- cleus and spindle elongate considerably in the late prophases and metaphases, and by the time of the late anaphases the nuclear membrane has usually disappeared entirely. The formation of the daughter nuclear membranes and the telophasic reconstruc- tion stages of the nuclei are not well known, al- though figure 76 suggests that the daughter chromo- some groups become surrounded by clear spaces, the boundaries of which later become the nuclear mem- branes. Nuclear division in the so-called antheridia and oogonia is also mitotic (figs. 68 to 76). In O. I'exans, however, Barrett found prophase stages in which the chromatin was aggregated in synaptic- like masses at one side of the nucleus (fig. 72), but he did not believe that they relate to prophases of meiosis. Resting Spore Development and Sex Differentiation As has been noted in the generic diagnosis above the resting spores of Olpidiopsis may develop par- thenogenetically without sexual fusion or as the re- sult of fusion of a large female thallus with one to several smaller male thalli. Some species, i.e., 0. gracile and O. Pythii, appear at present to be wholly parthenogenetic, while others are only partially so or entirely sexual. The small male and larger female thalli are generally referred to in the literature as antheridia and oogonia, respectively, and the fusion of these cells has been regarded as a primitive or rudimentary type of heterogamous and oomycetous sexual reproduction. Petersen and Scherffel re- garded the resting spores of Olpidiopsis as an oospore in an oogonium which lacks periplasm, and on these grounds the latter worker in particular postulated the origin of a Pythium-Peronosporaceae series from simple species through Olpidiopsis. Use of the terms antheridia and oogonia for the male and female thalli respectively in this genus is obviously open to serious question since these terms in their proper sense relate to gametangia which produce more or less differentiated gametes. Furthermore, in some species, i.e., O. andreei, the thalli which fuse may be equal in size, so that sexual reproduction is occasionally isogamous. Nevertheless, the develop- ment and evolution of antheridia and oogonia and the oomycetous type of sexual reproduction is clearly foreshadowed in Olpidiopsis. In the discus- sion which follows the non-committal terms male and female will be used for the thalli which fuse. In the early developmental stages in living ma- terial, the female thalli are identical in appearance to those which are to develop into zoosporangia, and it is not until thev have attained considerable size OI.l'iniOl'SIDAf EAE 39 tli.it they can be distinguished. All thalli therefore appear to be potential soosporangia and male or fe male thalli in the early developmental stages. This is strongly suggestted by Mauriaio's figure 7 of 0. major which shows two male thalli attached to a larger female thallus with an aborted exit tube. The male thalli art' indistinguishable from small young ■OOSporangia also except lor their close association with the female thalli (tig. 54). In fixed and stained material, on the other hand, the female thalli can be recognised quite clearly by their staining reaction. Barrett found that they have a marked affinity for Orange (i. while the zoosporangia and male thalli readilv take up gentian violet. Mel. arty likewise noted that the female thalli may he distinguished in the young stages by numerous fatty bodies which stain brilliantly with crystal violet. Successive developmental stages of a parthenogen- etic and a sexual resting spore are shown in figures 55 to 58. In hoth of the incipient spores are numerous large refractive fatty globules, which later appear to decrease in size hut increase in number. The endo- spore is well developed in figures 56 and ■">(), hut in figure 53 there is yet no evidence of the exospore. In- stead, the incipient spores are surrounded by hyaline or slightly amber-colored zones. The formation of the exospore usually first Incomes evident as a homo- geneous, amorphous layer which develops centri- pctally around the spores and gradually replaces the closely surrounding granular host protoplasm shown in figure 54. It is in this layer or zone apparently that the host protoplasm is transformed into spines, warts, knobs, or a smooth undulating layer. In O. Pi/tlui | figs. 118-120) Butler reported that the host protoplasm condenses centripetally, so that at one period the outer ends of the spines appear sharp and fully formed while the proximal part is still envel- oped in host protoplasm. The investing band of pro- toplasm described by Butler is probably a zone in which the host protoplasm is being transformed and deposited as spines. A resting spore of 0. Achlyae in the process of exospore formation from fixed and stained material is shown in figure 59. The conden- sation or deposition appears to be occurring along radially oriented lines, and in certain regions the lines an- localized and organized into conical groups or bundles, which apparently represent incipient spines. It is to be further noted that the lines do not extend all the way iii. but are progressing from the outer margin toward the center. That the layer or zone shown in figure 55 is not merely a region filled with cell sap may be demonstrated by microdissec- tion. Mel. arty found by such studies that this zone is a comparatively tough structural layer. After the spines have been fully formed the boundary of this layer may often persist as a thin membrane-like structure ( rigs. ."Hi. 60) around the tips of the spines. which gives the impression that the resting spore Lies in an empty hyaline vesicle. Mel. arty found that the exospore may be poorly developed in resting spores which use up most of the host protoplasm in the early developmental stages, and suggested that the extent of exospore formation, i.e.. length, thick- ness, and abundance of spines, warls. knobs, etc.. is dependent on the amount of host protoplasm present at the time of its development. In that event, it will obviously vary to a high degree and is not to be re- garded as a stable diagnostic character. Further more, the exospore composed of spines, warts, knobs, or a s oth undulating layer does not give a positive- cellulose reaction when tested with chloro iodide of zinc. As noted above, the exospore may exhibit marked variations in a single species. In 0. .lclili/ac it may be smooth, even, or undulating in contour (figs. 56, (il, 65, 66) as in 0. incrasxata ; composed of fine, thread-like spines (fig. 61) as in 0. fihrillosa; broad triangular spines, as in 0. minor (figs. 60, 63, 67) ; long tapering curved spines (fig. 62) as in (). curvi- spinosa; or partly smooth and spiny (fig. 65). Oc- casionally, two resting spores and two male cells may be enveloped by one exospore (fig. 66). Parthe- nogenetic spores may vary in exospore structure to the same degree as the sexual spores in O. Achlyae. Similar but less extensive variations have been de- scribed by Shanor ('39a) for 0. variant, and an examination of figures 91 to 1 1 1 shows how variable the earlier known species of Olpidiopsis also are. The empty male thalli or companion cells likewise may be smooth, echinulate, warty or spiny. Obvi- ously, a character as variable as the exospore is of little diagnostic value in distinguishing species. Returning to the description of plasmogamy and karyogamy, it is to be noted that the male and female thalli are multinucleate before they show any marked visible differentiation as gametes, except for relative size. Their nuclei may continue to divide mitotically (figs. 68-76) up to and even during (fig. 78) the initial stages of plasmogamy as has been shown by Barrett and McLarty. The first step in plasmogamy in species in which it occurs through a pore, according to Barrett, is a swelling and gela- tinization of a portion of the intervening wall be- tween the fusing thalli (fig. 77). In fixed and stained material this region is usually heavily stained. A more advanced stage of gelatinization is shown in figure 78 where the cell wall material ap- pears to be diffusing into the two thalli. The nuclei in the male thallus are dividing while those in the female are at rest, but it is not uncommon to find them dividing in both gametes during plasmogamy. After the so-called fertilization pore has been formed the protoplasm of the male thallus begins to How into the female (tigs. 57. 79). The passage may be completed within a few minutes or last several hours. Following plasmogamy, the fused protoplasts change in their susceptibility to stains and have a greater affinity for safranin. according to Barrett. The gametic nuclei become irregularly distributed in groups and decrease considerably in size. At the same time the number of refractive oil globules in- creases, and the fertilization pore closes. During these processes the exospore undergoes differentia- tion, as described above, and attains its definitive •10 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES character. There are no size differences between the male and female nuclei, so that it is impossible to distinguish them on this basis, according to Barrett and McLarty. Both of these workers found nuclei in pairs, and Barrett figured a few stages of what he believed to be nuclear fusion (figs. 80-82). Although he did not find conclusive evidence of nuclear fusions in pairs, he nonetheless believed it occurs. McLarty, on the other hand, failed to observe fusion and held that the occasional occurrences of nuclei in pairs may be merely fortuitous. Therefore, the problem of the type of karyogamy, i.e., whether the numerous gametic nuclei fuse in pairs or all but one pair de- generate, in Olpidiopsis still remains to be solved. That plasmogamy of male and female thalli is not always essential to resting spore development is evident in the species which are partly or wholly parthenogenetic. In 0. Achlyae, McLarty observed cases in which only part of the male protoplast passed into the female th alius. Occasionally one male may "serve" two female thalli, and in some instances as many as two to eight empty male thalli have been found attached to a single resting spore. Apparently in these instances there are supernu- merary male nuclei following plasmogamy, but whether or not the unmated ones degenerate is not known. Obviously, sexual reproduction in Olpidiop- sis presents numerous unsolved cytological prob- lems, and until these have been solved it will be im- possible to determine how closely Olpidiopsis is re- lated to the higher Oomycetes. It is also probable that male thalli are capable of developing androgenetieally into resting spores. At least this is suggested by the small spore shown in figure 108. In some species the male thallus is at- s tached to the female by an attenuated neck or canal (figs. 143, 144, 149, 150, 156), through which the male protoplast passes during plasmogamy. As in other organisms this neck is generally referred to as a conjugation or fertilization canal. Sometimes the male thalli may occur in tandem (fig. 149) but whether or not the content of the terminal one passes through the adjacent companion cells to reach the female in such cases is not known. Sex Determination It has been generally assumed by most mycolo- gists that species of Olpidiopsis are heterothallic, inasmuch as the resting spores are formed usually by fusion of thalli of unequal size. However, the monospore culture experiments of McLarty and Slianor on O. Achlyae and O. varians have discred- ited this belief, and it now seems that most, if not all, Olpidiopsis species are homothallic or haplosy- noecious as was earlier suggested by the author ( '39) and McLarty ('39b). As noted elsewhere McLarty and Shanor found that sexually formed resting spores may occur readily in cultures propagated from a single zoospore. Similar results will probably be secured from other species when they have been studied in monospore cultures. In light of what is known to occur in haplonts, meiosis probably oc- curs during the first division of the diploid (?) nu- clei in the germinating resting spore, but whether or not sex is genotypically differentiated at this stage is not absolutely certain inasmuch as McLarty and Slianor did not make monozoospore cultures from germinating resting spores. However, the fact that a single zoospore from a sporangium will give rise to cultures which later form male and female thalli shows that it carries the potentialities of both sexes. If sex is genotypically determined at meiosis in the germinating resting spore the resultant zoospores would be male and female in equal numbers and de- velop into sporangia of opposite sexes, which is con- trary to the results obtained by McLarty and Shanor. According to their data sex in Olpidiopsis appears to be determined phenotypically at some stage in the haploid generation. Olpidiopsis Ach- lyae and 0. varians accordingly seem to be hap- losynoecious. At which stage in the life cycle sex differentiation occurs is not known. As has been pointed out above incipient zoosporangia as well as the male and female thalli are multinucleate and quite similar in appearance, and until differentia- tion occurs it is impossible to tell which type of re- productive structure is going to develop from them. It seems that all thalli in the early stages are poten- tial male and female cells which under certain ex- ternal environmental and internal conditions become differentiated and develop into gametes. Cellular Relations Between Host and Parasite As has been noted elsewhere, all species of this genus appear at present to be obligate parasites with a limited host range. So far they have not been successfully grown on synthetic media, although Diehl ('35) was able to bring zoosporangia to ma- turity on agar. According to his observations, the maturation stages of zoosporangia are not depend- ent on the presence of the host. All Olpidiopsis spe- cies which parasitize members of the Saprolegniales and Pythium usually cause marked local hyper- trophy of the infected hyphae but do not induce sep- tation except in the case of Pythium. In the latter host the supporting hyphae may occasionally be de- limited from the remainder of the mycelium by cross walls (figs. 112, 113). The swellings in the host hyphae may vary markedly in shape and size, and may be terminal, intercalary, or in some cases pro- ject out as lateral diverticula. Most species which parasitize algae cause little or no hypertrophy, but O. zopfii and O. appendiculata may induce local swellings which are two to four times the normal diameter of the algal filaments. Infection by O. Oedognoriorum leads to the formation of a conspicu- ous plug of cellulose by the host cell (fig. 131 ) at the point of entry of the germ tubes. In cases of infection by O. Achlyae, the penetra- tion of the germ tube and entrance of the parasite oll'llilol'sin ICE \K H may cause ■ localised temporary agitation of tin- host protoplasm, according to McLarty. The refrac- tive granules in the latter swirl in eddies around the young parasite (fig. 10) and soon obscure it from view. This reaction, however, is of short duration, because when the parasite again becomes visible it is closely surrounded by the host protoplasm and hardly distinguishable from ordinary protoplasmic inclusions. The two protoplasts appear to be inti- mately associated, and no visible antagonism is ex- hibited. At hast, there is no retraetion of the host protoplasm away from the parasite. The host nuclei appear normal in its immediate vicinity and appar- ently are not stimulated to divide by its presence. In 0. ickenkiana (fig. 133), 0. Oedogoniorum, and 0. andreei (fig. 162 |, as noted before, tin- young para- site migrates toward and becomes closely applied to the host nucleus, and in the ease of 0. andreei (P. Ectocarpii) may completely engulf it. As the thalli increase in size the free floating phase ends and the parasites Income more or less localized in the hyphae. At this stage the host protoplasm be- gins to How toward and accumulates around the thalli. and in a short time hypertrophy of the host begins. In some instances the swelling appears to be initiated in the immediate vicinity of the parasite, hut this is not the general rule. Furthermore, hyper- trophy does not invariably occur. In some oogonia and hyphae containing limited amounts of proto- plasm McLarty found little or no distortion follow- ing infection by 0. Achlyae. Accordingly, he be- lieved that the swellings are not due to direct stimu- lation by the parasite but to the great accumulation of the host protoplasm in its immediate vicinity. That the host wall is stretched in such regions has been demonstrated by Diebl's ('35) plasmolytic ex- periments. As the swellings increase in size conspicuous vacuoles appear in the host protoplasm (figs. 1. 54). These soon become traversed by more or less radiat- ing strands of protoplasm moving slowly towards the parasite. This movement continues until all or most of the protoplasm has been attracted to and ab- sorbed by the developing thalli. In the species which parasitize green algae the plastids and nuclei art- destroyed, and at maturity the sporangia (tig. 1-16) and resting spores are partly surrounded by a mass of degenerated protoplasm. In 0. Ricciae on Riccia, however, no harmful effects are apparent, accord bug to du Plessis. This species occurs only in the rhizoids and basal swelling of the same, and al- though they become infected when young they de- velop normally. No distortion, swelling, rupture or necrotic effects are produced, and du Ph-ssis accord- ingly believed that the relationship between host and fungus may possibly be symbiotic. PARASITES OF SAPROLEGNIA O. SAPROLEGNIAE ( Braun) Cornu, I.e.. ),. I 15. PI. :i, figs. 1-10. Chytridium Saprolegniae Braun, 1855a, Ber. K'gl. i'n-iiss Akad, \\iss. is.-,;,: 384. 1855b. Abh. K'gl. Akad, «iss. Berlin is:,;,: (il. PI. .",, ftg. -':!. oipitliiiiu Baprolegniat Braun, I.e.. p. ".">. Diplophysa Saprolegniae Schroeter, 1886. Cohn's Krj pt'fl. Schlesiens :i: L95. I'.-i mini /liiliii hi Saprolegniae Fischer (pro parte) 1892. Rabenhorst's Krypt'fl. I, t: 85. OlpidiopsU echinata Petersen, 1909. Hoi. Tidsskr. 39: 405. Pig. XVIIIa. 1910. Ann. Mycol. 8: 540. Fig. X Villa. Zoosporangia usually numerous in a host cell, hyaline, smooth or spiny (?), variable in size and shape, spherical, 15-150 /i, oval. (i7 /i )< 00-100/*, ellipsoid and elongate 15-25 p X 20-150 p, with one to several short or elongate, straight, curved, or irregular exit tubes which end Hush with the surface of the host cell or extend considerably beyond it. Zoospores isocont ( ? ). oval, or slightly bean-shaped with the flagella attached near the anterior end. Resting spores parthenogenetic (?) or sexual, brown, oval spherical, 28-107/*; endospore thick, exospore covered with numerous short (?) spines; companion or male cells when present 1 to 4 per resting spore, hyaline, smooth, oval, spherical, 18— 32 p; germination unknown. Parasitic in Saprolegnia sp., S. fcrajc, S. fhitreti, and S. mixta in Germany [Nageli, '44 (?); Braun, '55a, '55b; Pringsbeim, '60; Reinseh, '78 (?); Behla, '03; Minden, '11; Diehl, '35]; Saprolegnia sp., in France [Cornu. I.e.; Dangeard, '00; Varit- chak, '31 (?)], Russia (Sorokin, '83, '80), Rou- mania (Constantineanu, 01); S. dioica and S. monoica in Denmark ( Petersen, '00, '10) ; S. thureti, S. diclina, S. delica, S. mixta, S. littoralis, S. mono- ica, Saprolegnia sp., Isoachlya anisospora, I. uni- spura, and /. recent rica in the U. S. A. (Barrett, '12; Davis, '14; Schwarze. '22; Harvey, '27. '42; Graff. '28; Maneval. '37; Shanor, '40; Couch. '41; Wolf. '41); S. thureti and >S. monilifera in Japan (Tokunaga, '33) causing large terminal and inter- calary swellings in the host hyphae. According to Shanor, this species is limited in host range to species of Saprolegnia and Isoaclili/a and will not infect Achlya, Aphanomyces, Aplanes, Dictyuchus, Leptolegnia and Protoachlya species. If this is true, the parasites described by Petersen ('09, '10). Coker ('23). Gilman and Archer ('20) and Sparrow i '32. '33) as O. Saprolegniae in Ach- lya relate to another species, unless these workers were mistaken about the identity of the host plants. Sparrow ('83) was of the opinion that Coker's fun- gus is 0. luxurians, but this .seems unlikely since tin- latter species is confined to . / plm mini geex hosts, ae cording to Shanor ('40). Inasmuch as Coker inter- preted 0. Saprolegniae in the sense of Fischer i '92 I, it is not improbable that the species which he ob- served in A. flagellata and ./. imperfecta may pos sibly be (). fusiformU or 0. various. In view of tin- fact that sporangium size and shape and the char- acter of the exospore an- no longer diagnosl ie.ill v specific, and in the light of Shanor's contentions that the species are restricted to certain hosts, it is 42 THE SIMPLE HOLOCARl'IC BIFLAGELLATE PHYCOMYCETES obviously impossible to determine which of the para- sites described in the older literature relate to 0. Saprolegn'tae. Olpidiopsis Saprolegn'tae Cornu is the type spe- cies of the genus and probably the parasite which Pringsheim mistook for a developmental stage of Saprolegnia. Cornu limited the name 0. Sapro- legn'tae to Saprolegnia — inhabiting parasites the resting spores of which are covered with numerous fine spines, but Fischer ('92) included Cornu's spe- cies in Pseudolpiditim and restricted the name 0. Saprolegn'tae to a species with hemispherical or blunt, hyaline, up to 3 /^ high, warts or pegs on the resting spores. Barrett interpreted 0. Saprolegn'tae in the original sense of Cornu and created a new spe- cies, 0. vexans, for the parasite with warty resting spores described by Fischer. Diehl and Shanor sup- ported Barrett's interpretation, but Coker and Graff accepted Fischer's distinction. The present writer is following Barrett's interpretation of 0. Saproleg- n'tae to a certain degree but only temporarily until all species have been more critically studied. Olpi- diopsis Saprolegn'tae Fischer and 0. vexans Barrett are accordingly reduced to synonyms of 0. incras- sata. However, this does not completely solve the taxonomic problems involved nor greatly aid begin- ners in recognizing and distinguishing Olpidiopsis species. In the first place, 0. incrassata, for instance, is supposedly characterized by resting spores with a wavy undulating exospore, and the introduction un- der this name of synonymous species, 0. Saproleg- n'tae Fischer and 6. vexans, with warty or knobby resting spores destroys this distinction. On the other hand, MeLarty ('41) has clearly shown that 0. Ach- li/ae also may form resting spores with a wavy un- dulating exospore (figs. 58, 61, 66), which obviously indicates that this character is not specific for 0. in- crassata alone. Furthermore, 0. Saprolegn'tae Cornu, according to Shanor ('10), is limited to the same Saprolegnia and Isoachltja hosts as 0. incrassata, with the exception of /. eccentrica. Therefore, on the basis of host relationship there is no distinction between these two species. In view of the fact that sporangium size and shape, number and length of exit tubes, and the character of the exospore no longer appear to be constant for a species, and in the event that Shanor's host range results are con- firmed, it may perhaps be taxonomically expedient to lump all reported Saprolegnia parasites, with the possible exception of O. irregularis, under the name of O. Saprolegn'tae Cornu. In that event, Cornu's species would have the following synonomy: Chytridium Saprolegniae Braun, I.e. Olpidium Saprolegniae Braun, I.e. Olpidiopsis incrassata Cornu, I.e., p. 146. O. Saprolegniae Fischer, I.e. O. major Maurizio, 1895. Jaliresber. Nat. Ges. Griiu- bundens 38: 15. O. echinata Petersen, I.e. O. oexans Barrett, 1913. Ann. Bot. -2i>: -231. Diplophysa Saprolegniae Schroder, I.e. Pseudolpiditim Saprolegniae Fischer, I.e. P, incrassatum Fischer, I.e. Such a classification is based entirely on host re- lationship, which is often a questionable criterion of distinction. Nevertheless, the author is inclined to agree at present with Petersen's view that 0. Sapro- legniae and 0. incrassata may possibly be identical. The results of Shanor's cross inoculation experi- ments appear to be fairly conclusive, but the number of monospore infections which he made is epiite small. It is not altogether improbable that more ex- plate 1 1 Figs. 88 to 90. Germinated resting spore and zoospores of O. varians. Exit tube passing through empty male thallus. Shanor, I.e. Figs. 91 to 93. Echinulate, knobby and spiny resting spores of O. Saprolegniae. Cornu, "1-2 ; Petersen, '09, '10; and Shanor, '39b, respectively. Fig. 94. Resting spore of O. echinata. Petersen, '09, '10. Figs. 95 to 97. Smooth resting spores with attached male thalli of O. Saprolegniae var. laevis. Coker, '23. Fig. 98. Three parthenogenetic and one sexual resting spore of O. incrassata with broad undulating exospores. Cornu, I.e. Fig. 99. Greatly enlarged resting spore of O. major with three male thalli. Maurizio, '95. Figs. 100, 101. Echinulate and knobby resting spores of O. vexans. Barrett, I.e., and Shanor, '39b, respectively. Figs. 102, 103. Irregular lobed zoosporangium and heterocont zoospores of O. irregularis. Constantineanu, '01. Fig. 104. Fusiform zoosporangia of O. fusiformis. Peter- sen, '09, '10. Fig. 105. Broad-spined resting spore of O. fusiformis. Cornu, I.e. Fig. 106. Similar resting spore of O. minor. Sparrow, '32. Fig. 107. Resting spore of O. index with echinulate male cell. Cornu, I.e. Fig. 108. Large and small resting spore of O. fusiformis (?). Small spore may possibly be androgenetie. Coker, I.e. Fig. 109. Resting spore of O. spinosa with spiny male cell. Tokunaga, '33. Fig. 110. Knobby resting spore of O. Aphanomycis. Petersen, '09, '10. Fig. 111. Spiny parthenogenetic resting spore of O. Aphanomycis. Whiffen, '12. O. Pythii (All figures after Butler, '07) Fig. 112. Three sporangia in a swollen spherical hyphal tip; supporting hypha with a cross wall. Fig. 113. Mature sporangium. Fig. 114. Zoospores clustered at mouth of exit tubes. Figs. 115, 116. Bean-shaped, isocont zoospores with re- fractive granules. Fig. 117. Spiny, parthenogenetic resting spores. Figs. 118 to 120. Stages in the formation of spines on the resting spore. O. .. occasionally in asso- ciation with Rosella septigena, in Roumania (Con- stantineanu, I.e.) and Denmark (Sparrow. '84), causing large terminal clavate swellings in the host hyphae. Tliis speeies takes its name from tile irregular shape (fig. 102) of the sporangia, hut sporangium shape is obviously a questionable diagnostic char- acter in parasites as variable as Olpidiopsis speeies. Constantineanu was doubtful about its identity be- cause no resting spores were found, and he assigned it tentatively to Olpidiopsis as a new species. It dif- fers from the other parasites in Saprolegnia, as far as they are now known, by heterocont zoospores. As noted above. (). irregularis may be associated with R. teptigena, and Constantineanu was of the opinion that it feeds of the latter's thallus. PARASITES OF ACHLYA O. FUSIFORMIS Cornu, I.e., p. 147. pi. +, figs. 1-4. I), miliar Fischer. I.e., p. 39. /'..< nihil jiiiliiim fusiforme Fischer, I.e., p. 37. Zoosporangia solitary or numerous, smooth or spiny, elongate, fusiform. L'(i-78 p X 98-350 p, oval, 7-10 a X 21.7-80 /x X 120 /J., spherical, 10-120 ^, with 1 to 3 exit tubes. Zoospores isoeont (?) egg- shaped, oval, slightly elongate. 2 X 4 /"•• Resting spores parthenogenetic or sexual, solitary or nu- merous, yellowish-brown, spherical. 80—60 fi, cov- ered with fine short, or broadly conical and tri- angular spines up to 10.5 \>. in height; contents coarsely granular with one to several refractive globules; companion or male cells when present 1 tu 3 per resting spore, hyaline and smooth, oval, spherical 16— 24/t; germination unknown. Parasitic in Achlya leucosperma, A. racemosa and Achhia sp., in France (Comu, I.e.) ; ./. /lar/ellata, A. leucosperma, A. racemosa and A. polyandra in Germany [Cienkowski, ">"i (?); Reinsch, '78 (?); Fischer, '82, '92; Minden. 'llj; Achlya sp.. and Saprolegnia sp. i ?), in Russia (Sorokin, '83, '89); Achltfa sp.. in I)e ark (Petersen. '09. '10) J '. flagellata and A. flagellata var. yesoensis and A. racemnsa in Formosa and Japan I Sawada. '16, 19; Tokunaga, '.'(3 i : Achlya sp., A. flagellata, A. race- mosa, A. imperfecta, A. klebsiana, and Saprolegnia sp.. ? ) in the I'. S. A. (Sparrow, ''.i'2 ; Matthews, '85; Shanor, '89, '40); Achlya sp., in England (Sparrow. '86), and ./. racemosa in Czechoslovakia ( ejp, '84 I, causing large terminal and intercalary fusiform and clavate swellings in the bust hyphae. This speeies was named fiisiformis by Cornu I" cause of the fusiform, elongate, and almost linear shape of its zoosporangia. This character, however, is not very specific, since fusiform and greatly elon gale zoosporangia have been reported in other spe eies as well. Furthermore, resting spores with broad triangular hyaline spines, which arc reported to be characteristic of (). fiisiformis, may occur in 0. Achlyae and (). variant also. Shanor ('40) found that (). fiisiformis is limited in host range to ./. racemosa and ./. imperfecta and will not infect the other Achlya species which he tested (table 1). Particularly noteworthy is the fact that it did not infect ./. flagellata, although seven in- fection attempts were made. These results contra- dict the reports of Sawada, Tokunaga, and Matt- hews of its occurrence in this host. Achlya imper- fecta and A. klebsiana were heavily parasitized, but A. racemosa was infected only slightly in Shanor's experiments. Sorokin and Sparrow are the only two workers who have reported (). fiisiformis in Saprolegnia, and here again it is possible that they were mistaken about the identity of the host plants. On the other hand, they may equally well have had 0. Saproleg- niae or 0. incrassala at hand. Sparrow believed that the fungus which Petersen reported as 0. fiisiformis relates to (). Aphanomyces (O. luxurious), but this is unlikely inasmuch as the latter species is limited in host range to Aphanomyces. As has been pointed out elsewhere, the parasite of A. imperfecta and A. flagellata which Coker ('23) described as 0. Saprolegniae Fischer may possibly relate to 0. fiisiformis or 0. varians, or in part to both species. Whether 0. index (Cornu) I.e., p. I 15, pi. 3, (fig. 11) is a valid species or identical to O. fiisiformis is not certain. Cornu described it as a parasite of Ach- lya sp., usually with solitary, very large elliptical zoosporangia and resting spores and echinulatc com- panion cells (fig. 107). No measurements were given of the size of the sporangia, zoospores, and resting spores. The presence of echinulate companion cells was nevertheless regarded by Cornu as specific, and he accordingly diagnosed the parasite as a distinct speeies. However, it is very doubtful that the oc- currence of echinulations and spines on the com- panion cells is a specific character, since both smooth and spiny male cells have been reported in 0. va- rians, (>. curvispinosa, and 0. brevispinosa. Olpidiopsis spinosa (Tokunaga. '33. Trans. Sap- poro Nat. Hist. SOC. 13; 25. PL 2, figs. 10-11) para- sitizes ./. flagellata and occurs in association with 0. fusiforme .and (). minor in Japan. Tokunaga de- scribed it as follows: Zoosporangia solitary or nu- merous, hyaline, smooth, ellipsoid, elongate or cylin- drical, 34-61 pX 92-198/1, with one or two exit tubes; zoospores isoeont. ellipsoid or elongate, size unknown, with the flagella attached laterally near the anterior end; resting spnres hyaline, spherical. 51-73//. covered with numerous line. 9.6 ju long spines; germination unknown; companion cells sin 46 THE SIMPLE IIOLOCAKPIC BIFLAUELLATE PHYCOMS CETE8 gle, hyaline, globose, 25.2 /x— 32.4 /x, covered with numerous fine spines. The size and shape of the sporangia of this spe- cies are strikingly similar to those of 0. fusiformis, and besides the presence of long, fine spines on the companion cells (fig. 109) there are few or no char- acters to distinguish it from the latter species. While the spines on the resting spores of 0. fusiformis and O. minor are reported to be broad and triangular, it is not improbable that they vary considerably in thickness, shape and length and may attain the di- mensions of those described by Tokunaga. The pres- ent writer is accordingly inclined at present to re- gard 0. spinosa as a synonym of O. fusiformis. It is quite possible that Pseudolpidium stellatum (Sawada, 1912. Spec. Bull. Agr. Expt. Sta. For- mosa, 3: 70, pi. 8, figs. 11—16) is synonomous with this species also. Sawada found this species in A. prolifera in 1912 and 1919 in Japan, and it was sub- sequently reported by Tokunaga in 1933. Zoospo- rangia and zoospore were not observed, and the rest- ing spores were reported to be hyaline, spherical, ovoid, or globoid, 24-100 p., and covered with long 9-24 ii, pointed and sharp spines. No male or com- panion cells were found. Sawada reported that P. stellatum may occur independently or in association with O. fusiformis. O. VARIANS Shanor, 1939. Jour. Elisha Mitchell Sci. Soc. 55: 171. PI. 24. Zoosporangia solitary or numerous, smooth, warty or spiny, spines up to 7 ju, in length, spherical, oval, ellipsoid, 40-140 jit by 60-350 /x, frequently 80 X .200 ft, with 1 to 5 exit tubes. Zoospores isocont, oval to elongate, 2.3-3 yu. X 3.8-4.6 /u; flagella 4.2 to 4.6(11 long. Resting spores yellowish-brown, spheri- cal 26-83 jx; exospore hyaline to yellowish in color, 1.2 fi thick, usually bearing coarse, abruptly-taper- ing spines, 8.6 /x high, which are connected by a reticulum; endospore yellowish-brown, 1.7 fi thick; companion or male cells 1 to 2 per resting spore, usually spherical, 17 to 30 /x, occasionally smooth, usually enveloped by the spiny exospore of the rest- ing spores, spines 1.7 /x long; resting spore trans- formed directly into a zoosporangium in germina- tion with an exit tube which usually penetrates the companion cell. Parasitic in Achlya flagellata, A. racemosa, A. colorata and A. proliferoides in North Carolina, U. S. A. (Shanor, '39a, '39b, '40) causing large terminal or intercalary swellings in the host hyphae. Shanor found that this species is limited to the Achilla species listed above and will not infect A. americana, A. imperfecta, A. klebsiana, A. recurva, A. apiculata, A. glomerata, nor any of the species of Saprolegnia, Aplanes, Protoachl i/a, Isoachl i/a, Aphanomyces, Dictyuchus, and Leptolegnia shown in table 1. This species is highly variable in sporan- gium size and shape as well as in the character of the exospore, and was named varians because of its variability. The spines are broad and triangular as in some specimens of O. fusiformis and O. Achlyae (figs. 86, 87), and some of the resting spores are strikingly similar to those of O. minor (fig. 106). Furthermore, the companion cells are usually en- veloped by the spiny exospore of the resting spore, although the spines in the vicinity of such cells are usually shorter. A similar envelopment has been shown to occur in O. Achlyae (fig. 66). O. ACHLYAE McLarty (ad int.) 1941a. Bull. Torrey Bot. Club. 68:62, figs. 1-26. 1941b, Ibid. 68:75, figs. 1-80. Zoosporangia solitary or up to 50 in a hypha, smooth or covered with fine or coarse noncellulosic spines or bristles, variable in size and shape, spheri- cal, oval, ellipsoid or elongate, 13.2-112.4 X 115- 666.4 ix. with 1 to 3 exit tubes which may extend considerably beyond the surface of the host fila- ment. Zoospores hyaline with numerous small re- fringent granules, oval or somewhat reniform 2.3— 2.9 /x X 4.3-5.7 /x, usually about 3.1 X *.2 p., with two approximately equal flagella attached laterally near the anterior end. Resting spores parthenogene- tic or sexual, spherical or oval, 22.8-122.4 fx, usu- ally 41 X 50 fx, brown, with several or usually one large refringent globule; endospore smooth cellu- losic, 1 to 1.5 /x thick; exospore noncellulosic, 1 to 11.4/x thick, covered with warty protuberances, small or large, narrow or broad-based spines, hair- like fibrillae, or with an entire, undulant or slightly serrate margin ; companion or male cells 1 to 3 per resting spore when present, thin-walled, hyaline, smooth, sometimes embedded in the exospore, oval or spherical; resting spore transformed directly into a zoosporangium with an exit tube in germina- tion. Parasitic in Achlya flagellata, London, Ontario, Canada (McLarty, '39, '40, '41), causing large ter- minal and intercalary swellings in the host hyphae. McLarty diagnosed this parasite temporarily as a new species, until the other Olpidiopsis species with which it appears to be identical have been more intensively studied. As is shown in Plates 9 and 10, it is highly variable in structure and may produce resting spores with exospores which are characteris- tic of most species of this genus. In general it resem- bles O. fusiformis most closely, so that the writer and his student, McLarty, were inclined to regard it as closely related or identical to this species. But if Shanor's data that O. fusiformis will not infect A. flagellata are correct, these two species are different in host range at least. Since O. Achlyae occurs on the same host and shows much the same variations as O. varians, it is possibly identical to the latter spe- cies. Although spiny companion cells have not been observed in O. Achlyae, this does not exclude the possibility of its being the same as O. varians. On t lie other hand, it is equally probable that O. various, (). Achlyae and possibly O. index and 0. spinosa may be biological varieties or races of O. fusiformis which are limited to particular hosts. If this proves 0LPIDI0P81DACKAG 47 to be true, all Achlya-inhaibit'mg parasites may pos sibly be grouped as a single species with several pos sible physiological races of varieties. To determine this possibility an intensive study of the degree of morphological variation of all species and their liost range must be made. PARASITE OF APHANOMYCES O. APHANOMYCIS Cornu, I.e., p. 148, pi. 1, figs. 6-11. Pti udolpidium Aphanomycit Fischer, I.e., p. 37. <>. luxuriant Barrett, l.c.,p. 831. PI. 33, figs. 1, 5, 6, 9-14, In 18, .'II. .':i: pi. 84, figs. M :ii. 88 31; pi. -V.. figs. t:i til: pi. 86. Zoosporangia Military or numerous, up to 20 or more in a hypha, smooth, or spiny, spherical, oval, fusiform and elongate, dimensions unknown; one to several exit tubes which may extend considerably beyond the surface of the host cell. Zoospores iso- cont, oval, egg- and slightly bean-shaped, size un- known: coming to rest in a mass at the mouth of the exit tube for a few minutes and then swimming away; flagella inserted at (?) or near the anterior end. Resting spores parthenogenetic or sexual, hrown, oval, spherical, 25— SO p; endospore thick, exospore comparatively thin and covered with conical spines, 2.5 p in height, or hlunt warts; contents granular with one or more large refractive globules; com- panion or male cells when present 1 to 3 per resting spore, hyaline, smooth, oval, ellipsoid, spherical, 10-2.5 //, germination unknown. Parasitic in Aphanomyces sp. and Pythium sp. - ) in France (Cornu, I.e.; Dangeard, '90); Apha- nomyces sp.. in Denmark ( Petersen. '03, 09, '10) and Germany (Minden, II); A. laevis in India (Butler. '07; Sydow and Hutler, '07; Butler and Bishy, '3 1 ) and the U. S. A. (Barrett. I.e.; Shanor, '39. 10) and A. cladogamous (Whiffen, 12) caus- ing large broadly fusiform intercalary and almost spherical terminal swellings in the host hyphae. As noted above, Dangeard reported this species as a parasite of Pythium, but Butler ('07) and Shanor were unable to secure infection of P. mono- spermunt, P. proliferum, P. gracile, and /'. aphani- dermatum with it. Butler nevertheless believed that tin- resting spore figured by Dangeard relates to 0. dphanomycet, but as Minden (11) and Shanor :;!i suggested it is probably the resting spore of 0. [Pseudolpidium) Pythii. Shanor (10) was un- able to transfer O. A phanomycis to Aphanomyces itellatut, Achlya, Saprolegnia and other water molds, and concluded that it is limited in host range to Aphanomyces laevis. Miss Whiffen, however, re- ported its occurrence in ./. cladogamOUS. It is to be noted, however, that her fungus did not infect ./. laevis, which suggests at once that it may be a physiological race of <). Aphanomycis. This remains to be shown, however, from more extensive cross inoculation experiments involving Saprolegnia, Achhia and other similar host species. PARASITES OK l'YTIIUM O. PYTHII (lintler) comb. nov. Pteudolpidium Pythii Butler. 1907. Mini. Dept. Agrlc. India. Hot. Ser. 1 No. 5:127. PI. 7, figs. !> Hi. Zoosporangia solitary or numerous, hyaline, smooth, oval, and ellipsoid, up to 35 p. in the great est diameter, with a single exit tube of varying length which extends for a short distance beyond the surface of the host. Zoospores isOCOnt, hyaline, uni equilateral, somewhat kidney-shaped with one lo several small refractive granules; flagella laterally inserted; swarming in the vicinity of the exit canal for a brief period, then coming to rest for a few minutes in a dense cluster; finally swimming away slowly. Resting spores parthenogenetic. solitary or numerous, often in association with zoosporangia. oval or spherical, 19.2— 30 /x, brown, comparatively thin-walled and covered with fine, thread-like, short, evenly spaced spines; germination unknown; com- panion or male cells lacking. Parasitic in Pythium monospermum, P. rostra- turn, P. vexans, and P. intermedium in France (But- ler, I.e.), Pythium sp.. in Germany (Minden. '11), P. oryzae in Japan (Tokunaga, '33), and Pythium sp., in England (Sparrow, '36), causing oval, spher- ical, obpyriform or balloon-shaped enlargements at the end of the host hyphae or in lateral diverticula, and occasionally leading to septation of the hyphae. O. GRACILE (Hutler) comb. nov. P. gracile Hutler, I.e., p. 129, pi. 7, figs. 1-8. Zoosporangia solitary or numerous, up to 10 in a single swelling, hyaline, smooth or spiny, spherical, •1—52 /x, with 1 to 5 contorted and swollen exit tubes of varying lengths which may project considerably beyond the surface of the host cell. Zoospores, iso- eont ( ?). hyaline, obclavate. elongate, and some- what curved with one to several minute refractive granules, size unknown; one flagellum inserted near the anterior end, the other laterally; swimming mo- tion smooth, body of spore often revolving on its long axis. Resting spores parthenogenetic, single or numerous, occurring in association with the zoo- sporangia. spherical to oval. 12— 27 p exclusive of spines, yellowish, containing a large refractive glob- ule surrounded by a peripheral layer of vacuolate protoplasm; endospore .7 to 1.2 p. thick, exospore 1.7 to 2.5 p thick and covered with long. 1 p., taper- ing, thick, crowded spines; germination unknown; companion or male cells lacking. Parasitic in Pythium intermedium in France ( Butler. I.e.) and P. rostratum in the I". S. A. (Whiffen, 12) causing terminal enlargements and Lateral, oval- or balloon-shaped diverticula in tin- host hyphae which may be 80— 90 p in their greatest diameter. Whether the zoospores are hi -terocont or isocont is not certain from Butler's description. He reported that one Hagellum is inserted near the anterior end while the second I is lateral, but his figure (fig. 48 THE SIMPLE HOLOCARPIC MELAGELLATE PHYCOMYCETES 12) suggests that they are both lateral in position. According to Miss Whiffen, 0. gracile will not in- fect P. torulosum, P. pvlchrum, P. proliferum nor the unidentified Pythium hosts of O. brevispinosa and O. curvispinosa. O. CURVISPINOSA Whiffen, 1042. Amcr. Jour. Bot. 29:610. Figs. 1, .5, 21. Zoosporangia solitary or numerous, spherical to oval, 12-68 fx in greatest diameter, hyaline, smooth or covered by short bristles, with one to three exit tubes. Zoospores with numerous oil globules, elon- gate and somewhat reniform, size unknown; flagella of about equal length and attached near anterior end. Resting spores hyaline, spherical to oval, 17— 24 p., containing a large refractive globule sur- rounded by vacuolate protoplasm ; exospore covered by curved spines up to 5 /x in length. Companion or male cell consistently present, hyaline, spherical, or oval, 14-20 p., smooth or with short, closely-set spines; germination unknown. Parasitic in Pythium sp., and P. torulosum in North Carolina, U. S. A., causing large terminal or intercalary swellings in the host hyphae. O. BREVISPINOSA Whiffen, I.e., p. 610. Figs. 2, 22, 21. Zoosporangia solitary or numerous, oval, spheri- cal, 10.6-68.1/1, with one to three exit tubes. Zoo- spores elongate and somewhat reniform with sev- eral oil globules; flagella of about equal length and attached near the anterior end. Resting spores dark brown, spherical to oval, 10.6—15.1 xx, containing a large refractive globule surrounded by vacuolate .protoplasm ; exospore 1.7-2.5 /x thick, covered by short, fine spines up to 3.5 /x in length, endospore .75— 1.32 p. thick; companion cell consistently pres- ent, oval, spherical, 7.1-25.5 /x, smooth or spiny; germination unknown. Parasitic in Pythium sp., from Louisiana, U. S. A., causing large terminal and intercalary swellings, up to 125 p in diameter, in the host hyphae. This species is limited in host range to an uniden- tified species of Pythium and will not infect P. ros- tratum. nor the host of O. curvispinosa, according to Miss Whiffen's cross inoculation experiments. PARASITES OF ALGAE O. SCHENKIANA Zopf, 1884. Nova Acta Ksl. Leop.- Carol. Deut. Akad. Nat. 47: 168. PI. 15, figs. 1-32. Pleocystidmm parasiticum Fisch, 1884. Sitzb. Phys.- Med. Soc. Erlangen 16: 60. Figs. 24-3!). Olpidiopsis parasitica (Fisch) Fischer, 1H92. Raben- horst's Krypt'fl. I, 4: 40. Diplophysa schenkiana (Zopf) Schroeter, 1897. Engler und Prantl, Die Nat. Pflanzenf. I, 1: 85. Pseudolpidiopsis schenkiana ('/opt') Minden, 1911. Krypt'fl. Mark Brandenburg 5: 257. /'. parasitica (Fisch) Minden, I.e., p. 258. Zoosporangia solitary or numerous, hyaline, smooth, spherical, oval, ellipsoid, egg-shaped, elon- gate, 21.6-26.4 xi X 30-81.6 it, with one or two stout, short or elongate, up to 60 /x long, straight or plate 12 O. gracile Fig. 123. Mature zoosporangium with 4 exit tubes; ac- companied by a resting spore. Butler, I.e. Figs. 124, 125. Pyriform beteroeont (?) zoospores with refractive bodies. Butler, I.e. Fig. 126. A large diverticulum with numerous sporangia and resting spores. Butler, I.e. Fig. 127. Smooth-walled resting spore. Whiffen, '42. O. curvispinosa and O. brevispinosa Fig. 128. Resting spore of O. curvispinosa with long curved spines. Male cell spiny. Whiffen, I.e. Fig. 129. Spiny resting spore and male cell of O. brevi- spinosa. Whiffen, I.e. O. schenkiana Fig. 130. Infection of Spirogyra cell. Zopf, '84. Fig. 131. Cellulose plug on cell wall at point of entry of germ tube. Scherffel, '25. Fig. 132. Forked germ tube, and young naked vacuolate parasite in host cell. Scherffel, I.e. Fig. 133. Young parasite next to larger host nucleus (P. parasiticum). Fisch, '84. Figs. 134 to 136. Zoosporangia and emission of zoo- spores. Zopf, I.e. Fig. 137. A flagellate amoeboid primary swarmer with contractile vacuole. Scherffel, I.e. Fig. 138. Side view of pyriform, beteroeont secondary swarmer with contractile vacuole. Scherffel, I.e. Figs. 139, 140. Optical and cross-section views of same. Scherffel, I.e. Fig. 141. Early stage in resting spore formation. Zopf, I.e. Fig. 142. Resting spore with one companion cell. Zopf, I.e. Fig. 143. Resting spore with four companion cells. De Wildeman, '96. Fig. 144. Similar resting spore (P. parasiticum) Fisch, I.e. Fig. 145. Germination. Only one flagellum shown on zoospores. Zopf, I.e. Figs. 146 to 148. Zoosporangium and resting spores of O. zopfii. De Wildeman, I.e. Fig. 149. Resting spore of O. fibrillosa. Spines not shown. Two male cells in tandem. De Wildeman, I.e. Fig. 150. Same with fibril-like spines. De Wildeman, I.e. Fig. 151. Resting spore of O. appendiculata. De Wilde- man, I.e. O. Oedogoniorum (All figures after Scherffel, '25) Fig. 152. Mature vacuolate zoosporangium. Fig. 153. Isocont primary swarmer. Fig. 154. Cystospores. Figs. 155, 156. Resting spores in elongate hyaline vesi- cles with attached companion cells. O. Hiccioe Fig. 157. Empty zoosporangium in a rhizoid. Fig. 158. Anteriorly biflagellate, beteroeont zoospores. Figs. 159, 160. Resting spore with companion cell, and elongate parthenogenetic (?) spore. 0I.P1DI0P8IDACEAE 40 PLATE 12 so THE SIMPLE HOLOCARPtC BIFLAGELLATE PHYCOMYCETES curved exit tubes which may project considerably beyond the surface of the host cell or extend through adjacent cells. Zoospores heterocont, oval, pyriform, 4 X 6 ft, and slightly bean-shaped ; hyaline with several small refractive granules and a contractile vacuole ; emerging singly, fully developed, and swimming directly away, or emerging and lying in a mass for a few minutes at the mouth of the exit tube before becoming amoeboid and flagellate and swimming away; flagella lateral (?), shorter flagel- lum extending forward and the longer one backward in swimming. Resting spores hyaline, smooth, oval, egg-shaped or spherical, 30-10 p., thick-walled with a large refractive globule ; companion or male cells 1 to 5 in number, hyaline, smooth, oval or spherical. 16.8—21.6 fx; resting spore transformed directly into a zoosporangium with an exit tube in germination. Parasitic in Spirogyra sp., Mougeotia sp., and Mesocarpus sp., in Germany (Zopf, I.e.; Fisch, I.e.; Minden, '11); Spirogyra sp., in Hungary (Scherffel, '25); Spirogyra sp., in Belgium (de Wildeman, '90, '91, '96), Roumania (Constanti- neanu, '01), India (Butler, '07; Butler and Bisby, '31), Japan (Tokunaga, '33), causing no or only slight hypertrophy of the host cell. The writer also has frequently observed this parasite in Spirogyra sp., in the vicinity of New York. Fisch and Zopf, among the early workers, de- scribed the zoospores as uniflagellate, and for this reason Minden included this species in his new genus, Pseudol pidiopsis. Scherffel's observations, however, leave no doubt about the number of flagella, and Zopf s species may now be returned to the genus Olpidiopsis. Obviously the previous investigators had failed to observe the second flagellum. Fisch's Pleocystidium parasiticum is included here as a synonym of Zopf's species, since it occurs in the same host and appears to have the same structure and type of development. Fischer and Minden re- garded both species as distinct because of the pres- ence of up to five companion cells on the resting spores of P. parasiticum, but de Wildeman found up to four male cells per resting spore in O. schen- kiana also. In view of the variations which Maurizio, Barrett, Diehl, McLarty, Shanor and others have observed in other species of Olpidiopsis, the number of companion cells present is a questionable diag- nostic character. O. ELLIPTICA (Schroeter) Fischer, I.e., p. 41. Diplophysa elliptica Schroeter, 1886. Cohn's Krvpt'fl. Schlesiens 3: 196. Pseudolpidiopsis elliptica (Schroeter) Minden, I.e., p. 260. Zoosporangia and zoospores unknown. Resting spore obliquely ellipsoid, slightly less in diameter than the host cell, and covered with fine, scattered spines; companion or male cells slightly smaller than the spores, brown and smooth; germination un- known. Parasitic in Mesocarpus sp., in Germany. This species has been reported only once, but it is not altogether improbable that other species de- scribed from Mesocarpus may be identical or closely related to it. It is reported to differ from O. schen- kiana chiefly by the presence of spines on the resting spores. O. SOROKINII de Wildeman, 1890. Ann. Soc. Beige Micro. 14: 22, fig. 7. Zoosporangia solitary, hyaline, smooth, elongate, sac-like or cylindrical with a single short exit tube which ends flush with the surface of the host cell. Zoospores small. Resting spore unknown. Parasitic in Tribonema {Conferva) bombycinum in Belgium. This is a very doubtful species which de Wilde- man thought might be identical to O. fusiformis var. Oedogoniarum Sorokin. Later in his Census Chytri- dinacarum ('96), however, he listed it as Olpidium sorokinii. Inasmuch as the resting spores are un- known its validity as a member of Olpidiopsis is very questionable. O. ZOPFII de Wildeman, 1895. La Notarisia 10: 34. 1896, Ann. Soc. Beige Micro. 20: 25, pi. 1, figs. 1-3, 5-7. Pseudolpidiopsis zopfii (de Wildeman) Minden, I.e., p. 259. Zoosporangia solitary or numerous, hyaline, smooth, spherical, egg-shaped or ellipsoid with a single exit tube of varying length which usually pro- jects beyond the surface of the host cell. Zoospores unknown. Resting spores spherical, 16— 22/x, with one or more refractive globules, thick-walled and covered witli numerous stout, broad-based, abruptly tapering spines; companion cells 1 to 3 in number, small, oval, spherical, 12 /t, smooth, hyaline; germi- nation unknown. Parasitic in Spirogyra sp., in Luxemburg, causing local swellings, up to twice the normal diameter of the filaments. O. FIBRILLOSA de Wildeman, 1895. I.e., p. 34. 1896. Ann. Soc. Beige Micro. 20: 27. PI. 2, figs. 13, 14, 18, 19. Pseudolpidiopsis fibrillosa (de Wildeman) Minden, I.e., p. 259. Zoosporangia solitary, hyaline, smooth, oval or ellipsoid, witli a single exit tube more or less broad- ened at the base. Zoospores unknown. Resting spores hyaline, thick-walled, spherical, 20-25 ft, oval, egg- shaped and ellipsoid witli one to several refractive globules ; exospore profusely covered with fine, radially oriented hair-like spines or fibrillae which give it the appearance of a halo; companion cells, 1—3, hyaline, smooth, spherical or pyriform, occa- sionally occurring in tandem; germination unknown. Parasitic in Spirogyra sp., in Belgium (de Wilde- man, I.e.) and Germany (Minden, I.e.), causing only slight swelling of the host filaments. 0LPIDI0P8ID M 1 \ I ."> 1 O. APPENDICULATA ilc Wildeman, 1898. I.C., p. 3*. 1896. \nn. Soc Beige Micro. W: 19. PL I. flgs. I. 8-19. Pt0udolpidioptii apptndieulata (de Wildeman) Mto- den, I..-., p. W9. Zoosporangia solitary, hyaline, smooth, spherical, oval or ellipsoid with a single . and 27 it looks as if the content of a sporangium has un- dergone endogenous division with the original thal- lus wall remaining intact. The method by which the /oospores get out of the host is not known. According to Dangeard they are liberated within the host, but it is obvious that some of them eventually escape. Otherwise additional hosts would not bcc< ■ infected. Mitchell suggested that they might escape through the "mouth" vacu- ole or by rupture of the host cell. The mature free swimming zoospores are pyriform .and pointed at the apex with two unequal flagella inserted a short dis- tance back of the anterior end ( fig- I )■ Their move ineiit in swimming is more even, straight forward .and less irregular and darting than in Sphaerita. 56 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES According to Dangeard, the structure and activ- ity of Euglena polymorpha are not greatly affected at first by the presence of the parasite, and in ex- ceptional cases of monoinfection this host may con- tinue its normal activities even after the parasite is mature. The plastids may remain green and un- changed, except for a reduction in size, up to the time of sporulation (figs. 16, 17). In instances of heavy infection, however, the injurious effects may appear sooner. As the parasites develop and ma- ture the starch grains become corroded, the chloro- plasts turn lighter in color, and the cytoplasm be- comes reduced in quantity. The vacuome, stigma, and nucleus, on the other hand, remain normal for a longer time. The initial effect on the nucleus is an increase in chromaticity as densely stainable rods and fragments appear in the reticulum. Later the nucleus decreases in size and finally disinte- grates. Like the remainder of the host cell it does not enlarge or divide because of the presence of the parasite. Mitchell also reported that the parasite has no toxic effect on E. caudata. No differences in activity could be detected in infected individuals, although some of them were so crowded with para- sites that little or no green color was visible. In E. viridis, on the other hand, infected specimens were nearly always rounded, and in fixed and stained preparations early degeneration of the nucleus and chromatophores was evident in such individuals. In the late stages of development the parasite was often envoloped by a mass of degenerating cytoplasm, in- cluding traces of the host nucleus and plastids. Pseudosphaerita includes at present P. Euglenae and possibly another species, P. radiata comb. nov. .However, the reports of Pumaly ('27) and Cejp ('35) that Sphaerita endogena and S. dang ear dii have biflagellate zoospores suggest that additional species exit. It is equally possible that Sphaerita may have biflagellate zoospores and does not differ fundamentally from Pseudosphaerita. The parasite of E. sanguinea described by Niigler (11) as P. Euglenae probably does not relate to this species be- cause it develops long exit tubes like Pseudolpidium Sphaeritae. The taxonomic position of Pseudo- sphaerita and its relation to other genera with bi- flagellate zoospores is very uncertain at present. Dangeard ('95) first regarded it as a member of simple olpidiaceous chytrids closely related to Sphaerita, but in 1933 he created a separate family, Pseudosphaeritaceae, for it among the Archimyctes because of its characteristic type of development. Mitchell included the species which he studied in the Sporozoa under the Haplosporidia. P. EUGLENAE Dangeard, 1895. I.e., fig. 9. 1933, ibid. 25: 30. PI. 4, figs. 3-16. Zoosporangia solitary or numerous, oval, spheri- cal, elongate, coiled, or slightly irregular, hyaline and smooth, forming 64 to 128 zoospores. Zoospores pyriform, 2.5-3^ X 6/*; flagella 2.5 and 7 /x long respectively. For further details see the generic de- scription above. Parasitic in Euglena viridis and E. pol umorpha in France (Dangeard, I.e.); E. caudata in Georgia, U. S. A. (Mitchell, I.e.). This species is possibly the parasite with pyri- form biflagellate zoospores which Stein (1878. Abt. Ill, 1. PI. 20, fig. 21) figured in E. viridis in Ger- many. He also illustrated parasites with biflagellate zoospores in Chlamudomonas alboviridis (PI. 14, figs. VI 4-14) and C. pulvisculus (PI. 15, fig. 36), but since the flagella are posteriorly attached it is doubtful that these parasites relate to Pseudospha- erita. P. RADIATA (Dangeard) comb. nov. Sphaerita radiata Dangeard, 1890. Le Bot. 2: 54. PI. 2, fig. 20. Zoosporangia solitary or up to 3 in a cell, hyaline, smooth, oval and egg-shaped, size unknown; lib- erated or expelled to the outside by the rupture of the host cell. Zoospores hyaline with a refractive globule, oval and elongate, isoeont (?), size un- known ; liberated by the breakdown of the sporan- gium wall. Resting spore unknown. plate 14 (Figs. 2-5 after Dangeard, '95; figs. 1, 6-8 after Dan- geard, '33; figs. 28-31 after Dangeard, '90; figs. 19-27 after Mitchell, '28.) Pseudosphaerita Euglenae Fig. 1. Biflagellate heterocont zoospores with flagella inserted in a small depression near the anterior end; shorter flagellum directed forward. Fig. 2. Uninucleate oval parasite (Sphaerita sp. ?) in E. viridis. Fig. 3. Multinucleate coiled thallus. Fig. 4. Cleavage stages (?) of multinucleate thalli. Fig. 5. Euglena polymorpha with 17 uninucleate para- sites which have apparently developed from zoospores liberated within the host cell. Fig. (i. Uninucleate parasites slightly larger. Figs. 7, 8. Uni- and multinucleate parasites. Figs. 9-15. Stages in the division of the parasites fol- lowing each mitosis. Fig. 16. A multinucleate parasite shortly before spo- rogenesis. Fig. 17. Sporangium with fusiform zoospores. Fig. 18. Zoospores liberated within host cell. Fig. 19. Euglena caudata with one uninucleate thallus. Figs. 20-22. Successive stages of growth and division of the thallus into spores in E. caudata. Fig. 23. Two uninucleate thalli (Sphaerita dangeardii ?) in E. viridis. Fig. 24-26. Stages in the development of a multinu- cleate thallus in E. viridis. Fig. 27. Sporangium filled with spherical and oval spores. Pseudosphaerita (?) radiata Figs. 28, 29. Biflagellate iso- and heterocont and uni- flagellate zoospores. Fig. 30. Cryptomonas ovata with two small parasites. Fig. 31. Cryptomonas ovata with a large parasite in which the refractive globules are radially oriented. 0LPIDI0P8IDAI I M 57 PLATE 14 Pseudosphaerita 58 THE SIMPLE HOLOCAUPIC BIFLAGELLATE PHVCOMYCETES Parasitic in Cryptomonas ovata in France. This species was apparently observed by Dan- geard in 1889 (PI. 1, fig. 15) and mistaken for the endogenous germs of the host. Its outstanding char- acteristic, according to Dangeard ('90), is the radial orientation of the refractive globules in the thallus (fig. 31). The inclusion of this species in Pseudo- sphaerita is obviously questionable, because the thal- lus is expelled from the host as in species of Sphaer- ita. Although Dangeard figured most of the zoo- spores as biflagellate he failed to include this spe- cies in Pseudosphaerita. Nevertheless, it is included here tentatively although nothing is known about the development of the thallus and the type of cyto- kinesis. The oval and elongate "nuclei" which Stein (1878, pi. 19, figs. 29, 31) figured in the same host may possibly relate to this species, although no radially oriented refractive globules are shown. BLASTULIDIOPSIS Sigot, 1931. C. R. Soc. Biol. 108 : 37. (plate 17, FIGS. 10-12) Thallus intramatrical, unicellular, lobed, pluri- locular, irregular, and holocarpic. Zoosporangia soli- tarv in host cell, hyaline, smooth, irregular, lobed and plurilocular with a low exit papilla. Zoospores biflagellate and isocont, developing completely and swarming in the zoosporangium, swimming directly away after emerging. Resting spores unknown. 1 The thallus of this monotypie genus in very simi- lar in appearance to that of Blast ulidium, but the type of infection and thallus development are more like those of species of the family Lagenidiaceae. The zoospore comes to rest on the Cyclops egg and forms a germ tube which penetrates the host wall. The content of the spore does not pass into the host cell as a more or less naked protoplast as in Olpidi- opsis, Ectrogella, etc., but instead the tip of the penetration tube enlarges, elongates, branches and eventually forms the irregular lobed thallus. Sigot did not observe germination, infection and the stages of thallus development in living material, but based his account on studies of fixed and stained prepara- tions. In the early stages of development, the thallus contains numerous small vacuoles (fig. 10) which later fuse to form a large central one. By this time the contents of the host cell have been largely con- sumed, and the parasite usually occupies the entire cavity. After the vacuoles have fused, the more vis- cid, visible part of the protoplasm forms a thin parietal layer in which the nuclei lie (fig. 11). Cy- tokinesis is apparently accomplished by centrifugal cleavage furrows which cut out uninucleate spore rudiments. The latter develop into zoospores which soon begin to swarm within the sporangium. Shortly thereafter the tip of the exit papilla deliquesces, and the zoospores swim out and away. No evidence of diplanetism has so far been observed. As is shown in figure 12, the zoospores are oval and slightly elongate with two flagella inserted near the anterior end at which lies a conspicuous refractive globule, similar to that described by Sparrow ('34, '36) for the zoospores of Sirolpidium and Petersenia. The taxonomic position and relationships of Blas- tulidiopsis are obscure, since nothing is known about its resting spores. As noted previously its type of development, according to Sigot, is suggestive of species of the Lagenidiaceae, while the appearance of the centrally vacuolate sporangia, swarming of the zoospores within, etc., are similar to those of 01 pidiopsis, Sirolpidium, Petersenia and other re- lated genera. B. CHATTONI Sigot, I.e., figs. 1-3. Zoosporangia solitary, hyaline, smooth, irregular and lobed, size unknown. Zoospores 6 X 8 /j. with a refractive globule at the anterior end; flagella 15— 20 ix long, inserted near the anterior end and extend- ing in opposite directions. Resting spores unknown. Parasitic in eggs of Cyclops in France, destroy- ing their content but causing no enlargement or divi- sion of the inflated cell. PYTHIELLA Couch, 1935. Mycologia 27: 160. (plate 15) Thallus intramatrical, holocarpic. oval, ellipsoid and spherical ; solitary or up to 1 in a swelling. Zoo- sporangia centrally vacuolate with 1 to 5 simple or branched exit tubes. Zoospores fully delimited in the zoosporangia, diplanetic; primary zoospores aflagel- late, gliding out and encysting at the tip of the exit tube; content of cysts emerging after about an hour; motile secondary zoospores oblong with a longitu- plate 15 Pythiella vernalis Fig. 1. Germinated zoospore with young parasite within Pythium hypha. Fig. 2. Beginning of host hypertrophy. Figs. 3-7, 9-13. Successive stages of the maturation of a thallus into a zoosporangium, cleavage, zoospore emis- sion, encystment, and emergence from cysts. Fig. 8. The so-called esealloped or "balled" stage of sporogenesis. Fig. 9. The homogeneous stage following cleavage. Figs. 14—10. Successive stages of emergence of the zoo- spore from a cyst. Fig. 17. A mature biflagellate isocont zoospore. Figs. 18, 19. Young antheridia and oogonia in hypha] swellings. Figs. 20, 21. Beginning and completion of plasmogamy. Fig. 22. An egg fertilized by two antheridia. Fig. 23. Mature oospore within an oogonium and an empty attached antheridium. ni.rimni'sin \< :e \v. 59 PLATE 15 Pythiella 60 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES Carpenterella sp. (?) Text-fig. A. Amoeboid thalli and spherical bodies in sugar cane. Drawn from photograph 5B after Carpenter, -4(). Text-fig. B. Two almost equal, paired spherical bodies. Drawn from photograph 7, left, after Carpenter, '40. Text-fig. C. Association of a large and a small sphere. Drawn from photograph 7, right, after Carpenter, '40. Carpenterella Molineq (All figures after Tehon and Harris) Text-fig. D. "Thalli in fiber cell showing plasmodial en- largements and bead-like knots." Text-fig. E. "Thallus in ray and wood parenchyma cells, showing connections through pits." Text-fig. F. "Net-like thallus in parenchyma cell, sending plasmic projections into an adjoining trachea through half bordered pits." Text-figs. G to L. "Stages in the formation of the oospore, showing shrinkage of the male cell to form the com- panion cell of the oospore." Text-fig. M. "Mature oospore with dense alveolar cyto- plasm, granules, heavy wall, and companion cell." dinal groove, laterally biflagellate and isocont, one flagellum directed forward, the other backward in swimming; swimming movement slow in a spiral path, zoospores rotating on their axes. Oospores formed by the fusion of the contents of one or more small thalli (antheridia ?) and an egg cell (?) lying within a rudimentary (?) oogonium; fusion canal fine and delicate; male thalli remaining attached to the oogonium as empty hyaline vesicles or compan- ion cells ; germination unknown. This genus includes a single species, P. vernalis, which combines in its life cycle many of the char- acters of the Olpidiopsidaceae, Lagenidiaceae, Saprolegniaceae, and Pythiaceae. It is strikingly similar to Ectrogella, A phanom i/copsis , Achli/a and Saprolegnia in the method of formation and be- havior of the zoospores, but differs from these gen- era, according to Couch, by the appearance of its protoplasm which has a pale whitish fatty gleam like that of Lagenidium, Myzocytium, Olpidiopsis, etc. In type of sexual reproduction it resembles to some degree Olpidiopsis sehenkiana, but differs from this species by the presence of periplasm in the oogo- nium. By the latter character it resembles species of P y thiu m. Pythiella vernalis parasitized Pythium gracile and P. dicti/osporum which in turn are parasitic in species of Spirogyra. As is shown in figure 1 the zoospore of P. vernalis comes to rest on the Spiro- gyra filament, encysts, and then develops a fairly long germ tube which penetrates the algal cell until it reaches the Pythium hyphae within. The latter is then pierced, and the content of the zoospores passes into the host cell as a more or less naked globule of protoplasm (fig. 1), like that of Olpidiopsis, Ectro- gella, etc. The zoospore ease and penetration tube remain behind and persist for a long time after in- fection. The young parasite assumes a spherical or oval shape in the Pythium hyphae (fig. 2), but it is not certain that it possesses a well-defined wall in the early stages of development. Couch believed that it may be enveloped by a membrane at this stage, but his figures do not show it. No evidence of amoeboid movement or migration of the young parasite has been observed. As the thallus develops, the host hy- phae enlarge in the region of infection so that broadly oval, spindle-shaped and spherical swell- ings or galls are produced (figs. 2, 13, 18-23). How- ever, the host does not form cross septa and delimit 0LPIDIOP8ID VCKAK 61 the parasite as in cases of infection by species of Rozella. The young thallns usually includes a large number of small vacuoles (fig. 8), .'111(1 as it becomes larger these increase in size also and eventually fuse to form i large central vacuole (fig. t). As in the sporangia of Saprolegnia species, this vacuole may extend up through the center of the exit tube and often follows ■ spiral path (figs. T. 8). The wall of the thallns and sporangia is well defined at matur- ity, but, unlike that of Olpidiopsis and other simi- lar fungi, does not show a marked cellulose reaction when tested with chloro-iodidc of /inc. The exit tuhes may be simple or branched and vary from 1 to S per sporangium. They are usually quite long and extend not only beyond the host cell hut through the wall of the Spirogyra filament and far beyond its surface. The central vacuole increases in si/e as the spo- rangia mature until the remainder of the protoplasm forms a comparatively thin parietal layer (figs. 4- 8). The border of the vacuole becomes quite irregu- lar as broad cleavage furrows are formed (fig. 7) which progress ccutrifugally towards the periphery, .hist before these furrows reach the plasma mem- brane the parietal layer of protoplasm has a char- acteristic scalloped appearance (fig. 8) which corre- sponds to the so-called spore initial stage in the Saprolegniaceae and the "hailing" stage described by Scherffel ('25) for Ectrogella and Aphanomy- copsis. As the cleavage furrows attain the periphery the central vacuole collapses and disappears. The boundaries of tin cleavage segments become quite invisible and the protoplasm appears to occupy the entire volume of the sporangium (fig. !)). The latter decreases slightly in si/e at this stage, due possibly to loss of water during the collapse of the central vacuole. This stage is strikingly similar to the so- called homogenous phase of sporogencsis in Olpidi- opsis, "Ectrogella, and the Saprolegniaceae. Very shortly afterwards the fully formed spores become visible i fig. 10) and soon glide out of the sporan- gium as the tip of the exit tube ruptures (fig. 1 1 ). They arc first elliptical in shape and contain two or more conspicuous granules, hut soon round up and encyst and thus form a cluster around the tip of the exit canal (fig. 1 2 ) as in Achlya and species of liogenidium, Ectrogella, Aphanomycoptis, etc. Within an hour or two the content of the cyst emerges (figs. 1:5—1(5) and is transformed into an oblong bifiagellate isocont zoospore (fig. 17) which soon swims away. Sexual reproduction in /'. vernalis is heterogam- ous. The so-called anthcridiuin and oogonium are quite unequal in size and lie in tin- same gall or swell- ing fig. 18). The anthcridiuin show-, no structural differentiation as a gametangium, and it is accord- ingly questionable whether or not it should be desig- nated as an anthcridiuin in the original sense of the term. The oogonium, on the other hand, contains a large central vacuole and parietal layer of proto- plasm which appear to undergo some degree of dif- ferentiation into ooplasm and periplasm, according lo Couch's description. The anthcridiuin forms a fine fusion canal which penetrates the wall of the OOgO nium into the ooplasm (figs. "JO. 21 ). The content of the antheridium thereby flows into the ooplasm and fuses with it. As the zygote matures it forms a fairly thick wall, while most if not .ill of the periplasm gradually disappears (fig. 23). Occasionally two antheridia may fertilize one egg cell (fig. 22) as in species of < )l pidiopsis. Nothing is known concerning the origin of the respective gametes in this genus. Whether the thalli which develop into the antheridium and oogonium respectively are derived from zoospores from the same or different zoosporangia is not known. It is accordingly impossible to say at present whether sex differentiation is genotypic or phenotvpic. Fur- thermore, it remains to be seen whether the gametes are multinucleate and their nuclei fuse in pairs or all but one nucleus in each gamete degenerate before karyogamy occurs. P. VERNALIS Couch, I.e., figs. 1-27. Zoosporangia solitary or up to I in a swelling, spherical or subspherical, 10-.'50 p., sometimes flat- tened when several occur in a gall; exit tubes up to 50 p long by 1 p in diameter. Motile zoospores .'5.7- ■i p in diameter. Oogonia spherical or subspherical, 1 1-18.5 p. Antheridia hyaline, smooth, slightly flat- tened or spherical, 5 p. Oospore spherical, 9- 15 /i. hyaline, smooth and thick-walled. Parasitic in Pythium gracile and P. dictyosporum in North Carolina, U. S. A. In connection with the Olpidiopsidaceae brief mention may be made of two unusual and incom- pletely known parasites which Carpenter (TO), and Tehon and Harris ('H) described as forming oospores in somewhat the same manner as 01 pidiop- sis. However, in referring to them here the author does not imply that they should be included in the Olpidiopsidaceae as this family is now recognized, because their thalli are amoeboid and plasmodium- like, and zoospore are not definitely known to occur. The first of these fungi was reported by Carpenter to be associated with chlorotic streak disease of sugar cane in Hawaii. Two developmental phases of the parasite were observed, but the connection be- tween them was not definitely established by Car- penter. The first phase consists of a naked amoeboid or plasmodium-like thallns (text-fig. Ai suggestive of that of tin- Plasmodiophorales and Woroninaceae. However, no individual movement of the thallns or streaming of the protoplasm was observed, nor docs the parasite cause cell stimulation or hypertrophy of the host tissues. The second and most conspicuous phase consists of spheres of protoplasm which occur in the parenchyma of the stalk and vary from 5—60/1 in diameter and hyaline to gray, brown or black and opaque in color. The hyaline spheres. :i 25 ». may have thick walls and resemble hypnospores which, according to Carpenter, "appear to be formed by copulation of two units, the content of one sphere 62 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES entering the other to form hypnospores, while the empty sphere may remain as a companion cell." (Text— figs. B. C.) Carpenter was uncertain of the identity and relationships of his fungus. Nonethe- less, he referred to it as a chytrid and frequently compared it with Physoderma maydis. The second of these fungi was reported by Tehon and Harris as inhabiting the xylem of a diseased Moline elm from Wisconsin. It is very similar to the species found by Carpenter, and they accord- ingly named it Carpenierella Molinea. Its vegeta- tive thallus may appear in two slightly different forms, one elongate, attenuate and thread-like with few to many enlargements (text-fig. D), the other amorphic and amoebic in appearance (text-fig. E). This vegetative phase occurs in wood parenchyma, wood fiber, and ray cells but not in trachae. The thallus may be confined to one cell or extend through pits in the walls to adjoining cells (text-fig. F). The thalli figured by Tehon and Harris are somewhat suggestive of the pseudo-plasmodium of Labyrinth- ula, but the bead-like enlargements are not as dis- tinctively spindle-shaped and cellular as those of the latter genus. No zoosporangia have been found in C. Molinea, but the occurrence of zoospores is sug- gested "by the presence in some host trachae of numbers of minute, mononucleate, rounded plasmo- dium-like bodies, some few of which seem to possess a single polar cilium," according to Tehon and Harris. They have not, however, observed motile flagellate cells. The origin of the so-called male and female thalli which are reported to fuse is not clear and certain, but Tehon and Harris believed that the swollen ends of strands of the thallus which project into the trachae (text-fig. F) become detached and assume a spherical shape. These spheres later become asso- ciated in pairs, and as the staining reaction of one of them increases in intensity the other sphere becomes more hyaline and empty and decreases in size (text- figs. G— L). This shrinkage was interpreted by Tehon and Harris to mean that the protoplasm of one sphere had flowed into the other, and they ac- cordingly designated the two thalli as male and fe- male. They reported that the fusing thalli are equal in size, but text-fig. G shows clearly that the male cell may be considerably larger than the female. The mature resting spore or oospore is spherical, 10 p, with dense opaque protoplasm and numerous refrac- tive globules, smooth, thick-walled, and accom- panied by a small hemispherical or lunate companion cell (text-fig. M). Germination of these spores has not been observed. Tehon and Harris regarded their fungus as a chytrid but were not certain about its taxonomic position. They believed that the character of the thallus and the presence of a vesicle or companion cell on the resting spore indicate relationships with the Woroninaceae (interpreted in the sense of Min- den) or the Olpidiaceae. They accordingly placed C. Molinea and Carpenter's fungus in the latter family near Pseudol pidiopxis. This disposition is ob- viously untenable because Pxeudolpidiopxix is syn- onymous with Olpidiopxis and belongs in the Olpi- diopsidaceae. Whether or not these fungi belong in the last named family will not be certain until the presence or absence of zoosporangia and zoospores has been demonstrated. The method of resting spore formation is nevertheless very similar to that of many species of the Olpidiopsidaceae, while the amoebic, plasmodium-like vegetative thallus sug- gests some relationship to or a parallelism in devel- opment with the Plasmodiophorales and the family Woroninaceae as these groups have been interpreted by the author. While the origin and phylogeny and relationships of Carpenierella are not clear, it is nevertheless a significant genus and serves to empha- size again that there may be many more simple fungi to be found, the discovery of which will doubtless change many of our present-day concepts concern- ing the Phycomycetes. BIBLIOGRAPHY : OLPIDIOPSIDACEAE Atkinson, G. F. 1909. Ann. Mycol. 7:441. Behla, R. 1903. Die Pflanzenparasitiire des Krcbses. Ber- lin. Butler, E. J., and G. R. Bisby. 1931. The Fungi of India. Calcutta. Carpenter, C. W. 1940. The Hawaiian Planter's Record 49: 19. Cejp, K. 1935. Spisv vyd. Priridov. Fakul. Karlovy Univ. Prahall, Alb. (i Chatton, K., and A. Brodsky. 1909. Arch. Protistk. 17: 1. Cienkowski, L. 1855. Bot. Zeit. 13:801. Couch, J. N. 1941. Amer. .(our. Bot. 38: 704. Dangeard, P. A. 1889. Le Bot. 1: 1. 1890, ibid. 2: 63. Davis, J. J. 1914. Trans. Wise. Acad. Sci., Arts, Letters. 2: 846. Diehl, H. 1935. Zentralbl. Bakt. Parasit. II, 92: 229. Fischer, A. 1880. Bot. Zeit. 38: 689. — . 1882. Jahrb. wiss. Bot. 13: 286. Graff, P. W. 1928. Mycologia 20: 158. Gilman, J. C, and W. A. Archer. 1929. Iowa Jour. Sci. 3:299. Harvey, J. V. 1927. Trans. Wise. Acad. Sci., Arts, Let- ters 23: 551. — . 1942. Jour. Elisha Mitchell Sci. Soe. 58: 39. Jabn, T. L. 1933. Arch. Protistk. 79: 349. Karling, J. S. 1939. Abstracts, Third Int. Cong, for Microbiol, p. 22.>. Krafka, J., and J. E. Miller. 1926. Ann. Entomol. Soc. of America 19: 464. Maneval, W. E. 1937. Univ. of Missouri Studies 12, 3. Matthews, V. D. 1935. Jour. Elisha Mitchell Sci. Soc. 51: 306. McLarty, D. A. 1939a. Abstracts, Third Int. Cong, for Microbiol, p. 226. . 1939b. Amer. Jour. Bot. 26: 194. Mitchell, J. B. 1928. Trans. Amer. Micro. Soc. 47: 29. Muller, F. 1911. Jahrb. wiss. Bot. 49: 421. Nageli, C. 1844. Zeitschr. wiss. Bot. 1, no. 3: 22. Nagler, K. 1911. Arc*. Protistk. 22: 262. Petch, T. 1940. The Naturalist No. 998:68. Petersen, H. E. 1903. Jour, de Bot. 17: 214. Pringsbeini, N. I860. Jahrb, wiss. Bot. 2:205. Pumaly, A. 1927. Bull. Soc. Bot. France. 74: 472. Reinsch, P. 1878. Jahrb. wiss. Bot. 11: 283. SIKDI.IMIIIACK.VK 68 Sawada, K. 1919. Hull. Agr. Bxpt. Stat. Formosa III. Stein, F. R. 1878. Der Organismus des Infuslonsthlere III, 1919, Ibid. 19, »bt. I, .'. Leipzig. Shanor, I .. 1939. Jonr. Ellsha Mitchell Sci. Soc. 55: 179. Tehon, It. It., and II. A. Harris. 1941. Mycologia 33: 18. 1940, ibid. 56: 165. Valkanov, A. 1931. Arch. Protistk. 73:361. Sparrow, I'. K. 1939. Mycologia 24: »68. 1933, ibid. 25: Varitchak, B. 1931. C. H. Acad. Sci. Paris. 192:371. 513. [939, ibid. 31:443. 1943, ibid. 34: 116. Wildeman, de, !•'.. 1891. Bull. Soc. Hoy. Bot. Beige. 30: Sydow, H.. and P., and E. J. Butler, 1907. Ann. Mycol. 169. ,-): is , Wolf, F. T., and F, A. Wolf. 1941. I loydia 1: -'To. Chapter V Sirolpidiaceae Sparrow, 1942. Mycologia 34: 11 .'5. This family was established by Sparrow for the genera Sirolpidium and Pontisma which Petersen ( '()."> ) had previously made the basis of the family Holochytriaceae. Thirteen years earlier, however, Fischer ('92) had proposed the same family name as an alternate tor the Ancylistaceae to include My- zocytium, Achlyogeton, I. age nidi urn and Ancylistes. There was thus no agreement between Petersen and Fischer as to which genera comprise the Holochy- triaceae, but they nevertheless placed it in the My- cochytridiales. While the Holochytriaceae may have priority over Sparrow's family name, the Suffix chytriaceae carries the connotation that these fungi are chytrids. which is incorrect in light of present- day knowledge. The name is therefore no longer ap- propriate and descriptive. The present author is ac- cordingly adopting the Sirolpidiaceae in preference to the 1 loloch ytriaccae. but only as a temporary con- venience because it is not at all certain that Sirol- pidium and Pontisma constitute a distinct family. So far only vegetative thalli, zoosporangia, .and zoo- spores have been adequately described, and very little, if anything, conclusive is known about the n sting spores and their method of development. Since the thalli and zoospores of Pontisma an not strikingly different from those of Sirolpidium, the two genera are herewith merged, and the former genus is reduced to a synonym of the latter. Peter- Senia in a limited sense is also included in this fam- ily, because its thalli are frequently similar to those oi Sirolpidium. Obviously, this arrangement also may be completely invalidated by future discoveries. As the family is herewith presented it includes two genera of incompletely known holocarpic species characterized by olpidioid or elongate and some- times filamentous thalli which may or may not un- dergo segmentation. In some species the segments separate and become transformed directly into zoo sporangia. SIROLPIDIUM Petersen. 1905. Overs. Kg!. Dansk. Vids. Selsk. Fori). 5: 478. Pontisma, Petersen, I.e., p. 482. (plates 16, 17) Thallus predominantly intramatrica] but becom- ing partially extramatrical under certain conditions; olpidioid or elongate and filamentous; transformed directly into a single sporangium or undergoing sep- tation and fragmentation to form a row of separate sporangia; fragmentation reduced or lacking in some species. Zoosporangia usually numerous in the host cell, variable in size and shape with one simple or branched exit tube which varies markedly in length and may extend considerably beyond the surface of the host wall, or occasionally opening within the host cell. Zoospores isocont with the flagella attached at or near the anterior end (?) and extending in op- posite directions; swarming within the sporangia. emerging fully developed and swimming directly away; occasionally liberated within the host cell. Resting spore doubtful or unknown. This genus was created by Petersen for de Bruyne's Olpidium Bryopsidis after he had found that the zoospores arc biHagcllate instead of uni- flagellate. In the writer's opinion, I'ontixina docs not differ fundamentally from Sirolpidium, and on the basis of present-day knowledge it may well be merged with the latter genus. Sparrow (':>!) main tained that it differs from Sirolpidium by its more irregularly tubular thallus and the fact that the segments ilo not separate and form isolated and free sporangia. Nevertheless, both he and Petersen re- port that in exceptional cases the thalli appear to fragment and give rise to trie or loosely connected 64 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES sporangia as in Sirolpidium. This striking similarity becomes evident when figures 13 and 14\ Plate 16, of S. Bryopsidis are compared with figures 4 and 5, Plate 17, of S. (Pontisma) lagenidioides. The tend- ency to greater or less fragmentation may well be a specific instead of a generic difference. Sparrow further reported that the zoospores are slightly dif- ferent in the two genera, but his descriptions and fig- ures of the positions of flagella are somewhat indefi- nite and unclear. Here also the differences may be only specific. Infection of the host and the early developmental stages are not well known in all species, and the fol- lowing account of these processes is based largely on S. Bryopsidis. As in Eurychasma and E.cirogella, the zoospore comes to rest on the host cell, encysts, and soon develops a germ tube which penetrates the host wall. Its content flows into the host cell, while the spore case and penetration tube are left behind and remain attached for some time after germination. Ac- cording to de Bruyne, the young thallus (figs. 6-8, plate 16) very early develops a wall or membrane which thickens with age and shows a weak cellulose reaction when tested. The thallus may develop into an oval, pyriform, ellipsoidal sporangium or elon- gate into a tubular filament, become septate, and then fragment into a number of segments (figs. 11, 12, 13, plate 16). These fragments then develop into olpidioid sporangia of various sizes and shapes (figs. IK 15. plate 16) and form one simple or branched exit tube of variable length. The latter may curve about in the host cell or penetrate the latter's wall and project for a long distance on the outside (fig. I. plate 16). The same type of development appar- ently occurs in >S'. lagenidioides with the exception that the segments of the irregularly elongate thalli rarely separate. The protoplasm of the thalli and incipient zoo- sporangia is glistening and refringent in appear- ance with numerous suspended globules ( figs. 6-9, plate 16; figs. -1, 5, plate 17). When young the zoo- sporangia contain numerous small vacuoles (figs. II. 15, plate 16; fig. 6, plate 17) which apparently flow together at maturity and form a large central one as in Olpidiopsis, Pythiella, and other similar genera. So far nothing is known about cytokinesis, but it is apparently accomplished by centrifugal cleavage furrows which progress from the border of the central vacuole to the periphery and thereby de- limit uninucleate spore rudiments. The zoospores complete their development in the sporangium (fig. 1, plate 16) and become very active and motile be- fore the tip of the exit tube deliquesces. According to Sparrow they swim directly away after emerg- ing, but de Bruyne reported that in .S'. Bryopsidis they may pause for a few moments at the tip of the exit tube and become amoeboid. He also figured them as anteriorly uniflagellate and occasionally under- going division (figs, i, 5, plate 16). Petersen re- ported them to be uni- and biflagellate, but accord- ing to Sparrow they possess two flagella of equal length inserted at or near the anterior end (fig. 2. plate 16). His figures of fixed and stained zoospores (fig. 3, plate 9), however, show the two flagella lat- erally attached. In S. lagenidioides, he reported that the two flagella appear to arise from the con- cave central region (fig. 2, plate 17), while in some zoospores they seem to be attached to the narrow anterior end (fig. 3. plate 17). The presence of resting spores has not been dem- onstrated with certainty in Sirolpidium. In S. Bry- opsidis, de Bruyne reported that the contents of oval and globular thalli may contract and become in- vested with a thick hyaline smooth wall (fig. 18, plate 16), and, according to Sparrow ('34) Peter- sen also observed occasional thick-walled spores which he believed relate to this species. So far none have been found in S. lagenidioides. Unlike Eurychasma and Eurychasmidium, Sirol- pidium does not cause enlargement of the infected cells. Furthermore, neither they nor adjacent healthy ones are stimulated to divide. The effects of the fungus are local and confined to infected cells. In the case of Bryopsis infected with S. Bryopsidis, heavily parasitized plants may be recognized by the presence of blackened areas along the fronds, which are apparently areas in which the cells have been killed. As the parasite increases in size the plastids turn greenish-brown in color and eventually become clumped together with the remainder of the degen- erating protoplasm, according to de Bruyne's fig- ures. Sirolpidium lagenidioides, on the other hand, appears to be a weak parasite or saprophyte on Ceramium and is capable of growth and develop- ment under conditions unfavorable to its host. plate 16 Sirolpidium Bryopsidis (Figs. 1, 4-9, 18 after de Bruyne, '90; fig. 11 after Peter- sen, "05; figs 2, 3, 10, 12-17 after Sparrow. "34.) Fig. 1. Tip of Bryopsis plumosa branch with four zoo- sporangia containing zoospores; the exit tube of one spo- rangium is entirely intramatrical. Fig. 3. Free hand drawing and interpretation of the zoospore showing tapering anterior end with a refractive globule and the ventral groove from which flagella ap- parently arise. Fig. 3. Zoospore killed in osmie acid fumes. Figs. 4, 5. Division of zoospores. Figs. 6-8. Young thalli with numerous refractive glob- ules. Fig. 9. Elongate and branched thalli. Fig. 10. Young stage of fragmenting thallus. Fig. 11. Early stage of thallus division. Fig. 1-'. Elongate thallus fragmenting; traces of old thallus wall connecting the fragments. Fig. 13. Elongate fragmented thallus. Fig. 14. Fragments becoming transformed into zoo- sporangia. Fig. 15. Incipient, vacuolate, lobed zoosporangiuni with long exit tube. Fig. 16. Emergence of zoospores from olpidioid spo- rangia. Fig. 17. Tip of Bryopsis filament with numerous olpi- dioid sporangia. SIROLPID1 VCKAE 65 PLATE 16 y 7 . |8 <2>@ I 7 0;;:/%:,;)^ Sirolpidium 66 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES S. BRYOPSIDIS (dt- Bruyne) Petersen, I.e., p. 479. Fig. XI, 1-8. Olipidium Bryopsidis de Bruyne, 1890. Areh. Biol. 10: 85. PI. 5, fig's. 1-15. Thallus usually intramatrical, becoming partially extramatrical under certain conditions ; small, uni- cellular and olpidioid, or elongate, tubular and fila- mentous ; frequently becoming septate and undergo- ing fragmentation into unicellular segments which develop into sporangia. Zoosporangia usually nu- merous in a cell, hyaline and smooth, spherical, oval, ellipsoid, 12-17 xx'x 13-38 xi, elongate, cylindrical, tubular, 3-5 xi X 6-165 /x. Zoospores narrowly pyri- form and slightly arched, 2 X 4 /x, with a refring- gent granule at the anterior end; flagella inserted near the anterior end ( ?). Resting spore (?) spheri- cal, oval and elongate, hyaline and smooth, germi- nation unknown. Parasitic in Bryopsis plumosa in Italy (de Bruyne, I.e.), Denmark (Petersen, I.e.; Sparrow, '34) and Massachusetts, U. S. A. (Sparrow, '36); and saprophytic (?) in Cladophora sp., in Massa- chusetts, U. S. A. (Sparrow, I.e.). In material studied at Woods Hole, Mass., Spar- row found that the growth of the thallus may be markedly influenced by environmental conditions. When the host is removed from its normal habitat and exposed only to dripping sea water the fungus grows out of the host and becomes distinctly filamen- tous and hypha-like. Sparrow found that additional extramatrical growth could be induced by transfer- ring the infected material to solutions of low sugar concentrations. It is obvious from these preliminary culture studies that .S'. Bryopsidis is highly variable in growth and development. S. LAGENIDIOIDES comb. nov. Pontisma lagenidioides Petersen, I.e., figs. X, 1-3. Thallus intramatrical, occasionally unicellular, lobed, curved and olpidioid; usually elongate, lobed, irregular and septate, frequently constricted at septa; rarely fragmenting into isolated segments. Zoosporangia hyaline and smooth, usually con- nected, occasionally free; oval, elliptical, 13-15 xi X 14-16 /x, elongate, cylindrical, 130-200 /x in length, or irregular and slightly lobed. Zoospores pvriform and arched, 2.5-3 xi X 4.5-7 p., with a re- fractive granule at one or both ends ; flagella later- ally inserted (?) on the concave side and oppositely din cted; occasionally liberated within the host cell; motion erratic and tumbling in swimming. Resting spores unknown. Weakly parasitic or saprophytic in Ceramium ntbritm, Ceramium sp., C. fructiculosum, C. tenuis- simiim, and C. diaphanum in Denmark (Petersen. I.e.; Sparrow, '34) and Massachusetts, U. S. A. ( Sparrow, '36). Sparrow reported that the zoospores of this spe- cies are strikingly similar to those of Butler's (I.e.) Rozellopsis inflaia, and believed that on these grounds Butler's species shows affinities with S. lagenidioides and species of Olpidiopsis. It is to be noted again, however, that the flagella of S. lageni- dioides (fig. 3, plate 17) also appear to be attached to the narrow anterior end of the zoospores. PETERSENIA Sparrow, 1934. Dan.sk. Bot. Ark. 8: 13. (PLATE 18) Thallus entirely intramatrical, unicellular, elon- gate, narrowly cylindrical, irregularly lobed and contorted, rarely ellipsoid, and olpidioid; occupying one or more host cells. Zoosporangia solitary or nu- merous, variously shaped with 1 to 4 exit tubes of variable length. Zoospores laterally (?) biflagellate, isocont; flagella extending in opposite directions; developing completely and swarming in the sporan- gium before emerging, swimming directly away without anjT pause at the mouth of the exit tube. Resting spores doubtful or unknown. This genus was established to include species of Pleotrachelus which were found to have biflagellate zoospores. It is not improbable that other marine species of the latter genus may also be transferred to Peiersenia when their life cycles and method of de- velopment are completely known. Petersenia an- dreei is apparently a species of Olpidiopsis and is accordingly excluded from this genus which leaves only one valid species, P. lobata. The thallus of PLATE 17 Si ml i lid in in lagenidioides (Fig. 1 after Petersen, '05; figs. 2-9 after Sparrow, '34.) Fig. 1. Elongate irregular septate, constricted thallus with four exit tubes. Fig. 2. Arched zoospores with a refractive granule at each end and two equal, laterally (?) attached flagella. Fig. 8. Free hand drawing and interpretation of zoo- spores showing flagella attached near anterior end. Fig. 4. Irregular septate thallus. Fig. 5. Group of thalli showing "rudimentary fragmen- tation." Fig. (i. Vacuolate sporangium with a branched exit tube. Fig. 7. Curved elongate, continuous and solitary spo- rangium with quiescent zoospores. Fig. 8. Emergence of zoospores. Fig. 9. Empty loosely attached sporangia. ISIii.stiiliilinp.iis chattoni (All drawings after Sigot, '31) Fig. 10. Young vacuolate lobed thallus in egg of Cy- clops. Fig. 11. Section of Cyclops egg showing lobes of spo- rangium in section; nuclei lying in a thin peripheral layer of cytoplasm. Fig. 12. laterally biflagellate isocont zoospore with nu- cleus near the center and a large refringent body at the anterior end. SIROLPID1 \< KAK 87 PLATE IT Sirolpidium, Blastulidiopsis <38 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES this fungus may be strikingly similar in appear- ance to those of species of Sirolpidium, with the exception that it does not become septate and frag- ment into segments. Should the latter characters prove insignificant in generic diagnoses and phy- togeny, Petersenia, in the present sense, may per- haps be merged with Sirolpidium. On the other hand, the olpidioid thalli bear a strong resemblance to those of Olpidiopsis, particularly to 0. irregularis, according to Sparrow ('34). Zoospore germination and infection of the host have not been observed in this genus, but these proc- esses are probably similar to those of Sirolpidium, Ectrogella, etc. Sparrow ('34) reported that in the early stages the thallus is "somewhat plasmodial in nature" but he did not illustrate any of the initial developmental phases. At maturity, however, a well- defined wall is present which stains a dark, ruby color when tested with chloro-iodide of zinc. As noted previously the thallus varies markedly in size and shape (figs. 3-8). Within the tetraspores of the host it usually assumes the shape of the confining cell (fig. 4), but even under such conditions lobed .specimens may occur, as Feldman ('40) has shown. In the vegetative state the protoplasm is refractive and vacuolate (figs. 4, 7), and as the thallus is trans- formed into a sporangium, the small vacuoles pre- sumably flow together and form one or more larger central ones. The late stages of cleavage and spo- rogenesis closely resemble those of Pi/thinm, accord- ing to Sparrow. The incipient spore initials undergo an individual rocking movement which becomes more pronounced as they separate and acquire their ma- ture form. At the same time traces of flagellary mo- tion become visible at the periphery of the spore 'mass, and this increases in intensity until the zoo- spores are mature and swarming within the sporan- gium. As the tip of the exit tube deliquesces they emerge (fig. 3) and swim directly away. According to Sparrow, the zoospores (figs. 1, 2) are elongate, pyriform, shallow-grooved, and contain a refractive body at the anterior end. The flagella are reported to be inserted laterally, but some of Sparrow's fig- ures suggest that they arise near the anterior end. P. LOB ATA (Petersen) Sparrow, I.e., p. 13, pi. 2, figs. I-N; 1936. Biol. Bull. 70: 2U. PI. 2, figs. 1, 2. Pleotrachelus lobatus Petersen, I.e., p. 4(>0, figs. V. 1-7. Zoosporangia solitary or numerous, often occupy- ing more than one host cell, or filling it completely and conforming to the latter's size and shape; usu- ally markedly and irregularly lobed, elongate and tubular, or oval, ellipsoid and olpidioid with 1 to 3 simple or branched exit tubes of variable length. Zoospores elongate, pyriform, slightly arched and shallow-grooved, 3 X 4.5 /j.. Resting spores un- known. Parasitic in the vegetative cells and tetraspores of Spermothamnion tumeri, S. repens, Callithamnion corymbosum and C. hookeri, in Denmark (Petersen, I.e.; Sparrow, I.e.), C. roseum in Massachusetts, U. S. A. (Sparrow, '36) and in the disporangia of Seirospora interrupta near Villefranche-sur-mer in the Mediterranean (J. and G. Feldman, '40). x This species may occur in whitened and dead cells of its hosts which suggests that it is only weakly parasitic. According to Sparrow, it is not assisted by other organisms in the early stages of invasion, but in old infections, bacteria and protozoa are always present and aid in the destruction of the content of the host cell. Whether or not Pleotrachelus pollagaster Peter- sen (figs. 9—11) belongs in Petersenia is question- able. Sparrow ('34) included it provisionally in this genus, because he found its zoospores to be similar in shape and size to those of 7'. lobata. He did not, however, determine the number and position of the flagella. and until these points have been conclu- sively settled the exact generic position of P. polla- gaster will remain doubtful. Sparrow ('36) found two other fungi which he assigned tentatively to Petersenia as unidentified species. One occurred in the eggs of a microscopic animal, possibly a rotifer, adherent to filaments of Ceramium diaphanum. The parasite filled the whole interior of the egg (fig. 12) and was transformed at maturity into a sporangium, 20 X 50 /n, with 1 to 3 short broad, 8 /n in diameter, exit tubes. The forma- tion and emergence of the zoospores were not ob- served, although a number of the spores which had failed to emerge were found within sporangia. These bodies were reniform, "of the laterally biciliate type," 2X*Cj and resembled the zoospores of 1 Bull. Soc. Hist. Nat. Afrique Nord 31: 73. PLATE 18 (Figs. l-(>, 11-14 after Sparrow, '3-1, '36; figs. 7-10 after Petersen, '05. Figs. 13, 1+ drawn from photographs.) Petersenia lobata Fig. 1. Group of isoeont zoospores; point of attachment of flagella uncertain. Fig. 2. Freehand, enlarged drawing and interpretation of zoospore. Fig. 3. Emergence of zoospore from olpidioid zjcspo- rangium. Fig. 4. Infected tetraspores of Spermothamniv/m. Fig. 5. Olpidioid and nodular thalli. Fig. fi. Irregular thallus with four short branches. Fig. 7. Elongate, lobed and constricted multivacuolate thallus occupying two host cells. Fig. 8. Empty zoosporangium. Pleotrachelus (Petersenia) pollagaster Fig. 9. Lobed thallus with three long exit tubes. Fig. 10. Olpidioid sporangium. Fig. 11. Irregular resting spore. Petersenia sp. Fig. 12. Sporangium in rotifer (?) egg with two bi- flagellate isoeont zoospores. Fig. 13. Young thallus of Petersenia sp. saprophytic in ( V ru in in in diaphan it in. Fig. 14. Empty zoosporangium with three exit tubes. SIIIOI.IMMACKAK <)9 PLATE IS Petersenia 70 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES Pythium. The other unidentified species occurred as a saprophyte in Ceramium diaphanum which had been kept in a laboratory aquarium for several weeks. One to several spherical (figs. 13—14) and irregular thalli of variable size, 20-96 fi in diameter, were found in a single internode. Each thallus de- veloped into a sporangium at maturity with up to ten or more radiating, narrow tapering exit tubes, 7 /x in diameter, which penetrated the host cell wall. Zoospores and resting spores were not observed, and it is accordingly uncertain whether or not this spe- cies belongs in Petersenia. Chapter VI Lagenidiaceae Schroeter, 1897. Engler und Prantl, Die Nat. Pflanz'f . I, 1 : 88. This family includes a number of saprophytes and parasites of algae, higher plants, nematodes, insects, and other animals which are characterized primarily by reniform, laterally biflagellate zoospores, and sexually formed resting spores. The family was formerly included in the Aneylistales, but in light of Miss Berdan's ('37, '38) discovery that Ancylistes is a genus of the Entomophthorales, the name Ancy- listales is no longer tenable. Accordingly, in 1939 the author raised the family Lagenidiaceae to ordi- nal rank, and since that time Sparrow ('42) has in- eluded the Olpidiopsidaceae. and Sirolpidiaceae as well as the Lagenidiaceae in this order. Whether or not these families constitute a distinct order of equal rank with the Saprolegniales, Leptomitales, Perono- sporales, etc., is very questionable. According to Sparrow's interpretation the Lagenidiales include species with iso- and heterogamous types of repro- duction as well as iso- and heterocont zoospores, and as such it obviously cannot be regarded as more than a temporary and convenient expedient of classifica- tion. In view of our lack of knowledge relative to many of the species, genera, and families included in this order, it is perhaps wiser for the time being to avoid placing the Olpidiopsidaceae, Sirolpidia- ceae, and Lagenidiaceae in a distinct order. The thallus of the Lagenidiaceae varies from a simple ovoid, unicellular, Olpidium-\ike cell to an extended filamentous, branched, septate mycelium which may be confined to a single host cell or occupy several cells. These parasites and saprophytes gain entrance info the host by an infection tube from germinating zoospores. The thallus develops as an extension and enlargement of the tip of the germ tube and soon becomes long and filamentous or en- larges into a globular, oval, lobed, and irregular structure. It may remain unicellular and continuous in some species or divide transversly into several segments. With further growth these segments may become oval, ellipsoid, and spherical, making the thallus deeply lobed at the septa, or they may remain cylindrical with little or no constrictions in the re- gion of the cross walls. At maturity these segments are holoearpically transformed either into zoospo- rangia or slightly differentiated gametangia. In all species which have been tested the walls of the thal- lus give a marked positive cellulose reaction. The protoplasm, particularly in Lagenidium and Myzo- cytium, usually includes a large number of refrac- tive globules of various sizes, which give it a char- acteristic refringent and gleaming appearance, but at maturity and as sporogenesis begins it becomes more greyish granular. In the majority of species the content of the spo- rangium emerges as a globular mass from the exit tube and undergoes cleavage into zoospores on the outside in much the same manner as in Pythium. The presence of a vesicular membrane around the proto- plasmic mass and the zoospores which are subse- quently formed has been reported in a number of species, but appears to be lacking in others. There is considerable disagreement in the literature about the presence of this structure, and further intensive study of its occurrence in the Lagenidiaceae is needed. In a few species the zoospores are com- pletely developed in the sporangium, emerge, and swim directly away, or they are discharged prema- turely, come to rest in a mass and complete their de- velopment on the outside. In other species they en- cyst in a loose mass at the mouth of the exit tube as in Achlya and exhibit marked diplanetism. It is ac- cordingly obvious that the process of zoosporogene- sis and the initial behavior of the zoospores vary from the Olpidiopsis to the Pythium and Achlya types. The zoospores throughout the family are pre- dominantly reniform and somewhat pyriform in shape, and in some species a distinct ventral groove is present in which the flagella are inserted. Hetero- cont zoospores have been reported in two species. Sexual reproduction is predominantly heterogam- ous, but in Lagena and Resticularia it is reported to be isogamous. Isogamy is present in Lagenidium sacculoides also, according to Serbinow ('07). The segments of elongate thalli, as well as entire uni- cellular thalli, which function as male and female gametangia are only slightly or not at all differen- tiated as sexual organs. They may occur among the sporangia in the same thallus or in separate thalli, but the presence of heterothallism has not been defi- nitely proven. No monozoospore cultures and infec- I.AHENIDIACEAE 71 tions have yet been made to determine whether the ■oospores carry the potentialities of one or both sexes. In some of the unicellular species separate thalli may function as male and female gametangia, but it has not been proven that they represent dis- tinct male and female strains. In light of our meager present-day knowledge it would be premature to discuss homo- and hcterothallisin in the Lagenidia- ceae. In some species the unicellular th alius may divide at maturity into two cells which then function as niab- and female gametangia, respectively. In most species, however, the female gametangium is usu- ally larger, more vesicular, and frequently barrel- shaped, while the so-called antheridium is usually elongate and tubular. In Lagena, as noted before, the unicellular thalli which fuse are equal in size and indistinguishable. For this reason, the terms oogonia and antheridia may be used only tentatively and with reservation for the sexual organs in the Lageni- diaceae. Differentiation of an egg cell and periplasm in the female gametangium has not been convinc- inglv demonstrated, but the ooplasm may contract and aggregate toward the conjugation tube or pore during plasmogamy. Shortly before fusion a con- necting pore is formed between the two gametangia. or the antheridium forms a tube or canal which pro- jects into the oogonium. In Lagena, however, the tube fuses with the surface of the oogonium without entering it. The content of the antheridium then slowly flows into the oogonium and fuses with the ooplasm, after which the zygote becomes invested with a thick wall. The resting spore thus formed lies free in the oogonium, resembles the oospore of the higher OomyceteS, and is generally referred to in tin- literature as an oospore. In some species the antheri- dium is lacking, with the result that the resting spores are formed parthcnogeneticallv. The cytology of sexual reproduction from fixed and stained material has been studied in only one species, and very little is known about the gametic nuclei and their behavior during plasmogamy and karvogamy in the family as a whole. Until more is known about these developmental phases the rela- tionships of the I.agenidiaceae with the Saproleg- niales and Peronosporalcs will remain obscure. As it is herewith presented the I.agenidiaceae in- cludes Lagenidium, Myzocytium, and Lagena. The first two genera are very similar and appear to be closely related, and in light of present-day knowl- edge it is questionable whether they should be sepa- rated. As Cook '88 i has already noted, the differ- ences are perhaps only specific instead of generic. Lagenidiopsis is merged with Lagenidium, while Achlyogeton and Mitochvtridium are excluded be- cause of their uniflagellate zoospores. Restieularia is listed as doubtful genus, but it may possibly prove to be identical to and synonymous with Lagenidium. Its reported isogamous and zygomveetous type of sexual reproduction is very similar to that of /,. sac- culoidet. On the other hand, future studies and dis- coveries may necessitate the inclusion of Lagena. Restieularia and /.. sacculoides in a separate family because of their characteristic method of sexual re- production. Protascus is excluded from the Lageni diaceae because of its lack of zoospores. A full de SCription and illustration of this genus is neverthe- less presented here to emphasize again to mycolo gists the priority of Dangcard's Protascus over the same generic name proposed by Wolk (13) for an- other fungus. Gaumann and (iaumann and Dodge included Ectrogella in the I.agenidiaceae, but subsequent workers have not followed this viewpoint. The pies enec, however, of isocont primary zoospores with flagella inserted just below the anterior end anil laterally biflagellate heterocont secondary swarm spores indicates a closer relationship, as Scherffel has pointed out, with the Saprolegniaceae. Tokunaga included Aphanomycopsis in this family on the grounds that it lacks a typically developed mycelium and is holocarpic. The shape, structure, size and general appearance of the th alius and zoospores are strikingly like those of the Lagenidiaceae, and in the encystment of the swarmspores in a cluster at the mouth of the exit tube this genus is similar to L. Oedogonii. Furthermore, the locally paunchy cell in which the asexual or possibly parthenogenetic rest- ing spore is formed is quite like the oogonium in species of Lagenidium. There is thus good structural evidence to support Tokunaga's viewpoint. Whether certain stages of Borzi's Rhizomyxa belong here is also problematical. Its reported mode of sexual re- production is nonetheless strikingly similar to that of Lagenidium and Myzocytium, with the exception that an egg cell and periplasm are formed before fertilization occurs. In the latter character it is somewhat similar to Pythiella. LAGENIDIUM Schenk, 1859. Verh. Phys. Med. Ges. Wursburg 9 : 27. Lagenidiopsis de Wildeman, 1896. Ann. Soc. Belg. Micro. 20: 109. (plates 19, 20) Thalli intramatrical, solitary or numerous, con- fined to one cell or extending through several host cells; frequently elongate, straight, crooked, curved, irregular, coiled, tubular, hypha- and mycelium like, with numerous blunt protuberances; lobed. branched or unbranched. slightly constricted or un- COnstricted at the cross walls; multicellular or uni- cellular, the latter continuous, globular, oval, ellip- soidal, sac-like and irregular; often attached to tin- host cell wall by the infection tube and zoospore case; holocarpic. transformed into sporangia or gametangia at maturity. Sporangia of the same shape and size as the individual segments and uni- cellular thalli, with one to several exit tubes of vary- 72 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES ing length, diameter, contour, and shape; content of sporangium usually emerging to form a globular mass at the mouth of the exit tube. Zoospores bean- shaped, reniform and somewhat pyriform, laterally biflagellate, with several small refractive globules, mono- or diplanetic ; primary swarmers isocont, secondary swarmers heterocont ; formed ( 1 ) extra- matrically by progressive cleavage of the extruded globular mass of protoplasm which may be naked or surrounded by a vesicular membrane as in Pythium; (2) delimited in the sporangium, emerging singly and completing development at the mouth of the exit tube; or (3) completely developed in the spo- rangium, emerging in succession and swimming di- rectly away. Antlieridia borne on the same or differ- ent thalli; oogonia terminal or intercalary, variously shaped ; differentiation of egg cell or oosphere prior to fusion absent or very doubtful; epiplasm lacking; content usually contracting toward the conjugation canal during plasmogamy. Antlieridia when present usually more slender, elongate and cylindrical, fre- quently forming a conspicuous perforation and con- jugation tube which extends into the oogonium; fused protoplasts contracting and becoming in- vested with a definite wall. Oospores sexual or parthenogenetic, lying free in the oogonium, usually spherical, oval or ellipsoidal, smooth or warty, hya- line or colored, thick-walled with one or more large refractive globules; germinating by giving rise di- rectly to biflagellate zoospores. This is the largest genus of the family and in- cludes approximately fifteen species, some of which are doubtful, incompletely known, and possibly synonymous. The majority are parasites of algae; ,two occur in tissues of higher plants, and two live in the body of insects. A number of species occur on the same host and are structurally similar. It is thus probable that when extensive cross inoculations have been made and the range of variation of the indi- vidual species is known some of them will prove to be identical. As to geographic distribution, they have been reported from Asia, Europe, and North America. As is shown in figure 1, the zoospores come to rest on the host cell and penetrate it by a germ tube of varying length and diameter, tip of which enlarges as the content of the spore passes into it. This tip soon elongates into a comparatively thick hypha- likc tubular strand as in L. rabenhorsiii (figs. 2-4) or enlarges into a globular, oval, vesicular, sac-like and somewhat irregular structure as in L. brachy- stomum, L. enecans, L. Oedogonii, etc. (figs. 30, 39, 45, 49). This enlargement of the tip eventually de- velops into the mature thallus and in several species is attached to the host wall by the persistent zoo- spore case and infection tube. With further growtli and increase in diameter, the thallus of the more ex- tensive and elongate species develops a few side branches and numerous protuberances which often make it very irregular and crooked. As its ends ap- proach the limits and cross walls of the host, they may either penetrate into adjacent cells or double back in the same cell (fig. 34). Very shortly trans- verse septa are formed at more or less regular inter- vals in such thalli, and they thus are divided into a linear series of elongate, cylindrical or irregular segments. In some species like L. Closterii, L. marchalianum, L. giganteum, etc. (figs. 34, 37, 54) the thallus is quite narrow, mycelioid and Pythium- like, while in L. pygmaeum, L. Cyclotellae, L. Oedogonii, and L. oophilum it may be reduced to a single globular cell as in Olpidium (figs. 25, 39, 49, 60). The protoplasm of the thallus includes numerous fairly large refractive bodies which give it the whit- ish, refringent gleam characteristic of the family Lagenidiaceae. In addition several small vacuoles are usually present. The segments of the thallus or whole thalli are transformed directly into sporangia, oogonia and antlieridia. In the case of sporangia the small vacuoles may run together to form a large cen- tral one by the time the exit tubes have developed. As sporogenesis approaches, the large refractive bodies apparently break up into smaller fragments and become highly dispersed, so that the protoplasm loses much of its refractive appearance and becomes more greyish granular. The exit tubes vary consider- ably in length, diameter, shape, contour, and the ex- tent to which they project beyond the host wall. They may be inflated at the base or just before they pass through the host wall, constricted or uncon- stricted. straight, curved, irregular or tortuous, and end almost flush with the surface of the host, or ex- tend considerably beyond it. In all species except L. pygmaeum, L. Cyclotellae, and L. oophilum the protoplasm of the sporangium is reported to emerge at maturity and form a spheri- plate 19 Lagenidium rabenhorstii (Figs. 1-14, 16 after Zopf, '84; figs. 15, 17 after Cook, '35; figs. 18-22 after Wildeman, '96.) Fig. 1. Early infection stages of Spirogyra cells. Figs. 2-4. Successive developmental stages of thallus. Fig. 5. Sporangium with emerged contents surrounded by a membrane. Figs. 6-8. Successive stages of cleavage and maturation of the zoospores. Fig. 9. Small, reduced thallus with zoospores swarming in a vesicle. Fig. 10. Mature zoospore. Figs. 11-14. Stages in fusion of the contents of antheri- dium and oogonium. Fig. 15. Prefusion stage showing differentiation of an egg cell in the oogonium. Fig. 16. Mature oospore in oogonium of an elongate thallus. Fig. 17. Single, large zoospore produced by germinated oospore, Lagenidium ( Lagenidiopsis) redmetwm Figs. 18, 19. Young and elongate unicellular thalli. Fig. 20. Antheridium, oogonium, and warty oospore. LAQENIDIACEAE 78 PLATE 19 i ■■". °-MJf".b ^^ Lagenidium, Lagcnidiopsis 74 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHVCOMYCETES cal, oval or slightly irregular, globular mass at the mouth of the exit tube. As will become more evident in the diagnoses of individual species, investigators are not in agreement as to whether this mass is naked or enclosed in a definite membrane as in Pythium. According to present data the latter is apparently present in some species and lacking in others, but a careful restudy of this structure is necessary before the problem is settled. The protoplasmic mass may be vacuolate and undergo marked rocking or oscillat- ing movements shortly after emerging, and in some instances it mav even move or be carried away from the exit tube. In L. giganteum the protoplasm may occasionally emerge in several separate masses, ac- cording to Couch ('35). Cleavage begins very soon, and in most species it appears to be progressive and centripetal. In the masses which possess a large central vacuole, i.e., L. Oedogonii and L. giganteum, cleavage is largely centrifugal in direction. A\ hile cleavage is going on the slow oscillating or rocking movement continues, and as the process is completed and flagella develop at the outer periphery of the in- dividual segments, and this motion is augmented by that of the rudimentary zoospores. Cleavage stages in L. giganteum have been intensively studied at dif- ferent time intervals by Couch. As the protoplasm emerges it includes one or more large central vacu- oles and numerous small peripheral ones (fig. 55). The central vacuoles fuse (fig. 56), but the periph- eral ones remain intact and are eventually included in the zoospores. Flagella in pairs are formed on the periphery of the mass opposite the small vacuoles, and shortly thereafter cleavage furrows develop centrifugally from the central vacuole and divide the mass into biflagellate, univacuolate segments. The central vacuole collapses as the furrows reach the periphery, and as a result the zoospore mass con- tracts (fig. 57). The zoospores soon begin to oscil- late individually and glide upon each other as they mature, and within a few minutes they are actively swarming in a localized and restricted region (fig. 58) It is this localized swarming in numerous other species which suggests or indicates the presence of a retaining membrane, although it often cannot be clearly seen. Shortly thereafter the swarmspores separate very quickly as if they had been freed by the rupture "or deliquescence of the membrane. In species where no membrane occurs, the zoospores pull apart more gradually as they mature, and soon swim away. In L. pygmaeum and L. oophihim the incipient zoospore segments are delimited in the sporangium, emerge in succession, and complete their develop- ment near the mouth of the exit tube, while in L. Cyelotellae they are developed completely in the sporangium, emerge singly, and swim directly away, according to Scherffel ('25). Lagenidium Oedogonii is particularly interesting and significant relative to its zoospores. They may develop either extrama- trically in a vesicle, as in Pythium, or within the sporangium. In the latter case they collect in a cluster at the mouth of the exit tube after emerging PLATE 20 Figs. 23, 24. Irregular contorted thalli of L. entophytum with smooth and warty oospores. Zopf, '84. Fig. 25. Olpidium-like thallus of L. pygmaeum with partially formed zoospores emerging in a vesicle. Zopf, '87. Figs. 26, 27. Encysted and motile zoospores of L. pyg- maeum. Zopf, I.e. Figs. 28, 29. Mature oospores of L. pygmaeum. Zopf, I.e. Fig. 30. Empty thallus of L. enecans from a Cymato- pleura solea cell. Scherffel, '25. Figs. 31, 32. Heterocont secondary swarmers or zoo- spores of L. enecans. Scherffel, I.e. Fig. 33. Oospores, L. enecans. Scherffel, I.e. Fig. 34. Portion of filamentous thallus of L. Closterii. Couch, '35. Fig. 35. Inflation of exit tube before passing through host wall. Couch, I.e. Fig. 36. Zoospore of L. Closterii. Couch, I.e. Fig. 37. Thallus of L. marehalianum in Oedogonium cell. Couch, I.e. L. Oedogonii Fig. 38. Germinated zoospore and cellulose plug formed around germ tube. Couch, I.e. Fig. 39. Unicellular thallus transformed into a zoospo- rangium with contents beginning to emerge. Couch, I.e. Fig. 40. Vacuolate content of sporangium after emerg- ing. Couch, I.e. Figs. 41, 42. Side and ventral views of heterocont, sec- ondary swarmers or zoospores. Scherffel, I.e. Fig. 43. Encysted zoospores at mouth of exit tube. Scherffel, I.e. Fig. 44. Oospore. L. brachystomum. Scherffel, I.e. Fig. 45. Elongate, unbranched thallus from Gompho- nema cell. Scherffel, I.e. Fig. 46. Zoospores in a vesicle. Couch, I.e. Fig. 47. Zoospore. Couch, I.e. Fig. 48. Oospore. Scherffel, I.e. L. Cyelotellae Scherffel, '25 Fig. 49. Olpidium-Wke thallus undergoing cleavage. Fig. 50. Zoospore. Fig. 51. Oospore. Lagenidium sp. Couch, '35 Fig. 52. Lagenidium sp., in Oedogonium. Couch, I.e. Fig. 53. Diplanetic zoospores. L. giganteum Couch, '35 Fig. 54. Portion of filamentous thallus. Fig. 55. Vacuolate content of sporangium shortly after emerging. . . Fig. 56. Early stage of sporogenesis; flagella arising adjacent to peripheral vacuoles. Fig. 57. Later contracted stage following disappearance of central vacuole; peripheral vacuoles incorporated in the zoospores. Fig. 58. Zoospores in a vesicle. Fig. 59. Various views of the zoospores. L. zoophthomm Sparrow, '39 Fig. 60. Lobed thallus in rotifer egg. Fig. 61. Emergence of zoospores. Fig. 62. Zoospore. I.AOKN1DIACEAE PLATE 20 75 76 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES and encyst (fig. 43), later germinating and leaving a hyaline shell behind as in Achlya, Ectogella, etc. Diplanetism has also been shown by Scherffel and Couch to occur in L. enecans and Lagenidium sp. (figs. 52, 53). It is thus obvious that species of Lagenidium may exhibit a wide range of variation in place and time of sporogenesis and zoospore be- havior. The zoospores are generally described as bean- shaped, but in species which have been critically studied this appears to be the initial shape only. As they grow older they become more pyriform and reniform with a pointed anterior and a rounded posterior end and a ventral groove. The flagella are inserted laterally in this depression, and in most species they have been figured as equal in length. The secondary swarmers in L. enecans and L. Oedo- gonii (figs. 81, 32, 41, 42), however, are heterocont with the shorter flagellum extending forward, ac- cording to Scherffel ('25), but in Lagenidium sp., Couch illustrated them as isocont (fig. 53). Their method of swimming is rather smooth and regular in contrast with the darting movement of the chytrid swarmspores, and in this respect they are very simi- lar to those of Achlya, Saprolegnia, etc. The antheridia and oogonia may occur in the same thallus and among the sporangia (fig. 16) or in sepa- rate thalli. The elongate multicellular thalli more often bear both gametangia. In the small unicellular species the thallus is usually divided by a transverse septum into two cells at maturity, which become the so-called antheridia and oogonia, respectively, while in other reduced species conjugation may occur between separate unicellular thalli. Species in which both gametangia are borne on the same tli alius have been generally referred to as monoe- cious, while those in which the respective gametangia are borne on separate thalli are regarded as dioe- cious. It is not known and has never been demon- strated, however, whether the so-called dioecious thalli have arisen from zoospores of the same or different sporangia and thus represent distinctly male and female strains. Until monozoospore stud- ies have been made and it has been shown that such thalli possess the potentialities of only maleness or femaleness or both, it is premature to describe some species of Lagenidium as heterothallic or dioecious. The so-called oogonium may be elongate, spindle- shaped, oval, ellipsoidal, almost spherical, locally paunchy, and irregular, with or without conspicu- ous protuberances. The antheridium is usually smaller, more elongate and cylindrical, but varies somewhat in the different species. In L. rabenhorstii, L. marchalianum and L. enecans it is relatively slender and cylindrical like the vegetative filaments. In L. Cyclotellae and L. Oedogonii it is usually slightly smaller than the oogonium and not particu- larly different in shape. In most species it forms a conspicuous perforation or conjugation tube — i.e., L. rabenhorstii (fig. 14), L. marchalianum (fig. 37), L. enecans (fig. 33), etc, while in the smaller species, L. Oedogonii and L. Cycloiellae, the tube is not very evident, according to Scherffel's drawings (figs. 44, 51). Zopf's description of fertilization in L. raben- horstii is the only careful and detailed account of the process for the whole genus. After the conjuga- tion tube has pierced the oogonium wall, the granu- lar refractive protoplasm of the antheridium con- tracts into a globular mass and accumulates at the side adjacent to the oogonium (fig. 12). Shortly thereafter it begins to flow into the latter, and after approximately three hours the process is completed (figs. 13, 14). While this is going on the ooplasm be- gins to contract toward the tip of the conjugation tube, and at the same time the granules, bodies, and discrete elements of the protoplasm undergo visi- ble movements. As the contraction continues the ooplasm becomes more and more coarsely granular, and by the time the antheridium is empty, the gran- ules have coalesced into two large refringent glob- ules (fig. 13), which later usually fuse into a single larger one (fig. 14). Fusion is then complete, and eventually the zygote becomes invested with a thick wall. It is to be particularly noted from Zopf's account that no egg cell and periplasm are differentiated prior to fusion as in the Saprolegniales and Perono- sporales, respectively. The contraction of the ooplasm during plasmogamy, however, may perhaps foreshadow this development. Cook ('35), on the other hand, described the formation of an egg cell with a definite wall prior to fusion in L. rabenhorstii, and in his treatment of the whole genus he fre- quently referred to the presence of an oosphere. His figures, however, are not very clear and convincing, and in the writer's opinion the presence of a well- differentiated egg cell remains to be shown. In parthenogenetic species the antheridium is lacking, and the ooplasm contracts, rounds up and becomes invested with a thick wall. Germination of the oospores has been reported only in one species. In L. rabenhorstii this occurs within 24 hours after fertilization, according to Cook. "The wall of the oospore breaks down and a single zoospore is lib- erated, which .... is almost spherical in shape, 8 /i in diameter and is provided with two large flagella" (fig. 17). He described this motile cell as a sexual zoospore in contrast to the asexual zoospores pro- duced in sporangia. Inasmuch as nothing is known about the time and place of meiosis as well as sex determination in Lagenidium, Cook's use of the term sexual in this relation is obviously premature and unwarranted. So far no cytological study of fixed and stained material has been made of the genus. Accordingly nothing is known about mitosis and the details of cytokinesis. It also remains to be seen whether the gametes are uni- or multinucleate at the time of fer- tilization, whether karyogamy immediately follows plasmogamy, and at what stage meiosis occurs. Such problems must first be solved before the relationship of Lagenidium with the higher Oomyeetes becomes clear. i u.i \1|>I vck.vk 77 L. RABENHORSTI1 Zopf, 187a Verh. Bot. Ver. l'rov. Brandenburg 90: T9. 1884 Nova Acta Ksl. Leop.- Carol. IV.it. AJtad. Nat. 17: 145. PI. l. flgs. 1 -'*; pi. .'. Bgs. 1-9. Th alias usually elongate, filamentous, tubular, hypha-like when young, becoming septate, thicker, . vesicular and more irregular, curved, and crooked, with several short branches and protuber- ances; Frequently attached to the host cell by the infection tube and aoospore case; confined to single cill or extending into adjacent host cells; usually slightly constricted at the septa; segments elongate, Id 20 p, cylindrical and often irregular, sometimes breaking apart and separating; dwarf thalli usually unicellular and often Olpidium-likt. Sporangia of the same siae and shape as the thallus segments with one straight, curved or tortuous, narrow, rarely con- stricted exit tube, 2— 3 ju \ 5—20/1, which does not project very far beyond the surface of the host; con- tent of sporangium emerging and undergoing cleav- age into zoospores outside of host; vesicle present. or doubtful. Zoospores at first bean-shaped, later be- coming more pyriform and reniforin, 6 X 8.5 /x, isocont. Gametangia borne on the same or different thalli: OOgonia terminal or intercalary, spindle- and egg-shaped, locally paunchy and irregular, or al- most spherical, up to 15 /t in diameter; antheridia usuall v elongate and cylindrical. 5 X 15 /i, or some- what irregular; sometimes borne on a delimited branch from the oogonial cell, usually on an adja- cent, or intercalary cell; developing a protuberance toward the oogonium which elongates and tapers into a perforation tube and pierces the oogonial wall ; granules, bodies and discrete elements of the ooplasm undergoing slight movement, and the whole content contracting during plasmogamy; fused pro- toplasts contracting further and becoming invested with a wall. Oospores spherical 10— 15 /i, hyaline, smooth, thick-walled with a large central refractive globule; germinating within 24 hours by giving rise directly to a large spherical 8 /i, biflagellate zoo- spore ( : ). which soon infects the host cell. Parasitic primarily in the vegetative cells of Spirogyra sp., Mougeotia sp.. and Mesocarpus sp. in Germany (Zopf. I.e.. '79; Minden. '11 ); Spiro- gyra sp. in Belgium (de Wildeman, '91. '93. '95) and Houmania Constantineanu. '01); OedogOnium sp. in Denmark (Petersen, 09, ' 1 0 J ; Spirogyra sp. in New York and Mass.. I". S. A. (Atkinson. '09; Spar- row. '32 ) ; Oedogonium pluciosporum and S. ortho- spira in Montana. U. S. A. (Graff, '28); Spirogyra sp. and Mougeotia sp. in Bulgaria ( Valkanov, '31 ) ; Spirogyra sp. S. mirabilis and Zygnema sp. in Hun- gary (Cejp, '85; Domjan, '85). Spirogyra sp. in England and Wales (Cook, '32. '33. '35). The writer also has frequently found it in Spirogyra sp. and Oedogonium sp. in New York City. Investigators are divided in their observations and opinions about the presence of a vesicular membrane around the young zoospores in this species. Zopf and Sparrow reported that zoospore cleavage and de- velopment occur within a vesicle, like in Pythium, but Atkinson and Cook ('85) described the exuded protoplasmic mass as naked. In a previous paper ('82), however. Cook had reported tin- appearance of a thin membrane, while figure 9 and plate 1 of his 1935 contribution arc very suggestive of its pres- ence. Atkinson further described fusion of zoo spores, but this appears to be an abnormal and pos sibly pathological behavior and apparently has no sexual significance. Cook ('35) maintained that the content of the oogonium contracts and becomes invested with a wall before fusion, forming thus a definite oosphere or egg eel] which is attached to the oogonium wall by a stalk. Zopf, on the other hand, who carefully watched the successive stages of fusion at different time intervals reported that contraction does not oc- cur previous to but during plasmogamy and that a wall or membrane is formed only after the process has been completed. Cook's figure and description of fusion are not particularly clear, and what he de- scribed as an oosphere attached by a stalk seems to be a fertilized oospore and a conjugation tube (tig. 15). Whether or not Cocconi's ('94) L. papillosum is identical with this species is uncertain. Saccardo ( '88 ) and Minden (11) regarded it as related, while Cook believed it to be an incompletely described specimen of L. rabenhorstii. According to his calcu- lations of Cocconi's drawings, the thallus is about 5/i in diameter, the sporangia 17 /t, zoospores 4 X 6/i, oogonia 16 /i. and the oospores 10-12 /i in di- ameter. The oospores, however, have a distinctly warty wall, while the zoospores are figured as pyri- form with two equal anterior flagella. Cocconi's drawings of the zoospores, however, may possibly be inaccurate. It is to be noted in connection that in his early papers ('78, '79) Zopf also described the oospores of L. rabenhorstii as being golden in color and warty, but these observations possibly relate to L. entophytum. L. ENTOPHYTUM (Pringsheim) Zopf, I.e., p. 154: pi. .', 6gs. 10-18; pi. 3. figs. 1-3. Pythium entophytum Pringsheim, 1858. Jahrb. Wiss. Hot. 1: 2sr, 305. pi. J, tip. l. L. americaiium Atkinson, 1009. Hot. Gaz. 48: 334. Fig. 6. Thallus tubular, vesicular, short, relatively thick. 4-8 /i, curved, crooked and very irregular with nu- merous short primary, secondary and tertiary branches or protuberances; usually constricted slightly at the cross septa; dwarf thalli continuous. Sporangia of the same size. 5 >' 12 15 /<. and shape as the thallus segments and dwarf thalli. exit tubes numerous, up to 20 or more, cylindrical and tortuous. 2 /i or more in diameter and of variable length. USU ally inflated before passing through host wall, and extending considerably beyond it; contents of Spo rangia emerging and forming an irregularly glob- ular mass at the mouth of the exit tube, which may sometimes float away before cleavage is completed; vesicular membrane doubtful or absent. Zoospores bean-shaped and reniforin. 4 X 8 /i, isocont. Oogo- 78 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES nia locally vesicular or paunchy ; antheridia lack- ing. Oospores numerous, parthenogenetic, formed by the contraction and encystment of the oogonium content; spherical, 12 p, with a bright-golden, thick, smooth or warty wall, and a large central refractive globule ; germination unknown. Parasitic in the zygospores of Spirogyra sp. (Pringsheim, Zopf, I.e.), Euastrum humerosum and Microasterias mahabuleshwarensis var. wallichii (Schultz-Danzig, '23) in Germany; Spirogyra sp. in Belgium (de Wildeman, '91, '93, '95) ; S. varians, S. calospora, and S. insignis in New York, U. S. A. (Atkinson, I.e.), and Spirogyra sp. in Wales and England (Cook, '33, '35). This species appears to have been described and figured first by Carter ('56; pi. 9, figs. 9-10) as a developmental stage of an Astasia-like flagellate in the zygospores of Spirogyra, and later by Pring- sheim as a species of Pythium. It differs primarily from L. rabenhorstii by its shorter, thicker, more crooked and irregular thallus, parthenogenetic oospores, and its localization to the zygospores of the host, although de Wildeman ('95) claims that L. rabenhorstii also may occur rarely in zygospores of Spirogyra. On the other hand, L. entophytum is strikingly similar to L. gracile which inhabits the same cells, and there is a strong possibility that the two species may be identical. Pringsheim figured and described the zoospores of his fungus as being formed exactly as in Pythium within a definite vesicular membrane, but Cook re- ported that the latter structure is missing and that the extruded mass of protoplasm is naked. Atkinson likewise failed to observe a membrane and reported that the protoplasmic mass may float away from the exit tube before cleavage. Cook further regarded the contraction and encystment of the oogonium con- tents as the differentiation of an egg cell or oosphere as in L. rabenhorstii. In view of the fact that no other workers have found this species in other but Spirogyra zygospores it is perhaps questionable whether Schultz-Danzig's fungus in Euastrum and Microasterias relates to L. entophytum. His fungus may possibly belong to Petersen's Mysocytium irregulare or the unidenti- fied species of Lagenidium reported by de Wilde- man ('95) in Euastrum oblongum. Whether Atkin- son's L. americanum is identical to L. entophytum or L. gracile, or distinct from both is at present largely a matter of personal interpretation, but the author is inclined to agree with Minden that it re- lates to L. entophytum. L. ENECANS Zopf, I.e., p. 154. Scherffel, 1925. Arch. Protistk. 52: 20. PI. 2, figs. 60-09. Thallus sparingly branched with short plump, finger-like branches, 6-12 ft X 37-156 /x; attached to host cell by infection tube; apparently continu- ous, transformed completely into a zoosporangium at maturity. Exit tube cylindrical, 3—6 p. X 9-36 p, extending only slightly beyond the surface of the host; thickened and inflated at base to form a "spreading apparatus" which enables it to pass be- tween the valves of the host cell. Zoospores egg- and kidney-shaped, elongate with a ventral groove, 5.7 yu X 8-12.5 p; secondary swarmers heterocont with the short flagellum directed forward; vesicular membrane not clearly evident. Oospores spherical, 18 /x, broadly oval, 15—22 /x X 20-24 p, and irregu- lar with a smooth thick wall, large central refractive globule, and finely granular protoplasm ; germina- tion unknown. Parasitic in Stauroneis phoenocenteron, Cocco- nema lanceolatum and Pinnularia sp., in Germany (Zopf, I.e.) ; various diatoms in Belgium (de Wilde- man, '93) ; Gomphonema constrictum, Cymbella cymbiformis var. parva, C. gastroides, Cymato- pleura solea, Stauroneis phoenocenteron, Amphora ovalis, and Cocconema lanceolatum in Hungary (Scherffel, '02, '25); Navicula cuspidata var. am- bigna and Stauroneis phoenoceuteron in China (Skvortzow, '31 ). Inasmuch as Zopf and none of the subsequent workers except possibly de Wildeman had figured this species, Scherffel was not certain that the form which he found relates to L. enecans, although he described it as such. L. PYGMAEUM Zopf, 1887. Abh. Naturf. Ges. Halle 17: 97. PI. 1, figs. 21-39; pi. 2, figs. 1-12. Thalli usually solitary, sometimes 2-4 in a host cell, oval, spherical, ellipsoidal and Olpidium-like, or elongate, irregular and lobed with one or several short branches or protuberances ; often completely filling the host cell; unicellular or dividing into an antheridium and oogonium at maturity. Exit tubes short, thick, tapering, and rarely branched, usually extending but a short distance beyond the host cell. Zoospores bean-shaped, 5 X 8 /x, tapering at the anterior and more rounded at the posterior end with a ventral groove and several small refractive gran- ules; delimited in the sporangium, emerging in suc- cession, and completing their development in an ex- tramatrical vesicle ; swarming in the latter and freed by its rupture ; intermittently amoeboid. Oogonia oval, paunchy and slightly irregular with protuber- ances ; antheridia smaller with none or fewer and less conspicuous protuberances; conjugation canal usually well developed. Oospores predominantly spherical and oval, sometimes ellipsoidal and slightly elongate, 18-29 p in diameter, hyaline, smooth, and thick-walled, with a large refractive globule; germ- ination unknown. Parasitic in pollen grains of P. sylvestris, P. aus- triaca, P. laricio, P. pallasiana, Pinus sp., and Cos- marium pyramidatum in Germany (Zopf, I.e.; Schultz-Danzig, '23). pollen grains in Switzerland (Maurizio, '95) and conifer pollen in Belgium (de Wildeman, '95) and Denmark (Petersen, '09, '10). The author ('41) collected this species in pollen of P. austriaca in New York City and succeeded in transferring it to pollen of P. sylvestris, P. bank- siana, P. densiflora, P. thunbergii, P. strobus, P. austriaca var. nigra and hemlock. Attempts were also made to infect living and killed cells of Nitella fle.vilis, Char a coronata, Cladophora glomerata, LAOENIDIACBAE 79 Pitkophora sp.. Stigeoclonium tenue, Ulothris sonata, Oedogonium sp.. Spirogyra sp., S. crtuta, Mougeotia sp., and Hydrodictyon reticulatum with- out success. These results oast doubt on Schultz- Danaig's report of the occurrence of this species in Cotmarium. He based his claim on the presence of an irregular, lobed, sac-like thallus with an exit tube which is rarely branched, and the presence in the same culture of pollen grains infested with /.. /','/<7- macum. It is not improbable that his fungus relates to dwarf thalli of MysOcytium or another species of Lagenidiutn. Zopf's report that the zoospores are li; to I8/1 long is obviously incorrect. The present writer has observed their formation and activity nu- merous times and found them to he approximately 5 X8 ft in size and bean-shaped with a ventral groove. Thalli of this species may look strikingly like those of Olpidium, and unless zoospore emergence is observed they may readily be mistaken for this chy- trid. Fischer believed that the intramatrical resting spores of R. pollinis noted by Cornu ('72. p. 121) relate to /.. pygmaeum also. Atkinson (09) believed that the zoospores of L. pygmaeum species are di- planetic — the emergence of the incompletely de- veloped zoospore segments representing the initial motile stage. Whether Scrbinow's ('99) Olpidium ramosum relates to this species or belongs at all in the genus Lagenidium is very doubtful. Mention is neverthe- less made of it here because it occurs in pollen grains of l'inus sylvrstr'is in Russia and is reported to form oospores. However, the zoospores are fully formed in the ^oosporangium, possess a single posterior flagellum, and swim directly away after emerging from the branched exit tubes. In sexual reproduc- tion two thalli, apparently of unequal size, fuse within pollen grains and become invested with a thick wall. This type of fusion is suggestive of that which occurs in Olpidiopsis, but the presence of posteriorly uniflagellate zoospores excludes O. ramosum from this genus as well as from Lageni- dium. L. GRACILE Zopf, I.e., p. 158. Cook, 1932, New Pbytol. SI: 140. Figs. 32-38. [936. Arch. Protistk. 8i>: hk. pi. 3, fijrs. _>ii 32. Thallus very similar to that of L. entophytum but usually narrower, 4.5 /x, and less irregularly branched, sometimes penetrating adjacent host Cells. Sporangia less irregular, tubular, cylindrical. 1.5 /' in diameter, and occasionally almost spherical with a narrow uneonstricted exit tube of variable Length, which may become inflated before passing through the zygospore and gametangium wall of the host; extending for varying distances beyond. Zoo- spores bean-shaped, 4 X 7.5 ft., formed in an extra matrical vesicle (?); vesicular membrane doubtful. Oogonia intercalary, rarely terminal, oval, globular, paunchy; antheridia lacking. Oospores few or nu- merous, parthenogenetic, formed as in /.. entophy- tum, spherical, 13—14/1, with a thick smooth wall; germination unknown. Parasitic in the zygospores of Spirogyra sp. in Germany (Zopf, I.e.) ; S. grevilleana in Belgium (de Wildeman. '!»">). and Spirogyra sp. in England ( Cook, I.e.). From the above description, the validity of this species seems very questionable. The slight differ enees in diameter, irregularity of branching, length and diameter of exit tubes, etc., noted by Zopf and Subsequent workers are not Sufficient to distinguish it sharply from /,. entophytum, and inasmuch as both are parthenogenic and inhabit the zygospores of Spirogyra, the author is strongly of the opinion that they are identical. Zopf's claim that the oospores differ by being smooth and not bright golden in color does not seem particularly significant, since such oospores have been reported in L. entophytum also. L. ZOPFII r intercalary swelling and wit li further growth becoming somewhat lateral in position luit continuous with the main axis. Antheri- dia oval, clavate, and cone-shaped; borne on the oogonium and delimited from the latter by a cross wall ; usually disintegrating and disappearing after fertilization; conjugation tube usually well-devel- oped and conspicuous. Oospores single, rarely double, spherical, oval, ellipsoid and egg-shaped, I i 19/1 in diameter, with a thick rough or warty wall: content granular with one or more refractive globules; germination unknown. Parasitic in the oogonia of Chara in Switzerland. De Wildeman created the genus Lagenidiopsis as an intermediate group between the I.agcnidiales and l'cronosporales. primarily because the thallus is filamentous and unicellular. These characters, how- ever, are no longer of significance in this case, since similar thalli have subsequently been found to be characteristic of certain species of Lagenidium also. Furthermore, the method of sexual reproduction in LagenidiopsU is typical of that in the former genus, and on these grounds it seems logical to merge the two genera. Their identity or difference, however, cannot be definitely settled until the sporangia and zoospores of LagenidiopsU have been found. L. MARCHALIANUM «V Wildeman, 1897. Ann. Soc. Beige Micro. SI: 8. PI. 1, figs. 1-9. Thallus filamentous, cylindrical. 2.2-6.7 /* in di- ameter, sometimes irregularly swollen, slightly or not at all constricted: occasionally confined to a single cell, but usually extending through six or seven host cells; enlarged up to 7 \i. in diameter before entering the cross septa of the host and constricted to 1 ;i as it passes through. Sporangia cylindrical, elongate. 30-60 p, narrowly spindle-shaped with a delicate. 1.5-2 ft thick, exit tube which extends \ 5 \>. beyond the host cell. Zoospores unknown. Oogonia spherical. 20ft, intercalary, rarely terminal; an- theridia adjacent to oogonia on the same filaments, or arising as a branch from an adjacent filament. Oospores spherical, 8-14 /x. hyaline, smooth, thick- walled, rarely parthenogenetic; germination un- known. Parasitic in Oedogonium sp. in Belgium (de Wildeman, I.e. ) and Virginia. L*. S. A. (Couch. '35 | . L. OEDOGON1I Scherffel, 1903. Hedwigia 41: (105). 1925. Arch. Protistk. 52: 109. PI. :,, figs. 209-219. Thallus usually single, rarely two or more in a cell, ovoid, vesicular, 20-25 /' .■' 35—52 //. irregular. lobed. with blunt protuberances, rarely filamentous. filaments when present several hundred microns in length and coiled; non-septate and continuous with One exit tube which may end .almost Hush with the surface of the host cell or extend considerably be- yond it. Zoospores mono- or diplanetic ; fully formed in the sporangium or delimited in an extramatrical vesicle with an indistinct membrane; in the former Case emerging singly and encysting in a group at the mouth of the exit tube, later germinating and leal ing the t li.fi /■ in diameter, cysts behind as in .leh- lya; secondary zoospores or swanners pointed at the anterior and round at the posterior end with a ventral groove, heterocont with the short llagellum directed forward; forming an apprcssorium on the host wall in germination. Oospores globular, spheri- cal. 12-1 t/i, with a 2 p. thick, hyaline, smooth wall and containing coarsely granular protoplasm and a large eccentric globule; germination unknown. Parasitic in Oedogonium sp. in Hungary (Schcr- fifel, I.e.) and Missouri, U. S. A. (Couch, '35). This is a significant species because its zoospores exhibit several characteristics common to Pythium and Achlya. The zoospores may be formed extrama- trically in a vesicle as in Pythium, or within the sporangium and then emerge and encyst at the mouth of the exit tube as in Achlya. It is to be noted in this connection that the zoospores of Olpidiopsis Oedogoniorum have the same characteristics, while its resting spores and their method of formation are also strikingly similar to the oospores of L. Oedo- gonii. Scherffel accordingly pointed out that O. Oedogoniorum has much in common with Lageni- dium, and was of the opinion that it may relate to the latter genus. From his drawings and descriptions of the thalli one might believe that the two species are closely related or even identical, but the elongate thalli of L. Oedogonii which Couch figured are dis- tinctly unlike those of Olpidiopsis. It is nevertheless obvious that further study and comparison is very essential to an understanding of the two species. In this species Scherffel found segments of the thallus or possibly of sporangia the contents of which had contracted, become septate, and thick- walled. He regarded these resting structures as com- parable with the gemmae of the Saprolegniaceae, but it is doubtful that they are of any particular morphological or phvlogenetic significance. L. SACCULOIDES Serbinow, 1924. I.a Defense ties Plantes 1 : Hj. Thallus short, unicellular, sac-like with lobes or short branches, or narrowly elongate, .'5.5-7.6 jj. in diameter, with occasional septa. Zoospores appar- ently completing their development in an extrama- trical vesicle; spherical, 3.5 ft, in fixed and stained preparations; position and relative lengths of fla- gella and presence of diplanetisin unknown. Sexual reproduction isogamous ; contents of two adjacent cells flowing together and forming a zygospore (?) in the space between them. Zygospores hyaline, spherical, 13.8 p., oval, elongate. 7.6 ft X 15.2 /x, with a sculptured outer .and a smooth inner wall; containing a large refractive globule; germination unknown. Parasitic and saprophytic in Closterium ralflii var. hybridum in the Menzelinsk district of the Ufimsk province in Russia. 82 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES Serbinow's study of this species relates to mate- rial collected in 1913 and fixed in glycerine jelly. Consequently the method of zoospore formation, motility and behavior of the zoospores, relative lengths and position of the flagella, as well as the successive stages of sexual reproduction were not observed. Whether or not it belongs in Lagenidiitm is questionable. Because of the lack of or reduced branching of the thallus Serbinow regarded it as intermediate between this genus and Myzocytium. Its method of sexual reproduction, however, seems strikingly similar to that described by Dangeard for Resticularia nodosa. Until more is known about L. saccidoides, its relationship to the above-mentioned genera will remain doubtful. Serbinow did not illus- trate this species, as far as the present writer is aware. Its effect on the host is quite marked. It kills the desmid cells very quickly and soon destroys their contents, but it is not an obligate parasite, according to Serbinow. It may also attack dead and partly empty cells. L. CYCLOTELLAE Scherffel, I.e., p. 18. PI. 2, figs. 49-59. Thallus small, sac-like, and continuous, attached to the extramatrical persistent zoospore case by the germ or infection tube; transformed completely into a single sporangium at maturity, with a short, 3 jx wide exit tube. Zoospores fully formed in the spo- rangium ; emerging singly and swimming directly away; oval, egg-shaped, 3.5 jx X 6 P> slightly con- cave with a refractive mass near the posterior end ; flagella attached slightly below the apex. Oospores globose, 10 n, broadly oval, 8-10 p. X 10-12 p., angular and somewhat irregular, hyaline, smooth, thick-walled; containing a large refractive globule, granular protoplasm, and a lateral spot ; germina- tion unknown. Parasitic in Cyclotella kutzingiana in Hungary. The manner of zoospore formation and emergence in this species are very similar to those of L. pyg- maeum and L. oophilum. In shape and appearance, however, the zoospores are more like those of Ectro- gella bacilliariacearum, according to Scherffel. He did not observe diplanetism but believed that it oc- curs. Scherffel regarded this species as a connecting link between Ectrogella and the Lagenidiaceae (Ancylistaceae). L. BRACHYSTOMUM Scherffel, I.e., p. 21. PI. 2, figs. 70-85. Thallus elongate, 1-7.5 ^ X 150-250 fx, usually unbranched or with short side branches and pro- tuberances; continuous, and transformed completely into a single sporangium at maturity with one or rarely two very short, tapering cone-shaped exit tubes, the wall of which is greatly thickened at the base to form a spreading apparatus. Exit tubes forc- ing the valves of host cell apart, boring through the wall. Zoospores kidney-shaped with a ventral groove, 4 X 6—8 fx, formed in an extramatrical vesi- cle as in Pythium. Oospores formed parthenogene- tically or by sexual fusion, globose, broadly-oval, 6— 10 fx. X 11— 24/t, hyaline, smooth, thick-walled with one or two large refractive globules ; germina- tion unknown. Parasitic in Synedra ulna, Cymbella cymbiformis var. parva, Gomphonema constrictum and Nitzschia linearis in Hungary (Scherffel, I.e.) and Synedra sp. in North Carolina, U. S. A. (Couch, '35). This species differs from L. enecans, according to Scherffel, by its unbranched thallus, thin wall, short, cone-shaped exit tubes, and the fact that it parasit- izes small diatoms. As he pointed out, however, it may also occur in Cymbella cymbiformis var. parva, which is also often parasitized by L. enecans. Many of the structural differences which Scherffel de- scribed above may possibly be due to the smaller hosts in which this species lives and do not relate to fundamental specific characters. Until extensive cross inoculation experiments have been made, the validity of L. brachysiomum must be regarded with question. Scherffel (I.e., p. 23; pi. 2, fig. 86) further de- scribed a species of Lagenidium with a long spar- ingly branched, multiseptate thallus in Pinnularia sp., which bears some resemblance to L. raben- horstii. The exit tubes are fairly long and cylindrical and extend for some distance beyond the surface of the host cell. No zoospores nor their method of for- mation were observed. The oospores are solitary, globose and appear to have arisen by sexual fusion. Scherffel was doubtful about whether this species is homo- or heterothallic, but he felt certain that it is not identical to L. enecans. L. GIGANTEUM Couch, 1935. Mycologia 27: 376. Figs. 1-19. Thallus coarse, extensive and mycelioid, branched, constricted or unconstricted; extramatri- cal branches somewhat fine and delicate. Sporangia elongate and cylindrical, 6-40 /x X 50-300 p, with a single, long 6-10 p. X 50-300 /x, exit tube; content emerging through the tube to form one or several globular, naked and undifferentiated masses, which undergo cleavage into zoospores. Zoospores slightly oval, 8-9 jii X 9—10 /x, with a ventral groove in which two equal flagella are attached; freed by the rup- ture or deliquescence of the vesicular membrane. Monoplanetic and rather sluggish. Sexual repro- duction unknown. Weakly parasitic on mosquito larvae, copepods and Daphne in Virginia, U. S. A. (Couch, I.e.; Matt- hews, '35) and mosquito in North Carolina, U. S. A. (Couch, I.e.). Couch succeeded in growing this species on vari- ous synthetic culture media and isolated what lie be- lieved to be a mutant of the original strain. His is the first report of the culture of a species of Lageni- dium apart from its host tissues. Since sexual repro- duction has so far not been observed, Couch was somewhat in doubt about whether this species re- i 1GEN mi vck vk 83 lates to Lagenidium. It differs from any of the other species in being a weak faculative parasite and hav- ing -in extensively branched filamentous, mycelioid thallns. Another unidentified species has been recorded by Conch ('85, p. 886, tigs. 32—84) in Oedogonium which he took tn be /.. brachystomum. The thallns is moid and slightly irregular, 7—10/* X 15— 20 it. The ■oospores are formed in an extramatrical vesicle, ami after swimming about tor a short while, encyst. Within one to throe hours they emerge and become motile again. In rare cases encysted spores which have germinated with a tube emerge, Leaving the germ tube and cyst behind. No stages of sexual re- production nor oospores have heen observed.* L. OOPHILUM Sparrow, 1989. Mycologia 31: 531. Figs. 1 1 t. L'i'jt tin oophilum Sparrow, I.e. Thallns solitary or several in a host cell, irregu- larly saccate, ellipsoidal, broadly Iobed or non- lobed; converted holocarpically into a thin-walled hyaline /oosporangium. 12—25/1 wide by 20— 10 fj. long, with a short sessile or slightly prolonged exit papilla, MS ,» in diameter. Zoospores grape seed- shaped, laterally birlagellate. isocont, 6 X 8 /i, emerging individually and maturing in a globular group at the exit orifice, vesicle doulitful or un- known: cystospores ■> — 1> /j. in diameter. Sexual re- production unknown. * Since this volume went to press another species of Lagenidium has been reported and described by Couch in tlie e. Thallns predominantly intramatrieal, mycelioid, coarse, irregularis branched, sparingly septate, thin-walled, S i 12.6 m i" diameter; each segment becoming a spor- angium. Extramatrical emergence papilla of sporangium tubular. II — .'9 (i / -'.') — 70 ft; protoplasm emerging as an irregular, subspherical or spherical mass, up to 100 m in diameter, and becoming enveloped DJ 8 persistent. thick, gelatinous envelope or vesicular membrane; cleav- ing into zoospores as in Pythium. /oospores swarming ill persistent vesicle and later liberated by its rupture: tapering at the anterior and rounded at the posterior end, !».'i ■ i-'-(>/'. segments with a single exit tube which is inflated, globular 3.7— 1.2 fi. in diameter, irregularly lageiiil'orin and appressorial-like inside of host wall, and may e\ tend to a distance of 150/1 on the outside of host. Size, structure .and behavior of zoospores unknown. Antheridia oval and spindle-shaped; oogonia oval, barrel-shaped. 12-19.5 p X 7.4-12 p ; oospores Spherical, 7.4—13/*, with a thick, hyaline, smooth wall and several refractive globules; germination unknown. Parasitic in Closterium attenuatum and Spiro- taenia sp. in Belgium (de Wildcman, '93, '95, '96) ; Closterium sp. in Manchuria (Skvortzow, I.e.); Closterium sp. and Pleurotaneum trabecula in Bo- hemia (Cejp, '.'55); <". striolatum and C. areolatum in North Carolina. U. S. A. (Berdan, '38). Whether or not .1/. megastomum (de Wildcman) forma Skvortzow (I.e.. p. 431), which occurs in Closterium sp. is a variety or form of de Wildeman's species is uncertain, but the writer is at present of the opinion that it is identical with the latter. It is characterized by globular and spherical, 12.9— 22.5 jj.. sporangia, 10-23.5 /x long exit tubes, and spherical, 11— 13/i, smooth, hyaline oospores. .1 uei/listes miurii Skvortzow is possibly identical to de Wildeman's species also. The author is ac- cordingly listing it as a synonym and presenting fig- ures of its thallus and resting spores (figs. 38-10). As Miss Berdan has pointed out, the infection hy- phae which Skvortzow figured may be nothing more than exit tubes for the emission of the zoospores. Until the presence of eonidia and direct infection by hyphae have been demonstrated, Skvortzow's spe- cies will remain a doubtful species of either dncy- listes or Mysocytium. M. ZOOPHTHORUM Sparrow, 1936. .lour. Linn. Soc. London, Bot. 50: 461. PI. 19, figs. 1-14. Thallus rarely branched, constricted or uncon- stricted, septations narrow and inconspicuous, seg- ments .5-17 ju. in diameter, variable in length. Zoo- sporangia irregular, sac-like and lobed with a single short exit tube. Zoospores 6— 7 fi X 10-11 /u.; par- tially or wholly delimited within the sporangium, emerging in succession, and forming a subspherical mass at the mouth of the exit tube, which soon sepa- rates into irregular segments. Sexual fusion through a pore; oospores hyaline, smooth, thick-walled, spherical, 12-15 /v.. with a large refractive globule; germination unknown. Parasitic in rotifers and rotifer eggs in England and Denmark. Sparrow was uncertain about the generic position of this species. In some respects it resembles re- duced thalli of M. vermicolum, while in other in- stances the tubular, contorted segments are reminis- cent of /.. pygmaeum. In sexual reproduction, how- ever, if is like Mysocytium. More recently ('39) Sparrow has pointed out its similarity to L. oophi- Iiiiii which also parasitizes rotifer eggs. The pOSSi' 90 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES bility that it is not identical to the latter species thus remains to be shown. Sparrow ('36, p. 463, fig. 4q) further described an elongate th alius consisting of a linear series of elliptical segments, 20-22 p X 18-20 p., connected by narrow cylindrical, refractive isthmuses in Syne- dra sp., which he believed may likewise relate to Myzocytium. He did not, however, observe any de- velopmental and reproductive stages. In connection with the above report of doubtful Myzocytium species it may be pointed out that Stein ('51, pi. 18, figs. 1-7; '59, pi. 4, figs. 49-55) figured an elongate body in Vorticella microsoma which he believed relates' to the developmental cycle of this animal. At maturity this thallus becomes contorted and lobed and give's rise to bean-shaped spores in a spherical, extramatrical vesicle. The structure and appearance of the sporangia and spores suggest very strongly that they may relate to a species of Myzo- cytium'. He ('59,' pi. i, fig. 9) also showed another vesicle with spores in V. nebulifera which may also possibly belong to a similar parasite. Preissecker ('05, p. 3, fig. 43) figured and briefly described a linear series of oval pale golden cells in the roots of tobacco which he believed might repre- sent a dwarf individual of Myzocytium sp., the larg- est cell of which measures 28 X 37 ^ (fig. 52). Zoo- spores and oospores were not observed. As Preis- secker pointed out, the extremely thick walls of the cells militate against the possibility that this is a species of Myzocytium. It is not improbable that the heterogamous sexual stages which Borzi ('84) included in the life cycle of Rhizomyxa hypogea may relate to a root inhabit- ing species of Myzocytium. This is the viewpoint expressed by Schroeter ('97) and Minden ('11). "More recently Barrett ('35) found similar sexual stages in association with a plasmodiophoraceous species in roots of Stellaria media and likewise con- cluded that they relate to a species of Lagenidiaceae. In view of these observations two of Borzi's figures have been included in plate 22 of Myzocytium. Whether or not the fungus figured by Turner ('92) in Oedogonium sp. relates to Myzocytium or to the Lagenidiaceae is very doubtful. Superficially, it bears some resemblance to the thallus of Myzocy- tium, but the presence of several connecting isth- muses between adjacent segments militates against its inclusion in this genus. LAGENA Vanterpool and Ledingham, 1930. Canad. Jour. Res. 2: 177. (plate 23) Thalli intramatrical, unicellular, coenocytic, soli- tary or numerous, sac-shaped, oval, elongate, tubu- larj lobed and branched; attached to the host cell wall by a short neck the end of which fits into a thickened collar; transformed holocarpically into zoosporangia or gametangia at maturity. Zoospor- angia hyaline, smooth, and of the same shape as the thallus; content emerging at maturity through a short exit tube into an extramatrical vesicle and cleaving into zoospores. Zoospores bean-shaped, iso- cont, flagella inserted in a lateral depression. Male and female thalli fairly equal in size and usually in- distinguishable, hyaline, smooth, oval or slightly elongate; conjugation canal of variable length, de- veloped by the male thallus ; no differentiation of an egg cell and periplasm; multiple fertilization rare. Oospores single or rarely numerous, hyaline, smooth, oval, spherical, thick-walled, simple or compound with one or two large refractive globules ; germina- tion unknown. This monotypic genus has many characteristics in common with Lagenidium, Myzocytium, and Py- thium. The isocont bean-shaped zoospores (fig. 8) have two laterally inserted flagella and the same characteristic method of swimming as in these gen- era, but sexual reproduction is predominantly iso- gamous. In germination the zoospores form an in- fection tube which penetrates the host cell wall (fig. 1 ), and after it has grown into the host cell its tip begins to enlarge and eventually develops into the mature thallus. The extramatrical zoospore case gradually disappears in the meantime, but the intra- matrical portion of the germ tube remains attached to the thallus as a neck in contact with the host wall. A thick collar is formed around its upper end by the host cell wall at maturity, which gives it a character- istic appearance when viewed from above (figs. 2, 11-16). The mature thalli may be comparatively small, oval and oblong as in Olpidium (figs. 1, 2) or greatly elongate, curved, lobed, branched, and hypha-like (fig. 3), as in Lagenidium. A single thallus may com- pletely fill a host cell, or several small ones may be present in one cell. They may develop directly into plate 23 Lagena radicicola (Figs. 3, 17, and 18 drawn from photographs after Tru- scott; other figures after Vanterpool and Leding- ham.) Fig. 1. Stages of infection and development of the thal- lus. Fig. 2. Two mature thalli and an empty sporangium. Fig. 3. An elongate, tubular branched thallus. Fig. 4. Mature sporangium with elongate exit tube. Figs. 5-7. Stages of the emergence of the protoplasm into a vesicle and cleavage into zoospores. Fig. 8. Rupture of vesicle and liberation of the zoospore. Fig. 9. Encysted zoospore. Fig. 10. Empty sporangium and an encysted zoospore on surface of host cell. Figs. 11-15. Stages in oospore development; content of male thallus passing into female thallus. Fig. 16. A free mature oospore. Fig. 17. Multiple fusion; contents of three male thalli passing into one female thallus. Fig. 18. Compound oospore. I.AOKN'IDIACKAK 91 1'LATK J.5 Lagena 92 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES zoosporangia or male and female gametangia. In the former ease a short exit tube grows out from the neck of the thallus (fig. 4), and as the protoplasm begins to move out its tip gradually enlarges into a spherical vesicle into which the entire contents of the thallus emerges (figs. 5-6). Vanterpool and Ledingham regarded this vesicle as the sporangium proper and referred to the thallus which gives rise to it as a presporangium. The emerged mass of pro- toplasm soon begins to cleave progressively into segments (fig. 7), and the whole mass of zoospores shows the same movement and behavior as in Py- thium. Sexual fusion may occur between two or more thalli in the same cell. One of these, which is desig- nated as the male, puts out a conjugation tube of variable length which fuses with a female thallus (figs. 12. 13, 17). If the two are almost in contact the tube may be reduced to a small swelling on the side of the male thallus at the point of contact with the female. The content of the male then passes very slowly into the female thallus (figs. 12, 13), where the combined protoplasts eventually contract and assume an oval or spherical shape (fig. 16). No de- limitation or differentiation of an egg cell and peri- plasm occurs in the female thallus in preparation for fertilization, according to Vanterpool and Leding- ham, but Truscott's ('33) report that several oospores may be formed in one female thallus sug- gests at least that division of the ooplasm may take place. On the other hand, division may possibly oc- cur after fusion lias been completed. A thick wall is eventually formed around the zygote, and after a short while the empty remains of the male and fe- male thalli disintegrate, leaving the oospores free (fig. 16). Occasionally two or more male thalli may fuse with one female (fig. 17). The conjugants are multinucleate, according to Vanterpool and Leding- ham, but nothing is known about the behavior of the gametic nuclei before and during fusion. The formation of oospores may be increased by drying out the soil slightly, and Vanterpool and Ledingham therefore concluded that sex is largely determined by adverse environmental conditions. They described Lagena as dioecious but were uncer- tain whether the zoospores which give rise to male and female thalli respectively come from the same or different zoosporangia. They nonetheless as- sumed that zoospores from sporangia and germi- nated oospores may be of three types: i.e., + and — > — j and _)_, as shown in the diagram below. Vanterpool and Ledingham emphasized the strik- ing similarity of Lagena to reduced species of Py- thium and Lagenidium and regarded it as a possible connecting link between the Lagenidiaceae and Py- thiaceae. L. RADICICOLA Vanterpool and Ledingham, I.e. Pis. 1, 2. Figs. 3-7. Truscott, 1933. Mycologia 25: 263. Figs. 1-11. Thalli 14 X 35 p. or more, exit tubes 4 X 10- 20 p.; zoospores 7X 11/*; oospores 10-25^. (For additional details see generic description above.) Parasitic in roots of Triticum aestivum, T. durum, Hordeum vulgare, Secale cereale, Agropyron repens, Zea mays, and other wild grasses in Ontario and Saskatchewan, Canada. According to Truscott, this species may occur on a number of wild grasses, but Vanterpool and Led- ingham found it to be more limited in host range. Avena sativa, A factua, Agropyron Tenerum, A. spicatum, Bromus biennis, Poa compressa, and Sinapsis arvensis remained immune to attack when grown among infected wheat plants. Lagena radi- cicola causes a root disease which is characterized by stunted, curved roots. The fungus has a predilec- tion for cells in the root tip, and its interference with nuclear and cell division doubtless leads to the shortening and curvature of the roots. In- fected roots have yellowish-brown lesions in the re- gion of infection and the root system as a whole is reduced. No enlargement of cells nor hypertrophy of roots have been observed. The stems of infected plants are considerably shorter than those of normal specimens, while the leaves become pale-green and lighter in color. The thalli described by Truscott from Toronto were more elongate, cylindrical, tubular, and branched than those found by Vanterpool and Led- ingham in Saskatchewan, and it is thus evident that the thallus of L. radicicola may vary markedly in size and shape. Truscott reported and figured com- pound oospores (fig. 18) and found evidence that as many as six oospores may possibly be formed in one female thallus. DOUBTFUL GENERA RESTICULARIA Dangeard, 1891. Le Bot. 2 : 96. (plate 24) Thallus intra- and extramatrical, broadly elon- gate, tubular, vesicular and filamentous; irregular and undulating in contour, constricted at irregular intervals, witli numerous short protuberances and ▼ ! Zoospores — (±) thallus — zoosporangia — zoospores --►Zoospores-^ + > t|™]J"s-00e0»iu,m \-oospore-zoospores ■ -^■/.uobpurii, ^ — ^ thallus — anthendium/ ' LAGENIDIACEAE 98 branches, confined to a single host filament or be coming extramatrical and infecting several algal threads. Zoosporangia no! sharply differentiated (?), content-, emerging as a mass and undergoing cleavage as in Pythium (':). Zoospores oval, later ally biflagellate and isocont. Sexual reproduction imperfectly known: two similar-sized protoplasts of adjacent swellings in the same thallus fusing to form spherical resting spores (oospores, zygo- spores?); germination unknown. This genus was created by Dangeard for a fila- mentous parasite of Lyngbya aestuarii found in France. H<' placed Resticularia in the Lagenidiaceae (Ancylistales) close to Lagenidium and Myzocy- tium. hut his description of its development and life cycle was meager and incomplete. As a result the identity and relationships of this genus have been the subject of much discussion and disagreement among systematists in mycology who are not par- ticularly familiar with the Lagenidiaceae. Saccardo ('91, '12) followed Dangeard's disposition of this genus, but some mycologists (Minden, 11; Fitz- patrick. '80 ) regarded it as a doubtful member of this group, principally because of the observations of Fritsch ('03). Other mycologists (Fischer, '92; Wildeman. '9(>; Schroeter. '97: Fritsch. I.e.) have placed it next to Ancylistes and looked upon it as related to this genus or a transition form between the Lagenidiaceae and Ancylistes. The latter views of course antedate tile discovery that Ancylistes be- longs among the Bntomopthorales and does not re- late to the Lagenidiaceae. Observations on a parasite found in Lyngbya in the laboratories at Columbia suggest that the organ- ism found by Dangeard is a valid member of this family. This view is further supported by the recent discovery of Couch ('41) that the zoospores of Res- ticularia sp. are laterally biflagellate and isocont. However, the question of whether Resticularia should stand as a distinct genus or be merged with Lagenidium or Mysocytium remains to be answered. At present, the author is of the opinion that his fungus and probably Dangeard's R. nodosa relate to species of Lagenidium. Further studies on the method of sexual reproduction are necessary before this point can be settled. The author is further of the opinion that the fungus which Fritsch described as R. nodosa as well as R. Roodlei ill species of Toly- jjnlhri.r do not relate to Resticularia in the sense of Dangeard. They are accordingly listed as doubtful or excluded species. Descriptions and illustrations of them are nevertheless included in plate 24 to make these data available to research students. According to Dangeard, the zoospores are poste- riorly uniflagellate, but it is not improbable that he may have overlooked a second flagellum of the type shown ill figure I. I'Im- lar^e zoos].,, res come to rest on the algal filament and form a broad germ or in- fection tube which penetrates the host cells I hs;. 2 ). The tip of this tube elongates, increases in diameter, and eventually develops into the mature vegetative thallus i figs. 2 5) while the zoospore case remains on the outside. At maturity the thallus may branch Several times, grow out beyond the host, and infect other algal filaments. Whether or not it becomes septate is not obvious from Dangeard's description. The nuclei are rather evenly distributed along the length of the thallus (fig. 7. 8). No sharply differ entiated zoospora ngia were figured by Dangeard, which suggests that elongate segments of the thallus function in this capacity as in filamentous species of Lagenidium. At any rate the sporeplasm emerges through an exit tube ( lig. (i) and undergoes cleav- age into zoospores. Very little is known about sexual reproduction, and no well-defined anthcridia and oogonia have vet been described. According to Dangeard, the proto- plasm in portions of the thallus contracts into two masses in adjacent swellings (fig. 9) which fuse to form oval, ellipsoidal, and spherical resting spores (figs. 10. 11). Inasmuch as the protoplasts as well as the swellings in which they accumulate are usu- ally equal in size, Dangeard referred to the resting spores as zygospores. The type of spore formation shown in figure 9 is suggestive of sexual reproduc- tion in Mysocytium, although intervening septa are lacking. Fischer was of the opinion that if Dan- geard's account of sexual reproduction is correct Resticularia is to be regarded as a forerunner of the Zygomycetes. R. NODOSA Dangeard, I.e. PI. 4, figs. 85-31 ; pi. 5, figs. 3,4, Resting spores usually numerous, oval, ellipsoidal, elongate and spherical, (i-10 fi in diameter, contents coarsely granular with a large refractive globule, wall thick and double-layered. For additional de- tails see generic diagnosis above. Parasitic in Lyngbya aestuarii in France, killing the cells and causing the filaments to turn light yel- low or colorless. Fritsch found a similar looking fungus in Toly- pothrix in England which he took to be the same as Dangeard's species. The endophytic mycelium is comparatively coarse. t-o" /x, irregular, frequently septate, and forms numerous brown, oval, spherical and ellipsoidal, 6—9 /t. thick-walled chlamydospores (figs. 12. 14), while the ectophytic mycelium is much finer, 0.5—1 jjl. more branched, and bears single chlamydospores on short lateral branches (tig. 13). Fritsch believed that the zygospores described by Dangeard are nothing more than chlamydospores, the formation of which does not involve sexual fu- sion. While tin- endophytic mycelium of Fritsch's fungUS resembles the thallus of R. nodosa, it possi bly does not relate to Dangeard's species at all since Fritsch failed to observe zoosporangia or zoospores. Whether the fungUS reported by Sparrow ('32) in filaments of Tolypothrix in Massachusetts relates to R. nodosa or Fritsch's organism is uncertain because neither zoosporangia and zoospores nor sexual re- production Were observed. Resticularia boodlei is apparently further re- moved from Dangeard's species than the two above- 94 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES mentioned fungi. The endophytic mycelium is never- theless irregular, 5-8 ft, with occasional septa (figs. 16-20) as in the previous species, but the ectophytic mycelium, 1.5—5 /x in diameter, is highly branched, septate, and bears numerous thin-walled conidia (12-1.5 /x in diameter) in chains on lateral branches (fig. 15). Zoosporangia, zoospores, resting spores, and chlamydospores are unknown. Whether or not R. Oedoffonii Skvortzow ('25, p. 432, fig. 14) is a valid lagenidiaceous species is uncertain at present. This species parasitizes Oedo- gonium sp. in North Manchuria and is character- ized by a branched, hyaline, fine, 1-17 /x thick endophytic and a sparse ectophytic mycelium. The resting spores are hyaline, smooth-walled, 11.5- 18.5 /x long by 7.4-1 1.1 /x wide, and contain a large refractive globule. Zoosporangia and zoospores have not been observed. shaped and laterally biflagellate Achlyogeton might well be merged with Myzocytium provided both genera are also similar in type of sexual reproduc- tion. The presence of posteriorly uniflagellate zoo- spores with a single refractive globule and the lack of antheridia and oogonia at present militate against this view. Achlyogeton is accordingly excluded from the Lagenidiaceae for the time being. It may be noted here that its thallus resembles that of Septolpidium which is likewise characterized by uniflagellate zoo- spores. The latter, however, do not encyst at the mouth of the exit tube as in Achlyogeton but swim away after a brief pause — a characteristic which precludes close relationship with the latter genus, according to Sparrow ('36). Six years later, how- ever, Sparrow ('42) reversed his opinion about this characteristic and included Achlyogeton with Sep- tolpidium and Bicricium in a new family, the Achlyo- getonaceae, of the Chytridiales. EXCLUDED GENERA ACHLYOGETON Schenk, 1859. Bot. Zeit. 17: 399. Thallus intramatrical, usually elongate and sep- tate, consisting of a chain or linear series of fairly short oval, ellipsoidal, egg- and spindle-shaped seg- ments with truncate ends ; constricted at the septa ; rarely dwarfed and unicellular, holocarpic. Spo- rangia of the same size and shape as the thallus segments or unicellular thalli, with one exit tube of variable length which may or may not be inflated before passing through the host wall, extending a short distance beyond surface of host. Zoospores delimited in the sporangium; diplanetic, emerging singly in succession, and encysting in a loose cluster at the mouth of the exit tube as in A My a; emerg- ing from the individual cysts and swimming away ; posteriorly uniflagellate (?) with a small refractive globule. Resting spores (doubtful) formed asexu- ally (?) by the contraction and encystment of the cell content; germination unknown. The development and structure of the vegetative thallus are so strikingly similar to Myzocytium that it is very difficult to avoid a suspecion that Schenk may have been incorrect about the number, relative lengths and insertion of the flagella on the zoospores. This possibility is further suggested by the fact that he figured the swarmspores of Myzocytium, Lageni- dium, and Pythium as uniflagellate also. Although Martin and Tokunaga saw encysted zoospores, they unfortunately did not determine the number of flagella and thus settle this important question. It is to be noted in this connection that the zoospores of Lagenidium Oedogonii also may encyst in a cluster at the mouth of the exit tube, which shows that such a character is common to the Lagenidiaceae and is in itself no basis for excluding Achlyogeton from this family. Should the zoospores prove to be bean- A. ENTOPHYTUM Schenk, I.e. PI. 13, figs. Al-8. Thallus composed of one to 15 segments. Spo- rangia oval, broadly ellipsoidal and egg-shaped with truncate ends, 15.6-33.6 /x X 9.6-20.4 ti; exit tubes 27-60 /x X 3.6 xi. Primary zoospores elongate as they emerge; cysts spherical, 4/x; secondary swarmers more oval, rounded at the anterior and tapering slightly at the posterior end ; flagellum ap- proximately three times the length of the spore. Resting spores hyaline, smooth, oval and spherical. Parasitic in Cladophora sp. in Germany (Schenk, I.e.) ; Cladophora sp. and Anguillula sp. in Russia plate 24 (Fig. 1 after Couch, '41; figs. 2-11 after Dangeard, '91; figs. 12-20 after Fritsch, '03.) Fig. 1. Laterally biflagellate isocont zoospore of Resti- cwlaria sp.; anterior flagellum with tinsel; posterior flagel- lum with tail piece. R. nodosa Fig. 2. Germination of zoospore and infection of Lxjng- bya filament. Figs. 3, 4. Later developmental stages of thallus. Fig. 5. Coarse irregular branched thallus. Fig. (i. Emerged vesicular mass of protoplasm prior to cleavage; encysted zoospore above. Fig. 7, 8. Distribution of nuclei in thallus. Fig. 9. Plasmogamy of adjacent protoplasts in oospore (zygospore) development. Figs. 10, 11. Young and mature oospores (zygospores). Fig. 12. Mycelium with internal chlamydospore. Fig. 13. Stages in chlamydospore formation. Fig. 14. Mature chlamydospores. R. boodlei Fig. 15. Extramatrical mycelium with spores. Fig. 1G. Young thallus from germinated spore. Figs. 17, 18. Intramatrical mycelium. Fig. 19. Infection of two Tolypothrix filaments. Fig. 20. Thallus with germinated spore and three infec- tion hyphae. I \(.I-NII)IACEAE 90 PLATE 24 Resticularia 96 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHVCOMYCETES (Sorokin, '76, '83, '89); Cladophora sp. in Iowa, U. S. A. (Martin, '27) and Japan (Tokunaga, '31). The thalli which Sorokin ('76) figured in Anguil- lula are somewhat similar to those of Myzocytium, and there is accordingly the possibility that he may have confused this species with M. vermicolum. He is the only one to have reported A. entophytum on hosts outside of Cladophora. He nevertheless re- ported that the zoospores encyst in a cluster at the mouth of the exit tube in the same manner reported by Schenk, although lie did not illustrate them. Tokunaga found resting spores accompanied by a small, spherical, hyaline companion cell which he believed may relate to a species of Olpidiopsis para- sitic in Achlyogeton. Achlyogeton solatium Cornu ('70), parasitic in Oedogonium obsidionale, is imperfectly known, very doubtful, and has never been figured. Its thallus is filamentous, branched, and apparently extends through several host cells. The sporangia are de- limited at irregular intervals along the thallus and form a single exit tube which is seven to eight times the diameter of the host cell in length. Three to twelve zoospores emerge from the sporangia and encyst in a cluster at the mouth of the exit tube, and after a while they emerge leaving the cysts behind as in Achlya. In addition, Cornu, reported the pres- ence of an extremely irregular, cylindrical oogonium with one to several oospores, but he did not observe the character of the antheridium. Fischer ('92) re- garded Cornu's fungus as a species of Pythium, while Minden disregarded it entirely. Achlyogeton rostratum Sorokin ('76) is a doubt- ful species. It parasitizes Anguiliula and consists of chains of short oval segments or sporangia, 5—6 //, X 7—9 fj., with one straight, curved, or tortuous exit tube which becomes markedly inflated before pass- ing through the host wall (figs. 11, 12). Zoospores and resting spores are unknown. Inasmuch as Soro- kin did not observe the zoospores and their behavior, the relation of this species to Achlyogeton is ques- tionable. The thalli shown in his figures are funda- mentally similar to those of Myzocytium and may equally well relate to that genus. The inflation of the exit tube is not a distinctive specific character since Schenk has shown that it may occur in A. ento- phytum also. Achlyogeton salinum Dangeard ('32) which para- sitizes the marine algae Cladophora laetevirens and C. flavaescens in France is likewise too little known to ascertain its identity and validity as a member of this genus. Dangeard observed only developing and mature thalli, including sporangia and quiescent zoospores ; so that nothing is known about the num- ber, relative lengths, and position of the flagella in this species as well as its method of sexual reproduc- tion. The mature thalli (figs. 13, 14) are strikingly similar to those of A. entophytum which parasitizes a fresh-water species of Cladophora. On the other hand, they are also similar to the thalli of Myzocy- tium and may equally well relate to a species of this genus. PROTASCUS Dangeard, 1903. C. R. Acad. Sci. Paris 136: 628. (Not Protascus Wolk, 1913.) (plate 25) Thalli intramatrical, single or numerous, elon- gate, cylindrical, unbranched and unconstricted, straight or curved, and septate; segments separat- ing at maturity and with further growth becoming transformed into sporangia and gametangia. Spo- rangia cylindrical, flask-shaped, uteriform, pyri- form, and slightly irregular, usually with a single curved or straight short tapering exit tube which may end almost flush with the surface of the host cell or extend for a short distance beyond. Spores, non-motile, slightly curved and clavate, forcibly ejected from the sporangia; adhering to the host cell for some time after germination. Gametangia occurring among sporangia, unicellular, holocarpic, unequal in size, formed from the same or different thalli; conjugation usually lateral, sometimes sca- lariform or end to end; both gametangia contribut- ing to the formation of the conjugation canal; con- tents of the larger female and smaller male game- tangia often contracting toward the canal before plasmogamy; no differentiation of an egg cell and periplasm ; protoplast of male flowing into the fe- male gametangium and fusing with the ooplasm. Resting spores rarely parthenogenetic, lying free in the female gametangium, spherical and smooth with a fatty granular content which gives it a blackish, opaque appearance ; germination unknown. In ignorance of its method of sexual reproduction Dangeard placed this genus among the Hemiascales because of its non-motile spores and the manner in which they are ejected from the sporangium. At the same time he called attention to the similarity of its thallus to those of Myzocytium and Lagenidium. In his opinion Protascus may possibly be a transitional genus between the Phycomycetes and higher Asco- mycetes. Since the discovery of its phycomycetous type of sexual reproduction by Maupas, however, Dangeard's views are no longer tenable. Maupas called the resting spores, zygospores, but pointed out the similarity of their method of formation to that of the oospores of Myzocytium. He regarded Pro- tascus as a possible member of Fischer's Merolpidia- ceae, the direction of growth of which has become distinctly oriented by its elongate host. Maire, on the other hand, assigned it to a position between the Lagenidiaceae and what was formerly known as the Ancylistaceae and proposed a new family, Pro- tascaceae, to include it. Fitzpatrick regarded the resting spore as an oospore but was doubtful about the relationship of Protascus with the Lagenidia- ceae. The lack of zoospores sharply delimits this genus from the Lagenidiaceae as the family is now recognized, and it is accordingly excluded. How- ever, inasmuch as it has often been described in re- lation to Lagenidium, Myzocytium, etc., the author I M.I \ mi ICEAE 97 feels thai the following brief description is war- ranted. According to Dangeard and Maupas, tliis para- Bite may occur in great abundance and can be easily cultured in living nematodes lor a long time. The spores are predaceous, retain their vitality for a long time, and up to l"> days they are capable of in- fecting nematodes with which they come in contact. The slender end of the spore apparently is adhe- sive) since it is at this end that it becomes stuck to the nematode as the latter brushes against it. In spite of the squirming and writhing of the host, the spores remain attached in this position and soon germinate. They send a fine, 0.8-0.4 p, germ tube through the cuticle into the nematode (tigs. 5, 6), and as the content of the spore passes into its tip it swells into a globular structure. This elongates in a linear direction and becomes filamentous. The young thallns is first uninucleate (tig. 9) but very shortly the primary nucleus undergoes division. These divi- sions ire simultaneous, so that a large number of mitotic figures in the same stage may be found in the large sporangia (figs. 12, 13). Dangeard was not certain whether division is direct or indirect, but lik figures indicate that it is mitotic. After the thallus has attained its mature length. it divides by transverse walls into two to ten fairly equal segments (fig. 11). These soon separate at the septa, become free, and with further increase in Length and diameter are transformed into either spo- rangia or gametangia. Dangeard' s description and figures suggest that dwarf unicellular thalli may also be formed as in Lagenidium and MysOcytium. The details of cytokinesis and sporogenesis are not well known in spite of Dangeard's description. The incipient sporangia usually possess several small vacuoles which apparently coalesce to form a large central one as they mature (fig. 1.3). and the nuclei lie in the primordial utrical surrounding the vacuole. The spores arc doubtless delimited by progressive cleavage as in other sporangia, and with maturity become clavate and oriented with the thick rounded end directed toward the exit tube (fig. 11). The lat- ter may be straight, curved, or bent at right angles to the surface of the sporangium. As the neck of the sporangium perforates the host wall and deliquesces, the spores are all forcibly ejected at one time or in successive groups from the sporangium (fig. 15). In some respects sexual reproduction is similar to that of MysOcytium and Lagena. Since conjugation is predominantly lateral (fig. 1(3) Maupas believed that most of the male and female gametangia are segments of different thalli. I leterothallism has not, however, been definitely established. End to end or scalariform conjugation may also occur (fig. 18), which suggests that the respective gametangia have arisen from the same thallus. The segments which are to become gametangia do not usually increase much in size, and are frequently elongate and cylin- drical. Since the resting spore develops in the larger of the two gametangia and the content of the smaller is mobile, the two have been designated as male and female respectively, l'.ach sends out a protuberance toward the other as in some species of SpirOgyra and as these come in contact they fuse at the tips. The content of each ganietangium then usually contracts toward this common canal, and as the intervening wall breaks down the male gamete slowly passes over into the female gametangium and fuses with the ooplasm. No differentiation of an egg cell and peri- plasm has so far been observed, but the contraction of germ plasms toward the conjugation tube seems somewhat similar to that described by Zopf in Lagenidium rabenhorstii. Furthermore, conjugation in Protascus is also similar to sexual reproduction in Lagena, with the exception that in the latter genus the gametangia are usually equal in size and indis tinguishable. and the conjugation tube is formed ex- clusively by the male. The zygote soon becomes invested with a thick wall and goes into the resting condition (figs. 17- 20). As noted above. Maupas called it a zygospore, while Fitzpatrick referred to it as an oospore. Since reproduction is to a slight degree heterogamous, and the resting spore lies free in the female gametan- gium, the latter's terminology is perhaps more de- scriptive. The writer is nonetheless using the non- eommital term, resting spore, for the time being, since the relationships of Protascus are still ob- scure. No cytologieal study of sexual reproduction from fixed and stained material has yet been made, and it is not known whether the gametes are uni- or multinucleate at the time of fusion. The presence of the parasite does not hinder the activities of its host and produce any marked patho- logical effects until after two or three days. By this time, however, the nematode gradually loses its ability to contract and move and becomes slow and heavy. Later as paralysis becomes more marked it undergoes tetanic contractions which last for a long time. In the end a final violent contraction occurs which leaves the animal in a stiff, rigid, twisted posi- tion. In a short while it begins to distend and straighten out as death occurs. P. SUBULIFORMIS Dangeard, I.e. 1906. Le Hot. 9: _>.-,<>. Pis, 15-16. /'. auhuKformis vsx. mauposii Maire, 1915. Bull. Sue. Hist. Xat. Afrique Nord. (i: 50. Thallus .5-10 ix X 100-100 (u; sporangia 6-7 /x X 1(1-1 10 ix, irregular ones up to 26-28 /x in diameter; spores 8-200 in a sporangium, 0.6—3 /x X 20-25 p., apparently adhesive at the slender end; gametangia usually slightly smaller than the sporangia; resting spores 15— 30 ju in diameter, wall 1 -2 fx ; thick. (For further details sec the generic analysis above.) Parasitic in nematodes in France (Dangeard. I.e. ) ; Rhabditis trrcs, H. giardi, and R. dolichura in Algiers ( Maupas, '15). Maupas' attempts to infect Cosmarium sp., Clot terium lunula, Cladophora sp., and Stigeoclonium sp. as well as numerous nematodes including Diplo- gatter ttriatut, I), gracilis, Cephaloleut rigidut and 98 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES Rhabditis monohystera with this parasite were un- successful, and his results suggest that P. subuli- formis may have a limited host range. It seems doubtful that Dangeard's species is dif- ferent from Maupas' fungus, as Maire has sug- gested. The predominantly unicellular thalli which he describes and figures relate perhaps to segments of a longer thallus which have separated. MITOCHYTRIDIUM Dangeard, 1911. Bull. Soc. Mycol. France 27: 202. This genus was created for a single intramatrical species, M. ramosum, which parasitizes desmids of the genus Docidium. Dangeard regarded this spe- cies as intermediate between the Chytridiaceae and Ancylistaceae, but Butler ('28) was of the opinion that it should be included in the Cladochytriaceae, close to Catenaria. Couch's ('35) discovery of this species in North Carolina and his confirmation of the presence of rhizoids and posteriorly uniflagel- late zoospores justifies Butler's view, in the author's opinion. RHIZOMYXA Borzi, 188-t. Rhizomyxa, nuovo ficomicete, Mes- sina. This genus has been fully discussed by the pres- ent author in his book on the Plasmodiophorales, } 942. and need not be treated further at this point. See discussion under Myzocytium also. bibliography: lagenidiaceae Atkinson, G. F. 1909. Ann. Mycol. 7: 441. Barrett, J. T. 1935. Phytopath. 25: 898. Berdan, H. B. 1938. Mycologia 30: 396. Bessey, E. A. 1937. Textbook of mycology. Phila. Butler, E. J. 1907. Dent. Agric. India I, no. 5: 1. . 1928. Ann. Bot. 42: 813. Carter, H. J. 1856. Ann. Mag. Nat. Hist. 2nd ser. 17: 101. Cejp, K. 1932. Rozpravy Ces. Akad. 42 cis. 3. 1933, Ibid. 43, cis. 9. 1935, Ibid. 45. Chaudhuri, H. 1931. Arch. Protistk. 75: 472. Cocconi, G. 1894. Mem. R. Acad. Sci. Inst. Bologna 4: 361. Coker, W. H., and V. D. Matthews. 1937. North Amer. Flora 2, pt. 1: 17. Constantineanu, J. C. 1901. Rev. Gen. Bot. 13: 369. Cook, W. R. I. 1928. New Phytol. 27: 243. 1933. Glamoran County Hist. Xat. 1: 213'. Cornu, M.1869. Bull. Soc. Bot. France 16: 222. 1870, Ibid. 17: 297. . 1872. Ann. Sci. Nat. 5th Ser. 15: 21. . 1877. Bull. Soc. Bot. France 24: 266. Couch, J. N. 1935. Jour. Elisha Mitch. Sci. Soc. 51 : 293. . 1941. Amer. Jour. Bot. 28: 704. Dangeard, P. A. 1906. Le Bot. 9: 157, 207. De Bary, A. 1884. Vergleichende Morphologie der Pilze. Deckenbach, C. 1903. Flora 92: 278. Domjan, A. 1935. Folia Cryptog. 2: 31. Fitzpatrick, H. M. 1930. Pbycomycetes. New York. Fritsch, F. E. 1903. Ann. Bot. 17: 649. Gaumann, E. A. 1925. Vergleichende Morphologie der Pilze. Ziirich. and Dodge. 1928. Comparative morphology of fungi. New York. Graff, P. W. 1928. Mycologia 20: 158. Gwynne-Vaughan, H. C. I., and B. Barnes. 1926. The structure and development of fungi. Cambridge. 2nd ed. 1937. Karling, J. S. 1939. Amer. Jour. Bot. 26: 518. . 1941. Mycologia 33: 356. . 1942. The Plasmodiophorales. New York. Lind, J. 1913. Danish fungi as represented in the her- barium of E. Rostrup. Copenhagen. Lohwag, H. 1926. Arch. Protistk. 55: 1. Lotsy, J. P. 1907. Vortr. Bot. Stammengeschichte. Jena. Maire, R. 1915. Bull. Soc. Hist. Nat. Afrique Nord 7: 50. Martin, G. W. 1927. Mycologia 19: 188. Matthews, V. D. 1935. Jour. Elisha Mitch. Sci. Soc. 51: 306. Maupas, E. 1915. Bull. Soc. Hist. Nat. Afrique Nord 7: 34. Maurizio, A. 1895. Jahrb. Nat. Gesell. Graubundens 38: 9. Minden, M. 1911. Krypt'fl. Mark Brandenburg 5:423. Mundkur. B. B. 1938. Fungi of India. Suppl. I. Petersen, H. E. 1910. Mycologia 8: 494. Preissecker, K. 1905. Fach. Mitt. K. K. Gen.— Dir. Osterr. Tabakregie 5:1. Rabenhorst, L. 1864. Flora Europaea III. Ramsbottom, J. 1915. Trans. Brit. Mycol. Soc. 5: 143. Reinsch, P. F. 1878. Jahrb. Wiss. Bot. 11: 283. Saceardo, P. A. 1888. Sylloge Fungorum 7: 277. Ibid. 8: 850. 1891, Ibid 9: 348. 1912, Ibid. 21: 857. Scherffel, A. 1902. Nov. Kozl. I. 1902: 107-111. . 1926. Arch. Protistk. 54: 211, 245, 246. Schroeter, J. 1886. Cohn's Krypt'fl. Schlesiens 3:225. . 1897. Engler und Praiitl. Die Nat. Pflanz'f. I, 1 : 64. Schultz-Danzig, p. 1923. Schr. Siissw. -und Meereskunde 11: 173. PLATE 25 Protascus subuliformU (Figs. 4, 5, 9, 10, 12-14 after Dangeard, '06; figs. 1-3, 7, 8, 11, 15-20 after Maupas, '15.) Figs. 1-4. Spores with refractive adhesive (?) content. Fig. 5. Early infection stage; content of uninucleate spore passing into host. Fig. 6. Later stage; parasite lying in host as an oval globule. Fig. 7. Heavily infected nematode with numerous at- tached spore cases and several thalli within. Fig. 8. Nematode with three elongate thalli. Figs. 9, 10. Uni- and tetranucleate thalli. Fig. 11. Elongate, curved, segmented, vacuolate thallus. Fig. 12. Separation of multinucleate thallus segments and their transformation into sporangia. Fig. 13. Mitosis in a sporangium. Fig. 14. Nematode with numerous sporangia, two of which are about to expel the spores. Fig. 15. Expelled comma-like spores. Fig. 16. Early stages in fusion of thallus segments con- nected by fusion canals. Figs. 17-19. Zygospores. Fig. 20. Nematode with numerous empty sporangia and zygospores. , AOEN IDI ACE A E !)!! PLATE 26 Protascus 100 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES Serbinow, J. 1899. Trav. Soc. Nat. Petrograd 30: 255. Tokunaga, Y. 1934. Trans. Sapporo Nat. Hist. Soc. 13: Skvortzow, B. W. 1925. Arch Protistk. 51: 428. 1927, Ibid. $27. 57 : ~0i- Turner, W. B. 1892. Kongl. Svensk. Veten.— Akad. Hand. Sorokin, N. 1870. Ann. Sci. Nat. 6 ser. 4: 63. 25 5. j Sparrow, F. K. 1932. Mycologia 24: 268, 289. 1933, Ibid. Valkanov, A. 1931. Arch. Protistk. 73: 361. 2.5: 513. 1942, Ibid. 34: 113 Vuillemin, P. 1908. Prog. rei. Bot. 2: 1. Stein, F 1851 Zertschr. W.ss. Zool. 3: 475. Wettstein, R. 1935. Handb. der Svstemat. Bot. 4 ed. Leip- . 18o4. Die Intusionsthiere unci lhre Entwickelungs- geschichte. Leipzig. zig. -. 1859. Der Organismus der Infusionsthiere. Abt. Wildeman, E. de. 1895a. Ann. Soc. Micro. Beige 19: 63. 1-1(55 189 1895b, Ibid. 19: 215. Tavel, F. 1892. Vergleichende Morphologie der Pilze, -. 1896. Bull. Soc. Roy. Bot. Belgique 35: 7. Jena. Thompson, G. E. 1934. Mycologia 26: 118. Wolk, P. C. 1913. Mycol. Centralbl. 3: 153. Zopf, W. 1897. Hedwigia 18: 94. Chapter VII Phylogeny Discussions of phylogeny at any given period of time must obviously be based on existing knowledge and data relative to the group of organisms in ques- tion. Relationships which thus seem obvious at pres- ent may be completely invalidated by future studies and discoveries. Therefore, very few definite conclu- sions can be drawn at present about the origin and evolution of these holocarpic, biflagellate Phyeomy- cetes as a whole because so little is known about the critical developmental stages of many of the genera and species. The present discussion will accordingly be confined to pointing out similarities and differ- ences between these fungi, the lower organisms and higher fungi witli which they appear to be related. Since it is not certain that all of the families de- scribed in the previous chapters constitute a natural phylogenetic series of closely related species, dif- ferences in origin and relationship are to be ex- pected. As has been briefly noted before, these rela- tionships involve principally the Proteomyxa or Monadineae, Plasmodiophorales, Saprolegniales, and Peronosporales and are based on similarities or differences in thallus structure, type of development, relative lengths and position of flagella, diplanetism, presence of cellulose in the cell walls, and type of sexual reproduction. Present day evidence suggests very strongly that most of these holobiflagellomy- eetes are either remotely or closely related to the higher Phycomycetes. However, it is not clearly evident whether they are primitive or reduced and degenerate, and many of the controversies on phylog- eny in the past have centered on these questions. While the views of the early mycologists in this re- spect do not relate to groups as specific as those included in these so-called holobiflagellomycetes, they nonetheless apply here in a general sense. DeBary ('81, '84), Tavel ('92), Gaumann ('26), Gaumann and Dodge ('28), Mez ('29), Wettstein ('35) among others regarded most of the biflagellate species as reduced and degenerate oomycetous fungi resulting from their assumption of a parasitic mode of life. On the other hand, Dangeard ('86, '06), Lotsy ('07), Vuillemin ('08), Atkinson ('09), Cavers ('15), Scherffel ('25), Fitzpatrick ('30), Cook ('28), Bessey ('42), and others believed that they are primitive and represent an ascending evo- lutionary line. Lotsy and Bessey suggested that they may have been derived from the Isocontae and unicellular Heterokontae, respectively. Atkinson did not attach much significance to the number of flagella and derived them from the Chytridiales. Dangeard, Cavers, Scherffel, and Cook, however, believed that together with the Chytridiales they originated from the zoosporic Monadineae or Proteomyxa. The evidence bearing on the origin and relation- ships of these holobiflagellomycetes will now be con- sidered in greater detail. The provisional family, Woroninaeeae, interpreted as a convenient dumping ground or a heterogeneous collection of genera which are quite probably unrelated, appears to be the most primitive and stands somewhat apart from the other families because its vegetative thallus is reported to be plasmodial in structure and mode of nutrition. As noted before, in IVoronina the plasmodium cleaves into segments which are transformed directly into zoosporangia or resting spores. These struc- tures may be united into compact sporangio- and cystosori, respectively, in TV. polycystis, while in W. glomerata they lie comparatively loose and free. The striking similarity in type of development of these species to that of the Plasmodiophorales is obvious. Zopf ('94), Maire and Tison ('11), and Winge (13) and others early recognized this simi- larity and stressed the relationship of W. polycystis to Ligniera and other genera of the Plasmodio- phoraceae. This relationship was further empha- sized by Ledingham's ('33, '39) and Couch's ('39) discoveries of Polymyxa and Octomyxa, respective- ly. The latter genus, particularly, is almost identical in life cycle to W. polycystis, as was stressed by the present writer ('42) in his book on the Plasmodio- phorales. Sparrow ('42) included Woronina in the latter order and discarded the family name Woroni- naeeae altogether. As has been stated already, future studies may possibly prove that W. polycystis is a species of the Plasmodiophorales, but so far as is now known, it differs in several respects from the valid members of this order. In the first place, it is not definitely known whether the zoospores are iso- or heterocont and whether the flagella are lateral or I'llYI.DI.I N 1 101 anterior in position. Secondly, schizogony of the Plasmodium has not been reported in "'. polycystic, anil nothing is known about the types of nuclear divisions in the vegetative and sporogeneous thalli. Schiaogony and the occurrence of "promitosis" are claimed to be outstanding characteristics of the Plasmodiophorales. Thirdly, the sporangia and rest i nii spores of W. polycystic give a positive cellulose reaction when tested with chloro-iodide of sine, while those of tile Plasmodiophorales do not. Fur- thermore, in germination the content of the zoospore • liters the host directly through a penetration tube, leaving the empty spore ease on the outside of the host cell as in Olpidiopsis, RoBellopsis and other similar genera. In the Plasmodiophorales. on the other hand, the zoospores are reported to enter the host directly as a naked amoeboid body. How sig- nificant these minor differences are in phylogeny and whether or not they outweigh the similarities in thallus structure and type of development remains to be seen from future studies. Nevertheless, the presence or absence of cellulose is regarded as fun- damentally significant by many students of phylog- eny and evolution. Jf'oronina glomerata differs from the previous species in several ways. Instead of forming hut one zoospore in germination as in W. polycystic and the plasniodiophoraceous species, the resting spore functions as a sporangium and pro- duces a large number of zoospores. Furthermore, the Plasmodium is animal-like in mode of nutrition. according to Zopf ('91) and Scherffel ('25). and engulfs plastids. starch grains, and other solid bodies. This material is digested in well-defined food vacuoles, and the extraneous waste material is dis- carded to the outside in preparation for sporogene- sis. This type of feeding and digestion is character- istic of the Proteomyxa. and for this reason Zopf and Scherffel relegated W, glomerata to the zoo- spore group of the Myxozoidia or Proteomyxa. Thus, within the same genus, as Woronina is now interpreted, occur species with seemingly diverse relationships. However, these differences of rela- tionship may not prove to he as significant as they now appear, because evidence is accumulating which suggests that certain species of tin- Proteomyxa, Plasmodiophorales. and Woronina may possibly be closely related. Turning to the other two genera. Pyrrhosorus and Rozellopsis, which are temporarily included in tin- Woroninaceae. it becomes evident that the rela- tionships are not well defined. Zoosporangia and resting spores apparently do not occur in Pyrrho- SOmS. Instead, the plasiuodium cleaves into spore mother cells which unite into a sorus and later undergo three divisions, forming eight free spores. The- latter are transformed directly into birlagellate- isocont zoospores. Despite these- differences the presence of a plasmodium and sorus suggests some degree of relation to or parallelism in development with the Plasmodiophorales. .1 ml I '01) was uncer- tain of the relationship of Pyrrhosorus, but he em- phasized the striking similarity of its method of spore development to that of Tetramyxa. As tin writer ("1-2) has already pointed out. had Octo myxa been known at that time, duel would doubt less have emphasized the relationship of his fungus with the Plasmodiophorales even more strongly, Winge ('IS) also regarded it as clo8ely related to the- Plasmodiophoraceae and made extensive com- parisons between its life cycle and that of Sorolpi (Hum. He considered the- sporangiosori of the latter genus as homologous with the sori of spore- mother cells of Pyrrhosorus and believed that the absence of walls around the spore mother cells is of minor significance. Cook ('33). on the other hand, be lieved that the relation of this genus to the Plasmo diophorales is very questionable. The origin and relationships of the provisional genus Rozellopsis are even more obscure. Compact or loose sporangio- and cystosori are unknown, and the only significant characters which it has in com- mon with the two previous genera are its plasmo- dium-like vegetative thallus. which may or may not undergo schizogony or division, and birlagellate zoospores. Since- the presence of a plasmodium has not been conclusively demonstrated in this genus, the inclusion of Rosellopsis in the same family with Jl oronina and Pyrrhosorus becomes even more ques- tionable. However, the anteriorly biflagellate hetero cont zoospores of R. simulans, according to Tokuna- ga's ('33) drawings, are strikingly similar to those of the Plasmodiophorales, but in infecting the host they behave like those of II'. polycystis, Olpidiopsis, Ectrogella, etc. Instead of entering the host direct lv. they form an infection tube through which their content passes into the host cells. On the other hand, the structure and development of the thallus and resting spores in the aseptigenous and septigenous species are identical to those of the mono- and poly- sporangiate species, respectively, of the chytrid genus. Rosella and Pringsheimella dioica, as far as is now known. Whether this indicates merely a parallelism in development from different ancestors or direct relationship is not certain. According to Bessey's ('42) theory of origin through the reten- tion or loss of the- second flagelluin. Rozellopsis is more primitive than Rozella and Pringsheimella and may have given rise to these genera by the loss of one flagellum. While this theory se-ems plausible, it is obvious that the loss of one flagellum, without change in position of the remaining one. from the zoospore of Rozellopsis would not lead directly to the distinctly posteriorly uniflagellate zoospore of Rozella and Pringsheimella, since- both flagella in Rozellopsis are reported to be either late-ral e>r anterior in position. Loss of one flagellum in R. siinu- lans, for instance-, would make the zoospore ante- riorly uniflagellate-. The- other four families to be- considered, namely, the- Kctrogellaceae. Olpidiopsidaceae, Sirolpidia ceae, and Lagenidiaceae, appear t < > be more- closely related as a whole- and constitute- an aseiniling or descending line-, depending on which viewpoint one holds. The- principal genera of these- families e-on 102 THE SIMPLE HOLOCARPIC BIFLAOELLATE PHYCOMYCETES SAPROLEGNIINEEN-PERONOSPORINEENSERIES ZOOSPORES BlClUATE, DlPLANETK OOSPORES TYFKALLY DEVELOPED IN OOGONIA CELLULOSE TYPICAL. SAPROLEGNIINEAE CENTRAL SAP WCUOLE ZOOSPORES FORMED BY AGGREGATION AT 7>€ PERPHZRY GERM- IWWN IN TUBE OR SPORAN&JA SELDOM CON/QIA LACK'VJ y PYTHUM-PERONOSPORINEAE FIRST S*ARM STAGE I ACXM fcuPPRESSEC) PYTHUM-TYPE AMD DIRECT DEVELOPMENT OF SECONDARY SmRMERS PREDOMINATING TUBE GERMNATIQN ABUNDANT CONIDiA FERTILIZATION OO- GONIUM WITH ONE EGG PERPLASM SAPROLEGNIACEAE FIRST SWARM STAGE PRESET OR REDUCED ACHWA-TYPE PREDOMINATING PARTHENO- GENESIS ABUNDANT OOGON- IUM USUALLY WITH SEVERAL EGGS NO PERPLASM LEPTOMITACEAE THALLUS CONSTRICTED EIRS T SWARM STAGE OF- TEN COMPLE TEL Y SUP • PRESSED AND THE SEC- ONDARY StWPMERS AL- READY FORMED IN THE SPORANGrVM FERTIL- IZATION TYPICAL OO- GOMUM WITH ONE EGG PERIPLASM. APHANOMYCOPSIS ZOOSPORES DiPLANETlC ACH.YA-TYPE SEV- ERAL ASEXUALLY FORMED RESTING SPORES OF THE SAPROLEGN'ACEaE ■ T YPE IN A RUDIMENTARY OO - GONIUM. I ECTROGELLA - CENTRAL SAP CAVITY ZOOSPORES FORMED BY AG- OREOATCN ATT>£ PERpfCPY SEVERAL EATT CAN - ALS ZOOSPORES OPLANETlC(ENCYSTNli WITH TWO I QUA RESTNS SPORES SLIGJAUT FQRMCD NC L1Q&GRHORAE AMYLOPHAGUS SAP VACUOLES DISTRIBUTED FOOD VACUOLES PASSING OVER INTO Tf€ ZOOSPORE RUDIMENTS ZOOSPORES WITH T*0 UNEQUAL CHJA. ONE RESTING SPORE PER CYST , PROTOMONAS A*vfrLl \ FORMING A PLASMODIA* PSEUDOSPOROPS/S ZOOPORES WITH Z UNEQUAL OLIA PYTHIOGETON NO OOSPHERE NO PERPLASM I ANCYUST/NEAE PYTHIUM-TYPE PREDOMINANT FERTILIZAT- ION TYPICAL NO PREFORMED OOSPHERE NO PERIPLASM OLPtDIOPSlS OEDOCONiORUM PYTHIUM-AND ACHLYA-TYPE OOSPORE NOT FILUNG OOGOnVM NO PERIPLASM I OLPfOOPSG h SC&NKIANA AS THE TYpty ■ CENTRAL SAP VACUOLE ZOOSPORES BIOUATE, DiPLANETlC WITHOUT ENCYSTHG, DIRECTLY trans- formed AN OOSPORE SEXUALLY FORMED MONOBLEPHARIDINEAE boOSPOPES UNICILIATE NO CELLULOSE OOSPOPE \DEVELOPEO IN AN OOGONIUM SPEPMATOZOCS MONOBLEPHAROACCAE MONOBLEPHARIS GOHAPODrA CHYTRDINEEN-SERIES UNICIL1ATE, ZOOSPORE MONOPLANETIC CELLULOSE LACKING OR EXCEPTIONAL AfC7>€N minimal ChfYTRID/ACEAE NO CENTRAL SAP VACUOLE ZOOSPORES POSTE- RIORLY UNIOUATE MOTION GLIDING AND DARTING RESTING SPORES BORNE FREE, SEYUALLY OR ASEY- UALLr DEVELOPED. GERMINATING TO FORM ZOO- SPORES BLAST OCLAUNAE ZOOSPORES POSTERIORLY UNIOUATE SHGLE RESTING cell formed free IN .. AN ^CONSPICUOUS OOGONIUM GERMI- NATING TO FORM ZOOSPORES NO CELLULOSE BLASTUUDUvf CENTRAL SAP MCUOLE OUT OL 'UM SPHAER/TA, CLPlDlUM POOOPROCTA (ECT08ELLA) PLATEAU// NO RECEPTION OF FORMED FOODS [i) EYTRANEOUS FOOD RESIDUE PRESENT' ZOOSPORES with TWO EQUAL CHJA PSEUDOSPORA LEPTODERMA CENTRAL SaPCaviTY ZOEtSPORES FORMED BY AG- GREGATION AT Tf€ PER/PMJ- y TMO SHWPhASES BARBETA PSEUDOSPORA f UWSTWTit HARTOG ZOOSPORES WfTH TWO EQUAL QUA C tNTRAL SAP CAVITY ZOOS- - PORES FORMED BYAXR EGAT/OH AT Tf£ PERlPlCPY ECTOBELLA BAMBEKII / NO EYTRUSON OF FORMED MJTFfliONAL RES- CUE ZOOSPORES UWOLMTE RESTING SPORES OF P€ QVTROiACEEN-TrPE PSELCOSPORA tvfYZOCYTODES ^ ZOOSPORES IN CYSTS RESTING SPORES^- * <* PSEUDOSPORA (PS PARASiTCA AS TYPE) WORON1NA GLOMERATA^ _APHELILaOPS!S_ zoospores bicil1ate GYMNOCOCCUS CLADOPHORAE _ AMOEBOAP HEL!DIUM_ ZOOSPORES WITH vUT CILIA APHELIDIUM -GROUP ZOOSPORES POSTEPOPLT UHCA.IATE AMOEBOID NAKED PROTOPLAST M/TPITION ANTMAL-LIXE ZOOSPORES AND RESTING SPORES NOT EOPUTD IN CrSTS Diagram 1. Showing the origin of the Pliycomycetes from the zoosporic Monadineae or Proteomyxa. After Scherffel, '25. stitute the basis and starting point of what Scherffel n('25) earlier named the Saprolegniales-Perono- sporales series of Oomycetes, as is shown in dia- gram 1. In his opinion, this series has four outstand- ing characters which distinguish it from the Chytri- diales on one hand and the Monoblepharidiales- Blastocladiales series on the other. These characters are : ( 1 ) biflagellate diplanetic zoospores which lack a large conspicuous refringent globule; (2) grayish granular appearing protoplasm and the presence in the zoosporangium and oogonium of a large central sap cavity or vacuole surrounded by a relatively thin parietal laver of protoplasm, and the occurrence of simultaneous centrifugal cleavage (ballung) ; (3) lack of motile male cells or spermatozoids and the production of sexual or asexual oospores in oogonia, and ( t) the presence of cellulose in the cell walls. Scherffel believed that these characters in- dicate close affinity within the series and that these fungi constitute an ascending evolutionary line ori- ginating in the zoosporic Monadineae and culminat- ing in the Peronosporales. Although Scherffel pre- sented more specific and pertinent data in support of this view, his theory is fundamentally the same as that proposed by Dangeard in 188(i and 190(5. Mez, on the other hand, concluded from his serum diagnosis method of determining affinities that the origin and relationships of the holobiflagellomycetes are otherwise. He believed that the Saprolegniales originated from the Siphonales near Vaucheria and by reduction gave rise to the Lagenidiaceae, from which in turn was derived the Woroninaceae (in the broad sense of Minden) by further reduction. How- ever, his belief concerning the two last named fami- lies was not based on experimental data, because of the difficulty of obtaining sufficient material for serum analysis. Mez's view is accordingly scarcely more than a revival of the reduction hypothesis of DeBary, Tavel, and other workers. More recently Bessey has suggested that the Olpidiopsidaceae (in- terpreted as including all of the biflagellate species except the Lagenidiaceae) as well as the Chytridi- ales have evolved from unicellular heterocont algae through the loss of chlorophyll and the assumption of a parasitic mode of life. As is shown in diagram 2, his theory of origin and relationships of the Pliy- comycetes is based primarily on whether the second flagellum is retained or lost in evolution — the Olpi- diopsidaceae and Lagenidiaceae being derived from those ancestors which have retained both flagella. If we examine closely the data on phylogeny in these four families we find, however, that they are very incomplete and not so convincing as the above- mentioned workers would have us believe. Beginning with the Rctrogellaceae, for instance, it is obvious PHYLOOENY Kl.-i that the four genera and approximately nine species which comprise this family ••ire too poorly known to warrant definite conclusions for the present. As has been pointed oui earlier, the- type genus Ectrogella was formerly included in the chytrid family. Olpidia- ceae, by Fischer ('92), Schroeter ('97), Petersen (*05), Minden ('1 1 ). Gwynne-Vaughan and Barnes ('26, '87), Fitspatrick ('80), and others, although Zopf ( '8 t) emphasised its similarities to the Lageni- diaceae (Ancy lis teen). Scherffel's ('25) discovery that the zoospores are bifiagellate and diplanetic necessitated the removal of this genus from the chy- trids. and he accordingly made it the basis of a new family. The shape and size of the thallus offer no definite suggestions about to the origin of the Bctrogellaceae because it may he oval, spherical, ellipsoid, or elon- gate, as in many of the other families. Nevertheless. the grayish granular appearance of the protoplasm. the presence in mature sporangia of a large central vacuole surrounded by a parietal layer of proto- plasm, the method of cleavage or zoospore delimit.! tion (ball inifi ). and the subsequent occurrence of the homogeneous stage following cleavage indicate di- rect relationship with the Saprolegniaceae, accord- ing to Schcrffel. While such characters alone are not always indicative of close affinity, they are supported in this case by the diplanetic behavior of the zoo- spores. As Schcrffel has shown in Ectrogella, the primary swanners are usually apically bifiagellate and isocont and swim directly away for a brief period before encysting as in Saprolegnia, or they may be atlagcllate. glide out. and encyst in a cluster at the mouth of the exit tube as in Achlya. The sec- ondary swanners in Ectrogella are lemon-shaped and pvriform. usually with a ventral groove, later- ally bifiagellate and heterocont with the shorter and more active flagelbun extending forward in swim- ming. In the genus Eurychasma the primary swarm- era may encyst around the inner periphery of the sporangium as in Dicti/itchtis, but the secondary zoospores do not emerge through individual pores in the sporangium wall as in the latter genus. In- stead, they emerge from the cysts into the central portion of the sporangium and then swim out through the exit tube. In Eurychasmidium and Aphanomycopsis the primary zoospores are reported to behave like those of Achlya and Aphanomyces. Secondary zoospores, however, have not been ob- served in Eurychasmidium. Thus, in the family Bctrogellaceae the zoospores may exhibit striking similarities in behavior and structure to those of Saprolegnia, Achlya, Aphano- myces and Dictyuchut. Furthermore, in Ectrogella, Aphanomycopsis, and Eurychasma may be found the same degree of reduction of the primary swarm- ing period as occurs from Saprolegnia through Achlya and Aphanomyces to Dictyuchus. Whether, on these grounds, the members of the Bctrogellaceae an- to be considered primitive- or reduced and degen- erate aaprolegniaceoua species is not clearly evident. Mycologists who adhere to the reduction hypothesis MONOItt'HAtlOlACIAl IIAUOCIAOIACIAE RHIZIOIACtAI StNCMTTIIACIAE OlUDIACtAl INIOMO'HTKORAtU lAflOIIGNIACIAt IIPtOMITACIAI rl«ONO.PU«ALlAt ClADOCNVUIACIAt HT*HOCkTTRIAC(AE 'AIIEKiNACIAt 'YTHIACIAI lAGfNIDIACIAI OlPl0lO.',lDAt[A( »o.'.'-o> riogrllum HCIEROCONT UNICEIIULA* AIOAE Diagram 2. Phytogeny of the Phycomycetes based upon the theory of their origin from unicellular algae. After Bessey 19i2. may well argue that the thallus of this family has undergone reduction while the zoospores have re- tained their diplanetic behavior. Schcrffel. however, regarded them as primitive and held that the type of diplanetism exhibited is derived from the Proteo myxa or Monadineae instead of the Saprolegniales. In line with his belief that the Phycomycetes in gen- eral are derived from the Monadineae as shown in diagram 1, he accordingly concluded that Ectrogella and Aphanomycopsis may have originated from bi- fiagellate heterocont genera similar to Aphelidiop sis. Pseudosporopsis, and Amylophagus and possi hi v inherited their diplanetic habit from an ancestor like Pseudospora leptoderma. He also believed that the large central sap cavity or vacuole present in zoosporangia is a relic of a proteomyxean ancestor. On the basis of the type of sexual reproduction Schcrffel further believed that Ectrogella may be connected on one hand with the Saprolegniaceae anil Leptomitaceae through Aphanomycopsis and on the other hand with the Peronosporaceae through Olpi- diopsis, the Lagenidiaceae, and Pythiogeton. How ever, as has been emphasized before, the occurrence of sexual reproduction in the Bctrogellaceae lias not been conclusively proven. Resting spores are known in only three species. In E. per farcins they appear to be nothing more than vegetative thalli which have encysted and developed thick walls. Scherffel regarded the resting spore of /•.'. Licmn- phorae as an oospore in a rudimentary oogonium. although he did not actually observe sexual fusion. As the- present author has already peiinteel out. this resting spe,r>- may pe.ssibly be- nothing more than the 101 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES contracted and encysted content of an irregular, lobed thallus. In Aphanomycopsis bacillariacearum one or more asexual resting spores are formed in a thallus or a segment thereof, and Scherffel accepted this as an indication of eYen closer relation to the Saprolegniaceae. Obviously much more study on the occurrence of sexuality in this family is essential before this character can be used as a basis of com- paring relationships. Nevertheless, Scherffel's be- lief that there is a close affinity between the Ectro- gellaceae and the Saprolegniaceae has been rather widely accepted, although subsequent workers have not been certain about whether the former family represents an ascending or descending series in the evolution of the Phycomyeetes. Gaumann ('26), Gaumaim and Dodge ('28) included Eurychasma and Ectrogella in the Ancylistaceae (Lagenidia- ceae) and emphasized their close relationship to Lagenidium, Myzocytium, and the Saprolegniaceae. Sparrow ('33. '36) included Ectrogella and Apha- nomycopsis in the Saprolegniales without commit- ting them to any particular family, but in 1912 he placed them in the Ectrogellaceae and made this family the first and most primitive of the Sapro- legniales. Coker and Matthews ('37) also included the Ectrogellaceae in this order next to the Sapro- legniaceae. Very little can be said about the origin and rela- tionships of the Sirolpidiaceae at present, because this family is even less known than the Ectrogel- laceae. It has no particularly outstanding family characteristics which relate it distinctly to any of the other groups. The genera Sirolpidium and Pontisma were formerly included by Petersen ('05) ,in the Holochytriaceae of the Mycochytridiales, although he had discovered that the zoospores of the type species, S. Bryopsidis, are biflagellate and not chytrid-like. His findings were confirmed by Sparrow ('34. '36) who later ('12) proposed the family Sirolpidiaceae for these genera and placed it in the Lagenidiales between the Olpidiopsidaceae and Lagenidiaceae. Whether or not present-day knowledge warrants this position is obviously open to question, but the nature of the vegetative thallus of the Sirolpidiaceae nevertheless suggests such a relationship. The thallus has a tendency to become elongate, filamentous, and somewhat mycelioid and may fragment into sections like those of some species of Lagenidium and Myzocytium. On the other hand, the thallus may sometimes be unicellular and olpi- dioid like those of the Olpidiopsidaceae. These like- nesses are also correlated with similarities in the general appearance of the protoplasm, the presence of a large central vacuole bounded by a parietal layer of protoplasm in the mature zoosporangium before cleavage, and the method of cleavage. Size, shape. and structure of the thallus. however, are vegetative characters which vary markedly and by themselves are not always significant phylogenetically, so that too much emphasis must not be placed on them. So far as is now known the zoospores are not diplanetic. and in this respect do not show affinity with the Ectrogellaceae or the diplanetic members of the Lagenidiaceae. According to Sparrow ('31), the zoospores of S. lagenidioides are strikingly simi- lar in behavior and appearance to those of Rozellop- sis inflata, while in Petersenia lobata the late cleav- age and early zoospore stages resemble those of Pythium. Thus, aside from their arched, pyriform or slightly reinform shape and the presence of two flagella the zoospores offer few clews to the rela- tionship of the Sirolpidiaceae. Comparisons on the basis of type of sexual reproduction cannot be made because nothing is known about sexuality in this family. Resting spores are unknown in most species, and in those for which they have been reported they appear to be nothing more than vegetative tlialli which have encysted and become thick-walled. Most species of the family Olpidiopsidaceae are fully known as to life cycles and development, and the indications of relationship are accordingly more clearly defined. In thallus structure and appearance all species show a striking parallelism to the olpi- diaceous chytrids, and for this reason they were first included in the Olpidiaceae and later in the Pseudolpidiaceae and Woroninaceae by most my- cologists and designated as biflagellate chytrids. This close resemblance in vegetative structure is probably due to convergent evolution and may not be indicative of affinity. Sharply defined diplanetism does not occur in this family except in Olpidiopsis Oedogoniorum and Pythiella vernalis — two species which possibly do not belong in the Olpidiopsida- ceae. In most species of Olpidiopsis, however, the zoospores may come to rest, retract their flagella, become amoeboid, and then remain quiescent for a while, but they do not encyst. After a short while flagella are formed again, and the zoospores resume their motility. The insertion and position of the flagella appear to be the same during both motile periods. Butler ('07) compared this interruption of motility to diplanetism in the Saprolegniaceae. and later Scherffel ('25) described it as diplanetism without encystment. Whether or not the behavior of these zoospores is to be regarded as evidence of primitive and rudimentary diplanetism which fore- shadows the development of true diplanetism in the Ectrogellaceae, Lagenidiaceae, and Saprolegniaceae is, of course, a debatable question. In O. Oedogonio- rum, as noted before, true diplanetism has been re- ported by Scherffel, but the primary swarming pe- riod may be reduced to nothing more than the emer- gence of the zoospores and a slight beating of the flagella. Occasionally the entire content of the spo- rangium may emerge as a protoplasmic mass and then undergo cleavage into zoospores on the outside as in Lagenidium and Pythium. A similar behavior was occasionally noted by Coker ('23) in 0. Sapro- legniae. In P. vernalis the primary swarmers are aflagellate and merely glide out of the exit tube, near the mouth of which they encyst. The behavior of the zoospores in these three species ranges from that of imi\ LOOENY 10o Achlfia to Lagenidium and Pythium. As noted be- fore, however, 0. Oedogoniorum may possibly be a species of Lagenidium while /'. vernalis may relate to another family. In these events, the occurrence of true diplanetism in the Olpidiopsidaceae remains to be conclusively demonstrated. So far nothing is known of it> occurrence in Pseudosphaerita and BUutulidiopsis. The Bagella of Olpidiopsis, particu- larly of 0. Saprolegniae, are structurally similar to those of the Lagenidiaceae, Saprolegniales and Peronosporales, according to Couch ('41). One of the fiagella bears hairs or tinsels, while the other is of the whip lash type. Except for Pseudosphaerita, which is a doubtful member of this family, tin- appearance of the vacuo- late protoplasm and the method of zoosporogenesis of most species are very similar to those of the re- timed members of the Lagenidiaceae, and unless the type of sexual reproduction is observed it is diffi- cult and almost impossible to tell the species apart. On these grounds then the Olpidiopsidaceae and Lagenidiaceae appear to he directly related. To many mycologists the type of sexual repro- duction exhibited by the Olpidiopsidaceae is primi- tive and indicates an even closer relationship to the Lagenidiaceae. In Olpidiopsis the degree of sexuali- ty varies considerably in the same and in different species, .and sex does not appear to be well estab- lished for the genus as a whole. The resting spores i oospores? | in sonic species are entirely asexual or parthenogenetic and appear to be nothing more than encysted, thick-walled vegetative tballi. while in other species. (). Achlyae, for example. 75 per cent of them may be parthenogenetic and the remainder zygotic. At the other extreme are species in which the spores are 100 per cent zygotic. Further evi- dence of variability in degree of sexuality is shown by some partially parthenogenetic species in which only a portion of the male gamete fuses with the female. Also, one male gamete may occasionally "serve" two females, or one female may be fertilized by two to eight male gametes. Furthermore, except for size differences, the gametes are not markedly differentiated as such. Structurally, they do not ap- pear to In- very different from ordinary vegetative thalli or sporangia and are morphologically equiva- lent to these structures. The male thallus is usually smaller than the female, but occasionally the two are equal in size. Sexual reproduction in the Olpi- diopsidaceae is. nevertheless, predominantly hetcrn- gamous. However, no egg cell or oospore is differ- entiated in tin- so-called oogonium in preparation for fusion, and except for the questionable species. (). Oedogoniorum, the oospore completely rills the thallus in which it develops. The type of undiffer- entiated gametes together with the great variability in degree of sexual expression in Olpidiopsis suggest very strongly that this genus and other members of the Olpidiopsidaceae are primitive, but on tin- other hand they may equally well indicate reduction .iiiil degeneration. Nonetheless, Barrett. Cavers, Scherf- felj Cook, and others regarded Olpidiopsis as primi- tive. Cavers and Cook derived it from tin Olpidia- ceae in the Chytridiales. but Schertl'el believed that it originated from an /•'.ctrot/clla-Mkv ancestor (dia- gram 1 ). He reg.arded <). Schrukiana as representa- tive of the genus as a whole, and from such species evolution proceeded along the line of (). Oedogonio- rum to the Ancylistineae ( Lagenidiaceae). The lasl named species, according to him. is very significant phylogenetically, since the oospore lies free in a vesicle or rudimentary oogonium and is difficult to distinguish from species of Lagenidium, particularly L. Oedogonii. In Pythiella vernalis sexual repro duction resembles that of 0. schcnkiana but differs from that of Olpidiopsis in general and the Lageni- diaceae by the partial differentiation of an egg cell in the oogonium and the presence of a small amount of periplasm. By these characters P. vernalis resembles species of Pythium with which it may possibly be closely related. Scherffel's interpreta- tion of the relationships of Olpidiopsis and related genera has been followed very closely by Sparrow ('42) and Bessey ('42). Sparrow, as noted before, included the Olpidiopsidaceae in the I.agenidiales. The Lagenidiaceae is the most complex group of the holobifiagellomycetes and is generally regarded as the climax family. Due largely to the fact that many of the species are incompletely known, tliis family has undergone the usual vicissitudes of classi- fication and in mycological literature may be found in various relations to the Archimycetes and higher Oomycetes. The similarities of Myzocytium and Lagenidium to reduced specimens of Pythium were so striking that Schenk ('59). Pringsheim ('58). and W'alz ('70) at first included the type species of these genera in Pythium. Since that time a great many mycologists have recognized this close resem- blance to the Pythiaceae and included the Lageni- diaceae among the higher Oomycetes, but as in the case of the other families previously discussed these workers were not in agreement whether this family represents an ascending or degenerating line. The viewpoints of many workers were influenced by the generally held belief that Ancylistes and other simi- lar non-ZOOSporiC genera, were closely related to the Lagenidiaceae. Had they known that Ancylistes and probably other genera also are members of the En- tomophthorales, their interpretations would doubt- less have been different. The fact that their view- points provided for Ancylistis must be borne in mind relative to anv criticisms which arc made below. De Bary ('84), Schroeter ('80). Tavel ('92), Butler ('07), Clements ('09), Scherffel ('25), Clements and Shear ('31), Wettstein ('85), Spar- row ('86, '42), and others included the Lagenidia- ceae (Ancylistaceae) among tin- Oomycetes in close relation to the Pythiaceae and I'eronosporaeeae. but Bessey ('37) and Coker and Matthews ('87) regarded it as a family of the Saprolegniales. Gaumann ('25) and Gaumann and Dodge ('28) also included the Lagenidiaceae in the Oomycetes but discussed it as a family between the Blasto- cladiaceae and Saprolegniaceae. De Bary and Tavel 106 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES were of the opinion that it embraces only reduced and degenerate species which have arisen as the re- sult of submersed parasitism — a viewpoint which has been revived by Gaumann, Gaumann and Dodge, and Mez. However, the majority of students of this group, including Schroeter ('97), Minden ('11), Atkinson ('09), Cavers ('15), Scherffel ('25), Cook ('28), and Fitzpatrick ('30), believed that this fam- ily constitutes an ascending series which has given rise to various groups of the Phycomyeetes. Atkin- son related Lagenidium to the chytrid Polyphagia and postulated that the Lagenidiaceae may have originated from certain species of the Rhizidiaceae and in turn led to the development along more or less parallel lines to the higher Oomycetes and Zygo- mycetes. In this connection it may be noted that many years earlier Zopf ('84, p. 190) suggested that Rhinidiomyces apophysitis may be a type of species which relate the Rhizidiaceae with the An- eylistaceae (Lagenidiaceae) and Pythiaceae. While Cavers believed that the Phycomyeetes originated in the Proteomyxa, he thought that the Ancylistineae (Lagenidiaceae) are derived from the Chytridiales and lead to the Peronosporaceae. Scherffel, as noted before, believed that the Lagenidiaceae developed from Ectror/ella- and Olpidiopsis-like ancestors and is connected with his P^fc/am-Peronosporales series through Pythiogeton (diagram 1). Lagenidium Cy- lotellae, in his opinion, is a connecting link between Ectrogella and the Lagenidiaceae (Ancylistineae). Cook regarded the Aneylistaceae (Lagenidiaceae) as intermediate between the Chytridiales and Oomy- cetes proper and believed that it may have given rise on one hand to the Saprolegniaceae through the Blastocladiales and Leptomitaceae, and on the other band to the Peronosporaceae through the Pythiaceae and Albuginaceae (diagram 3). Inasmuch as the konobllphandmtO* Diagram 3. The origin of the Aneylistaceae (Lagenidia- ceae) and its relation to the higher Oomycetes, according to Cook, 19->8. zoospores of the Blastocladiales are uniflagellate and both gametes are motile, it is difficult to conceive how this order has arisen from the Lagenidiaceae. Present day evidence indicates that the Blastocla- diales may have originated directly from the Chy- tridiales. Sparrow ('42) placed the Lagenidiaceae at the top of the Lagenidiales next to the Perono- sporales, suggesting thereby that it may have origi- nated from the Olpidiopsidaceae and Sirolpidiaceae. Bessey ('42) likewise derived it from the Olpidiop- sidaceae and suggested (diagram 2) that it may have given rise in a more or less direct line to the Pythia- ceae, Albuginaceae and Peronosporaceae on one hand and to the Leptomitaceae and Saprolegniaceae on the other. Having reviewed briefly the various views on the phylogeny of the Lagenidiaceae, let us now examine the data on which they are based. In size and shape the thallus of some species of this family resembles the mycelium of the filamentous Oomycetes, but in other species it is like that of the Olpidiopsidaceae. These characters, therefore, do not always afford a fundamental basis of relationship. Fischer and Lot- sy, nevertheless, used them and the holocarpic nature of the thallus as the chief grounds for including the Lagenidiaceae in the sub-order Mycoehytridineae, following the Olpidiaceae and Synchytriaceae. At that time few species with extensive, filamentous, mycelioid thalli were known so that the oval, ellip- soid or tubular, irregular, vermiform and elongate shapes were regarded as more characteristic of the family. Since then species like Lagenidium marcha- lianitm, L. Closterii, L. giganteum, etc., have been described, the thalli of which can hardly be distin- guished from the mycelium of Pythium. Conversely, reduced, holocarpic, relatively short, vermiform and unbranched thalli may rarely occur in Pythium, Achlya, etc., so it is obvious that within certain limits size, shape, and extent of thallus are not always of fundamental value in judging affinity. In methods of zoosporogenesis and the behavior of the zoospores after emerging, several lines of relationship are suggested. The majority of species show distinct pythiacous tendencies because the primary swarm period is suppressed and lacking. The protoplasm emerges from the sporangium and undergoes cleavage on the outside with or without a surrounding vesicular membrane. Lagenidium Oedogonii and Lagenidium sp. Couch, on the other band, exhibit a combination of Pythium, Sapro- legnia and Achlya characteristics. In the former species the zoospores may be formed extramatri- cally in a vesicle as in Pythium or within the spo- rangium and then encyst at the mouth of the exit tube after emerging as in Achlya. In the latter spe- cies they are formed in a vesicle but after swim- ming about for a short while they encyst. Within one to three hours, they emerge from the cysts and become motile again as in Saprolegnia. In L. Cyclo- tellae, however, the zoospores are formed in the same manner and behave like those of Olpidiopsis and some species of Ectrogella. In shape, structure, position of the flagella, and type of swimming the zoospores of most species are essentially like those of Pythium and the secondary PMYI.OGKNV 107 swarmers of Saprolegnia and other related genera. In /.. Cyclotellae, however, they arc more similar to those of Ectrogella, while the markedly hetero- cont zoospores of /.. enecans and Mysocytium, de- scribed by Scherffel ('25) and Dangeard ('(Mi) are somewhat like those of 0. Ricciae, 0. irregularis, Pteudolpidium Glenodineanum, I'. Sphaerita, and Pseudosphaerita. Additional evidence of relation- ship between the Lagenidiaceae, Olpidiopsidaceae, Saprolegniaceae and Peronosporaceae is suggested by the fact that the zoospores of Resticularia and Mysocytium and probably other genera have one tinsel and one whip lash type <>f flagellum. In sexual reproduction some species of the La- genidiaceae may perhaps show a slight advance over that exhibited by the Olpidiopsidaceae by the fact that the oospore lies free in the oogonium and the gametangia are slightly more differentiated. In species of Lagenidium the oogonium is usually larger, more vesicular and frequently barrel-shaped, while the antheridium is tubular and elongate. In L. enecans, for example, the antheridium may be closely applied to the oogonium as in the Saprolegniaceae, according to Scherffel. In other genera like Mysocytium, Lagma and Resticularia, however, the gametangia are less differentiated and often appear to be nothing more than potential sporangia, with which they are morphologically equivalent. In no genus is an egg cell differentiated in the oogonium in preparation for plasmogamy, nor is periplasm present. In both of these respects the Lagenidiaceae differ from most of the Peronospo- rales, but show some resemblance to the Sapro- legniaceae by the absence of periplasm. The con- traction of the ooplasm during plasmogamy in L. rabenhorstii may perhaps foreshadow a tendency toward differentiation of an egg cell before fertiliza- tion. That some differentiation docs occur in the oogonium and antheridium is suggested by Dan geard's report that the supernumerary nuclei in 8f. Vermicolum degenerate and only one from each gametangium functions in karyogamy as in species of the PeroUOSporales. Only one species of the La- genidiaceae has been studied cytologically in this respect, and whether or not this type of nuclear behavior is characteristic of the family as a whole remains to be seen. Tin- so-called oospores are never- theless similar in appearance and structure to those of the Saprolegniales as well as the resting spores of many chytrids and species of the Proteomyxa. Since the gametangia and gametes are not highly differentiated. Atkinson. Barrett, Cook, and others regarded sexual reproduction in the Lagenidiaceae as a generalised oomycetous type with tendencies in more than one direction. Atkinson in particular emphasized the isogamous and zygomycetous po tentialities and their relation to the origin of the Zygomycetes from this family. As noted previously. sexual reproduction in Resticularia, Ziagena, and Lagenidium sacculoides is isogamous. which lends support to the hypothesis that the Zygomycetes also may have originated from lagenidiaeous ancestors. It is apparent from this discussion of origin and relationships that the so called holohitlagelloiiiyceti s have some characteristics in common with tin- I'ro- teomyxa. Plasmodiophorales, Chytridiales, Sapro- legniales, Peronosporales, and Zygomycetes. As to their origin, three principal theories have been pro- posed: (1) that they are reduced and degenerate oomycetes resulting primarily from submersed para sitism; (2) that they have been derived from hetero- COnt unicellular algae through the loss of chloro- phyll and the assumption of a parasitic mode of life, and (3) that they have originated from simpler fungi like the Chytridiales or the more primitive Proteo- myxa. Their resemblance to the Chytridiales appar- ently is due more to parallelism of development or convergent evolution than close relationships. The genera included in the provisional family Woronina- ceae show varying degrees of similarity to certain proteomyxean species and the Plasmodiophorales by their mode of nutrition and the presence of plas- modia and sori. The remaining families, on the other hand, exhibit marked Oomycete relationships by their diplanetic zoospores and predominantly hetcrogamous type of sexual reproduction. These affinities involve principally the Saprolegniales and Peronosporales. bibliography: phylogeny Atkinson, G. F. 1909. Ann. Mycol. 7:4+1. Barrett, .1. T. 1912. Ann. Hot. 26: 209. Bessey, E. A. 1937. Text-book of Mycology. Philadelphia. — . 19-k.'. Mycologia 34:366. Butler, E. J. 19117. Mem. Dept. Agric. India 1, no. 5: 132. Cavers, F. 191.5. New Phytol. 14:280. Clements, F. E. 19(19. The genera of fungi. Minneapolis. and C. L. Shear. 1931. The genera of fungi. Minne- apolis. Coker, W. C. 19J3. The Saprolegniaceae. p. 184. — , and V. Matthews. 1937. North American Flora .'. pt. 1: 17. Cook, W. R. I. 1928. New Phytol. 37:307. — . 1933. Arch. 1'rotistk. SO:. '.'3. Couch. .1. X. 1911. Amer. .lour. Bot. 28: 71)9. — , .1. Leitner, and A. Whiffen. 1939. Jour. Elisha Mitchell Sei. Soe. .-,.5:399. Dangeard, P. A. 1886. Ann. Sci. Nat. 7 ser. t: 876. . 1906. I.e Bot. 9: 1.57. De Bary, A. L881. Bot. /..it. 39: l. — . 188-t. Vergleichende Morphologie der Pilze. Leipzig. Fischer. E. 1892. Rabenhorst's Krypt'fl. I, 4:71. Fitzpatrick, H. M. 1930. The lower fungi Phvcomvcetes. New York. Gaumann, F.. A. 19,'ii. Vergleichende Morphologie der Pilze. Zurich. . mihI ('. \V. Dodge. 19-.'H. Comparative morphology of fungi. New York. Gwynne-Vaughan, II. ('. 1.. and B. Barms. 1926. The structure- and development of fungi. Cambridge. 2nd id. 1937. .Iii.l. H. (). 1901. Bih. K. Sv.-i.sk. Vet-Akad. Hand. 26, afd. III. n. i. 14: 1. Karling, .1. S. 1943. The Plasmodiophorales. New York. Ledingham, G. A. 1933. Phytopath. 23:20. . 1939. Canadian .lour. Res. ('. 17:60. I.otsy, .1. P. 19H7. VortrSge iiher botanische Stammen- geschichte 1 : 1 in. 108 THE SIMPLE HOLOCAKPIC BIFLAGELLATE PHYCOMYCETES Maire, R., and A. Tison. 1911. Ann. Mycol. 9:240. Mez, C. 1929. Schr. Kbnigsberger Gelehrten Gesell.- Naturw. Klasse 6:1. Minden, M. 1911. Krypt'fl. Mark Brandenburg 5:248. Petersen, H. E. 1905. Overs. Danske Videns. Selsk. Forh. 1905, no. 5:465. Pringsheim, N. 1858. Jahrb. Wiss Bot. 1:287, 305. Scbenk, 1859. Verb. Phys. Med. Gesell. Wurzburg 9:27. Scherffel, A. 1925. Arch. Protistk. 52:38. Schroeter, J. 1886. Cohn's Krypt'fl. Schlesiens 3: 225. . 1897. Engler und Prantl, Die Nat. Pflanzenf. I, 1:70. Sparrow, F. K. 1933. Mycologia 24: 530. — . 1934. Dansk. Bot. Ark. 8, no. 6: 1. . 1936. Jour. Linn. Soc. London 50:461. . 1942. Mycologia 34: 113. Tavel, F. 1892. Vergleichende Morphologic der Pilze. Jena. Tokunaga, Y. 1933. Trans. Sapporo Nat. Hist. Soc. 13:20. Vuillemin, P. 1908. Progr. rei Bot. 2: 1. Walz, J. 1870. Bot. Zeit. 28: 556. Wettsteln, R. 1935. Handbuch der Systematische Botanik, 4th ed., p. 204. Leipzig und Vienna. Winge, O. 1913. Ark. f. Bot. 12, no. 9:26. Zopf, W. 1884. Nova Acta Ksl. Leop.-Carol. Deut. Akad. Nat. 47:145, 190. . 1894. Phys. Morph. Nied. Organismen 2:3. Chapter VIII Hosts and Bibliography The fungi described in the previous chapters are widely distributed in nature and ubiquitous in host range. As noted before, they occur in fungi, fresh- water and marine algae, liverworts, mosses, gymno- sperms, angiosperms, infusoria, rotifers, nematodes, insects, and crustaceans. With the view of expedit- ing reference to these fungi and their hosts, a com- plete host index and bibliography is herewith pre- sented. The hosts are listed in solid type and their parasites in italics. The arrangement of the divi- sions, orders, and families of hosts does not follow any particular system of classification. Systemat- ists in particular fields will doubtless object to and take issue with the present arrangement, but the primary object of this index is not a classification of algae, fungi, higher plants, and animals. In order to avoid confusion through personal inter- 'pretation of synonomy, the hosts as well as their parasites are listed in the same manner as reported by the various workers. The exact identity of many of the early described parasites is doubtful. The early workers were not very specific in their re- ports and descriptions, so that it is not certain which species of Olpidiopsis, Myaocytium, Lageni- diuni, etc., Nageli, Cienkowski, Stein, Pringsheim. Reinsch and others, for example, referred to. Such parasites have, nevertheless, been listed with ques- tion marks in the index with the view of bringing them to the notice of research workers. THALLOPHYTA FUNGI Olpidiaceae Sphaerita endogena Olpidiii in Sphaeritae Dangeard, 1889. Le Bot. 1:51. Pseudolpidium Sphaeritae (Dang.) Fischer, 1892. Rabenhorst's Krypt'fl. I, 4:36. Olpidiopsis Sphaeritae (Dang.) Schroeter, 1897. Engler und Prantl. Die Nat. Pflanzf. I, 1 : 69. Rozella septigena Olpidiopsis irregularis (?) Constantineanu, 1901. Rev. Gen. Bot. 13:376. Saprolegniaceae Achlya sp. Woron inn polycystis Dangeard, i890. Le Bot. 2: 145. Hartog, 1890. Rept. 6th Meeting Brit. Assn. Adv. Sci. 1890:872. Petersen, 1909. Bot. Tidsskr. 29:426. 1910, Ann. Mycol. 8:557. Cook and Nicholson, 1933. Ann. Bot. 47:851. Sparrow, 1932. Mycologia 24:273. 1933, Ibid. 25:515. 1936, Jour. Linn. Soc. London, Bot. 50:425. Rozella simulans Maurizio, 1895. Jahrb. Nat. Gesell. Graiibundens 38: 9. Rozellopsis simulans (Fischer) Karling, 1942. Amer. Jour. Bot. 29:33. 1942, Mycolo- gia 34:207. Olpidiopsis incrassata Sorokin, 1883. Arch. Bot. Nord France 2:29. 1889, Rev. Mycol. 11:84. Pseudolpidium incrassata Sparrow, 1933. Mycologia 25:515. Olpidiopsis Saprolegniae Petersen, 1909. Bot. Tidsskr. 29: 404. 1910, Ann. Mycol. 8:539. Sparrow, 1932. Mycologia 24:270. 1933, Ibid. 25:515. Gilman and Archer, 1929. Iowa Jour. Sci. 3: 299. Olpidiopsis fusifqrmis. Cornu, 1872. Ann. Sci. Nat. 5 ser. 15: 147. Sorokin, 1883. Arch. Bot. Nord France 2:27. 1889, Rev. Mycol. 11:83. Pseudolpidium fusiforme Sparrow, 1932. Mycologia 24:272. 1936, Jour. Linn. Soc. London, Bot. 50: 425. Olpiilinjisis index Cornu, 1872, I.e. p. 145. Achlya americana Woronina (?) asterina Tokunaga, 1933. Trans. Sapporo Nat. Hist. Soc. 13: 26. Achlya colorata Olpiilinjisis various Shamir, 1940. Jour. Elisha Mitchell Sei. Soc. 56:171. mi- rfi v mi liliii.iouii \ i- 1 1 ^ 10!) Achlya tic- Banana Woronina polycyttit Cook and Nicholson, l «»:i:t. Ann. Bot. LI B57. Villi \ :i Bagellata Boa "" thnukau Tokunaga, 1933. Trans, Sapporo Nat Hist. Sue. 13: .'•'>. Roztlloptu simulant (Fischer) Marling. 1949. Am. .lour. Bot J9:S3. 1949, Mycologia 31: .'117. Olpidioptu Saproli gniae Coker, l ; • J" : * . The Saprolegniaceae, p. 184. Olpidiopiii fvriformu (?) Cienkowski, is:,:.. Bot Zeit 13:801. Olpidioptu minor Matthews, 1936. Jour. Elisha Mitchell Sci. Soc. 51:310. /'.,, n2. Couch, 1941. Amer. Jour. Bot. 28: 706, 707. Wolf, F. T., and F. A. Wolf. 1941. Lloydia 4: 270. Diplophysa Saprolegniae Schroeter, 188b". Cohn's Krypt'fl. Schlesiens 3: 195. Olpidiopsis irregularis Constantineanu, 1901. Rev. Gen. Bot. 13: 373. Sparrow, 1934. Dansk. Bot. Ark. 8:15. Pseudolpidium fusiforme Sparrow, 1932. Mycologia 24: 272. Pseudolpidium Saprolegniae Cejp, 1934, I.e. p. 226. Saprolegnia asterophora Pseudolpidium Saprolegniae Fischer, 1892. Rabenhorst's Krypt'fl. I, 4: 35. Saprolegnia delica - Olpidiopsis Saprolegniae Shanor, 1940. .lour. Elisha Mitchell Sci. Soc. 56: 170. Olpidiopsis incrassata Shanor, 1940, I.e., p. 170. Saprolegnia diclina Olpidiopsis Saprolegniae Shanor, 1940, I.e., p. 170. Olpidiopsis incrassata Shanor, 1940, I.e. Saprolegnia dioica Olpidiopsis echinata Petersen, 1909. Bot. Tidsskr. 29: 405. 1910, Ann. Mycol. 8:540. Saprolegnia ferax Woronina polycystis Cook and Nicholson, 1933. Ann. Bot. 47: 857. Chytridium Saprolegniae Braun. 1855a. Ber. Kgl. Preuss. Akad. Wiss. 1855: 384. 1855b, Abh. Kgl. Akad. Wiss. Berlin. 1855: 61. Olpidium Saprolegniae Braun. 1855b, I.e., p. 75. Olpidiopsis Saprolegniae Harvey, 1927. Trans. Wise. Acad. Sci. Arts, Letters 23: 551. 1942, Jour. Elisha Mitchell Sei. Soc. 58: 39. Shanor, 1940. Ibid. 56: 170. Olpidiopsis Saprolegniae var. laevis Coker, 1923. The Saprolegniaceae, p. 185. O Ipidiops is vexa n s Barrett, 1912. Ann. Bot. 26: 231. Olpidiopsis incrassata Shanor, 1940. Jour. Elisha Mitchell Sci. Soc. 56: 170. Saprolegnia hypogyna Olpidiopsis major Maurizio, 1895. Jahrb. Nat. Gesell. Graubiindens 39: 15. Saprolegnia lactea Olpidiopsis Saprolegniae (?) Pringsheim, 1860. Jahrb. Wiss. Bot. 2: 205. Saprolegnia littoralis Olpidiopsis Saprolegniae Shanor, 1940. Jour. Elisha Mitchell Sci. Soc. 56: 170. Olpidiopsis incrassata Shanor, 1940, I.e. Saprolegnia mixta Olpidiopsis Saprolegniae Diehl, 1935. Centralbl. Bakt. Parasitk. II, 92: 229. Shanor, 1940. Jour. Elisha Mitchell Sci. Soc. 56: 170. Olpidiopsis incrassata Shanor, 1940, I.e. Saprolegnia monilifera Olpidiopsis Saprolegniae Tokunaga, 1933. Trans. Sappora Nat. Hist. Soc. 13:24! Saprolegnia monoica Woronina polycystis Dangeard, 1890. I.e Bot. 2: 145. Fischer, 1892. Rabenhorst's Krypt'fl. I, 4: 66. Rozelln septigena. (Not R. septigena Cornu) Fischer, 1882. Jahrb. Wiss. Bot. 13: 321. Rozellopsis septigena (Fischer) Karling, 1942. Amer. Jour. Bot. 29: 33. 1942, Myco- logia 34 : 206. Olpidiopsis echino to Petersen, 1909. Bot. Tidssk. 29: 405. 1910, Ann. Mycol. 8: 540. Olpidiopsis Saprolegniae Graff, 1928. Mycologia 20: 159. Shanor, 1940. jour. Elisha Mitchell Sci. Soc. 56: 170. Olpidiopsis Saprolegniae var. laevis Coker, 1923. The Saprolegniaceae, p. 185. Pseudolpidium Saprolegniae (?) Fischer (pro parte), 1892. Rabenhorst's Krypt'fl. I, 4:35. Olpidiopsis incrassata Shanor, 1940. Jour. Elisha Mitchell Sci. Soc. 56: 170. Saprolegnia spiralis Woronino polycystis Cornu, 1872. Ann. Sci. Nat. 5 ser. 15: 177. Saprolegnia thuretii Woronina polycystis Fischer, 1892. Rabenhorst's Krypt'fl. I, 4: 66. Bozella septigena. (Not R. septigena Cornu) Fischer, 1882. Jahrb. Wiss. Bot. 13: 321. Rozellopsis septigena (Fischer) Karling, 1942. Amer. Jour. Bot. 29: 33. 1942, Myco- logia 34: 206. Olpidiopsis Saprolegniae Fischer, 1892, I.e., p. 38. Minden, 1911. Krypt'fl. Mark Brandenburg 5: 263. Davis, 1914. Trans. Wise. Sci. Arts, Letters 17, 2: 848. HOSTS AM) llllll. KM. II U'll V II 1 Psiudolpidium 8aprol«gniat (?) Fischer (pro parte)) 1893. Rabenhorst's Krypt'fl. I. I: 35. Tokunaga, 1933. Trans. Sapporo Nat Hist. Soc. IS: -'.• Olpidiopti* major Maurixio, 1895, Jahrb. Nat. Gesell Graiibundens 38: 15. Pythiaci at Pj thium sp. /'.** udolpidium Pythii Minden, 1911. Krypt'fl. Mark. Brandenburg 5: J69. Sparrow. 1936. Jour. Linn. Soc. Hot. 50: 135. Olpidiopsis Aphanomycis (?) Dangeard, 1890. Le Bot 2: 63. Pj thium dictyosporum l*i/fhit !!<> 7v rnalis Couch, 1935. Mycologia .'7: 160. Pythiunn gracile Pythii II" vi rnalis Couch, 1935, I.e. Py thium intermedium /'li olpidium in tint n in Butler, 1907. Mem. Dept. Agr. India I. no. 5: 126, 127. Hiizi lln/itis infliil" (Butler) Karlinir. 1942. Amer. .lour. Hot. 29 : 34. 1942, Myco- logia 34: 205. /'.-. udolpidium Pythii Butler, 19(17. I.e.. p. 127. /'*< udolpidium graeile Butler, 1907, I.e.. p. 129. Olpidiopsis i'ii rvispinosa Whiffen, Hit.1. Amer. Jour. Hot. .'it: 610. Olpidiopsis brevispinosa Whiffen, Hit.'. I.e.. p. mo. Pythium monospermum Pst udolpidium Pythii Hutler. 1907, I.e.. p. 127. Pythium oryiae 1'zi mini f > ill in m Pythii Tokunaga, 1933. Trans. Sapporo Nat. Hist. Soc. 13: -'-'. Pythium rostratum I'si udolpidium Pythii Hutler. 1907, I.e.. p. 127. Pst mini fii'lin hi 'ii-nrili- Whiffen, 1942, I.e.. p. «10. Pythium torulosum Olpidiopsis cvrvispinosa Whiffen, 1942, I.e.. p. 610. Pythium vexans Pst ml "I f i ill in in I' ii III ii Hutler. 1907, I.e..],. 127. Phytopbthora cryptogea /'/* nl jiiilin III sp. Waterhouse, into. Trans. Brit Mycol. Soc. ii: 7. Hit.'. II. ill. -'.'»: 317. /.■ , llopsis wiiii i'ii'. Karlintr. 1942. Amer. Jour. Hot. 29: 34. 1942, Myco- logia 34: 206. Phytophthora megasperma Pli nl fiiilin hi sp. Waterhouse, 1940. Trans. Brit. Mycol. Soc. -'t: 7. I'll.'. II, ill. .'."): :(17. linn ii'ipsi* wail ihiiiisi a Karling. lilt.'. Amer. Jour. Bot -'9 : 34. 1942, \lyeo- logia 34: 206. M iii-iifini in l'iloliolus s|). Wnrnllill" sp. '/.opt'. 1894. Physiol. Morph. med, Organismen 1 : 60. ALGAE MYXOPHYCEAE Oscillatoriaci ai Lyngbya aestuarii Hi siiinl" riii nodosa Dangeard, 1891. Le Hot. 2: 96. Sri/lnili' llliiri in Tolypothrix sp. Regticularia boodlei Fritsch, 1903. Ann. Hot. 17: 654. /'. nodosa (?) Fritsch, 1903, I.e.. p. 650. HETEROKONTAE Tribonemaceae Tribonema bombycinum Olpidiopsis sorokinii De Wildeman, 1890. Ann. Soc. Belg. Micro. 14: 22. i 'ryptomonadaceae Cryptomonas ovata 8 phat ril" ruiliiiiii Dangeard, 1890. I.e Hot. .': 54. Knijlt luivt'iii' Euglena sp. Myzocytium sp. (?) Sparrow, 1936. Jour. Linn. Soc. London Hot. .50: 403. Euglena caudata 1 1. ii ml"* /iliiu ril" F.injli inn Mitchell. 1928. Trans. Amer. Micro. Soc. 47: 30. Euglena polymorphs I'xt minx jihiu ril" E ii t/l rm ir Dangeard, 1895. I.e Hot. t: .'13. 1933, Ibid. 25: 36. Euglena sanguinea Pseudosphaerita Euylenae (?) Nagler, 1911. Arch. 1'rotistk. .'3: .'63. Euglena viridis Pseudosphaerita Euglt nai Dangeard. 1895. I.e Hot. 1: 243. 1933, //,/,/. 25: 36. Stein. in7s. Der Organismus tier [nfusionsthiere. Abt. III. pi. -'". fig. -'I. DINOFLAGELLATA Peridiniact at ( ilenodinium cinctum Olpidium ah iiiiiliiiiiniiiin Dangeard, 1882. Jour, de Hot. .': ISO. I'si mini /liilin in Hli nmliiiiiiiiii in Fischer, 1892. Rabenhorst's Krypffl. I. 1:36. DIATOMS Bacillariact at Amphora ovalis I. a, /i niiliii a, Bfiei Scherffel, 1925. Arch, l'n.tislk. 52: -'". 112 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES Cocconema lanceolatum Ectrogella bacillariacearum Gill, 1893. Jour. Roy. Micro. Soc. 1893: 1. Lagenidium enecans Scherffel, 1925, I.e., p. 20. Cyclotella kiitzingiana Lagenidium Cyclotellae Scherffel, 19*25, I.e., p. 18. Cvmatopleura solea Lagcn iditim enecans Scherffel, 1925, I.e., p. 20. Cymhella cymbiformis var. parva Lagenidium brachyoslomum Scherffel, 1925, I.e., p. 21. Cymbella gastroides A phanomycopsis bacillariacearum Scherffel, 1925, I.e., p. 14. Lagenidium enecans Scherffel, 1925. I.e., p. 20. Epithemia turgida Aphanomycopsis bacillariacearum Scherffel, 1925, I.e., p. 14. Gomphonema sp. Ectrogella bacillariacearum Zopf, 1884. Nova Acta Ksl. Leop.-Carol. Deut. Akad. Nat. 47: 177. Scherffel, 1925, I.e., p. 6. Domjan, 1935. Folio Cryptogam. 2: 9. Olpidium gill! De Wildeman, 1896. Ann. Soe. Beige Micro. 20: 41. Gomphonema const rictum Lagenidium brachyostornum Scherffel, 1925, I.e., p. 21. Gomphonema micropus Ectrogella Gomphonema lis Scherffel, 1925, I.e., p. 9. Lauderia borealis 01 piil in in Lauderiae Gran, 1900. Nyt. Mag. Nat. 38: 123. Eurychasma Lauderiae Petersen, 1905. Overs. Kgl. Dansk. Yids. Selsk. Forh. 5: 469. Licmophora sp. Ectrogella Licmophorae Scherffel, 1925. Arch. Protistk. 52: 10. Ectrogella perforans Sparrow, 1934. Dansk. Bot. Ark. 8, no. 6: 19. Licmophora abbreviata Ectrogella perforans Sparrow, 1936. Biol. Bull. 70: 239. Licmorphora Lyngbyei Ectrogella perforans Petersen, 1905. Overs. Kgl. Dansk. Vids. Selk. Forh. 5: 466. Meridion circulare Ectrogella bacillariacearum Scherffel, 1925. Arch. Protistk. 52: 6. Domjan, 1935. Folio Cryptogam. 2: 9. Navieula sp. Aphanomycopsis bacillariacearum Tokunaga, 1934. Trans. Sapporo Nat. Hist. Soc. 13: 227. Nitzsehia linearis Lagen id in m b rachyostomnm Scherffel, 1925, I.e., p. 21. Nitzschia sigmoidea Ectrogella bacillariacearum Gill, 1903. Jour. Roy. Micro. Soc. 1893: 1. . t phanomycopsis bacillariacearum Scherffel, 1925, I.e., p. 14. Pinnularia sp. Ectrogella bacillariacearum Zopf, 1884. Nova Acta Ksl. Leop.-Carol. Deut. Akad. Nat. 47: 177. Scherffel, 1925. Arch. Protistk. 52: 6. Sparrow, 1933. Mycologia 25: 531. Domjan, 1935. Folio Cryptogam. 2: 9. Ectrogella monostoma Sparrow, 1933, I.e., p. 531. A phanomycopsis bacillariacearum Sparrow, 1933, I.e., p. 530. Lagenidium sp. Scherffel, 1925, I.e., p. 23. Pinnularia viridis Aphanomycopsis bacillariacearum Scherffel, 1925, I.e., p. 14. Lagenidium enecaus Scherffel, 1925, I.e., p. 20. Pleurosigma angulatum Ectrogella bacillariacearum (?) Van Heurck, 1899. Traite des Diatomees. Anvers. Pleurosigma attenuatum Ectrogella bacillariacearum Gill", 1893. Jour. Roy. Micro. Soc. 1893: 1. Stauroneis phoenocentron Lagenidium enecans Scherffel, 1925, I.e., p. 20. Striatella unipunctata Ectrogella perforans Sparrow, 1936. Biol. Bull. 70: 239. Surirella sp. A phanomycopsis bacillariacearum Tokunaga. 1934. Trans. Sapporo Nat. Hist. Soc. 13: 227. Synedra sp. Ectrogella bacillariacearum Zopf, 1884. Nova Acta Ksl. Leop.-Carol. Deut. Akad. Nat. 47: 177. Gill, 1893. Jour. Roy. Micro. Soc. 1893: 1. Olpidium gilli De Wildeman, 1892. Ann. Soc. Beige Micro. 20: 41. Synedra lunularis Ectrogella bacillariacearum Zopf, 1884. Nova Acta Ksl. Leop.-Carol. Deut. Akad. Xat. 47: 177. Synedra ulna Ectrogella perforans Petersen, 1905. Overs. Kgl. Dansk. Vids. Selsk. Forh. 5: 466. Ectrogella bacillariacearum Scherffel, 1925. Arch. Protistk. 52: 6. Domjan, 1935. Folio Cryptogam. 2: 9. Ectrogella monostoma Scherffel, 1925, I.e., p. 8. mi- is \\i) Hiiu.ioi.ii win ua CHLOROPHYCEAE i hhnilililiilnoniiilitri ■■ 257. Diplophysa * Uiptica Schroeter, 1886. Cohn's Krypffl. Schlesiens 3: 196. Olpidiopsis elliptica Fischer, 1892. Rabenhorst's Krypt'fl. I, 4: 41. Pst udotpidiopris sllipHca Minden, 1911. Krypt'fl. .Mark Brandenburg 5: 260. Olpidiopsis ii/'i'i inlii'iih'tti I),- Wildeman, 1895. La Notarisia 10: 34. 1896, Ann. Soc. Beige Micro. 20: 29. Pst udolpidiopsis appendiculata Minden, 1911. Krypt'fl. Mark Brandenburg 5: 259. Lint* niiliiim nth* nhorstti Zopf, 1878. Verb. Rot. Yer. Prov. Brandenburg 20: 79. ism. Nova Acta Ksl. Leop.-Carol. Deut. Akad. Nat. 17: 145. M >> zocy t in in /i roliferu m Zopf, ISM. I.e.. p. 159. Scherffel, 1902. Nov. Kiizl. 1: (109). 1926, Arch. Pro- titsk. 54: 245. M . im gulan Cejp, 1935. Bull. Int. l'Acad. Sci. Boheme 1935: 7. Mesocarpus pleurocarpus Myzocytium proliferum Schroeter, 1886. Cohn's Krypt'fl. Schlesiens 3: 227. Mougeotia -p. Olpidioptit Scht iikiiimi Zopf, 1884. Nova Acta Ksl. Leop.-Carol. Deut. Akad. Nat. 17: 168. Lagt nit Hum rabenhorstU Zopf, 1884, I.e. p. 145. Yalkanov. 1931. Arch. Protistk. 7:i: :ifi."). "ilyzocytwm proliferum Schenk, 1858. Dber da- Vorkommen Contractiler Zellen im Pflanzenreich, p. 10. Zopf, 1884. Nova Acta K-l. Leop.-Carol. Deut. Akad. Nat. 17: 159. Scherffel, 1902, Nov. Kii/.l. (109). 1926, Arch. Protistk. 54: -'l">. Petersen, 1909. Bot. Tidskr. 29: W2. 1910, Ann. Mycol. 8: 538. Minden. 1911. Krypt'fl. Mark Brandenburg 5: 131. Sparrow. 1932. Mycologia .'I; 288. 1933, Ibid. 25: .»:!-'. Domjan, 1935. Folio Crypt -'; 51. .1/. irr< gulart Cejp, 1935. Hull. Int. l'Acad. Sci. Boheme 1935: 7. Spirogyra sp. Olpidiopsis schenkiana /.opt', issi. Nova Acta Ksl. Leop.-Carol. Deut. Akad. Nat. 17: 168. l)e Wildeman, 1890. Ann. Soc-. Beige Micro. II: 24. 1891, Hull. Soc. Roy. Hoi. Belg. 30: 17.'. 1896, Ann. Soc. Beige Micro. .'0: 28. Constantineanu, 1901. Rev. Gen. Hot. 13: 375. Butler, 1907. Mem. Dept. Agr. India 1, no. .".: III.".. Butler and Bisby, 1931. Fungi of India. Scherffel, 1925. Arch. Protistk. 53: 138. Pleocystidium parasiticum Fisch, 1884. Sit/.h. Phys.-Med. Soc. Erlangen Hi: no. Olpidiopsis parasitica (Fisch.) Fischer, 1892. Kahenhorst Krypffl. I, I: 40. Diplophysa schenkiana (Zopf) Schroeter, 1897. Engler und Prantl, Die Nat. Pflanzen'f. I. 1:85. Pseudolpidiopsis schenkiana (Zopf ) Minden, 1911. Krypt'fl. Mark Brandenburg 5: 257. Tokunaga, 1933. Trans. Sapporo Nat. Hist. Soc. 13: 82. P. parasitica (Fisch) Minden, 1911, I.e., p. 258. Olpidiopsis zopfii De Wildeman, 1895. La Notarisia 10: 31. 1N96. Ann. Soc. Beige Micro. 20: 25. Pseudolpidiopsis zopfii (de Wildeman) Minden, 1911. Krypt'fl. Mark Brandenburg 5: 259. Olpidiopsis fibrillosa De Wildeman, 1895. La Notarisia 10: 34. 1890, Ann. Soc. Beige Micro. 20: 27. Pseudolpidiopsis fibrillosa Minden. 1911. Krypt'fl. Mark Brandenburg 5: 259. Lagenidium rabenhorstii Zopf, 1878. Verh. Bot. Yer. Prov. Brandenburg 30: 79. 1879, Hedwigia 18: 94. 1884, Nova Acta Ksl. Leop.-Carol. Deut. Akad. Nat. 47: 145. De Wildeman. 1891. Bull. Soc. Hoy. Hot. Beige 30: 137. 1893, Ann. Soc. Beige Micro. 1": 45. 1895, Mem. Soc. Beige Micro. 19: 98. Constantineanu, 1901. Rev. Gen. Bot. 13: 379. Atkinson, 1909. Ann. Mycol. 7: 450. Yalkanov, 1931. Arch. Protistk. 73: 365. Scherffel, 1926. Tbid. 54: 215, 510. Sparrow. 1932. Mycologia 21:289. Cejp, 1935. Bull. int. l'Acad. Sci. Boheme 1935: 7. Dontjan, 1935. Folio Cryptogam. 2: 31. Cook, 193.'. New Phytol. 31: 112. 1933. Glamorgan County Nat. Hist. 1: 211. 1935, Arch. I'rotistk. 86: 63. Lagenidium entophytum Zopf. isst. Nova Acta Ksl. Leop.-Carol. Dent. Akad. Nat. 17: 154. I).- Wildeman, 1891. Hull. Soc. Hoy. Hot. Beige 30: 138. 1893, Ann. Soc'. Beige Micro. 17: 10. 16. 1895, Mem. Soc. Beige Micro. 19: 100. L'i if* iiii/iii in nun rica im in Atkinson. 1909. Hot. Caz. IS: 334. Pi/ /h'm m entophytum Pringsheim, 1858. Jahrb. Wiss. Hot. I: 287,305. liagt niiliiim ill-mill Zopf. 1HS1. Nova Acta Ksl. I.eop. -Carol. Dent, \kad. Nat. 17: 158. De Wildeman, 1895. Mem. SOC Beige Micro. 19: HI-'. Cook, 1932. New Phytol. 31: 140. 193.',. Arch. I'rotistk. sci: 88. 114 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES Lagenidiu m papillosum Cocconi, 1894. Mem. R. Accad. Sci. Inst. Bologna 4:363. Myzocytium proliferum Schenk, 1858. uber das Vorkommen Contractiler Zel- len im Pflanzenreich, p. 10. 1858, Verh. Phys.-Med. Gesell. 8: XXVII. 1859, Ibid. 9: 27. Cornu, 1869. Bull. Soc. Bot. France 16: 222. Zopf, 1884. Nova Acta Ksl. Leop.-Carol Deut. Akad. Nat. 47: 159. De Wildeman, 1893. Ann. Soc. Beige Micro. 17: 53. 1895, Ibid. 19: 68. Constantineanu, 1901. Rev. Gen. Bot. 13: 377. Scherffel, 1936. Arch. Protistk. 54: 345, 511. Skvortzow, 1927. Ibid. 57: 206. Valkanov, 1931. Ibid. 73: 365. Tokunaga, 1934. Trans. Sapporo Nat. Hist. Soc. 13: 228. Ce.jp, 1935. Bull. Int. l'Acad. Sci. Boheme 1935: 6. Puthium globosum "Schenk^ 1858. Verh. Phys.-Med. Gesell. 9: 27. Pythium globosum Walz, 1870 (pro parte). Bot. Zeit. 25: 556. Lagenidium globosum Lindstedt, 1872. Synopsis d. Saproleg., p. 54. Spirogyra affinis Myzocytium proliferum Chaudhuri, 1931. Arch. Protistk. 75: 472. Mundkur, 1938. Fungi of India. Suppl. I. Spirogyra calospora Lagenidium americaniim Atkinson, 1909. Bot. Gaz. 48: 334. Spirogyra grevilleana Lagenidium gracile De Wildeman, 1895. Mem. Soc. Beige Micro. 19: 102. Spirogyra insignis La gen idiu m it m e riean u m , Atkinson, 1909. Bot. Gaz. 48: 334. Spirogyra jurgensis Myzo eg t in m // rolife ru m Tokunaga, 1934. Trans. Sapporo Nat. Hist. Soc. 13: 229. Spirogyra mirabilis Lagenidium rabenhorstii Dom.jan, 1935. Folio Crypt. 2: 31. Spirogyra orthospira Lagenidium rabenhorstii Graff, 1938. Mycologia 20: 169. Spirogyra varians Lag en idiu m a me riean u m Atkinson, 1909. Bot. Gaz. 48: 334. L. rabenhorstii De Wildeman, 1891. Bull. Soc. Beige .Micro. 16: 138. Zygnema sp. Lagenidium rabenhorstii Dom.jan, 1935. Folio Crypt. 3: 31. Myzocytium proliferum Schenk, 1858. i'ber das Vorkommen Contracteler Zel- len im Pflanzenreich, p. 10. Zopf, 1884. Nova Acta Ksl. Leop.-Carol. Deut. Akad. Nat. 47: 159. De Wildeman, 1895. Ann. Soc. Beige Micro. 19: 76. Cejp, 1935. Bull. Int. l'Acad. Sci. Boheme 1935: 7. Py thium prol ife r u m Walz, 1870. Bot. Zeit. 28: 556. Pythium globosum Walz, I.e., p. 556. Zygnema cruciatum Myzocytium proliferum Graff, 1938. Mycologia 30: 168. Desmidaceae Arthrodesmus sp. Bicricium naso Sorokin, 1883. Arch. Bot. Nord France 3: 44. 1889, Rev. Mycol. 11: 138. Closterium sp. Lagenidium Closterii Petersen, 1910. Ann. Mycol. 8: 537. Ce.jp, 1933. Bull. Int. i'Aead. Boheme, 1933: 7. 193s, Ibid. p. 9. Couch, 1935. Mycologia 37: 384. Lagenidiu m intermedium Cejp, 1935, I.e., p. 8. De Wildeman, 1893. Ann. Soc. Beige Micro. 17: 54. 1895, Ibid. 19: 78. Myzocytvwm megastomum de Wildeman forma Skvortzow, 1925. Arch. Protistk. 51: 431. Myzocytium (Aneylistees) tniurii Skvortzow, 1925, I.e., p. 432. Myzocytium proliferum Cejp, 1933. Bull. Int. l'Acad. Boheme 1933: 5. Closterium acerosum Myzocytiu m proliferum Sparrow, 1933. Mycologia 24: 288. Closterium areolatum Myzocytium megastomum Berdan, 1938. Mycologia 30: 408. Closterium attenuatum Myzocytium megastomum De Wildeman, 1893. Ann. Soc. Beige Micro. 17: 53. Closterium didymotocum Myzocytium proliferum Reinsch, 1878. Jahrb. Wiss. Bot. 11: 300. Closterium ehrenherghii Lagenidium intermedium De Wildeman, 1895. Ann. Soc. Beige Micro. 19: 96. Closterium leiblinii Myzocytium proliferum Cejp, 1932. Bull. Int. l'Acad. Boheme 1932: 5. Closterium ralfsii var hybridum Lagenidium sacculoides Serbinow, 1924. La Defense des Plantes 1: 85. Closterium striolatum Lagenidiu m t'losterii be Wildeman, 1893. Ann. Soc. Beige Micro. 17: 43. Myzocytium megastomum Berdan, 1938. Mycologia 30: 408. Cosmarium sp. Myzocytium irregulare Cejp, 1935. Bull. Int. l'Acad. Boheme 1935: 7. Cosmarium Botrytis Myzocytium proliferum Reinsch. 1878. Jahrb. Wiss. Bot. 11: 300. HOSTS wo BIBLIOGRAPHY LIS Cosmarium connatum V iii.triilin in prolift rum Reinsch, 1*7*. I..-.. \>. 300. Cosmarium pyramidatum /..i.;. ni, limn pygmai iiiii Schulta-Danzig, 1993. Schr. f. Siissw.-und Meeresk. 11: L79. Cosmarium plangula Myzocytium proliferum (?) Reinsch, 1878. Jahrb. Wiss. Hot. 1 1 : 300. Docidium ehrenberghii Mitochytridium ramosvm Dangeard, 191 1. Hull. Soc. Mycol. France -'?: 203. Couch, 19SS. Jour. Blisha Mitchell Sci. Sue 51: -'93. Buastrum sp. Myzocytium proliferum IV Wildeman, 1895. Ann. Soc. Beige Micro. 19: 7T. Buastrum humerosum I. nil, ni, Hum entophytum Schults-Danxig, 1923. Schr. f. Sussw.-und Meeresk. II: 180. Euastrum olilonsruui L" niifimn t ntn/ilii/l u m Schultz-Danzig, L92S. Schr. f. SUssw.-und Meeresk. 11: 180. Microasterias rotate M uzocyl in in proliferum Reinsch, 1*7*. Jahrb. Wiss. Hot. 11: 300. M uzocytium irregulan Cejp, I9:i:f. Hull. Int. I'Acad. Sci. Boheme 1933: 8. 19SS, Ibid. p. 7. Microasterias truncata Myzocytium irregulari Cejp, 193.J. Ibid. p. 7. Penium digitus Lagt niiiiiim sp. Scherffel, L926. Arch. l'r.»listk. 54: .'Hi. Pleurotaenium sp. M ir."ri/fin m irregulari Cejp, 193.".. I.e.. p. 7. I'l urotacnitiin ehrenberghii . / film ni, m ycopeis barilla riaeearu m ( ? ) West and West, 1906. Trans. Roy. Irish Acad. B, S.i: 77. Pleurotaenium trahccula Lagi niiiiiim intermedium Cejp. 193.-,. I.e.. p. s. Spirotaenia sp. M uzocytium megaetomum iv Wildeman, 1893. Ann. Soc Beige Micro. 17: 50. Spirotaenia condensata Myzocytium sp. ScherfFel, 1926. Arch. Protistk, .'-I: .'Hi. Staurastrum sp. Myzocytium proliferum Scherffel, L9S6, I.e., p. 246. i 'Inn tophoraceai Draparnaldia glomerata Pseudolpidium deformans Serbinow, 1907. Scripts Hoi. Hort. Imp. Univ. Petrop. -M: .'■',. Oedogoniaceae Oedogonium sp. Myzocytium sp. (?) Turner, 1892. K'gl. Svensk. Vetens. Akad. Hand. n. t'. 95, no. 5: llil. Lit i/i n ill in in ni In n hit rs Hi Petersen, 1909. Bot. Tidsk. 9: 100. 1910, Ann. Mycol. 8: 536. L. -ttjilii De Wildeman, 1891. Hull. Soc. Beige Micro. 16: 139. Petersen, 1909. Hot. Tidskr. .'9: 101. It. syncytiorum Klebahn, 1892. Jahrb. Wiss. Hot. 24: 263. L. miift'ltitlittnum De Wildeman, 1897. Ann. Soc. Beige Micro. 21: 8. Couch, 1935. Mycologia 27: 384. L. Oedogonii Scherffel, 1902. Hedwigia 41: (105). 19->5, Arch. Protistk.o-': 109. Couch, 1935. Mycologia 27: 386. Liit/iii'iiHtim sp. Couch, 193.5, I.e., p. 38.3. OVpidiopsis Oedogoniorum Scherffel, 1925. Arch. Protistk. 52: 109. Sparrow, 1933. Mycologia 25: 516. O. fti.iiftirmi.i var. Oedogoniarum Sorokin, 1883. Arch. Hot. Nord France 2: 29. 1889, Rev. Mycol. 1 1 : 89. Olpidium Oedogoniarum (?) De Wildeman, 1894. Ann. Soc. Beige Micro. 18: 151. Resticularia Oedogonii Skvort/.ow, 1925. Arch. Protistk. 51: 132. ( ledogonium boscii Lit tit n itl in ni syncytiorum Klebahn, 1892. Jahrb. Wiss. Rot. 24: .'03. Oedogonium crassusculum var. idiosporium Woronina polycystic Cook, 1932. New Phytol.31: 131. ( ledogonium franklinianum 1,11 Iff uillill III Sp. (?) Scherffel, 1926. Arch. 1'rotistk. 51: 246. i Oedogonium obsidionale Achlyogeton solatium Cornu, 1870. Hull. Soc. Hot. prance 17: 298. ( ledogonium orthospira hag* niiittt in rabt nkorstii C.raff. 1928. Mycologia 20: 169. i 'ladophoract "• Chaetomorpha aerea Ltttjt niilin in 5 |>. Deckenbach, L903. Flora 92: 278. 116 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES Cladophora sp. Achlyogeton entophytum Schenk, 1859. Bot. Zeit. 17: 399. Sorokin, 1876. Ann. Sci. Nat. 6 ser. 4: 63. 1883, Arch. Bot. Nord France 2: 44. 1889, Rev. Mycol. 11: 139. Martin, 1927. Mycologia 19: 188. Tokunaga, 1934. Trans. Sapporo Nat. Hist. Soc. 13: 227. B icriciu m t ra nsi'e rsum Sorokin, 1883. Arch. Bot. Nord France 2: 43. 1889, Rev. Mycol. 11: 138. Myzocytium proliferum Walk, 1870. Bot. Zeit. 28: 553. Martin, 1927. Mycologia 19: 188. Tokunaga, 1934. Trans. Sapporo Nat. Hist. Soc. 13: 228. Sirolpidium Bryopsidis Sparrow, 1936. Biol. Bull. 70: 252. Cladophora flavaescens A chlyogeton salin u m Dangeard, 1932. Le Bot. 24: 240. Cladophora kuetzingiana M yzocytiu m p roliferwn Graff, 1928. Mycologia 20: 168. Cladophora laetevirens A chlyogeton salin » m Dangeard, 1932. Le Bot. 24: 240. Bryopsidaeeae Bryopsis plumosa Olpidium B ryopsidis De Bruyne, 1890. Arch. Biol. 10: 85. Sirolpidium Bryopsidis (de Bruyne) Petersen, 1905. Overs. Kge. Dansk. Vids. Selsk. Fork no. 5:479. Sparrow, 1934. Dansk. Bot. Ark. 8, no. 6: 9. 1936, Biol. Bull. 70: 252. Vaucheriaceae Vaucheria sp. - Woronina glume rata Scherffel, 1925. Arch. Protistk. 52: 59. Valkanov, 1931. Ibid. 73: 361. 1940, Ibid. 93: 240. Vaucheria sessilis Chytridium glomeratum Cornu, 1872. Ann. Sci. Nat. 5 ser. 15: 187. Woronina glornerata (Cornu) Fischer, 1892. Rabenhorst's Krypt'fl. I, 4: 64. Zopf, 1894. Phys. Morph. Med. Organismen 2: 46. Tokunaga, 1933. Trans. Sapporo Nat. Hist. Soc. 13: 26. Vaucheria terrestris Chy t ridin m glo m e ra t u m Cornu, 1872. Ann. Sci. Nat. 5 ser. 15: 187. Woronina glornerata (Cornu) Fischer, 1892. Rabenhorst's Krypt'fl. I, 4: 64. Zopf, 1894. Phys. Morph. Nied. Organismen 2: 46. Characeae Chara sp. Lagenidiopsis reducta De Wildeman, 1896. Ann. Soc. Beige Micro. 20: 109. PHAEOPHYCEAE Eetocarpaceae Akinetospora sp. Eurychasma dieksonii Petersen, 1905. Overs. Kgl. Dansk. Vids. Selsk. Forh. 5: 477. Ectocarpus sp. Eurychasma dickson ii Petersen, 1905, I.e., p. 476. Johnson, 1909. Sci. Proc. Roy. Dublin Soc. 12: 142. Dangeard, 1934. Ann. Protist. 4: 69. Petersenia andreei Sparrow, 1934. Dansk. Bot. Ark. 8, no. 6: 17. Ectocarpus confervoides Rhizophidium dieksonii Hauck, 1878. Oesterr. Bot. Zeitschr. 28: 321. Eurychasma dieksonii Petersen, 1905. Overs. Kgl. Dansk. Vids. Selsk. Forh. 5:477. Ectocarpus crinitus Rhizophidium dieksonii Hauck, 1878. Oesterr. Bot. Zeitschr. 28: 321. Wright, 1879. Trans. Roy. Irish Acad. 26: 369. Ectocarpus sandrianus En rychasma dieksonii Petersen, 1905. Overs. Kgl. Dansk. Vids. Selsk. Forh. 5:477. Ectocarpus granulosus Rh izoph id hi in dickson ii Wright, 1879. Trans. Roy. Irish Acad. 26: 369. Ectocarpus sandrianus Eurychasma dieksonii Petersen, 1905. Overs. Kgl. Dansk. Vids. Selsk. Forh. 5:477. Ectocarpus siliculosus Rhizophidium dieksonii Rattray, 1884. Trans. Edinburgh Roy. Soc. 32: 589. Petersenia andreei Sparrow, 1936. Biol. Bull. 70: 245. Pylaiella littoralis Rhizophidium dieksonii Wright, 1879. Trans. Roy. Irish Acad. 26: 369. Wille, 1899. Vids. Selsk.Math.-Nat. Klasse I, 3: 2. Lowenthal, 1905. Arch. Protistk. 5: 225. Eurychasma dieksonii Petersen, 1905. Overs. Kgl. Dansk. Vids. Selsk. Forh. 5:476. Striaria attenuata Rhizophidium dieksonii Wright, 1879. Trans. Roy. Irish Acad. 26: 369. Hauck, 1878. Oesterr. Bot. Zeitschr. 28: 321. Striaria attenuata var. fragilis Olpidium dieksonii var. Striariae Wille, 1899. Vid. Selsk. Math.-Xat. Klasse I, 3: 2. Stictyosiphon corbierei Eurychasma dieksonii Dangeard, 1934. Ann. Protist. 4: 69. Stictyosiphon tortilis Eurychasma dieksonii Petersen, 1905. Overs. Kgl. Dansk. Vids. Selsk. Forh. 5:477. UHODOPHYCEAE Ccraniiaceae Callithamnion corymbosum Pleotrachelus lobatus Petersen, 1905. Overs. Kgl. Dansk. Vids. Selsk. Forh. 5: 460. II..- I S Wll mill. I1H, IIA1MI V 117 Callithamnlon hookerl /'/. otrachi In* lobatui Petersen, 1906, l.c, p. 169. Callithamnion roseum l'i ti r.n ni'i Inlmlii Sparrow, i9:tii. Biol. Bull, 70: MS. Ceramium sp. Pontitma lagt nidioidet Petersen, 190S. Overs. Kgl. Dansk. Vids. Selsk. Forh. .-»: 189. I'll ill nirlii Ins (l'i ii r-'i ni'i) pollagasttr Sparrow, 1934. Dansk. Bot Ark. 8, no. 6: 15. Ceramium acanthonotum i hill riil in in liiinifiirii i/.-' Magnus, 1879a. Sitcb. Gesell. Nat. Preunde. Berlin 1879: B7. 1879b, Jahresb. Komm. Untersuch. Deut. Meere Kiel i: 76. is?:i. Hedwigia 19: 88. Ceramium diaphanum I'tintisnm lui/i iiiiliniili 8 Sparrow, 1936. Biol. Bull. 70: 259. h'liri/iliii.iiiiiiliiint liimifttrit nt Sparrow, 1936, l.c, p. 241. Pi ti r.n nin -p. Sparrow, 1936, l.c., p. -'43. Ceramium flabelligerum ' 'Imt riiliu in I ii inifiii-ii ii.i Magnus, 1879a. Sit/.l>. Gesell. Nat. Preunde Berlin 1879: 87. IST.'I). Jahresb. Komm. Untersuch. Deut. Meere Kiel 2: 76. 18T3, Hedwigia 19: 28. I tl fiiilin in I n mifitririt.i Fischer. 1899. Rabenhorst's Krypt'fl. I, 4: 27. Enri/rhns mill in in I n mifaciens Sparrow, lo:J(». Biol. Bull. 70: 241. Ceramium fructiculosum I'tilifixinu Ini/i niiliiiitliK SpaiTOW, 1934. Dansk. Bot. Ark. 8, no. Ii : 11. Ceramium rubrum I'mi Ii.i inn In iii iiiiliniili \e Petersen. 1911."). Overs. Kgl. Dansk. Yiils. Selsk. Forh. .-,: is.'. I'll ill rnrhiliiK jmllniiti.il i r Petersen, 1905, I.e., i>. 469. Ceramium tenuissimum I 'mi Ii.i inn III it i Iiiiliniili .1 Petersen, 1905, I.e., i>. 482. Seirospora interrupta /'. 1 1 r.n nin Inhata Peldmann, 1940. Hull. Soc. Hist. Nat. Afrique Nord 31: 79. Spermothamnion repens I'll i r.n nin liilml a Sparrow. 1934. Dansk. Hot. Ark. s. no. ii: 13. Spermothamnion turner! I'll nt nirlii ln.i liilml ii.i Petersen. 1905. Overs. Kgl. Dansk. Vids. Selsk. Forh. .-,: too. Ixhmlilmi ninri in 1 lalosaccion ramentaceum I'.iiriii-lni.'iiiii .'inriilii.1 Petersen, I905, I.e.. p. 477. Khoilmenia palmata Ii H f tlrlnts urn snrr ultl.i Petersen. 1110"). I.e.. p. 177. Rhodophyllidiaceae ( \ stoeloniuni pu rpn raseens I'lirrlmsnniK nut r in its Juel, 191)1. Kih. Kgl. Svensk. Vet. Ak.nl. Hand. 36, afd. III. no. ii: it. 1901, Rev. Mycol. _>i: in. BRYOPHYTA HEPATICEAE li irrinriitr Riccia sp. ( II fiii Hi i/i.i i.i liirritir l)u PleSSiS, 1933. Ann. Hot. 47: 761. Muse! Unidentified moss species Lagcnidiit m ell i [it irn m De Wildeman, 1893. Ann. Soc. Beige Micro. 17: 5. 1893, Jour. Roy. Micro. Soc. 1893: 765. SPERMATOPHYTA GYMNOSPERMAE I'initrt hi Allies canadensis Lag e it iil't ti m pyg m n nt m Karling, 1941. Mvcologia 33: 358. Pinus sp. Lagenidium pygmaeum Seluiltz-Danzig, 1923. Schr. Sussw.-und M 180. ieerest. 11: Pinus austriaca Lagenidium pygmaeum Zopf, 1887. Alili. Nat. Gesell. Halle 17: 97. Karling, 1941, I.e., p. 358. Pinus austriaca var. nigra Lagenidium pygmaeum Karling, 1941, I.e., p. 358. Pinus banksiana Lagenidium pygmaeum Karling, 1941, I.e., p. 358. Pinus densiflora Lfii/i niiHii in pygmat nm Karling. 1941. I.e., p. 358. Pinus larieio Lagenidium pygmaeum Zopf, 1887, I.e., p. 97. Pinus pallasiana Lagenidium pygmai nm Zopf, lSS7,l'.e.. p. 97. Pinus strobus Likii iiiilinm pygmat nm Karling. 1941, I.e.. p. 358. 118 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES Pinus sylvestris Lagenidium pygmaeum Zopf, 1887. Abb. Nat. Gesell. Halle 17: 97. Karling, 1941, I.e., p. 358. 1941, Torreya 41 : 108. Pinus thunberghii Lagenidium pygmaeum karling, 1941. Mycologia 33: 358. Unidentified conifer pollen grains Lagenidium pygmaeum Maurizio, 1895. Jahrsb. Nat. Gesell. Graiibundens 39:14. De Wildeman, 1895. Ann. Soc. Beige Micro. 19: 68. Petersen, 1909. Bot. Tidsskr. 29: 401. 1910, Ann. My col. 8: 537. ANGIOSPERMAE Gramineae Agropyron repens Lagena radicicola Vanterpool and Ledingham, 1930. Canad. Jour. Res. 2: 177. Truscott, 1933. Mycologia 25: 263. Hordeum vulgare Lagena radicicola Vanterpool and Ledingham, 1930, I.e. Saccharum offieinarium Chytrid sp. Carpenter, 1940. Tbe Hawaiian Planter's Record 1:44. Secale sereale Lagena radicicola Vanterpool and Ledingham, 1930, I.e. Triticum aestivum Lagena radicicola Vanterpool and Ledingham, 1930, I.e. Triticum durum Lagena radicicola Vanterpool and Ledingham, 1930, I.e. 7,ea mays Lagena radicicola Vanterpool and Ledingham, 1930, I.e. Other wild grasses Lagena radicicola Truscott, 1933, I.e., p. 363. Ulmaceae Ulmus americana Carpenterella molinea Tehon, L. R., and H. A. Harris, 128. Solanaceae ANIMALS INFUSORIA 1941. Mycologia 33: Nicotiana sp. (?) Myzocytium sp. (?) Preissecker, 1905. Fachl. Mitteil. Oesterr. Tabakregie 5, heft. 1 : 3. Caryophyllaceae Stellaria media Myzocyticuta sp. (?) Barrett, 1935. Phytopath. 25: 898. Vortieella sp. Ectro g el la pe rfo ran s Sparrow, 1936. Biol. Bull. 70: 241. Vortieella microsoma Myzocytium sp. (?) Stein, 1851. Zeitschr. Wiss. Zool. 3: 476. 1854, Infusionsthiere und ihre Entw. Leipzig. Die Vortieella nebulifera Myzocytium sp. (?) Stein, 1859. Der Organismus der Infusionsthiere. 1 abt., p. 106. ROTATORIA Philodina rosetta Chytridium elegans Perroncito, 1888. Centralbl. Bakt. Parasitk. 4: 295. Woronma elegant Fischer, 1892. Rabenhorst's Krypt'fi. I, 4: 66. Unidentified rotifers, eggs, and embryos Peters enia sp. (?) Sparrow, 1936. Biol. Bull. 70: 244. .1/ yzocytium zoophthorum Sparrow, 1936. Jour. Linn. Soc. London Bot. 50: 461. Lagenidium Oophilum Sparrow, 1939. Mycologia 31: 531. Lagena oophilum Sparrow, 1939, I.e. NEMATODA Anguillula sp. Achlyogeton (?) rostratum Sorokin, 1876. Ann. Sci. Nat. 6 ser. 4: 64. Myzocytium proliferum var. oermicolum Zopf, 1884. Nova Acta Ksl. Leop.-Carol. Deut. Akad. Nat. 47: 167. Myzocytiu m verm icolu m Fischer, 1892. Rabenhorst's Krypt'fi. I, 4: 75. Dangeard, 1906. Le Bot. 9: 207. Bicricium lethale Sorokin, 1883. Arch. Bot. Nord France 2: 37. 1889, Rev. Mycol. 11: 138. Protascus subuliformis Dangeard, 1903. C. R. Acad. Sci. Paris 136: 628. 1906, Le Bot. 9:256. Rhabditis doliehura Protascus sub u lifo rm is Maupas, 1915. Bull. Soc. Hist. Nat. Afric. 6: 34. Protascus subuliformis var. maupasii Maire, 1915. Ibid, 6: 50. Rhabditis giardi Protascus subuliformis Maupas, 1915, I.e., p. 34. Protascus subuliformis var. maupasii Maire, 1915, I.e., p. 50. Rhabditis teres Protascus subuliformis Maupas, 1915, I.e., p. 34. Protascus subuliformis var. maupasii Maire, 1915, I.e., p. 50. HOSTS \ Mi BIBLIOQB WHY 1 IS* Unidentified nematodes Anlsplia ausl riac i Myzocytnimvtrmicoliim Olpidioptis (?) uerainica Valkanov, 1931. ^.rch. Protistk. 73: 365. Wfase, 1904. Bull. Inter. L'Acad, Sri. Cracovie 1904: rin. Dll'l F.HA Cleonus punctivenl ris Olpidiopiu (?) uerainica Mosquito larvae Wire, 1904, I.e., p. 713. l.mji milium ingnnii-nm Couch, 1935. Mycolgia .•7: 376. Matthews, 1935. Jour. Elisha Mitchell Sci. Sue 51: CRUSTACEAE 309. ,. , I yclops >p. Dipterous pupae BUuUdi&iopti* chattoni Myrophagvs ureramicui Sigot, 1931. C. R. Soc. Biol. 108: 37. Sparrow, 1939. Mycologia 31: 443. Petch, 1940. The Naturalist no. 998:68. apnne sp. .,..,..,.,, Liii/i nullum iiiqiiiitiiim Entomophthora (Tanehtam) retxculata ■ .,„;.',, , ' v ' , ( .inch lOH.i \l\'rnlii. Unidentified copepods COLEOPTERA Lagenidium giganteum Couch, 1933, I.e., p. :i?li. Acanthonomus grandis Pteudolpidium *]>. (?) Callinectes s;q>i /iV, 79 sp., 83 THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMVCETES SPECIES INDEX Mitochytridium, 98 ramosum , 98 Myzocytium, 83 globosum, 86 irregulare, 88 linear e, 88 megastomum, 89 polymorphism, 89 proliferum, 86 vermicolum, 88 zoophthorum, 89 sp., 89, 90 Olpidiopsis, 31 Achlyae, 46 andrcei, 51 Aphanomycis, 47 appendiculata, 51 brernspinosa, 48 curvispinosa, 48 echinata, 41 elliptica, 50 fibrillosa, 50 fusiformis, 45 fusiformis var., Oedogoniarum 51 gracile, 47 incrassata, 44 index, 45 irregularis, 44 luxurians , 47 major, 44 minor, 45 Oedogoniorum, 51 parasitica, 48 Pyifeii, 47 Ricciae, 52 Saprolegniae, 41 , 44 Saprolegniae var., learis, 44 schenkiana, 48 sorokinii, 50 Sphaeritae, 54 spinosa, 45 ucrainica, 52 various, 46 vexans, 44 sopfii, 50 Petersenia, 66 andreei, 5 1 lobata, 68 sp., 68 Pleocystidium, 48 parasiticum, 48 Pontisma, 66 lagenidioides, 66 Protascus, 96 subuliformis, 97 subuliformis var., maupasii, 97 Pseudolpidium, 52 aphanomycis, 47 deformans, 54 fusiforme, 45 (ilenodinianum, 54 gracile, 47 incrassatum, 44 i'v^/u'i, 47 Saprolegniae, 41 Sphaeritae, 54 stellatum, 46 sp.. 55 Pseudolpidiopsis, 50 appendiculata, 51 elliptica, 50 fibrillosa, 50 parasitica, 48 schenkiana, 48 sopfii, 50 Pseudosphaerita, 55 Euglenae, 56 radiata, 56 Pyrrhosorus, 10 marinus, 10 Pythiella, 58 vernalis, 59 Resticularia, 92 boodlei, 93 nodosa, 93 Oedogonii, 93 Rhi/.omyxa, 90, 98 hypogea, 90 Rozellopsis, 12 infiata, 1 4 septigeua, 16 simulans, 16 icaterhouseii, 1 1 Sirolpidium, 63 Bryopsidis, 66 Lagenidioides, 66 Woronina, 6 aggregata, 8 asterina, 10 elegans, 8 glomerata, 8 pol ycystis, 7 polycystis var.. '•alariformis, 7 SiH.IKCT INDKX 121 SUBJECT INDKX Ablet, 79 Aehlya, 7. in. 16, 11. it. 16, 16. 108, 106 Acrasieae, 7 Aerotiphonia, 51 Agropyron, 92 Akinetotpora, 2 t Albuginaceae, 1 06 Amphora, 7s Amylophagus, 103 Aiii* pi i. 1. 2, 18, 100. 102, 105, 107 Chytridium, 8, 2 1. 26 ( lladochytriaceae, 98 Cladophora, 66, 79, 88, 94 Cleavage, 34, 36, 74, 102 Cleonut, 52 Closterium, 80, 82, 86, 88, 89, 97 Cocconema, 7s Copepod, s:i Ciixmiiriiim, 86, !<7 Crnstaceae, 1 1 9 Cryptomonat, 58 Cyclops, 58 Cyclotella, B2 Cymatopleura, 78 Cymbanche, 20 Cymbello, 30, 78, 82 ( ' yttoclonium, 10 Cystospores, 30, 36 Cystosorus, 7. 8, 10 Daphne, 88 Dictiiiuhiis, 38, 11,103 Diplanetism, 17. 20, 21, 23. 2S. 86, 76, 94, 10 1. 106 Diplogatter, 97 Dioecism, 92 Diiciiliiim, 98 Drapamaldia, 55 Ectocarpus, 23. 51 Entomophthorales, 93 Entomophthora, 52 Epiplasm, 72 Epithemia, 30 Euastrum, 78. 80 Euglena, ~>~i. 56 Eurychasmaceae, 17 Exospore formation, 13, 1 1, 39 Glenodinium, 54 Glycogen, 8 Gomphonema, 20, 22, 78, 82 Gymnococcaceae, 7 Gymnococcus, 7 Halo&accion, 24 Haplosynoecious, to Heteroeont. 36, 54, 81 Heterogamy, 38, 39, 59, 71 Heterothaliie. 40, 70, 71 Homothallic. 10, 70. 71 Hbrdeum, 92 Hydrodiciyon, 79 Hypertrophy, 21 Isoachlya, 33, 11. 11 Isocont, 10, 28. 31, 36, 92 Isogamy, 38. 92, 96, 105, 107 Karyogamy, 39. 10 Labi/riiitliula, 62 Lauderia, 2 t Leptolegnia, 33,4 1 Leptomitaceae, 106 lAcmophora, 21. 22 Ligniera, 6, 100 JLyngbya, 98 Meiosis, 38 Meridon, 20 Mesocarpus, 50, 5 1 . 77. 86 Microasterius, 78, 86, 88 Monadineae, 100, 102 Monoecism, 76 Monozoospore cultures, 32, 10 Mosquito, S3 Mosses, 80 Mougeotia, 50, 77. 86 Myxochytridiales, 1. 104 Myxozoidia, (i. 10 1 Navicula, 78 Nematodes, S3. 88, 96 "Net sporangium," 23 Nitella, 79 Nitsichia, 20, 30,82 Nuclear division, 38 Octomyxa, 6, 12, 100 Otdogonium, 51, 77. 79. 80, 81, 90, 96 Olpidiaceae, 17. 103 Olpidium, 20. 28, 51, 5 1. 63 Ooplasm, 76 Parthenogenesis, 88, 76, 78, 79 Pciiiiim, S3 Periplasm, 38, 76. 105. 107 Peronosporaceae, 100, 103, 106, 107 Philodina, S Phytophthora, 12, 15, 16 Pilobolus, 8 Pinnularia, 20. 30 l'imis, 78 Pithophora, 79 Plasmodiophorales, 6, 7. 98. 100. 101, 107 Plasmodium. 3, 5, 6, 7, 8, 10. 1 1 Plasmoganiy, 39, 10 Pleolpidium, 12, 11 Pleurosigma, 20 Pleurotaenium, 30. 80. 88 Pleotrachelus, 20. 26. 51. 68 Pon, 92 Polymyxa, 6,100 Pringsheimella, 7. 101 Proteomyxa, 6. 100, 101 Protoachlya, 33, 11 Pseudolpidiaceae, 2 Pseudospora, 103 Pseudosporopsis, 1 03 Pylaiella, 23 Pythiaceae, 1, 105, 106 Pythiogeton, 103. 106 P lithium, 14, 36. K). t7, 59, 77, 101. 105, 106 Rhabditis, 97 Rhisophidium, 22 Rhizidiomyces, 106 Rhodymenia, 21 Riccia, 52 Rotifer, 68, 83, 89 Rossella, 12, 13. 11. 101 Saprolegnia,7, 16. IS. H. 14, 108, 106 Schizogony, 6. 7. ioi Secede, 92 Septolpidium, 9 1 Sex determination. 39, 10 Sexuality, 30, 10 Seirospora, 68 Siim/ixix, 92 Sor olpidium, 1 2 Sorus. 2,6, 7. S. 10 Sphaerita, 5 1. 55. 56 Spermothamnium, 68 Spirogyra, 50, 77, 78, 79, 89 122 THE SIMPLE HOLOCARPIC BIFLAOELLATE PHYCOMYCETES Spirotaenia, 89 Spongomorpha, 51 Sporangiosorus, 5, 6, 7, 8 Spore mother cells, 12, 101 "Spreizapparat," 18, 19, 22 Staurastrum, 115 StauroneiSj 78 St ell aria, 90 Stictyosiphon, 24 Stigeoclonium, 79, 97 Striaria, 23 Striatella, 21 Surirella, 30 Symbiosis, 41 Synchytriaceae, 4, 1 8 Synchytrium, 18 Synedra, 20,21, 82, 89 Tetramyxa, 12 "Theilplasmodien," 7 "Tinsel" flagella, 95, 105, 107 Tobacco, 90 Tolypoihrij-,93 Tribonema, 50 Triticum, 92 V aucheria, 8 Vesicle, 70, 73, 77, 78, 84, 86, 88 Vorticella, 21, 89, 90 Zea, 92 Zygnema, 77, 86 Zygomycetes, 93, 107 AUTHOR INDEX Archer. 30,41 Atkinson, 77, 78, 79, 100, 106, 107 Barnes. 102 Barrett, 38, 39, 40, 41, 44, 47, 90 Behla, 41 Berdan, 70, 89 Bessey, 100, 105, 106 Bisby, 47, 50 Borzi, 71, 90, 98 Braun, 1, 41 Brodsky, 55 Butler,"]!, 15, 32, 39, 47, 50, 98 Carpenter, 60 Carter, 78 Cavers, 100, 106 Cejp, 45, 56, 77, 80, 88, 89 Chatton, 55 Chaudhuri, 88 Cienkowski, 1,45 Clements, 105 Cocconi, 77 Coker, 17, 28, 36, 41, 44, 105 Constantineanu, 36, 41, 44, 45, 50, 77, 88 Cook, 6, 7. 71. 76, 79, 100, 106 Cornu, 2, 6, 8. 31, 41, 45, 47, 79, 96 Couch, 7, 41, 58, 59, 74, 80, 81, 82, 93, 98,100 Cramer, 26 Dangeard, 7, 31, 41, 47, 54, 55, 58, 86, 92, 96, 97, 98, 102, 106 Davis, 41 De Bary, 100, 102, 105 De Bruyne, 66 Deckenbach, 83 Diehl, 41 Dodge, 71. 100, 105 Domjan, 20, 77 Du Plessis, 36, 52 Feldmann, 68 Fisch, 31, 32, 48, 50 Fischer, 4, 6, 8, 16, 24, 31, 32, 44, 45, 48, 88, 93, 96 Fitzpatrick. 93. 96, 97, 100, 102, 106 Focke, 21 Fritsch, 93 Gaiimann, 71, 100, 105 Gill, 20 Gilman 41 Graff, 41,77, 88 Gran, 24 Gwynne-Vaughan, 102 Harper, 17 Harris, 60 Hartog, 7 Harvey, 24, 41 Hauck, 23 Jahn, 55 Johnson, 23 Jokl. 51, 52 Juel, 10, 11 Karling, 6. 12, 13, 14, 21, 78, 79, 100 Klebahn, 79 Krafka, 55 Kiitzing, 24 Lagerheim, 51 Ledingham, 90, 92, 100 Lind. 88 Lindstedt, 86 Lotsy, 2, 100 Lowenthal, 22, 23 Magnus, 22, 24, 25, 26 Maire, 100 Maneval, 41 Martin, 94 Matthews, 17, 28, 45, 83, 105 Maupas, 89,96. 97 Maurizio, 7, 16,44, 78 McLarty, 32, 34, 38, 39, 40, 42, 46 Mez, 102 Miller, 55 Minden, 2, 4, 16, 45, 47, 50, 51, 102, 106 Mitchell. 31, 55 Mundkur, 88 Niigeli, 1.41 Niigler, 55, 56 Nicholson, 6, 7 Perroncito, 8 Petch, 52 Petersen, 7, 17, 21, 22, 24, 26, 41, 44, 51, 63, 68, 78, 88, 102, 104 Pfitzer, 20 Preissecker, 90 Pringsheim, 1, 20, 41, 77, 105 Pumaly, 56 Ramsbottom, 7, 20, 26 Rattray, 23 AUTHOR INDEX 128 Reinsch, 2, 82, 1 1 . i"> Thompson, 88, 89 Saccardo, 98 Tison, lot) Sawada, i">. Hi Tokunaga, 8, 10, 16,28, 15, 1-7. 50, 94, ioi Schenk, 2, 71,88, 86,94, 105 Truscott, 92 Scherffel, 8, 6, 8, 17. 20, 22, 28, 80, 50, 7 1. 78, 81, Turner, 90 82, 100, 102, L06 Valkanov, 8, 77, 88 Schroeter, 2, 24, 81, 1-8. 50, 70. 86, 102, 105 Van rleurck, 20 Schulta-Danaig, 78 Vanterpool, 90, 92 Schwarae, 17. H Vuillcmin,2, loo Serbinow, 5 1. 55, 7!'. 8 I Wala, 2, 86, 105 Shanor, 82, 84, H, 14, 15, Hi Waterhouse, 16 Shear, 105 West, 28, 30 Sigot, 58 Weston, 2 Skvortaow, 78, 89, !>.-i Wettstein, 100. 105 Smith. 7,20,26 Whiffen, 32, 1,7, 1-8 Sorokin, II, 1 1. 15,51,83,86,94,96 Wildeman, 20, 26, 32, 50, 71, 77, 78, 80, 81 Sparrow, •-'. 1. 6, 20, 21, 24, 26, 11, 14, 17. 51, 63, Wille, 23 66, 83, 89, 104 Winge, 1-'. 100 St,in. 56, 58, 89 Wize, 52 Swingle, 17 Wolk, 96 Tavel, 100, 102, 105 Wright, 23 T. lion. 60 Zopf, 2, 6, 7, 8, 17, 32, 48, 50, 76, 78, 86, 100, 106