88 



PLASMODIOPHORALES 



larities are incommensurable and that the two groups 

 have but little in common. Most of the objections 

 raised by Cook, however, are no longer tenable in 

 the light of more recent discoveries in the Plasmodio- 

 phorales. 



Plasmodiophorales, Proteomyxa, and Other 

 Protozoa 



Inasmuch as the names Monadineae, Myxozoidia, 

 and Proteomyxa are more or less synonymous and 

 have been ratlier loosely used in the literature, a brief 

 discussion of tiieir terminology is essential before 

 proceeding to the questions of relationship with and 

 origin of the Plasmodiophorales from this group of 

 simple organisms. The term Monadineae was first 

 employed by Cienkowski ('65) for a number of 

 primitive organisms whose vegetative reproductive 

 cell develops into amoeboid or plasmodial thalli 

 which are capable of engulfing solid food particles. 

 Following the feeding and growing stage the thalli 

 develop distinct membranes, discharge the extrane- 

 ous food material into a large vacuole, undergo cleav- 

 age, and form zoospores or small amoebae. At the 

 conclusion of this phase, resting spores are formed. 

 Cienkowski divided these organisms into two groups, 

 Monadineae zoosporeae and Monadineae tetraplas- 

 tae, depending on whetlier zoospores or Actinophrys- 

 like amoebae are produced. Many of these aquatic 

 monadinaceous species were later included by Klein 

 ('82) in a new family, Hydromyxaceae, but this 

 name was not widely accepted at that time. More re- 

 cently, however this family was emended by Jahn 

 ('28), raised to ordinal rank, and included as the 

 first order of the Myxomycetes. In 1884 Zopf gave 

 an extended account of the Monadineae in his book 

 on the "Pilzthiere or Schleimpilze" in which he con- 

 tinued Cienkowski's terminology for the whole group 

 but changed the division Monadineae tetraplastae to 

 Monadineae azoosporeae. The following ye ir, how- 

 ever, Lankester created a new class, ProtL.imyxa, of 

 protozoa to include the Monadineae of Cienkowski 

 and Zopf as well as Plasmodiophora and Tetramyxa. 

 In 1 893 Klebs pointed out that continued use of the 

 term Monadineae in the sense of Cienkowski would 

 lead to confusion inasmuch as this name had pre- 

 viously been applied to a group of flagellates of 

 which Monas is the type genus. Zopf ('91) accord- 

 ingly proposed an alternate name, Myxozoidia, for 

 Cienkowski's Monadineae. Doubtless because Zopf's 

 paper was not published in a prominent journal, his 

 term did not become generally known. Lankester's 

 term was accepted by most protozoologists and has 

 accordinglv displaced the terms Monadineae and 

 Myxozoidia in the literature on protozoa. Proto- 

 phytologists, however, have continued to use Cien- 

 kowski's term. According to present-day interpreta- 

 tions the Proteomyxa embraces several families of 

 incompletely known rhizopod-like species, which 

 protozoologists include in the sub-class Rhizopoda 

 of the Sarcodina. For the sake of emphasis and clar- 

 ity, relationships with the Proteomyxa will be dis- 

 cussed here apart from the Protozoa in general, but 



such treatment does not imply that this order is to 

 be excluded from the Rhizopoda. 



As Zopf early pointed out, the life cycles of cer- 

 tain monadinaceous species, particularly of the fam- 

 ily Gymnococcaceae, are similar in many respects to 

 those of the Plasmodiophoraceae, and for this rea- 

 son he included both families in the same division of 

 the Monadineae. Subsequent studies by de Bruyne 

 ('90), Scherffel ('2.5), and others have supported 

 Zopf's observations and emphasized these similari- 

 ties even more fully. As a result of such studies, some 

 of these proteomyxean species are now known to 

 have anteriorly biflagellate, heterocont zoospores, 



PLATE 17 

 Physarella, Fulii/o, and Diclymiiim 



Fig. 1. Anteriorly uniflagellate zoospore of Physarella 

 oblonc/a with two "basal bodies." Sinoto and Yuasa, '34. 



Fig. 3. Biflagellate heterocont zoospores of P. ohlonga 

 with two "basal bodies." Note tail piece at end of flagella. 

 Sinoto and Yuasa, I.e. 



Fig. 3. Biflagellate isocont zoospore of P. ohlonga with 

 two "basal bodies." Sinoto and Yuasa, I.e. 



Fig. -1. Triflagellate heterocont zoospore of Fuligo sep- 

 tica with two short flagella attached to one "basal body." 

 Yuasa, '35. 



Fig. 5. Biflagellate heterocont zoospore of F. scptica 

 with "two basal bodies." Yuasa, I.e. 



Fig. 6. Biflagellate heterocont zoospore of D. Xanthopus 

 with several "basal bodies." Stosch, '35. 



PgeiidoKporopsis, Amijlophagus. Gymnococnts, and 

 Aphelkliopsts 



Fig. 7, 8. Anteriorly biflagellate heterocont zoospores of 

 Pseudosporopsis sp. (Bodo ylobosus) with numerous en- 

 gulfed food particles. Short flagellum extending forward. 

 Scherffel, '-'5. 



Fig. 9, 10. Zoospores of same with contractile vacuoles 

 and nucleus. Scherffel, I.e. 



Fig. 11. Anteriorly biflagellate heterocont zoospores of 

 Amylophayus algarum with two contractile vacuoles. Long 

 flagellum extending forward. Scherffel, I.e. 



Fig. li. Amoeboid stage of same. Scherffel, I.e. 



Fig. 13. Anteriorly biflagellate heterocont zoospore of 

 P. rotatoriorum witb two contractile vacuoles; long flagel- 

 lum extending forward. Scherffel, I.e. 



Fig. U. Anteriorly biflagellate zoospores of .1 phelidiop- 

 six epithemiae. Scberftel, I.e. 



Fig. 15. Large plasmodium ( ?), J. epithemiae, with ex- 

 traneous food material in a large central vacuole. Scherf- 

 fel, I.e. 



Fig. 16. Zoocysts of J. epithemiae. Scherffel, I.e. 



Fig. 17. Deliquesced zoocysts and emerging zoospores of 

 ./. epithemiae. Scberffel, I.e. 



Fig. 18. Eleven zoosporangia, five of which are filled 

 with zoospores, from a single tballus of G. Cladophorae : 

 extruded waste material between sporangia. De Bruyne, 

 '90. 



Fig. 19. Zoocyst of -/. algannn. Scherffel, I.e. 



Fig. -20. Emergence of zoospore through zoocyst wall in 

 ./. algarum. Scherffel, I.e. 



Fig. 21. Sporocyst of P. rotatoriorum with six resting 

 spores. Scberffel, I.e. 



Fig. 22. Resting spores of J phelidiop.iis epithemiae. 

 Scherffel, I.e. 



