IMlVI.OliKNV AM) ItKI.ATIOXSlIll'S 



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spoki-ii. l-'itzpatrick (^'30) was tlit- first to ilctinitily 

 iiu-ludc this family in tin- C'liytridialcs lu'xt to the 

 W'tironiiiai-tai- and Syiu-liytriaccai'. and niaintaiiu'd 

 that tluy havi' inoro in coninion with these two oliy- 

 tridiaoeoiis families than witli the Myxomycotes. In 

 so doin^. however, he did not imply a elose relation- 

 ship. Fitzpatriek exi)ressed the opinion that the Syn- 

 ehytriaeeae. Woroninaeeae. and Plasmodiophor.a- 

 ceae "h.ive arisen more or less in p.-irallel from yet 

 more ))riinitive protozoa and wholly in(Ie])eti(leiit of 

 the Myxoii.-istres." W'ettstein ('8.">) .ilso ineluded the 

 I'lasniodiophorales amoiiir the ehytrids next to the 

 Synehytriaeeae and stated that their eytolo^y as 

 well as the prcscnee of eliitin in the walls indieates a 

 close rel.-itionship. Cadnian ('31) and Bessey ('3.5), 

 however, believed that the Plasniodio])horales show 

 a closer affinity to the Myxomyeetes. and the former 

 worker listed them as a sub-group of the Myxomy- 

 eetes. .Martin ( 3(>) listed the Plasmodio))lioralcs as 

 the lowest order of the Phyeomyeetes but distinct 

 from the so-called niyxochytridiales. 



On the other hand, Ciwvnne-\augiian .md Barnes 

 ('26, '37) maintained that the Plasniodio])Iiorales 

 and Myxomyeetes are not fungi and have doubtless 

 arisen from lower forms along inde))endent lines. 

 Cook ('26) agreed in general with these mycologists 

 and expressed the view that "it seems very desirable 

 to keep the Plasmodiophorales quite separate from 

 the Chytridiales and other fungi. If there is any rela- 

 tionship, it is most likely through the Mycetozoa." 

 In I92S. however, he held that the Plasmodiophora- 

 ceae and Myxomyeetes originated from a proteomyx- 

 ean eomiilex through the Lobosa and more s])eeifi- 

 cally .Ircella vuhfari.s and Amoeba miiscicola and 

 diverged at slightly different points. On the basis of 

 the type of nuclear division in the vegetative phase. 

 Cook lielieved that the Plasmodiophorales diverge 

 from the Amoeba series at a more distant point than 

 the Mycetozoa. Later ('33) he asserted that "no 

 close relationshi}) with either the fungi or ])roto/.oa is 

 l)robable." and that the Plasmodioiihorales "repre- 

 sent an independent group having their origin in the 

 Proteomyxa. " Cook tiuis revived and su))))orted the 

 earlier views of Zopf , Delage and Herouard. Lankes- 

 ter, and others on the relationship of the Plasmodio- 

 phorales to the Proteomyxa. 



Zoologists also have asserted their claims to the 

 Plasmodiophorales and included this order as a sub- 

 class of the -Myxomyeetes among the Protozoa, ])ar- 

 ticularly the Khizo))oda. Most protozoologists. how- 

 ever, have continued to use .Sehroeter's term. Phyto- 

 myxinae, for the group, although it has been evident 

 since the beginning of the present century that Phij- 

 tomi)xa, the genus after which Schroeter named the 

 order and family, is no longer tenable and relates to 

 what are now known as bacteria and mycorrhizal 

 fungi. Protozoologists. furthermore, have ignored 

 the discovery and presence of zoosjjorangia and bi- 

 Hagellate, heterocont zoospores in six genera of the 

 Plasmodiophorales and have adhered to the older, 

 outworn conceptions regarding these organisms. De- 

 lage and Herouard ('96) followed Zojjf's disposi- 



tion of Plasmoiliophorn and Tetrami/ja by including 

 them with (1 iiniiiococciix, P.ieiidospora, etc., in the 

 zoos))orie Proteomyx.i or .Mon.ulini.-ie their first 

 el.ass uniler the Hliizopod.i. Dotlein ('01) listed the 

 Mycetozoa as the fifth and last class of the Rhizo- 

 ))oda next to the Poramiuifera and divided it into 

 two subclasses of equal rank, the Protomyxidea and 

 Mveetozoidea. Plasmodiophora and Teframi/ja were 

 pl.ieed in the zoos])oric grouj) of the Protomyxidea. 

 ,1 classification which eorres])onds essentially with 

 that of ])revious ])rotozoologists. In subsequent edi- 

 tions of his text-book ('Oi), '11. 'Ki) DoHein placed 

 the Mycetozoa next to the Radiolaria and limited the 

 sub-class Protomyxidea to what are now generally 

 known as the azoosporic and zoosporic Proteomyxa. 

 For the plasmodiophoraceous genera he adopted 

 Seiiroeter's Phytomyxinae, made it a sub-class of 

 the Myxomyeetes, and ))laced it between the Acra- 

 siae and ]\Iyxogastres. In the sixth edition, however, 

 which was rewritten by E. Reichenow, the Phyto- 

 my.xine and Acrasiae were excluded from the My- 

 cetozoa proper and were discussed merely as an 

 "anhang " to this class. 



I.ankester ('8.5. '09) and Hartog ('06, '09, '22, 

 '36) also included Plasmodiophora and Tetra?)iy.i'a 

 in the Proteomyxa along with J ampyrella, Gi/miio- 

 coccus, Pseudo-spora, etc. Hartog. however, assigned 

 Plasmodiophora together with Protomi/.ra, Vampy- 

 rella, and Serumsporidiuvi to the non-flagellate or 

 azoosporic Myxoidea. In 1909 Calkins referred to 

 P. Brassicae as a mycetozoan and later ('33) in- 

 cluded the Phytomyxida (Phytomyxinae) as an or- 

 der in the Myxomyeetes. He believed that the lack 

 of peridia and capillitia in the plasmodiophoraceous 

 s])ecies is due to their parasitic mode of life. Min- 

 ehen ('12, '21) was uncertain of the relationships 

 of the Phytomyxinae and merely discussed them as 

 border-line organisms in relation to the Sarcodina. 

 Hertwig (19) listed the Mycetozoa as the fifth 

 class of Protozoa and of equal rank with the Rhizo- 

 ])oda and included Plasmodiophora among the My.x- 

 omycetes. Galiano (1921) also grouped the Phyto- 

 myxinae as a suborder of the ^lyxomvcetes, while 

 Rumbler ('23-'2.5) reverted to DoHein's ('09, '11) 

 classification. Kudo ('31, '39), on the other hand, 

 included the Phytomyxinae directly in the Myxomy- 

 eetes. 



It is evident from this review that several ))oints 

 of origin and lines of develoj)ment and relationship 

 have been em|)liasized for the Plasmodiophorales. 

 These suggested relationshi))s involve the Myxo- 

 myeetes, Chytridiales, Protozoa, Sporozoa, and Pro- 

 teomyxa. The evidence in support and against these 

 relationships will now be considered in greater de- 

 tail. 



Plasmodiophorales and My-xomvcetrs 



Inasmuch as the belief that the Myxomyeetes and 

 Plasmodio])horales are closely related is rather 

 widely held, this view will be presented in consider- 

 able detail. Proponents of this view have stressed the 

 presence of a large multinucleate plasmodium and 



