72 



PLASMODIOP MORALES 



sori or resting spores have not been observed in P. 

 marinus. 



It is apparent from this description that Juel's 

 fungns differs primarily from the valid species of 

 the Plasmodiophoraeeae by its laterally biflagellate, 

 isocont zoosjjores, naked spore-mother cells and 

 spores, lack of zoosporangia, resting spores, and by 

 its saprophytic nature. As .Juel emiihasized, the for- 

 mation of uninucleate spore-mother cells or sporonts 

 by fragmentation of the plasmodium and their sub- 

 sequent division into 4 and 8 cells is strikingly simi- 

 lar to spore development in Tetramy.ra. Had Octo- 

 mi/xa been known at that time .Juel would doubtless 

 have emphasized the relationship of his species with 

 the Plasmodiophorales even further. It is to be noted, 

 however, that in these two genera each mitosis in the 

 sporonts is not immediately followed by cell division 

 as in Pyrrhosoriis, and that the spores which are 

 formed encyst and pass through a dormant period 

 before giving rise to zoospores. It is possible that 

 under the conditions of .Juel's study the spores of 

 P. marinus failed to encyst and become dormant. It 

 is also possible that zoosporangia occur in this spe- 

 cies but were not present in Juel's material. In tiiat 

 event P. marinus would be very similar to Octomyxa. 

 However, its laterally biflagellate isocont zoospores 

 with an orange-colored eye-spot constitute a serious 

 obstacle to including it in the Plasmodiophorales at 

 present, unless, of course, .Juel was mistaken about 

 the relative lengths and insertion of the flagella. 

 These possibilities, however, are purely speculative. 

 On the other hand, the zoospores are similar to those 

 figured for species of the lower biflagellate Oomy- 

 cete-like fungi, but until more is known about P. ma- 

 rinus its relationship will remain obscure. Winge, 

 nonetheless, considered it closely related to the Plas- 

 modiophoraeeae and made extensive comparisons be- 

 tween its life cycle and that of Sorolpidiiim. He re- 

 garded the sporangiosori of the latter genus as homo- 

 logous with the aggregates or sori of spore-mother 

 cells of Pyrrhosorus, and believed that the absence 

 of wall around the sporonts in the latter is of minor 

 importance. Cook ('33), on the other hand, regarded 

 the relationship of Pyrrhosorus with the Plasmodio- 

 phorales as highly questionable. 



BIBLIOGRAPHY : DOUBTFUL GENERA 



Barrett, ,T. T. 193 j. Pliytopath. 25: 898. 



Cook, W. H. I. 19-'6. Trans. Brit. Mycol. Soc. 11: 310. 1937, 



11)1(1.1-2:282. 



. 1933. Hoiifr Koiifr Xat. Suppl. 1 : 38. 



. 1933. Arcli. Protistk. 80: 333. 



Fischer, A. 1893. Kabenhorsts Krypt. 1, aht. +:67. 

 Fitzpatriok, H. M. 1930. The lower fungi — Phycomycetes. 



New York : p. 03. 

 Guyot, A. L. 1937. Bull. Soc. Path. Yep. I'Ent, Agr. France 



14: 181. 

 Juel, H. O. 1901a. Bill. K. Svensk. Yet.-.\kad. Hand. 26 



afd. Ill, No. U: 1. 



. 1901b. Rev. Mycol. 34: 111. 



Maire, R., and A. Tison. 1911. C. R. .\cad. Sci. Paris, 153: 



30G. 

 Minden, M. 191.5. Krypt. Fl. Mark. Brandenburg 5: 378. 



Nemec, B. 1911. Osterr. Ungar. Zeitscbr. f. Zucker u. 



Landw. 40. 

 Palm, B. T., and M. Burk. 1933. Arcb. Protistk. 79: 363. 

 Rawlins, T. E. 1935. Pliytopath. 15: 737. 

 Saccardo, P. A. 1936. Sylloge fungorum 34, sect. 1: 17. 1931, 



Ibid. 35: 13. 

 Schroeter, J. 1897. Engler and Prantl, die Nat. Pflanzf. I, 



1:5. 

 Wildeman, E. 1893. Ann. Soc. Micro. Beige. 17: 35. 

 Winge, O. 1913. Ark. f. Bot. 13, No. 9: 29. 



EXCLUDED GENERA 



Herewith are presented descriptions and illustra- 

 tions of three genera which have been included in 

 the Plasmodiophorales by various workers, prima- 

 rih' for want of a better group in which to place 

 them. Uniflagellate zoospores are reported to occur 

 in Cystospora but are apparently lacking in Sporo- 

 myxa and Peltomyces. Except for a multinucleate 

 plasmodial stage, resting spores, and the occurrence 

 of intranuclear mitosis and schizogony these genera 

 have little in common with the Plasmodiophorales 

 as this order is now generally recognized. They are, 

 nevertheless, described here so that their validity as 

 members of this order may be judged independently. 



PLATE 14 

 Trematophli/ctis Leptodesmiae 

 (All figures after Patouillard) 



Fig. 1. Leaves of L. congestu with galls. 



Fig. 3. Portion of a branch with a large gall and three 

 open pu.stules. 



Fig. 3. Section of a gall showing several sori. 



Fig. 4. Naked plasmodium (?) filling greatlv enlarged 

 cell. 



Fig. 5. Group of resting spores formed by segmentation 

 of Plasmodium. 



Fig. 6. Individual resting spores. 



Pyrrhosorus niariinis 

 (All figures after Juel) 



Fig. 7. Laterally biflagellate isocont zoospores. 



Fig. 8. Uninucleate tballus. 



Fig. 9. Two paired young thalli. 



Fig. 10. Uninucleate thallus with enlarged primary nu- 

 cleus. 



Fig. 11. Four-nucleate tballus passing through cell wall. 



Fig. 13. Jlultinucleate tballus. 



Fig. 13. Multinucleate amoeboid thallus. 



Fig. 14. Cleavage of tballus. 



Fig. 15. A sorus of spore mother cells. 



Fig. 16. Isolated spore mother cell. 



Fig. 17. A sorus, the spore mother cells of wbieli liave di- 

 vided into groups of four daughter cells. 



Fig. IS. Spindle-shaped spore mother cells (?) in a 

 branched tballus. 



Fig. 19. Spindle-shaped spore mother cells and accessory 

 sterile cells in an elongate host cell. 



Fig. 30. Sorus with spore motber and sterile cells. 



Fig. 31. Sorus with spore mother cells undergoing mito- 

 sis. 



Fig. 33-34. Mitosis and cytokinesis of s|)ore mother cells. 



