PLASMODIOPHORALES 



Gw.vnne-Vaiif;han, H. C. I., and B. Barnes. 1937. The 



structure and development of the funiri. 2nd ed. Cam- 



bridfre. 

 Halsted, B. D. 1893. New Jersey Agr. Exp. Sta. Kept. 



1893: 33;.\ 

 Home, A. S. 1930. Ann. Bot. 44: 199. 

 Jahn, E. 1911. Ber. Dciit. Bot. Gesell. :^9: 231. 1936, Ibid. 



54: air. 

 Jones, P. M. 1928. Arch. Protistk. 6;2: 313. 

 Kunkel, L. O. 1915. Jour. Apric. Res. 4: iJ65. 

 Ledinfrham, G. A. 1933. Phytopath. 23: 30. 



. 1934. Xature 133: ,534. 1935, Ibid. 135: 3994. 



. 1939. Canad. Jour. Res. C, 17: 50. 



Maire, H., and A. Tison. 1909. Ann. Mycol. 7: 22n. 

 Massee, G. 1908. Jour. Bd. Agric. London 15: 592. 

 Milovidov, P. F. 1931. Arch. Protistk. 73: 1. 

 Nawaschin, S. 1899. Flora 80: 404. 



Xemec, B. 1911a. Ber. Deut. Bot. Gesell. 29: 48. 



. 1911b. Bull. Int. Empr. Fran. Joseph Acad. Sci. 



10: 09. 1913, Ibid. 18: 18. 

 Osborn, T. G. B. 1911. Ann. Bot. 2.o: 211, 327. 

 Schroeter, J. 1880. Cohn's Krypt. Fl. Schlesiens 3: 133. 



. 1897. Engler und Prantl, Die Xat. Pflanzenf. 1,1:7. 



Schwartz, E. J. 1914. Ann. Bot. 38: 227. 



Skupienski, F. X. 1938. Acta Soc. Bot. Poloniae 5: 355. 



Terby, J. 1934. Bull. Roy. Acad. Belg. 11:1. 



Tubeuf, K. F., and W. G. Smith. 1897. Diseases of Plants. 



London. 

 Wilson, M., and E. J. Cadman. 1938. Trans. Roy. Soc. 



Edinburgh 55: .555. 

 Woronin, M. 1877. Arb. St. Petersburg Nat. Gesell. 8: 109. 

 Zopf, W. 1884. Die Pilzthiere oder Schleimpilze. Encyklop. 



der Xaturwiss. 3: 139. 



Chapter II 

 Cytology 



"Promitosis" 



Cytological studies of the Plasmodiophorales dur- 

 ing the pa.st four decades have centered primarily on 

 the type of nuclear division in the plasmodiuni, the 

 so-called "akaryote" stage, nieiosis, karyogamy, 

 schizogony, and cleavage. Nuclear division in the 

 Plasmodium has been described by most workers as 

 promitotic and fundamentally similar to that which 

 occurs in the Umax group of amoebae and other lower 

 organisms. So consistently has this type of division 

 been rei)orted that many students have regarded 

 promitosis as one of the most diagnostic characters 

 of the wliole order, and one which distinguishes the 

 Plasmodiophorales from all other fungi and higher 

 plants. Cook ('28) in particular has stressed this 

 character as follows: "The diagnostic feature which 

 characterizes the Plasmodiophorales is their two 

 methods of nuclear division, and failing to show evi- 

 dence that both promitosis and mitosis occur in the 

 life cycle, and that these two types are separated by 

 a stage iu which at any rate ])art of the chromatin is 

 extruded into the cytoplasm, no new fungus should 

 be included in this group." At the same time, other 

 workers have maintained that these divisions are 

 typically mitotic with well-defined chromosomes, 

 centrosomes, and astral rays. There is thus sharp 

 disagreement concerning karvokinesis in the Plas- 

 modium, and inasmuch as the presence of promitosis 

 has been regarded as an index of relationship to the 

 amoeba, a full discussion of the so-called vegetative 

 divisions in the Plasmodiophorales is essential to an 

 understanding of this order. 



Nawaschin ('99) was the first to observe the char- 

 acteristic appearance of these divisions in Plasmodi- 

 ophora and to point out that they are different from 

 those which occur immediately before or during 

 spore formation. He nevertheless described the for- 

 mer mitoses as karyokinetic and regarded ('01) the 

 presence of the two types of division as an indication 



of nuclear dimorphism — a view much in vogue among 

 the protozoologists of that time. Nawaschin's obser- 

 vation was confirmed by Prowazek ('02, '05), Maire 

 and Tison ('09), Blomfield and Schwartz ('10), 

 Schwartz ('10), Winge ('13) and Lutman ('13) for 

 other species and genera. Prowazek, particularly, 

 and later Blomfield and Schwartz, also stressed the 

 resemblance of the vegetative divisions to those 

 which had been described by protozoologists in cer- 

 tain coccidia and amoebae. 



In the meantime, Nagler ('09) had proposed the 

 term promitosis for the type of nuclear division 

 found in Amoeba froschi, A. lacu.itrh, etc., which he 

 inter])reted to be a transition between amitosis and 

 mitosis. In these divisions neither chromosomes nor 

 well-defined spindles are formed, according to Nag- 

 ler. Division is intranuclear, and the large endo- 

 some or karyosome functions as a division center. 

 The latter elongates, and as it constricts the chro- 

 matin aggregates and forms a band across the equa- 

 tor of the nucleus. The karyosome then divides into 

 two bodies, and as these migrate toward the poles the 

 band of chromatin splits lengthwise. Each half ac- 

 companies a karyosome to the poles, and both are 

 there incorporated in the daughter nuclei. Subse- 

 quent workers, particularly Chatton ('10) and 

 Alexieff ('13) confirmed in broad outlines Nagler's 

 observations, but distinguished and defined other 

 similar and more advanced types of "primitive" mi- 

 tosis in amoebae. Since Nagler's time the term pro- 

 mitosis as a distinctive term has lost much of its ori- 

 ginal significance and has been employed rather gen- 

 erally for mitosis in lower organisms which are char- 

 acterized by an intranuclear spindle and chromatin 

 derived wholly or in part from a large karyosome. 

 In the process of division the latter is said to elongate 

 and divide and function as a nucleo-centrosome. 

 However, with tlie use of more refined and specific 

 fixatives and stains, many of the cases reported for- 



