198 AQUATIC PHYCOMYCETES 



its vitality. Attempts to infect Conjugatae with the fungus appear 

 to have been uniformly unsuccessful. 



Cytological observations by Dangeard (1 890-9 lc) showed that the 

 prosorus was uninucleate and that after formation of the sorus active 

 nuclear division occurred, accompanied by a distinct decrease in 

 nuclear size. 



MlCROMYCES PETERSENII Scherflfel 



Arch. Protistenk., 54: 209, pi. 10, figs. 78-79. 1926 

 Synchytrium petersenii (Scherflfel) Karling, Mycologia, 45: 278. 1953. 



Prosorus spherical, with sparingly dispersed short conical spines 

 covering the outer surface; sorus as in Micromyces zygogonii; zoo- 

 spores narrowly spindle-shaped, 6 jjl long by 2 \jl thick, with a large 

 laterally placed strongly refractive colorless oil globule and a long 

 extremely delicate posterior flagellum, movement somewhat amoeboid. 



In Mougeotia sp., Hungary. 



Scherflfel considers that the species is distinct from Micromyces 

 zygogonii on the basis of differences in host plant and character of 

 the spines and especially in the large (6 by 2 \x) fusiform rather than 

 spherical (1 \x in diameter) zoospores. Primarily because of these large 

 zoospores it is maintained here as a separate species. 



A fungus in Mougeotia referred to this species by Canter (1949c: 

 86, figs. 8 j-m, 10a, 12h, pi. 10, figs. 4-5), differs from it, as she indi- 

 cates, by its much longer spines (up to 6-12 u.), resembling in this 

 respect M. zygogonii and M. longispinosus. The ovoid zoospores, 

 5.5 by 1.5 [x, however, are much longer than those of either of them 

 and for this reason she has referred her fungus to M. petersenii. Whether 

 it is to be regarded as a variety or distinct from Scherffel's fungus is 

 uncertain. 



Micromyces longispinosus Couch 



Mycologia, 29: 592, figs. 9-14. 1937 

 (Fig. 16 A-B, p. 196) 

 Synchytrium longispinosus (Couch) Karling, Mycologia, 45: 278. 1953. 

 Prosorus more or less spherical, 10-33.6 u, in diameter (mostly 



