540 AQUATIC PHYCOMYCETES 



emerging and swarming in vesicle 2-32 minutes before breaking out 

 and swimming away; vesicle continuous with interior of sporangium. 

 Apophysis, when present, spherical to subspherical, 3-6 \x in diam. 

 Resting spores spherical (6-20 (J.), oval (6-10 u. X 12-16 u.), with a thick 

 (2 \x), golden-brown smooth wall and numerous closely packed granules 

 or globules; functioning as prosporangia in germination" (Karling, loc. 



cit.). 



Saprophytic in exuviae of mayflies and on chitin, Karling {loc. cit.), 

 Brazil; Karling {loc. cit.; 1948c: 509), United States. 



This species and Chytriomyces hyalinus were also grown on onion 

 skin, which indicates that they are not strictly confined to chitinous 

 substrata. 



Chytriomyces parasiticus Karling 

 Bull. Torrey Bot. Club., 74: 334, figs. 1-15. 1947 



"Sporangia smooth, hyaline, spherical, 8-30 \x, or slightly oval; 

 operculum ap'cal or subapical, 4-14 \x diam. Zoospores oval, 2.5-3 jx, 

 with a minute, 0.4-0.6 [j. diam., hyaline refractive globule; flagellum 

 14-18 jo. long. Apophysis intra- or extramatrical, globular, 3-6 la diam., 

 or angular; rhizoids relatively short and finely branched. Resting spores 

 unknown" (Karling, loc. cit.). 



Parasitic on Aphanomyces laevis, causing local swelling and excessive 

 branching of the mycelium, United States. 



Whether this turns out to be a species of Chytriomyces or Chytridium 

 will depend upon the position of the resting spores when they are found. 



The parasite eventually completely destroyed the host. The discharged 

 zoospores were capable of undergoing several intermittent periods of 

 swarming if escape was not at once effected from the confining vesicle. 



Chytriomyces closterii Karling 



Bull. Torrey Bot. Club, 76: 352, figs. 1-5. 1949 



"Sporangia hyaline, smooth, non-apophysate, spherical, 5-25 \x, or 

 broadly pyriform, 6-19 X 9-24 u., with one apical exit papilla; opercu- 

 lum shallow saucer-shaped, 4-6 u. diam., non-persistent. Zoospores 

 spherical, 2-2.5 jjl, with a minute, 0.4-0.6 u., hyaline refractive globule; 



