PLASMODIOPHO RALES 111 



of the host, sometimes in linear series, the segments up to 476 \i long 

 by 60 \x in diameter; sporangia varying in number according to the size 

 of the sorus, spherical, 8-33, mostly 15-21 \i in diameter, wall thin, 

 smooth, colorless, with a short discharge papilla; zoospores un- 

 equally biflagellate, 3-4 [i long by 2 [x wide, emerging through a pore 

 formed upon the dissolution of the papilla; cystosorus borne like the 

 sporangia sorus, dark, variable in size and shape, predominantly some- 

 what ovoid or ellipsoidal or linear; cysts (cystosporangia) golden- 

 brown, thick-walled, 4-8 jx wide, somewhat angular, each upon ger- 

 mination becoming more spherical, longer, thin-walled, and functioning 

 as a zoosporangium. 



Parasitic in Achlya polyandra, A. racemosa, Saprolegnia spiralis, Cornu 

 (loc. cit.), Achlya sp., S. monoica, Dangeard (1890— 91b: 86, pi. 4, figs. 

 1-4), France; Saprolegnia sp., Fischer (1882), Minden (1915:275), 

 Germany; Achlya racemosa, Sorokin (1883:39, fig. 51), European 

 Russia, Asiatic Russia; Saprolegnia sp., Maurizio (1895), Switzer- 

 land; Saprolegnia sp., Achlya sp., H. E. Petersen (1909: 425; 1910: 556, 

 fig. 27 a-b), Denmark; Achlya sp., Saprolegnia sp., Cook and Nicholson 

 (1933: 851, figs. 1-16), host (?), Forbes (1935b), Achlya spp., Sparrow 

 (1936a: 425), Saprolegnia ferax (?), Goldie-Smith (1954: 441, figs. 1-29), 

 Great Britain ; Achlya spp., Sparrow (1933c: 515), Saprolegnia sp., 

 (Michigan) United States ; in vegetative hyphae and reproductive or- 

 gans of Achlya americana, Achlya sp., Shen and Siang (1948: 190), 

 China. 



The fungus in Oedogonium sp. referred by Cook (1932a: 133, figs. 1-6) 

 to this species cannot be identified with it. 



Cook and Nicholson (loc. cit.) described the zoospores as spherical 

 and the resting cysts as oval or ellipsoid. Earlier, Fischer had stated 

 that the zoospores were elongate, often flattened on one side, and that 

 the cysts were polygonal. 



The fungus with posteriorly uniflagellate zoospores described by 

 Pringsheim (1860: 205, pi. 23, figs. 1-5) and commonly ascribed to this 

 species, has been placed in a separate genus, Pringsheimiella, by Couch 

 (1939b), seep. 157. 



Goldie-Smith's strain was confined to Saprolegnia. It was experi- 

 mentally induced to parasitize Isoachlya but not certain species of Achlya, 

 Aphanomyces, Thraustotheca, Pythium, Apodachlya, or Allomyces. In 



