662 AQUATIC PHYCOMYCETES 



Sporangia and gametangia usually sessile; both gametangia color- 

 less B. stubenii, p. 662 



Sporangia and gametangia usually stalked; male gametangia orange- 

 colored B. variabilis, p. 663 



Life cycle of the Cystogenes type, that is, the gametophyte represented 

 by a cyst bearing four isogamous gametes 



Resting-spore wall faintly areolate; cysts 8-10 \x in diameter 



B. cystogena, p. 663 



Resting-spore wall smooth; cysts 4-6 \i in diameter 



B. microcystogena, p. 664 



Life cycle of the Brachyallomyces type, that is, involving only resting- 

 spore and zoosporangial plants 

 Both zoosporangia and resting spores present 



Plants derived from planonts from resting spores all colorless 

 Thalli more than 500 \i in height; resting sporangia areolate. . . 



B. simplex, p. 664 



Thalli less than 500 \i in height 



Resting-spore wall verrucose B. asperosperma, p. 665 



Resting-spore wall smooth B. laevisperma, p. 666 



Plants derived from planonts from resting spores over 98 per cent 



colorless and less than 2 per cent orange-colored 



B. emersonii, p. 666 



Only zoosporangia present; thalli up to 300 \x high, usually stalked 



when on leaves B. stomophilum, p. 667 



Blastocladiella stubenii Couch and Whiffen 



Amer. Journ. Bot., 29: 588. 1942 

 (Fig. 45 A-D, p. 661) 



Sphaerocladia variabilis Stiiben, "Planta," Archiv wiss. Bot., 30 (3): 364, 

 figs. 1-12. 1939. 



Sporangium with a thin smooth wall, spherical or more or less ovoid 

 or ellipsoidal, averaging 60 \i in diameter when on flies, 140 u, on peptone 

 agar; rhizoids profusely developed; zoospores emerging through one or 

 several papillae, ellipsoidal, 3.5 by 4.8 u., the contents bearing in ad- 

 dition to a "food body," a lateral tear-shaped structure; resting spore 

 either ovoid, 13 by 17 \x (the brownish wall 0.5 u, thick), or spherical, 

 1 10 [j. in diameter (the wall 2.5 \x thick); planohaplonts one-half the size 

 of the zoospores, emerging through a prominent papilla which protrudes 

 through a crack in the resting-spore wall; gametophytes similar to 



