666 AQUATIC PHYCOMYCETES 



minating after several weeks' rest to form zoospores as in zoosporan- 

 gia" (Couch and Whiffen, he. cit.). 



On boiled grass leaves, from soil, coll. Philip Couch, United States. 



Blastocladiella laevisperma Couch and Whiffen 

 Amer. Journ. Bot., 29: 589, figs. 15-28, 36-39, 40, 42, 46, 65. 1942 



"Zoosporangial and resting sporangial thalli much as in B. aspero- 

 sperma except resting sporangia usually fill the case and have a smooth 

 wall except for a few ridges. Zoosporangia usually sessile on leaves and 

 stalked on hemp seed; 25-1 17 u. when spherical; stalk up to 26 x 105 \x. 

 Zoospores 3.8-4.6 X 6-6.5 \x when active, 5-5.4 \x when rounded up. 

 Resting sporangial case as a rule stalked on hemp seed but usually 

 sessile on leaves; rarely two resting sporangia may be formed on the 

 same stalk; spherical, ovoid, pyriform or sub-cylindrical, sometimes 

 constricted in the middle, at times lobed; 25-140 y. thick when spherical, 

 up to 63 x 95 u. when ovoid; stalk 30 x 155 \x, broadest at the top; 

 resting sporangia usually completely filling the case and conforming to 

 its shape, up to 126 \x thick when spherical ; wall 1.5-2.8 \x thick, reddish 

 brown or pale dull yellow, smooth except for one or several conspicuous 

 ridges. Germinating after a few weeks' rest to form zoospores which are 

 similar to those from zoosporangia" (Couch and Whiffen, he. cit.). 



Obtained from the same soil collection as Blastocladiella aspero- 

 sperma, United States. 



Blastocladiella emersonii Cantino and Hyatt 



A. v. Leeuwenhoek, 19: 67, figs. 1-14. 1953 



"'Thalli with short stalks, anchored to substratum by rhizoids, and 

 bearing single apical resistant sporangia [R. S.], thin-walled colorless 

 spore-sacs, or thin-walled spore-sacs with orange pigmentation. Under 

 controlled conditions on agar media, resistant sporangia, spherical, of 

 very uniform dimensions, sculpturing, and deep-brown pigmentation; 

 ca. 120 to 180 \x diameter, depending on media used, with wall 2.5 fx 

 thick, and containing pits and depressions (similar to those in B. sim- 

 plex) which function as preformed dehiscence ridges. Stalk always 

 thickest just beneath sporangium. R. S. germinate when mature and 



