762 AQUATIC PHYCOMYCETES 



lapsing after discharge; zoospores from sixty to one hundred in a 

 sporangium, very small, spherical or ovoid, anterior flagellum fairly 

 long, movement amoeboid, discharged with great speed from a lateral 

 pore; resting spore not observed. 



In ascocarp of a Helotium-Yike member of the Pezizaceae, on damp 

 poplar stump, Germany. 



Hyphochytrium catenoides Karling 



Amer. J. Bot., 26: 513, figs. 1-18. 1939 



(Fig. 56 A-B, p. 761) 



"Thallus predominantly polycentric and intramatrical ; usually hyphal- 

 like, and consisting of a linear series, up to 500 ;x in extent, of inter- 

 calary and terminal swellings and sporangia connected by tubular hy- 

 phae or isthmuses 1 to 138 \i in length and 2.2 to 4 \x in diameter; 

 occasionally monocentric, oval, elongate, spherical and 0/pidium-\ike. 

 Zoosporangia terminal or intercalary, delimited by cross septa, hyaline, 

 smooth, spherical, 10-35 \x, oval, 10 X 12 \x— 18-22 fx, broadly spindle- 

 shaped 6 x 10 [i. — 9 x 18 [jl, elongate and sometimes slightly irregular 

 with 1-4 single or branched, straight, curved, coiled, or irregular exit 

 tubes, 5-250 [x in length and 3-6 ;x in diameter. Content of sporangium 

 usually emerging as a naked spherical mass on the outside and under- 

 going cleavage into zoospores; occasionally undergoing complete or 

 partial cleavage in the sporangium whereafter the segments glide out in 

 succession. Zoospores anteriorly uniciliate, slightly flattened, oval, and 

 elongate, 1.5 x 3.5 jx — 2 x 3 [x, with several small, slightly refractive 

 granules. Sexuality and resting spores unknown" (Karling, be. cit.). 



Weakly parasitic and saprophytic in Zea mays, Nitella flexilis, and 

 Chara coronata, Karling (Joe. cit.), United States; air contaminant, 

 Siang (1949), Canada. 



Since there is sometimes partial or complete cleavage of the zoospores 

 within the sporangium, this species is retained in Hyphochytrium, but 

 see remarks under the family (p. 759). 



