CHYTRIDIALES 387 



branches stout, tips delicate; zoospores variable in number, spherical 

 or somewhat ovoid, 4—6 \x in diameter, with a large, colorless, eccentric 

 globule and a long flagellum, emerging individually through a pore at 

 the tip of the discharge tube and swimming directly away or forming 

 a temporary motionless mass at the orifice before escape, movement 

 swimming or amoeboid; resting spore spherical, subspherical, or broad- 

 ly ellipsoidal, variable in size, up to 22 by 28 u., wall thick, yellowish 

 or brown, the outer surface covered by minute short sharp spines, 

 apophysis and rhizoidal system like those of the sporangium, upon 

 germination either forming a tube and functioning as a zoosporangium 

 or becoming a prosporangium and producing a sessile thin-walled 

 zoosporangium. 



Saprophytic or weakly parasitic in dead or moribund internodal cells 

 of Nitella flexilis, Schenk (loc. cit.), N. mueronata, N. flexilis, Zopf 

 (1884: 191, pi. 19, figs. 1-15), Germany; Nitella tenuissima, Charapoly- 

 canthum, Dangeard (1886a: 296, pi. 13, figs. 20-23; 1890-91b: 91, pi. 4, 

 figs. 13-18), France; "Characeae," Petersen (1909:413; 1910:548), 

 Denmark ; Chara coronata, C. fragilis, C. delicalula, Nitella flexilis, 

 N. glomerulifera, Lamprothamnus alopecuroides, Lychnothamnus bar- 

 batus, Karling (1928b: 204, text figs. 1-2, pi. 14; 1930: 770, text figs. 

 1-2, pis. 46-49; 1936b: 469, text figs. 1-8; 1941b: 108; 1942c: 621; 

 1948c: 509), Nitella flexilis. Sparrow (1932b: 283, figs. 2e,j; 1936d: 321, 

 figs. 1-2; 1952d: 767), United States; Nitella sp., Shen and Siang 

 (1948: 183), China; Nitella sp., Sparrow (1952a: 37), Cuba; Nitella sp., 

 Canter (1953: 289), Great Britain. 



In spite of the fact that this species has been the object of a consider- 

 able amount of study there remain certain features in need of further 

 clarification. Sparrow (1936d), as mentioned earlier, presented evidence 

 for a sexual process essentially like that found in Siphonaria, Rhizo- 

 closmatium, and Aster ophlyctis. Small undeveloped thalli 10 u. high by 

 5 \x in diameter, with a small rhizoidal system, were almost constantly 

 associated with the resting spores. In particularly good specimens there 

 was a definite connection between the rhizoidal systems of the two types of 

 structures. Anastomosis was usually achieved by the rhizoid of the 

 larger body, into which the contents of the smaller presumably passed. 

 Sparrow's observations seemed to indicate that connection of the two 



