CHYTRIDIALES 575 



and persisting on the surface of the host cell after germination. Apophy- 

 sis elongate, transverse, usually spindle-shaped and medianly constricted ; 

 rhizoids arising as branches of its ends, extending occasionally over a 

 radius of 600 \x and often attaining a diameter of 5-6 \x.\ intercalary 

 swellings 4-8 \x in diameter. Resting spores smooth, light to dark amber, 

 usually somewhat kidney-shaped, flattened, depressed, occasionally ob- 

 pyriform, 10 X 18 [i — 17 x 26 \x, thick-walled with one or more refrac- 

 tive globules" (Karling, loc. cit.). 



Saprophytic in cells of Chara coronata, C. delicatula, Nitella flexilis, 

 N. gracilis, Karling {loc. cit.), Chara coronata, Karling (1941b: 108), 

 moribund cells of Chara sp., Sparrow and Barr (1955: 555), United 

 States. 



Nephrochytrium stellatum Couch 



Amer. J. Bot.. 25: 507, 509, text figs. 1-34. 1938 



(Fig. 34 H, p. 571) 



"Thallus endophytic beneath the cuticle of Nitella or sometimes on 

 inner side of cell membrane, monocentric. Each thallus consisting at 

 maturity either of a richly developed rhizoidal system, a more or less 

 spherical apophysis and a zoosporangium, or of a resting body with 

 rhizoids and apophysis. Sporangia roughly disc-shaped from pressure, 

 usually circular in outline in face view but sometimes irregular in out- 

 line, particularly when growing with Coleochaete, usually with a basal 

 columella which bulges into sporangium; 26-50 : 29-50 u.; with a 

 basal, globose, ovoid, or sometimes lobed apophysis, the latter being 

 connected to the sporangium by a narrow isthmus, apophysis 8.4-12.8 

 X 14.7-20 [L. The sporangium and apophysis, connected by a narrow 

 isthmus, have an hour-glass-like appearance, the sporangium being 

 much the larger part of the hour glass. Emergence pore formed near 

 columella, usually not tubular but penetrating through the cuticle of 

 the Nitella, bursting irregularly but always with a distinct cap. Spores 

 emerging slowly in a spherical mass and remaining quiet for a few 

 seconds at the sporangial mouth; spherical, about 5 \i thick, with a large 

 refractive globule and a very long cilium, 35-40 y. long; zoospore case 

 pyriform, becoming thick-walled, yellowish, and persisting on the sur- 



