46 



COMPARATIVE MORPHOLOGY OF FUNGI 



and become flask-shaped sporangia. The marked thickening of their 

 membrane continues beyond the sporangial neck, affects part of the 

 original hyphae and forms a peculiar tube (Fig. 29, 2). The mycelium 

 collapses very early, thereby liberating the sporangia which germinate 

 by a dissolution of the septum in the neck. Hypnospores are unknown. 



Cladochytrium and N owakowskiella are somewhat more highly dif- 

 ferentiated. In Cladochytrium the zoosporangia open by gelification of a 

 papilla, in N owakoivskiella by a lid. 



Cladochytrium tenue (Nowakow- 

 ski, 1876) is parasitic or saprophytic 

 in the tissues of aquatic angio- 

 sperms, as Acorus, Iris, Glyceria. 

 The mycelium consists of filaments 

 1 to 2fi thick, which penetrate the 

 infected part of the host intracellu- 

 larly in all directions and swell up 

 inside the host cells into turbinate 



Fig. 29. Fig. 30. 



Fig. 29. — Amocbochytrium rhizidioides. 1. Germ tubes from zoospores which were 

 unable to swarm. Below to the left, two young turbinate cells. 2. Zoosporangium show- 

 ing thickening of the walls. (After Zopf, 1885.) 



Fig. 30. — Cladochytrium tenue. 1. Mycelium from Iris pseudacorus with several 

 turbinate cells which later form zoospores. 2. Germinating and empty zoosporangium. 

 (1 X 400; 2 X 270; after Nowakowski, 1876.) 



cells (Fig. 30, 1). Each changes as a whole into a zoosporangium or is 

 divided by a septum into two daughter cells one or both of which become 

 zoosporangia. Their germination generally takes place through an emis- 

 sion collar which opens into water or into a neighboring host cell and 

 liberates the swarm cells jointed into a sphere. Under special conditions, 

 the sporangia germinate with germ tubes instead of zoospores. 



N owakowskiella ramosa was found by Butler (1907) on decaying 

 wheat stems in India. The mycelium lives both intra- and extramatri- 

 cally and is unusually well developed for the Chytridiales (Fig. 31, 1). 

 Eight to ten thick- walled hyphae arise from a basal piece; they branch 



