1004 



AQUATIC PHYCOMYCETES 



antheridium, however, still remains an undifferentiated segment of the 

 thallus, and this, together with the lagenidiaceous aspect of the cyto- 

 plasm, marks the fungus as belonging to Lagenidium. 



It appears to be a true parasite ; efforts to propagate it on dead cells 

 were unsuccessful. 



Occasionally the filament of the parasite as it emerges from the cross 

 wall is covered for a short distance with a rough layer of wall material 

 laid down by the living host in a futile effort to stop further invasion. 

 A similar formation has been noted by Scherffel and Couch on the 

 infection tube of Lagenidium oedogonii. 



Fig. 82. Lagenidium 



A-E. Lagenidium destruens Sparrow parasitic in Achlya sp.: A, mature 

 sporangium with discharge tube penetrating wall of host hypha; B-D, stages 

 in formation of zoospores at mouth of discharge tube; E, small thallus 

 bearing resting spores in varying stages of maturity. F-G. Lagenidium huma- 

 num Karling saprophytic on human skin: F, thallus; G, sexually formed 

 resting spore. 



(A-E, Sparrow, 1950; F-G, Karling, 1947c) 



