932 AQUATIC PHYCOMYCETES 



racemosa, H. E. Petersen (1909:406; 1910:541, fig. 18d), Denmark; 

 Saprolegnia sp., Valkanov (1931a: 361), Bulgaria; (?) Saprolegnia 

 thureti, Tokunaga (1933a: 22, pi. 2, fig. 5), Japan. 



Butler (1907: 131), Sawada (1912), and Domjan (1936:52) record 

 the fungus from the sporangial stage alone. 



Constantineanu's record can be accepted only with reservation, since 

 the ornamentation of the resting spore is not described. 



Marked hypertrophy of the host filament has been noted by all 

 observers of the species. Diehl (1935) reported that the form assumed 

 by the infected hyphae depended upon the size and abundance of pro- 

 toplasm in the host hypha and the number of parasites infecting it. 

 Considerable increase in diameter and cessation of apical growth 

 occurred in regions harboring the parasite. These "galls" assumed 

 various configurations in agar cultures. Under the conditions of culture 

 the discharge tubes of the sporangia reached great lengths. In the later 

 stages of development isolated parasites on agar reached maturity and 

 discharged their zoospores. 



Coker (loc. cit.) noted in a single sporangium that the contents were 

 discharged before cleavage of the spores had been completed. The 

 protoplasm remained at the orifice, and after fifteen minutes the spore 

 initials assumed a rocking movement. Eventually, they became separate 

 entities and swam away. This may not be typical of zoospore discharge, 

 but if it is, it affords additional evidence of the diplanetic nature of the 

 zoospores in the genus. His material also possessed resting spores in 

 which the wall sculpturing varied from low warts to definite spines. 



Cornu has retained Braun's specific name even though it is now 

 impossible to tell to what species the German fungus belonged. 



Tokunaga's collection is queried above because of the unusually 

 coarse spines on the "resting spore" (sporangium). The sporangia are 

 ellipsoidal, 34-120 \i in longer diameter, the zoospores ovoid, 4 by 2 \i, 

 apically and laterally flagellate, and the resting spores spherical or 

 ellipsoidal, 64-87 \x in diameter, with the wall covered by scattered 

 spines. These spines are described as "fine" in the text, but are far 

 coarser and longer than those figured by Fischer for his fungus. 



In view of the extensive cross-inoculation studies by Shanor (1940) 

 indicating that this species is confined to Saprolegnia and Isoachlya, the 



