BT MARJORIE I. COLLINS. 



279 



which encyst in tlie above manner, do not enter upon a second motile phase, but 

 germinate directly within the sporocyst. In some eases a germ tube from an en- 

 cysted zoospore has been observed to grow back through a series of empty sporo- 

 cysts and penetrate the hypha behind for some distance (Text-fig. 2) . The 

 Aplanes type of germination by penetration of the wall of the sporocyst, does not 

 occur under these circumstances. 



In cultures made upon white of egg, early sporocyst formation was decidedly 

 of the Saprolegnia type, but after some days, all the variations recorded ap- 

 peared in the culture. Owing to the rapidity of their formation, it was impos- 



Text-fig. 1. ShowiBg formation of new 

 sporocyst at base of old discharged 

 sporocysts. Note encystment of 

 some of the zoospores (luring pass- 

 age through empty sporocysts. 

 (x about 170). 



Text-fig. 2. (iermination of spore which 

 has encysted within old sporocyst. 

 Note penetration of hypha behind, 

 (x about 170) . 



sible to discover any definite sequence of formation of sporocyst types. It was 

 found, however, that normal sporocysts occur more abundantly in the young cul- 

 ture, though they continue to be formed to a slight degree, after the abnormal 

 forms have made their appearance. Leptolegma, Pythiopsis and Achlya condi- 

 tions were found to be more rare than Dietyuchus and Aplanes conditions. 



The most noticeable feature of the material was the prevalence, under both 

 natural and cultural conditions, of two forms of sporocyst unrecorded by previous 

 investigators. The first of these is certainly a Dietyuchus condition, though it 

 differs in salient features from either of the Dietyuchus conditions described by 

 Lechmere. In reference to the formation of the Dietyuchus condition on a white 

 of egg culture, Lechmere says : — 



"The numerous resting sporocysts present on the mycelium commenced to 

 develop into sporocysts. In by far the greater number of cases observed, the 

 spores encysted within the sporocyst before its discharge, in spite of the fact 

 that a tubular process was developed on the sporocyst before the spores encysted.'"' 



•New Phytologist, ix., 1910, p.316, PI. 2, figs. 30, 31. 



