SArROI.EGNIA 65 



This rare plant has hccn reported heretofore in America only by 

 Humphrey and by Picters. The former did not see the living plant, 

 hut recorded it from preparations by Trelease, who found it in eastern 

 Massachusetts (Cambridge and Woods Hole). Pieters found the plant 

 near Ann Arbor, Michigan, antl its occurrence is noted in Ann. Rep. Mich. 

 .Acad. Sci. 17: 195. 1915. He has kindly allowed us to examine his 

 unpublished notes and drawings. The species has been reported from 

 several places in Germany, but seems to be rare there also (Fischer, 

 •92, p. 343). 



This species is distinctly set off from the other members of the 

 genus by its fine, irregular hyphae and few-egged, papillate oogonia. 

 No other species of Saprolegnia has an average of so few eggs. If it were 

 not for the sporangia one would place it near Aphanomyces stellatus. 

 Its actual relationships are, hoWe\er, probably with the Racemosa group 

 of Achlya, particularly with A. hypogyna. The tips of the hyphae are 

 blunt and very hyaline, and sometimes die without apparent cause, the 

 hyphae being continued by a lateral branch just below, as in certain 

 species of Achlya. The mycelium grows to a greater diameter than in 

 other species under similar conditions, but is more thin and sparse than 

 others. The threads are rarely cylindrical, but are wa\'y and knotted. 



It is interesting to find that Pieters has also observed the "slow, 

 deliberate movement" of the discharging spores and the great scarcity 

 of the sporangia (unpublished notes). This shows that these characters 

 are not casual or accidental. In his notes Pieters says that in all re- 

 spects sa\-e only in the method of discharge of the sporangia Achlya 

 racemosa and Saprolegnia asterophora are quite similar and the question 

 arises whether the latter is not more closely related to some species of 

 Achlya than it is to other species of Saprolegnia. He bases this sugges- 

 tion in part on the apparent absence of gemmae in his cultures of Sapro- 

 legnia asterophora. We also find them absent or scarce in many cultures, 

 while in others there are not a few. There is no doubt, however, of the 

 striking similarity noted by Pieters, and his suggestion may correspond 

 with the facts. He makes the following interesting observations on this 

 species: "Physiologically this species differs from all other species of 

 Saprolegnia studied. It thri\-es on extremely small quantities of food in 

 solution. If a piece of nncclium grown in pea water is transferred to 

 water, and care is not taken to wash thoroughly, no sporangia are 

 produced but only oogonia and growth. In no other Saprolegnia studied 

 have I e\er gotten oogonia from a mycelium in water. If a good culture of 



