150 THE SAPROLEGXIACEAE 



imaginary, and if present at all is no more pronounced than in other water 

 molds. 



The species has been reported only a few times (by Biisgen, by Min- 

 den, by Weston, and by us) since its first discovery. DeBary got his 

 material from a collection taken in 1880 by Stahl from a fresh-water 

 lake at Vendenheim near Strassbourg, Germany, and kept it growing 

 in his laboratory for four years. 



On account of the unparalleled method of spore liberation it was 

 suggested by Solms-Laubach, who after deBary's death arranged and 

 edited his last paper, that this species might be considered as generically 

 distinct from the other species of Dictyuchiis. This was again remarked 

 on by Fischer ('92, p. 365), and the next year Humphrey was sufficiently 

 impressed with its distinction to give it generic rank. 



For our first account of this species, from which this is taken in 

 great part, and from which the plate is copied, see Alycologia 4: 87, pi. 63. 

 191 2. The most detailed study yet given to the plant is by Weston 

 ('18). He thinks that the sporangium wall breaks from the swelling 

 of the spores and that its fragility has been greatly over-emphasized. 

 Weston also observed sprouting of the eggs, which may form either 

 sporangia or an extensive mycelium, depending on the amount of nutri- 

 ment available. 



All the following cultures were made from No. 10 of January 30, 

 1913: 



In equal parts of maltose 5% and peptone .01%. Extensi\e growth. A few sporangia 



formed. Spores sprouting in position. A large number of oogonia initials but none 



maturing eggs. Most were more or less inflated. Some sent out sprouting tubes, 



others went to pieces inside. Culture repeated with similar results. 



On corn meal agar. Growth luxuriant. Many sporangia formed, often in rows like gemmae, 



but all forming spores and falling to pieces. Culture duplicated with same results. 

 On yolk of egg in distilled water. Strong vigorous growth. Great number of good sporangia. 



A good many oogonia, only a few of which matured their eggs. 

 On white of egg in distilled water. Vigorous growth. Only sporangia formed and they 

 not so abundant. Some of them seemed to dissolve and become surrounded by bac- 

 teria. 

 In addition to these manj- cultures were made, of course, on insects, etc., with normal 



results. 

 A pure culture on corn meal agar was put in a vial on March 15, 1913, and was found to be 



dead December i, 191,^. 

 A pure culture was put in an aquarium jar with algae in the laboratory in March, T913. 

 When tested for life September 18, 1917, no growth appeared. 



DICTYUCHUS Leitgeb, 1868, p. 503. 



Vegetative structure and appearance as in Achlya, but of much 

 more tardy de\-elopment in cultures (at least in D. sterile) ; tips of hyphae 



