365 
Physiology of the Saprolegniaceae. 
the different species. Whenever cultures became contaminated in any way 
they were immediately discarded. Contamination from other species 
of Saprolegnia , however, never occurred, since the instruments, &c., were 
always heated between using. Only in this way can permanent results 
be obtained. 
Experimental. 
All the cultures started were labelled by a letter. The following 
letters represent pure cultures from a single spore: C, F, H, I, K, L, M. 
After the development of fruiting bodies an attempt was made to determine 
the species ; it resulted as follows : — ■ 
C. Saprolegnia hypogyna , Prings. 
H. Saprolegnia mixta , De Bary ... a form ! 
F. ditto ditto 
I, L. Saprolegnia , sp. 
K. Pithy opsis , sp. ? 
M. Aphanomyces laevis. 
C. Saprolegnia hypogyna was collected, October 25, on Pontederia at 
Cedar Lake, west of Chelsea, Mich. The culture was made from this 
material January 9. 
In this species, which has not hitherto been reported for America, there 
is a short cell cut off by a cross-wall immediately below the oogonia. 
Maurizio (’ 94 ) studied this species, and also what he designated as five 
varieties, from a taxonomic point of view. After he had isolated a pure 
culture from the original, he found it so variable that he was led to begin 
the ‘ isoliren ’ anew, and obtained three forms closely related to S. hypogyna. 
This illustrates the shortcomings of his method. Later, he found other 
varieties from other sources. Only Pringsheim and De Bary had described 
the species before him, Pringsheim with a few figures as a variety of S. ferax, 
De Bary without figures but as a distinct species. 
Cultures were immediately made to study its behaviour. A transfer 
was first made to a capsule of pea-broth, as described by Klebs, by sterilizing 
three or four peas in 50 cc. of water. After three days the mass of resultant 
mycelium was taken out, washed in sterile water, and divided into equal parts, 
which were then transferred to the various solutions or substrata. 
For the sake of comparison with the work of other investigators, flies, 
wasps, and dry beef were also used in some cultures. On flies and wasps, 
Saprolegnia hypogyna formed sporanges and zoospores in great abundance 
after three or four days, of the characteristic Saprolegnia form and the 
method of emptying. In six to ten days the culture was full of oogonia. 
After a trial series of various substances, solutions of those substances were 
used which seemed to effect the production of sexual organs. The best 
substances, as found also by Klebs, were haemoglobin and leucin. 
C c 2 
