AN ACHLYA LACKING SEXUAL REPRODUCTION 359 
solutions of harmful concentration or at a temperature approaching 
the maximum, they tend to be irregular in shape (Fig. 8). In size 
the spores average about no />t in diameter, the size being apparently 
correlated with the vigor of the mycelium. The walls of the resistant 
spores formed aerially on rather dry cornmeal, or in water cultures 
kept cold, are thick (Fig. lo) ; but in spores grown in various solutions 
at laboratory temperature, the thickness is often less (Fig. 12). By 
chloroiodide of zinc the walls are colored not blue, but a muddy brick- 
red, showing that their composition is not of pure cellulose, and re- 
calling the reaction of the oogonial walls of other Saprolegniaceous 
species. 
Germination of the resistant spores varies with the environmental 
conditions to which these bodies are subjected. In water in the 
absence of food material, a tube is sent out which, after greater or less 
growth, gives rise to a perfectly normal Achlya sporangium (Fig. 12). 
In nutrient solutions, however, or on nutrient agar, germination is in- 
variably siphonoblastic, the tube or tubes of germination rapidly 
giving rise to an extensive mycelium (Fig. 11). At laboratory tem- 
perature the resistant spores germinate in from twenty-four to forty- 
eight hours in the presence of nutriment, and somewhat more slowly 
in pure water. Germination need not be preceded by a period of rest ; 
since no particular difference in behavior was observed between spores 
just formed and those two to four weeks old. The spores are very 
resistant to cold, those from one culture surviving an exposure to 
outdoor conditions during two winter months in which the water was 
repeatedly frozen and thawed. The writer has made no extensive 
investigation of the degree of resistance to extremes of temperature 
or to desiccation shown by resistant spores. There has been demon- 
strated, however, a degree of resistance that may perhaps be regarded 
as an indication that these spores play for the fungus the resistant 
role usually assumed in others of the family by spores of sexual origin. 
The formation of zoosporangia and resistant spores as described 
above completes the reproduction of the fungus. Under natural 
conditions of growth, the formation of sexual organs was never ob- 
served to take place throughout the two years in which the fungus was 
under investigation. Many attempts to induce the formation of 
oogonia and antheridia were made without success. Hoping to stim- 
ulate sexual reproduction vigorous mycelia were subjected to the 
influence of the solutions by means of which Klebs (7), Kauffman (6), 
