AN ACHLYA LACKING SEXUAL REPRODUCTION 
355 
slide. This drop was then added to 2 or 3 cc. of sterile water in an 
atomizer, and the resulting mixture sprayed on the surface of 2 percent 
beef-extract agar in petri dishes. By examination with a binocular 
microscope, the positions of single isolated zoospores were noted and 
marked. After two or three days of growth in a cool place, bits of the 
uncontaminated peripheral portions of the mycelia arising from these 
zoospores were transferred on agar chips to fresh nutrient substratum. 
2. A large number of vigorous resistant spores were washed re- 
peatedly in sterile water and plated out in a separation culture series 
of four or five plates of 2 percent beef extract agar. The spores were 
sufficiently resistant to remain uninjured by their exposure to the hot 
agar, and promptly germinated. In the last two or three plates some 
of the mycelia arising by germination of the isolated resistant spores 
were found to be uncontaminated; and from them transfers were 
made to fresh nutrient material. 
When uncontaminated mycelia of the fungus had been obtained 
by the above methods, stock cultures were maintained on firm corn- 
meal mush in 500 cc. flasks. For the investigation of the fungus, 
mycelia were grown in petri dishes in nutrient solutions of beef-extract, 
and of pea, corn, bean, and other vegetable decoctions, and transferred 
to sterile water or to various solutions in petri dishes or hanging drop 
cultures for further development according to the methods already 
worked out by Klebs (7), Kauft'man (6), Obel (13), Pieters (14), and 
others. 
DEVELOPMENT OF THE FUNGUS 
The normal life cycle of the fungus comprises the establishing of a 
branched mycelium which gives rise to large numbers of zoosporangia 
of the Achlya type. At first these zoosporangia are produced ex- 
clusively; but gradually they are superseded by abundant resistant 
spores which continue to be formed until the mycelium is exhausted. 
This regular cycle was observed for a space of two years in the original 
gross culture in which the fungus appeared; and since the conditions 
there probably closely approximated those of its natural habitat; we 
may infer that it would follow the same cycle in nature. 
In battery-jar cultures like those mentioned above, species of 
several Saprolegniaceous genera have been found by the writer to 
maintain their normal cycles of sexual as well as non-sexual repro- 
duction for long periods of time. This Achlya, however, under these 
conditions continued for two years to follow its cycle of unbroken 
