An Investigation of a Species of Saprolegnia. 307 
glass beakers, half filled with distilled water, upon which the flies 
were floated, after washing in absolute alcohol and distilled water. 
After one day’s growth, or sometimes later, a small piece of 
the medium with attached hyphse was teased off with two platinum 
needles, and transferred to a hanging drop culture in a Ward’s 
tube or glass ring slide. A method of blotting paper wads, which 
could he kept moist by a blotting paper syphon was found to act 
very well, and cultures could thus be kept going for a week with 
care. The hanging drop cultures could then be kept under the 
microscope for observation. Nearly all the drawings were made 
from living material in hanging drop culture. 
On examining the various cultures made in this way, very 
great variation was found in the methods of formation, discharge, 
and in the subsequent fate of the zoospores. At first it was thought 
the cultures could not be pure, but this was hardly likely, as these 
phenomena were observed in cultures which for three weeks had 
been daily isolated with the sterilized platinum hook from the 
extreme edge of the mycelium of the previous day’s growth. In 
many cases two or more of the variations to he described were 
found in the same hanging drop. 
Up to the present time, in spite of growing the culture under 
a great variety of conditions, no signs of sexual organs have been 
found, although a great variety of asexual forms of reproduction 
have been noted. 
Analysis of Genera. 
The work was started originally with the idea of repeating 
Kauffman’s work on the variability of sexual organs grown under 
various conditions of culture. These, however, I have entirely 
failed to obtain, the variability has been entirely with the asexual 
forms of reproduction. In order that these should be more easily 
followed a short analysis of genera is given, which is based upon 
variations in the asexual method of reproduction, and is compiled 
from the papers of Hartog (’95), De Bary (’88) and Cornu (’72). 
Saprolegnia .—Sporocysts born terminally on the hyphae ; after 
discharge a new sporocyst grows up inside the wall of the old one. 
Zoospores are discharged in a motile state and swarm actively for a 
short time, then come to rest and become spherical, encyst, then 
later become motile again, leaving their cyst walls empty and 
swarming actively. This period of swarming lasts much longer 
