May, 1921] 
KAUFFMAN — ISOACHLYA 
surrounded enclosure, to which a partially opened window gave access to 
outside temperature during the winter months. The temperature usually 
fluctuated between 6° and 10° C. The culture was four days old and had 
developed at these lower temperatures, and when examined on February 14 
had been in a temperature slightly below 8° C. for at least twenty-four 
hours. Zoosporangia were very abundant, all primary and apical, many 
mature, several empty, and with motile zoospores present in the upper 
layer of water. These primary zoosporangia were pyriform to ventricose- 
pyriform in shape. In the course of half an hour or so, during examination 
in the warmer temperature of the laboratory, many mature sporangia 
opened, and in a relatively short time the water was alive with zoospores. 
There was every indication that they were already ciliated in the sporangium. 
As they lined up more or less within the sporangium, after the latter had 
opened, they assumed an oblong shape, obscurely curved on one side and 
with rounded ends, and not at all pyriform as frequently described for 
Saprolegnias ; but, as was seen later during their evolutions immediately 
after escaping, they had an unequal diameter in their short axes, i.e., they 
were slightly flattened. 
A zoospore was uninterruptedly followed from its emergence, the instant 
it had become free of the opening at the tip of the zoosporangium. It was 
seen to turn over and over on its long axis, at the same time slowly getting 
away from the neighborhood of the others, which were all turning somer- 
saults in the same curious way. Meanwhile the elongated, sub-oblong 
or slightly sub-reniform shape was retained. This continued for about 
twenty minutes, during which time every movement could be followed. 
Neither this spore nor the others, as far as observed, ever exhibited the 
darting or rapidly swimming habit of zoospores of the species of Sap- 
rolegnia. At the end of this period other manifestations began to appear. 
The spore — always turning — began in a more or less spasmodic manner to 
hump itself somewhat on its convex side, then to straighten out again, and 
after several such performances to show signs of a shortening process. 
Gradually during the last five minutes, by a twisting and shrugging process, 
it became much shorter and one end became contracted, so that a short 
pyriform shape, or an oval form with a papilla, resulted; this was soon 
changed, however, to a more and more globular form until finally a perfect 
sphere resulted. No let-up of the turning which it had exhibited over its 
longer axis could be detected up to this time, and even for perhaps tw^enty 
seconds after it appeared to have become perfectly rounded it still continued 
to revolve. Then very quickly all motion ceased, and the spore assumed its 
first resting condition. 
Observations following this at intervals during the next few days showed 
that the spores, after rounding up, gradually sink to the bottom of the dish 
except when, sometimes in great numbers, they are caught in the mesh of 
mycelium surrounding the fly. After several days, the bottom of the 
