Cytology of a new variety of A chly a amencana . 141 
containing a solitary globule and surrounded by a single ring 
of similar globules. These were indistinguishable from the 
numerous oil-globules present, and attracted attention solely 
by their curious arrangement. Fig. 8 represents the state 
of the gametangia in the middle of this period. Finally, 
at 2.45 a.m. on 8/10/98, the protoplasm commenced to heap 
itself up at four points to form four oospheres (Fig. 9). 
At 3.15 a.m. these heaps were very obvious. The large oil- 
globules were at this time a very striking feature. They 
are more conspicuous in this species of Achlya than in 
any other member of the Saprolegnieae with which I am 
acquainted. 
In the antheridium the most obvious structures were a few 
large granules. In addition were clear patches of protoplasm 
free from granules, which might possibly represent the nuclei, 
as they differed in refractive power from the surrounding 
protoplasm and were of the proper size. 
Perhaps the most remarkable feature in the course of 
development so far outlined is the absence of the peculiar 
and striking vacuolated stage seen in species of Saprolegnia. 
In Saprolegnia the vacuoles are very large and obvious, and 
occur only for a relatively short period during the develop- 
ment of the oogonia. In Achlya the vacuoles are not con- 
spicuous, and they appear to be present at all stages in the 
development of the oogonia up to that which De Bary 
described as hailing. The observations having already been 
continued for a period of nineteen hours, they were of necessity 
interrupted. At 10 a.m. on the same day they were resumed, 
and a. note made to the effect that the oogonium was pro- 
vided with eggs and the fertilization-tubes had already 
reached them. 
A second series of observations, completed before the one 
just described, enables me to trace the whole course of 
development in a single oogonium from the first stage in 
the formation of oospheres up to and including the germi- 
nation of the oospores. At 10.45 a.m. on 21/9/98 the 
oogonium represented in Fig. 10 was brought under 
