on the Saprolegnieae. 2 1 1 
up in the formation of the cyst- wall when the spores come 
to rest. 
The discharge of the spores occurs thus. The end wall may 
open in various ways. (1) The front spore presses into the 
process and against the cap, pushing it up into a hemisphere. 
The end wall gets paler and lost to view a little before it dis- 
appears. (2) The end wall disappears before the spore reaches 
it ; discharge at once ensues. (3) I11 a few cases it lifted like 
a lid, and only disappeared after discharge was completed. 
(4) In cases where the end wall was unusually stiff and clearly 
outlined, the front spore pressed through an invisible opening, 
tearing to pieces in the passage ; a few others followed, under- 
going the same fate ; but these gradually enlarged the hole so 
that the rest could pass through normally, but very slowly, 
leaving part of the end wall in situ, which probably never dis- 
appears. In my paper I have described the first two modes 
of discharge ; the third I have not seen ; the fourth I have 
since observed in S. ferax ( monoica ). 
In discharge the front zoospore, which had retreated from 
the process, now moves up into it ; and as soon as it opens,, 
presses out and goes on its own spontaneous motion. The 
others follow, at first c stormily,’ the front ones close pressed 
against one another ; and this is sometimes the case with all ; 
quite as often, however, the later ones move to and fro, with- 
out haste, and only find the exit after much hesitation ; not 
infrequently do the last fail to find it, and encyst within the 
sporange. No change in calibre or length takes place in the 
sporange during this process. 
While this description of the formation of zoospores and the 
opening of the sporange is chiefly taken from Saprolegnia , it 
applies on the whole to the other species examined, including 
the Achlya polyandra of the Strassburg Laboratory. 
Rothert admits that his observations on Achlya were less 
complete and numerous than on Saprolegnia. Here ap- 
parently he has never seen the stage of swelling result in 
complete homogeneity; the planes of separation persisted 
throughout ; after this the spores, instead of contracting from 
