358 
WM. H. WESTON 
Most of these spores are formed in chains, and in some cases the 
terminal spores abjuncted by the pressure of the spores below are 
tipped over sideways, although still remaining attached. That these 
resistant spores should be borne aerially is of interest because of the 
close analogy presented to the aerially borne conidia of certain of the 
Peronosporaceae. It does not seem justifiable, however, to regard 
this phenomenon as of any further significance than an instance of 
convergence, of parallel development, in the two families. 
The process of resistant spore formation takes place as follows: 
The tip of a hypha becomes densely filled with coarsely granular pro- 
toplasm carried up by the streaming of the currents in the peripheral 
protoplasm. Gradually more and more material is accumulated in the 
tip forming a dense mass which slowly extends downwards to the base 
of the spore initial. Meanwhile the tip of the hypha swells to the 
spherical or oval shape of the mature resistant spore; and finally the 
spore initial is separated from the hypha by a wall. Around the inner 
surface of the terminal cell thus cut off, a wall of varying thickness is 
laid down by the dense, coarsely granular protoplasm which occupies a 
peripheral position around a large vacuole (Fig. 9). 
After the terminal resistant spore has been formed, as just de- 
scribed, other resistant spores are generally formed in basipetal suc- 
cession under the first as in figures 6, 9, and 10, giving a torulose 
series closely resembling the catenate oogonia of Saprolegnia torulosa 
de B. In gross cultures, the resistant spores are generally formed in 
this fashion, giving a very striking and characteristic appearance to 
the plant. After a time the fragile outer wall of the resistant spore is 
ruptured (Fig. 9), and the spore is set free in the water to be washed 
about and then to slowly settle to the bottom. Further development 
varies with the conditions of the environment, and will be considered 
later. 
The resistant spores are generally formed in a terminal series as 
above described, but they may be intercalary (Figs. 7 and 8) or may 
form branching systems of various types. In shape the resistant spores 
are spherical, cylindric, oval, or less often pyriform, or clavate. Under 
conditions closely approximating those of nature, the resistant spores 
are spherical (Fig. 10) or oval; and on fairly dry cornmeal cultures, 
they are the same. On vegetative mycelia transferred to sterile 
water and to solutions of various sorts, the resistant spores which are 
formed are at times cylindrical or club-shaped (Figs, i and 12). In 
