322 BOTANICAL GAZETTE [NOVEMBER 
In case they are distant from the exit, not finding it they round up 
into the motile zoospore form again and swarm around in the zoospo- 
rangium for a time, and coming to rest make another trial. It is 
evident that when the zoosporangium is filled with the zoospores the 
latter will escape quite rapidly 
for a time because so many of 
them are crowded successively 
against the exit. As the num- 
bers diminish there is greater 
freedom for swarming. The 
zoospores then swarm around 
and around in great circles 
Fic. t.—Rhizophidium globosum(A.Br.) inside the wall of the zoospo- 
eae A Ste Plant, eee after rangium, now and then coming 
Renae BS tae cee to rest and feeling around for the 
mature plant ready to form zoospores; exit. This same behavior has 
C zoospores escaping; D much smaller been observed in the case of a 
plants. . a 
number of other species. In 
addition to this a quite remarkable phenomenon was observed in 
the case of another species, Rhizophidium brevipes, which will be 
described below. 
In the presentation of these observations I shall make no attempt 
to arrange the genera in any natural order of relationship, this matter 
being reserved for a future work. Since a number of species of 
Rhizophidium were studied I will begin with this genus. 
RHIZOPHIDIUM BREVIPES 
This was collected in a pool beyond Forest Home, N. Y., 4 little 
more than one mile from Ithaca. It was attached to the wall of a 
fruiting cell of Spirogyra varians. The zoosporangium is oval with 
a small apical papilla. The wall shows two distinct layers, an outer 
rather thick one and an inner thin one. _At the time of the maturity 
of the zoospores the papilla of the outer layer becomes gelatinized 
at the apex, forming a minute opening about 4 » in diameter. 
One very characteristic feature of this species is the very rudi- 
mentary condition of the rhizoids. The very slender branched 
rhizoids so characteristic of R. globosum and other species appeat e 
awe 
