Ig09] ATKINSON—FUNGUS PARASITES OF ALGAE 325 
_ The slender germ tube, having penetrated the wall of the zoospo- 
_ Ttangium, extended ina tortuous course for a distance of 15-20. The 
_ preparation was examined several times during the day. Since one 
of the zoospores was located not far from the wall of the spirogyra, it 
was hoped that the thread would find the cell and enter it, inasmuch 
__ as it was pointed in that direction. The preparation was left in this 
condition during another night, the slender tube of the zoospore 
__ hearest the spirogyra cell not yet having reached it. On the following 
a Morning the preparation was examined again, and I was surprised to 
5 find that one of the zoospores was on the other side of the zoospo- 
Tangium. Close examination showed that both had moved during the 
night. Not being able to find any suitable nourishment, the proto- 
_ plasm in each germinating cell had migrated back from the inclosing 
_ Membrane into the zoosporangium, formed a zoospore, and had 
_ Passed through a second swarming period. Then coming to rest 
_ 4gain they had germinated, the germ tube of each having again 
_ enetrated the wall of the sporangium and formed a slender tube 
a 15-20 long. The preparation was kept for a day longer, but the 
_ Zoospores did not form again. 
This behavior of the zoospores is quite interesting, since it mani- 
fests not only a sort of “ingenuity” in the attempt to escape from the 
Z0osporangium, but, what is more important, the tendency, under 
_ ©értain conditions of existence which prevent the zoospore from 
_ Seeking a host cell by the normal planetic method, to migrate in the 
form of a true mycelial tube, which is quite different from the very 
q delicate slender absorbent rhizoids normally developed from the germ 
__ tube in other species of the genus. 
Rhizophidium brevipes, n. sp.—Zoosporangia oval, 21-24 u in diameter, with 
4 papilla at the apex, in which the exit pore is formed. Rhizoidal apparatus 
very rudimentary, consisting of the short, blunt, unbranched entrance tube 
Of the Zoospore, which projects but a very short distance beyond the inner 
: in diameter. 
= On walls of gametangia of Spirogyra varians in which zygospores are formed. 
_ Vicinity of Ithaca, N. Y. 
Zoosporangiis ovatis, apici uno, brevi, papilliformi ostiolo, basi, uno brevi, 
ga — tubulo. Zoosporis ovoidiis, 3 # latis, una guttula hyalina et uno cilio 
_ Praeditis, 
_ lamella of the wall of the host. Zoospores oval with an oil drop, uniciliate, 3 4 
