BULLETIN 
OF THE 
TORREY BOTANICAL CLUB. 
Vol. XIX.] New York, March 5, 1892. [No, 3. 
Abnormal Growth of Spirogyra Cells. 
By Emity L. GREcory. 
(Plate CXXV.) 
Some Spirogyra filaments were obtained for class work from 
the greenhouse of the Biological Department of the University of 
Pennsylvania, about the last of January, 1891. These were soon 
noticed to present an appearance of branching quite unlike that 
occurring in the ordinary process of reproduction. The regular 
Toutine of class work prevented any continued study of the pro- 
cesses of development, which soon showed themselves to be 
Caused by the attacks of some low organisms, probably the mo- 
nads described by Zopf. The only definite results obtained from 
“such desultory study as could be given them at odd times have 
reference to the peculiar manner of growth caused by the irrita- 
ting organism. 
In many cases the malformation caused by parasites preying 
on Alge is ofa similar nature to that occurring in higher plants. In 
other words, the abnormal growth seems to be governed by the 
necessities of the irritating organism and adapts itself in a greater 
or less degree to the needs of the latter. Familiar examples of 
this are the so-called Vaucheria galls, whose morphological signifi- 
fance is still a matter of doubt. Whether the gall arises from 
the metamorphosis of a fruit branch, as some claim, or whether 
an entirely abnormal growth from the side or end of the Vaucheria 
cell, it usually attains a size and shape to accommodate the little 
Totifer and its eggs. So also in the case of the galls of certain 
Species of Oscillaria, caused by the entrance of the zoospores of 
