Conjugation of two different species;of Spirogyra 
F. M. ANDREWS 
Instances of irregularity in the behavior and conjugation of 
Spirogyra have been observed from time to time by botanists. 
In some of these cases two different species have been seen con- 
jugating, of which the following is an example. 
A large quantity of the two species here shown was found in 
September in a pond, and all stages in the process of conjugation 
could be seen. Most of the same kind were conjugating together. 
In a good many cases, however, the two different species, as 
shown in the accompanying figure, were to be seen conjugating. 
In the figure the larger specimen, A, is Spirogyra crassa and the 
smaller one, B, is Spirogyra communis. Some of these two differ- 
ent species which were not in a state of conjugation did conjugate 
when brought into the laboratory and put under artificial 
conditions. 
LEG ie oY 
tis ALEX 
CLE 
Wwe 
LAVA i, 
Zr) 
LUA 
WF 
Conjugation of Spirogyra crassa, A, and S. tomcat: B. 
In most cases the contents of the cells of the smaller species, 
Spirogyra communis, passed over to the larger one, Spirogyra 
crassa, in the process of conjugation. This, however, was not by 
any means always the case, since instances were found, as shown 
by the accompanying figure, in which the contents passed from 
the cells of Spirogyra crassa to those of Spirogyra communis. 
Aside from a difference in size and form, the zygospores seemed 
perfectly normal. 
There are interesting questions connected with the hybrid 
form that would arise from the conjugation of two different 
species of Spirogyra, and investigations are in progress to deter- 
mine these points. 
INDIANA UNIVERSITY, 
LOOMINGTON, IND. 
299 
