Spirogyra 87 
SPIROGYRA. 
F. M. ANDREWS. 
A number of instances are on record where irregularities occur as 
to the form, conjugation or general behavior in the genus Spirogyra. 
Among these may be mentioned a paper by Gregory’ which illustrates 
a number of specimens of Spirogyra which show branches given off. In 
one instance a figure is given showing a branch which has itself divided 
into two branches. See Fig. 2 of Gregory’s paper. This, as the author 
states, is due probably to monads. Attention is also called to the well- 
known galls of Vaucheria and of Oscillatoria, the latter due to the 
‘entrance of zodspores of Chytridiae. In the Spirogyra cells which 
branch, as Gregory shows, these all proceed from the convex side of 
the cell. This appearance of these branches on the convex or stretched 
side of the Spirogyra cell recalls a similar disposition in the arrange- 
ment of roots on the convex side of the main root, which, however, in 
the case of the roots, is a response to the mechanical factors that are 
operative. 
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ihivedy ihe Spirogyra crassa x 300. 
A paper by the writer* in 1910 showed conjugation in two different 
species of Spirogyra, as Spirogyra crassa and Spirogyra communis. 
In another paper*® I have called attention especially to the question of 
irregular cases of conjugation in Spirogyra. 
In this paper also the literature is referred to in so far as it per- 
tains to the topic under discussion. Chief among these was the paper 
1Gregory, Emily L. Bulletin of the Torrey Botanical Club, 1892, Vol. 19, pp. 75-79. 
* Andrews, F. M. Bulletin of the Torrey Botanical Club, 1910, Vol. 38, p. 299. 
3 Andrews, F. M. Proceedings of the Indiana Academy of Science, 1912, pp. 89-91. 
