20, 5 Shaw: Janetosphaera and Volvox 487 
layer of atrophied cells,‘ this being surrounded in turn by inner 
and outer spore walls. The atrophied cells he regards as so- 
matic cells of a dwarf female coenobium of which the gynogo- 
nidium proper is the single reproductive cell. 
The cell membranes of the somatic cells, first adequately de- 
scribed by Meyer (’96) were diagrammatically shown in elaborate 
figures by Janet (’12, figs. 1, 2, 3, and 6) in his comprehensive 
monograph on Volvox. According to Meyer’s account, illus- 
trated by his diagrammatic figures that are reproduced here as 
text figs. 3 and 4, the ceils of Volvox globator are short prismatic, 
6-sided as seen in surface view (fig. 4) and rectangular as seen 
in a section normal to the surface of the coenobium (fig. 3). A 
fine, relatively thick membrane lamella, m, that he called the 
Fic. 3. Volvox globator. Diagram of Fic. 4. Volvox: globator. Diagram of 
cell membranes as seen in a cross- cell membranes as seen in surface 
section view of a portion of the coe- view and tangential sections of the 
nobium wall. After Meyer. . coenobium wall. After Meyer. 
“Hiilllamella,” unites the cells. The peripheral lamella, p, form- 
ing the outer boundary of the coenobium, is relatively thick. 
The lamella, h, bounding the cell toward the interior of the 
coenobium is of the same thickness as the lateral part of the 
lamella, m. The space between the “Hiilllamella” and the pro- 
“Unfortunately Janet’s preliminary note on the egg of Volvox globator 
was overlooked by Zimmermann (’21) at the time of the preparation of 
his most valuable paper on the development and cytology of Volvox, and 
the latter gives no account of the development of the oogonidium of this 
Species. So we still await detailed confirmation of Janet’s account of the 
cogonidial follicle. Although nothing like this follicle was found by Zim- 
mermann in the investigation of his material of Janetosphaera aurea, 
making it appear that the absence of such a follicle constitutes a difference 
between these genera, still the results will be more conclusive when we 
have a definite report on the subject made with this point in mind. 
