20, 5 Shaw: Janetosphaera and Volvox 481 
with all possible intermediate combinations of reproductive 
bodies; antheridia and daughter coenobia, oogonia and daughter 
coenobia, and finally antheridia, oogonia, and daughter coenobia 
in the same mother coenobium. 
The sexual coenobia are more commonly dioecious, but also 
monoecious, and then usually proterogynous, though rarely pro- 
terandrous or with both sexual elements maturing at the same 
time. 
The male coenobia, the so-called “Sphaerosira,’’ (when matur- 
ing within the mother coenobia, called “Endosphaerosira”) bear 
very numerous androgonidia, the number averaging between 300 
and 500, though sometimes as great as 1,100. 
Androgonidia round like the somatic cells, 9 to 12.5 » in diam- 
eter before segmentation, connected with each neighboring 
protoplast by only one, two, or at most three connecting fila- 
ments; formed from about one-third of all the cells of the male 
coenobia ; numbers in combination with other reproductive bodies 
at most. 12 to about 24. 
Antheridia usually in the form of platelets 12 to 18 » wide 
with at most 32, though less often 16 or only 8, spermatozoids. * 
More than 82 spermatozoids in an antheridium is exceptional. 
In some cases antheridia form hollow spheres of spermatozoids, 
These may reach diameters of 80 to 48 y», and contain many 
more sperms than do the platelets. 
The spermatozoids are 8.5 to 12.5 » long and 2 to 3 » thick; 
the chloroplast is clearly leaf green; the nucleus is roundish 
and contains a nucleolus; the cilia are terminal on the end of a 
Short colorless beak at the base of which are two contractile 
vacuoles and a stigma. The antheridia discharge the platelets 
or globoids into the water before the spermatozoids separate. 
* Zimmermann (’21, p. 270) determined that the number of chromosomes 
in the nuclei is the same in all stages of the antheridium as in the vege- 
tative development of the coenobia. In the 16-cell stage of the coenobia 
developing from oospores he counted the same number, thus establishing 
that, though the zygotes are diploid with respect to the chromosome 
number, the coenobia are haploid. Zimmermann also found that in the 
sixteen or thirty-two cells of the slightly cupped platelet of spermatogenous 
cells the nuclei do not migrate from the concave to the convex side of the 
platelet, as in the newly developed coenobia, but remain at the ends of 
the cells forming the concave surface of the platelet. In _this respect 
it is to be expected that the species of Volvox having globoid antheridia 
‘will be found to differ from Janetosphaera, and it may be that the dif- 
ference will be found to extend to those antheridia of Volvox that form 
Platelets of sperms. 
