32 
In the first place, these enlarged cells divide into four, then into eight, 
- dark-green cells, and thus form a dise-like group, which, by growing 
more rapidly in the middle than on the edges, soon becomes convex on 
the inner side. This process of cell-division and unequal growth goes 
on till the young ecenobium becomes a hollow sphere attached to the 
parent by the marginal cells of the hollow disc. At what exact period, 
or in what precise manner, the separation between the two takes place 
has not yet been determined. 
The above, which is essentially a process of cell-subdivision or 
emmiparous extension, is the ordinary mode of multiplication in 
Volvox, taking place at all times of the year, except when the sexual 
generation now to be described is in progress. r. Carpenter then 
describes the sexual generation as follows :—‘ Each sphere of Volvor 
globator (Fig. 22, bis. 6) contains both kinds of sexual cells, so that 
this species ranks as monecious. oth kinds of sexual cells are at 
