1894. | A New Genus of the Volvocinee. 281 
The path is parallel to this axis in upward vertical as well as 
in horizontal movement. 
The division of the gonidia was followed in a number of 
cases on different days. The first cell division took place 
about two hours after noon and the daughters escaped from 
the mother plant eighteen to twenty-four hours afterward. 
Previous to division the investing membrane of the-cell begins 
to swell up and withdraw from the protoplasm, doing so at 
first in a zone just back of the point of attachment. This for 
a time gives the forward end of the cell the form of a beak 
(fig. 6). The two cilia persist on the gonidium and are 
active even after the cell has divided several times. The 
succession of divisions is essentially as in Eudorina elegans.* 
The first two divisions are perpendicular to the surface of the 
whole sphere and to each other (fig. 2, a-c). Before the 
next division takes place the walls already formed become 
curved and oblique, so that seen from the front the cells over- 
lap slightly (fig. 3, d). The next division is anticlinal and 
somewhat oblique (figs. 2, d and 4, 4). As the division pro- 
ceeds a plate of cells is formed which becomes concave trom 
the front (fig. 4, c); the concavity increases until the plate. 
becomes bowl shaped, and the mouth of the bowl closes to 
form a hollow sphere of very closely arranged cells before the 
last division takes place. The cells separate slightly and 
become rounded; then the last division into about 128 cells 
occurs and the cells are again closer and flattened by contact. 
Finally the cells become gradually more and more separated 
from each other, though fixed in the common envelope. 
After the last division takes place the cilia begin to form 
as outgrowths, two from the outer end of each cell. Thus it 
is to be borne in mind that the cilia do not arise on that end 
of each cell which corresponds to the ciliated end of the 
mother gonidium, but on the opposite end. As the cilia be- 
come longer they acquire movement and each daughter plant 
rotates slowly within the swelled up membrane of the goni- 
dium from which it has developed. The daughter plants es- 
‘ape as spheres of cells which are all alike. One case was 
observed in which the formation of the cilia began before the 
young plants had reached the spherical stage. This was 1n 
he above mentioned sixty-three-celled plant. In this in- 
Goebel, Outlines Trans.) 37. 1887. . 
: , Ou of Class. and Sp. Morph. of Plants (Eng. Trans.) 3 
dian y ~ this point the sraucition Wad ack actually followed but traced by 
©nt stages present in each of two fixed mother p 
