98 ANIMAL LIFE 
gating cells are of two distinctly different kinds. When 
this kind of multiplication is to take place in the case of 
Eudorina elegans, to choose a common species, some of 
the cells of a colony divide into sixteen or thirty-two 
minute elongated cells, each 
provided with two flagella. 
These small cells escape 
Hie. 15.—Eudorina eleqaus. A, a mature colony (from Nature); B, formation of 
the two kinds of reproductive cells. 
from the envelope of the parent cell, remaining for some 
time united in small bundles. Other cells of the colony 
do not divide, but increase slightly in size and become 
‘spherical in shape. When a bundle of the small cells 
comes into contact with some of these large spherical 
cells the bundle breaks up, and conjugation takes place 
between the small flagellated free-swimming cells and the 
large non-flagellate spherical cells. Each new cell formed 
by the fusion of one of the small and one of the large cells 
develops a cellulose wall and assumes a resting stage. 
After a time from each of these resting spores a new colony 
of sixteen or thirty-two cells is formed by direct, repeated 
division. 
1%. Volvox.—Another interesting colonial protozoan is 
Volvox. The large spherical colonies of Volvoz globator 
