THE LIFE OF THE SLIGHTLY COMPLEX ANIMALS oT 
colony, the two cells conjugate (Fig. 14)—that is, fuse to 
form a single cell. This new cell formed by the fusion of 
two, develops a tough enveloping membrane of cellulose 
and passes into what is called 
the “resting stage.” That is, 
the cell remains dormant for a 
shorter or longer time. It may 
thus tide over a drought or a 
winter. It may become dry or 
be frozen, yet when suitable 
conditions of moisture or tem- 
perature are again present the 
outer wall breaks and the pro- 
toplasm issues as a large free- 
swimming cell, which soon di- 
vides into sixteen daughter 
cells which constitute a new 
colony. 
16. Eudorina,— Another colo- 
nial protozoan which much re- 
sembles Pandorina, but differs 
from it in one interesting and 
suggestive thing, is Hudorina. 
In Eudorina elegans (Fig. 15) 
the colony is spherical and is 
composed of sixteen or thirty- 
two cells. Each of these cells 
can become the parent of a new 
colony by simple repeated divi- 
sion. But this simple mode of 
reproduction, just as with Pan- 
dorina, can not persist indefi- 
nitely. There must be conjuga- 
tion. But the process of mul- 
A 
Fig. 14.— Pandorina morum (after 
GoEBEL). Three stages in the 
conjugation and formation of the 
resting spore. A, two cells just 
fused; B, the two cells completely 
fused, but with flagella still per- 
sisting ; C, the resting spore. 
tiplication, which includes conjugation, is different from 
that process in Pandorina, in that in Hudorina the conju- 
