368 NATURAL HISTORY. 
639. Though most of the Infusoria move freely about 
in fluids, some are attached, like Polypes, to some solid 
base. Many of them are not, however, always thus at- 
tached, but have the power of loosing themselves from 
their attachment to swim off by their cilia to find some 
other locality. This is the case with the Bell-shaped An- 
imalcules, one species of which is represented in Fig. 
278. ‘The body of the animal is shaped like a bell, and 
Jr 
ZE 
FRE 
nr) 
~P—@- 
S S25 
= 
Ws 
VSS 
Fig. 278.—Bell-shaped Animalcules. 
its margin, which is its mouth, is fringed with cilia. The 
actual length of its body varies, in different individuals, 
from the one two hundred and eightieth (,4,) of an inch 
to the one five hundred and seventieth (45). The tiny 
stem by which each animalcule is attached has a muscle 
