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 



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 ( 2 -J-o) of an inch 

 to the one five hundred and seventieth (-5-7-0)' The tiny 

 stem by which each animalcule is attached has a muscle 



