20 



INFUSORIA. 



are active in their movements and definite in their shape, we have 

 said enough to insure their not being confounded with any of 

 the creatures we have as yet examined. The evolutions of the 

 ciliated Infusoria are exceedingly vivacious ; they swim about 



FIG. 12. PARAMECIUM, &c. 



with great activity, avoiding each other as they pass in their rapid 

 dance, and evidently directing their motions with precision and 

 accuracy. Their instruments of locomotion are of various kinds : 

 some are provided with stiff bristle-like appendages which are 

 moveable, and perform in some measure the office of feet, and with 

 little hooklets serving for attachment to foreign bodies. But the 

 most important locomotive agents are, as has been already stated, 

 the cilia with which they are invariably furnished. Their vibra- 

 tions never seem to tire. At whatever period of the night they 

 may be examined, they are always found as actively at work as 

 in the day-time : they never sleep. 



The cilia are intrusted with another function equally important, 

 viz., the procuration of food ; for those situated in the vicinity of 



