178 WHEEL-BEARING ANIMALCULES. 



According to the observations of Dr. A. Farre, 

 the cilia, under a microscope of high powers, present 

 an appearance of waves rolling round and round in 

 a circle ; each wave is produced by a number of 

 cilia, those forming the highest point being at full 

 stretch ; the others folded down upon themselves 

 in an increasing ratio to the middle of the interval 

 between two waves, where they are most completely 

 lowered : these, however, become in turn the most 

 elevated, and those which were the highest, the 

 most lowered, and so on in alternate succession, and 

 with great rapidity, the waves appearing to roll 

 onwards. 



The cilia are certainly endowed with voluntary 

 motion ; they are regulated in their actions by the 

 will of the animal ; they can be urged into move- 

 ments of extreme rapidity, put into gentle and 

 tranquil action, or stopped in an instant. Some- 1 

 times, a portion only of the circlet of cilia is in 

 action, while the other portion is quiescent ; and 

 sometimes a few cilia alone are seen slowly bending, 

 and then stretching themselves ; when all at once 

 the whole begin to work with the utmost energy, 

 wave succeeding wave with wonderful velocity. 

 It is by the action of these cilia, that the animalcule 

 rows itself through the water, and traverses the 

 tiny ocean in which it revels, full of animation. 

 They are not, however, exclusively organs of loco- 

 motion ; they serve for the acquisition of food. 

 Fixing itself by means of a pair of forceps, ter- 



