WnEEL-BEARKTlS. 257 



CHAPTER XIY. 



WIIEEL-BEARERS. 



I MUST now introduce yon to a class of animals pecu- 

 liarly microscopic, since without our marvel-sliowing 

 instrument they are wholly beyond the sphere of hu- 

 man cognizance. Yet they have been ever since its 

 invention favourite objects with the microscopist ; and 

 I am free to confess that, among all the classes of ani- 

 mated beings, this of the Rotifera has been my own 

 special delight. Tlieir numerous and varied forms, often 

 of remarkable symmetry and elegance, their swiftly- 

 revolving wheels, their vigorous and sprightly motions, 

 their curious habits and instincts, their complex organi- 

 zation, and the ease and correctness with which this is 

 discerned through their tissues, which have the trans- 

 parent brilliance of the purest crystal — all combine to 

 impart a charm to the Wheel-bearers, which makes the 

 observer hail their appearance in his drops of water 

 with pleasure, and linger over them with unwearied 

 delififht. 



The peculiarity which specially characterizes them is 

 the presence of certain organs called cilia^ and their 

 arran£>:ement in such a manner that their motion <2;ives 

 to the observer the impression that two toothed wheels 

 are placed on the front of the animal, which are iu 



