"VVHEEL-BEARERS. 223 



CHAPTER XIV. 



WHEEL-BEARERS. 



I must now introduce to you a class of animals peculiarly 

 microscopic ; since, without our marvel-showing instru- 

 ment, they are wholly beyond the sphere of human cog- 

 nizance. 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 animated beings, this 

 of the Rot if era* has been my own special delight. Their 

 numerous and varied forms, often of remarkable sym- 

 metry and elegance, their swiftly-revolving wheels, their 

 vigorous and sprightly motions, their curious habits and 

 instincts, their complete organization, and the ease and 

 correctness with which this is discerned through their 

 tissues, which have the transparent 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 delight. 



The peculiarity which specially characterises them is 

 the presence of certain organs called cilia : and their 

 arrangement in such a manner, that their motion gives 

 to the observer the impression, that two toothed wheels 

 are placed on the front of the animal, which are in rapid 

 revolution on their axes. This was believed to be the 

 real fact by the earlier microscopists, though they were 

 utterly unable to conceive how such a movement could 

 consist with parts maintaining an organic connexion 



* From the Latin rota, a wheel, and/ero, I bear. 



