IXSECTA. 203 



which they sucked into their transparent bodies, its course 

 could be distinctly traced in the internal processes of a 

 stomach and intestinal canal. Although so exceedingly 

 minute, they differ greatly in form. Some are round ; 

 others flat or oval, cylindrical, shorter, or longer. The 

 bodies are mostly smooth ; some, however, have a gall- 

 like covering ; others a calcareous coat of mail, which is 

 of different forms either shell, shield, or mantle-shaped. 

 They all have, on the fore part, a very singular prolong- 

 ation, which is considered the organ of locomotion. 

 Below this are the tail and the wheel-like apparatus by 

 which they perform the rotatory vibrations from which 

 one class receive their name (Rotifera). This consists 

 of various tubes, fitted into each other, like those of a 

 telescope ; or else of numerous soft syphons in the vicin- 

 ity of the mouth, and surrounded with rows of cilia. 

 Many species have the faculty of prolonging the body in 

 front, and thus change its form ; others are clothed with 

 stiff hairs, or beards, and have horns, spurs, suckers, and 

 muzzles. The vibratile cilia is, however, with a some- 

 what different arrangement, found in most. These, placed 

 around the mouth, or often over the whole body, are 

 always in motion, and in water revolve in circles, serving 

 also as antennae. Some are dotted with red and black 

 points ; others have eyes placed just above the mouth ; 

 no others of the organs of the senses can be observed. 



The Infusoria abound in great numbers, and spring 

 into existence either by the simple, but ever active power 

 of creative nature, or else issue from eggs which they 

 produce in great numbers. Those which have a calca- 

 reous or fossil-like envelope, form, after dying, large hills. 

 This might seem incredible, that such minute creatures 

 could thus subserve so great a purpose, had it not been 



