8o INFUSORIA. PART in. 



unaided eye, have high functions assigned to them in 

 the economy of nature. They ' are useful for devouring 

 and assimilating the particles of decaying animal and 

 vegetable matter from their incredible numbers, uni- 

 versal distribution, and insatiable voracity they are 

 the invisible scavengers for the salubrity of the atmo- 

 sphere. They perform a still more important office 

 in preventing the gradual diminution of the present 

 amount of organic matter upon the earth. For, when 

 this matter is dissolved or suspended in water in that 

 state of comminution and decay, which immediately 

 precedes its final decomposition into the elementary 

 gases, and its consequent return from the organic to the 

 inorganic world, these wakeful members of Nature's 

 invisible police are everywhere ready to arrest the fugi- 

 tive organic particles, and turn them back into an 

 ascending stream of animal life. Having converted the 

 dead and decomposing matter into their own living 

 tissues, they themselves become the food of larger In- 

 fusoria, as the Rotifera and numerous other small 

 animals, which, in their turn, are devoured by larger 

 animals as fishes, and thus a pabulum fit for the nourish- 

 ment of the highest organized beings is brought back 

 by a short route from the extremity of the realms of 

 organized matter.' 5 



5 Lectures on Comparative Anatomy,' by Professor Owen. 



