424 THE MECHANICAL FUNCTIONS. 



ranked as a genus of the class mammalia. So 

 numerous, indeed, are the analogies which connect 

 the natural families of this class with our own race, 

 that vve must ever feel a deep interest in the accu- 

 rate investigation of their comparative anatomy and 

 ])hysiology ; and it has been found, accordingly, 

 that the progress, which has, of late years, been 

 made in this branch of science, has materially en- 

 larged our knowledge of the structure, the functions, 

 and the physical history of Man ; subjects with 

 which our welfare has obviously the closest and 

 most intimate relation. 



The principle of analogy, which prevails so gene- 

 rally in the inferior departments of the animal crea- 

 tion, may be also traced in the class mammalia ; for 

 we always find its influence more conspicuous in 

 proportion as the objects comprehended in the 

 natural series of beings are more numerous and 

 more diversified. Scarcely any of the great natural 

 assemblages of animals exhibit more variety in 

 their habits and modes of existence, than the one 

 we are now examining. Each race has its peculiar 

 destination with regard to the kind of food by which 

 it is nourished, and the means by which that food is 

 obtained. The carnivorous tribes wage war with 

 the larger animals, whom they either spring upon 

 unawares, or openly pursue and overpower, dis- 

 playing the savage energies of their nature, in 

 practising all the arts of ferocious and sanguinary 

 destruction. Others, intent on meaner prey, resort 

 to divers stratagems for its possession ; some are 

 designed to feed chiefly on the mollusca, and others 

 swallow insects only. The numerous tribes which 

 are formed to subsist on vegetable food exhibit, in 



