162 THE VITAL FUNCTIONS. 



diameter. The African ostrich, on the other hand, which 

 inhabits a country where the supply of food is very scanty, 

 has the colon forty-five feet long; each of the cseca is two 

 feet nine inches in length, and, at the widest part, three 

 inches in diameter; in addition to which, there arc broad 

 valves in the interior of both these cavities.* 



On comparing the structure of the digestive organs of 

 Man with those of other animals belonging to the class Mam- 

 malia, we find them holding a place in the series intermedi- 

 ate between those of tlie purely carnivorous, and exclusively 

 herbivorous tribes, and, in some measure, uniting the cha- 

 racters of both. The powers of the human stomach do not, 

 indeed, extend to the digestion either of the tough woody 

 fibres of vegetables, on the one hand, or the compact texture 

 of bones on the other; but, still, they are competent to ex- 

 tract nourishment from a wider range of alimentary sub- 

 stances, than the digestive organs of almost any other animal. 

 This adaptation to a greater variety of food may also be in- 

 ferred from the form and disposition of the teeth, which 

 coml)inc those of different kinds more completely than in 

 most mammalia, excepting, perhaps, the Quadrumana, in 

 whicii, however, the teeth do not form, as in man, an unin- 

 terrupted series in both jaws. In addition to these pecu- 

 liarities, we may also here observe, that the sense of taste, 

 in the human species, appears to be affected by a greater 

 variety of objects than in the other races of animals. All 

 these arc concurring indications that nature, in thus render- 

 ing man omnivorous, intended to qualify him for maintain- 

 ing life wherever he could procure the materials of subsist- 

 ence, whatever might be their nature, whether animal or 

 vegetable, or a mixture of both, and in whatever soil or 



* Lectures, &c. I. 470. In the account above given of the digestive or- 

 gans I have pui-poscly omitted all mention of the spleen; because, although 

 it is probably in some way related to digestion, the exact nature of its func- 

 tions has not yet been determined with any certainty. 



