172 



THE VITAL FUNCTIONS. 



ensure the tlioroiigli solution of their contents, by 

 preventing the exit of all such portions as have not 

 perfectly undergone this process. 



Supernumerary cavities of this kind, belonging 

 to the stomach, are more especially provided in 

 those animals which swallow food either in larger 

 quantity than is immediately wanted, or of a nature 

 which requires much preparation previous to diges- 

 tion. The latter is more particularly the case with 

 the horned ruminant tribes that feed on the leaves 

 or stalks of vegetables ; a kind of food, which, in 

 proportion to its bulk, affords but little nutriment, 

 and requires, therefore, a long chemical process 

 and a complicated digestive apparatus, in order to 

 extract from it the scanty nutritious matter it con- 

 tains, and prepare it for being applied to the uses 

 of the system. This apparatus is usually consi- 

 dered as consisting of four stomachs; and in order 

 to convey a distinct idea of this kind of structure, 



I have selected for representation, (in Fig. 3 J 2,) 

 that of the Sheep, of which the four stomachs are 



