HOW THE AM MAI, LIVKS Jl.> 



simple machine, which can, in all cases, turn out 

 a product exactly corresponding to the chemical 

 food elements which are turned into it. The 

 vital el»Mnent has always to be reckoned with. 

 One animal demands a little more of this class of 

 aliment, and another a little more of that, in 

 order to secure the best results; while in all cases 

 palatal)ility and facility of dii,'cstioii have a 

 controlling inlluence. 



3. Difjrsfinn of Food 

 3a. Whni digestion is 



377. Digestion is the process by means of 

 which the food becomes diss(^lve«l so as to bo 

 taken up by the blood. It takes place in the 

 alimentary canal, — the mouth, stomach, and 

 intestines. 



378. Digestion takes place un<lcr tin' action 

 of ditTerent secretions, each of which operates 

 on special constituents of the food, ('.msidered 

 ill the order in which they mingle with the 

 food, these digestive secn'tions are: (a) saliva; 

 (b) gastric juice; (c) bile, (d) pancreatic juice, 

 (e) intestinal juice. 



36. The saliva 



370. Saliva is furnished by a group of glands 

 located under the tongue, in the cheeks, and 



