8o THEORY OF FEEDING. 



to the degree in which the mastication of their food is 

 performed ; and that these glands are absent in birds which 

 swallow their food whole. Although dogs secrete saliva abun- 

 dantly, starch is not a component of their natural food. As 

 the requirements of a horse's digestion demand that he 

 should thoroughly chew his food, we ought to give it to him in 



Fig. 5. Lower Jaw moved to the left, as in Fig. 3. 



a condition that will induce him to eat slowly. Furthermore, 

 the amount of saliva secreted during mastication is more or 

 less proportionate to the dryness of the fodder ; for the dryer 

 it is, the more saliva will a horse require to enable him to 

 swallow it. Lassaigne gives, from experiment, the following 

 results : 



100 parts of grass require 49 parts of saliva. 

 ,, ,, oats ,, 113 

 ,, ,, barley ,, 186 

 ,, ,, dry hay ,, 406 ,, 



