SALIVA IN GENERAL. 199 



and swallowed it in 60 portions ; a second, an hour and twelve 

 minutes, and swallowed it in 95 portions ; a third, an hour 

 and a half, and swallowed it in 1 20 portions ; a fourth, which 

 was very small, took an hour and forty-four minutes to the 

 same quantity, swallowing it in 150 portions. On an average, 

 then, a horse takes 45 seconds to masticate an ounce of hay, 

 at the rate of from sixty to eighty strokes of the teeth per 

 minute. If from any cause there be a deficiency of saliva, the 

 amount of movement in the jaw required is very much in- 

 creased.* 



From the account already given, under the head of the 

 several animals included in this treatise, it sufficiently appears 

 how uniformly important the process of mastication is towards 

 the promotion of digestion. It seems certain that much has 

 yet to be discovered respecting the special uses of the saliva 

 in animals that differ in conformation. If the saliva has no 

 chemical effect but that of transforming starch into sugar, 

 it seems singular that such glands as the salivary should be 

 present so extensively throughout the carnivorous tribes of 

 the animal kingdom. 



In the ruminant animals the supernumerary stomachs may 

 be regarded as appendages of the mouth that is to say, as 

 concurring with the teeth and salivary glands in the prepara- 

 tion of the aliment for the proper ventricular digestion in 

 the fourth stomach. 



The act of swallowing has been sufficiently illustrated in 

 the several animals to which reference has been made in the 

 preceding pages. 



The effect of the stomach on the prepared aliment con- 

 sists principally in the application to it of the gastric juice 

 or peculiar secretion of the lining membrane ; and even 

 the muscular movement of the organ, besides the transinis- 



* Colin, 'Physiologiedes Animaux Domestiques.' 



