MASTICATION AND DIGESTION. 63 



this starch, into sugar, ceases on being neutralised by 

 coming into contact with the acid gastric juice. 

 Hence, it would appear that the chief office of the 

 saliva is to check undue acidity in the stomach. 



The frothy nature of saliva seems to aid digestion. 

 " The numerous air-bubles for which saliva is remark- 

 able have their special purpose ; since the presence of 

 atmospheric air in the stomach is accessory to diges- 

 tion." (Leared.) 



I submit that the foregoing observations indicate, as 

 a general rule, the advisability of giving grain in a dry 

 state. 



The presence of salt in the food excites the flow of 

 saliva in the mouth ; hence, if boiled or steeped food 

 be used, it should be given mixed with that condiment ; 

 because, owing to the moist and soft state of the grain, 

 a deficient amount of saliva will be secreted. 



Having reached the stomach the capacity of which 

 is from 3 to 3| gallons the food becomes mixed with 

 the gastric juice, which flows slowly at first. This 

 secretion is liable to become checked by violent exercise, 

 or by the stomach becoming unduly distended. If it 

 be largely diluted with water, its action will be arrested, 

 until the excess of that fluid be absorbed. Cold also 

 stops the performance of its functions ; for it will 

 not act at a temperature much below blood heat. A 

 moderate supply of hot spices stimulates its secretion. 

 When the supply or action of the gastric juice which 

 is a natural antiseptic is checked, the food that is in 

 the stomach at the time is apt to become decomposed 

 with the probable result of indigestion, flatulent colic, 

 and even rupture of the stomach, caused by the evolu- 



