DEGLUTITION. 271 



in the starch which result in its transformation, first into 

 dextrin and then into sugar. 



The majority of observers agree that the transformation 

 of starch into sugar ceases on the entrance of the food 

 into the stomach, or on the addition of gastric fluid to it in 

 a test-tube : while others maintain that it still goes on. 

 Probably all are right : for, although gastric fluid added 

 to saliva appears to arrest the action of the latter on 

 starch, yet portions of saliva mingled with food in mas- 

 tication may, for some time after their entrance into the 

 stomach, remain -unneutralized by the gastric secretion, 

 and continue their influence upon the starchy principles in 

 contact with them. 



Starch appears to be the only principle of food upon 

 which saliva acts chemically : it has no apparent influence 

 on any of the other ternary principles, such as sugar, gum, 

 mucous, cellulose, or (according to Bernard) on fat, and 

 seems to be equally destitute of power over albuminous 

 and gelatinous substances, so that we have as yet no infor- 

 mation respecting any purpose it can serve in the digestion 

 of Carnivora, beyond that of softening or macerating the 

 food ; though, since such animals masticate their food 

 very little, usually "bolting" it, the saliva has probably 

 but little use even in this respect, in the process of 

 digestion. 



Passage of Food into the Stomach. 



When properly masticated, the food is transmitted in 

 successive portions to the stomach by the act of deglutition 

 or swallowing. This act, for the purpose of description, 

 may be divided into three parts. In the first, particles of 

 food collected to a morsel glide between the surface of the 

 tongue and the palatine arch, till they have passed the 

 anterior arch of the fauces ; in the second, the morsel is 

 carried through the pharynx ; and in the third, it reaches 

 the stomach through the oesophagus. These three acts 

 follow each other rapidly. The first is performed volun- 



