DIGESTION AND FOOD. 15 



16. The saliva flows, during the process of mastication, in 

 some measure proportionate to the dryness of the food. The 

 salivary glands have a very active sympathy with the appe- 

 tite, and will sometimes send forth a flow of saliva at the 

 mere presence of savory food, so that the common saying, 

 that " one's mouth waters" at the sight of agreeable dishes, 

 is physiologically true. These glands are important assist- 

 ants in the masticating process, when they and the body are 

 in health ; but in fevers, and in some other diseases, these 

 organs refuse to act, and the mouth then is dry and parched. 



17. By the united operation of the teeth and the salivary 

 glands, the food is first ground into small particles, and then 

 made into a soft pulp, in the mouth. Both these operations 

 are necessary, for "we cannot swallow the morsels unless they 

 are divided and moistened, either naturally or artificially. 

 Let any one attempt to swallow a mouthfuj of dry bread 

 without chewing, or powdere4 cracker, without saliva or 

 other fluid to soften it, and he will find, that this process, 

 which, when proper preparation is made for it, is one of the 

 easiest and most agreeable, is now one of the most difficult 

 and unpleasant. If the food be not divided while in the 

 mouth, it cannot be done afterwards; there is no machinery 

 nor power in the stomach to effect this division. 



18. In the back part of the mouth is a second chamber, 

 called the pliarynx, separated from the anterior or front 

 chamber by a movable curtain, called the palate. This 

 curtain, hanging between these two chambers, is easily 

 seen when the mouth is partly opened, and seems then to be 

 the farthest boundary of the cavity. But when the mouth is 

 stretched widely open, this curtain is raised, and the other 

 chamber is disclosed behind it. A little knob or tongue of 

 flesh hangs down from the middle of the palate, nearly, and 

 sometimes quite, to the tongue, and partially or entirely 

 divides the passage-way from the front to the back chamber. 

 This gives the appearance of two passages, one on the right 

 and the other on the left side. 



19. Four passages open out from the back chamber; one 



