VII 



DIGESTION 



81 



who lived to be a very old man and yet possessed the 

 vigor of manhood to his very end, that he always chewed 

 every mouthful thirty-three times. 



The saliva, or spittle, is poured into the mouth while 

 the food is being masticated and is well mixed with it. 

 The saliva is very useful, as it keeps the mouth moist all 

 the time, aids in swallowing, and begins the digestion 

 of starchy foods. Now, if we chew well and eat slowly, 

 the saliva has an opportunity to act on a large amount 

 of starch. 



The proteids and fats are not changed in the mouth 

 except that they are broken up or ground into fine par- 

 ticles and so prepared for 

 the other digestive fluids. 

 Most of the salts and sugars 

 are dissolved in the saliva 

 and are then ready to enter 

 the blood. 



Where does the saliva 

 come from ? The three 

 glands shown in the dia- 

 gram manufacture it. They 



are \hz parotid, a little be- 

 low and in front of the 

 ears ; the submaxillary , at 

 the angles of the lower 

 jaw; and the sublingual, 

 in the floor of the mouth. 



FIG. 42. Showing salivary glands. 

 (From Huxley.) a, sublingual, 

 b, submaxillary glands with their 

 ducts opening under the tongue at 

 d ; c, parotid gland with its duct 

 opening at e. 



These glands pour three of 



four pints of saliva into the mouth daily. Chewing and 

 talking cause the saliva to flow freely. Tasting, seeing, 



