THE DIGESTIVE SYSTEM. 75 



special or peculiar substance from the blood. So, 

 one of the glands of the eye secretes tears, and the 

 salivary glands secrete saliva. Three pairs of these 

 glands are quite prominent. The largest pair is 

 just below and in front of the ears. The second pair, 

 in size, lies under the jaw-bone, and the third pair is 

 under the tongue. These glands, between meals, 

 furnish enough saliva to keep the mouth moist. But 

 when food is taken into the mouth and chewed, or 

 even at sight of something tempting to the taste, 

 they furnish it in great abundance. It not only 

 moistens the food so that it may be easily swallowed, 

 but it also begins the process of changing the food 

 material. 



The fourth step in digestion is swal- 



Work of the 



Pharynx and lowing. This is a much more familiar 



Oesophagus. ig the gci _ 



entific name for the same act. When the food has 

 been properly prepared in the " mill of the mouth," 

 it is swallowed, or sent to the stomach. The cavity 

 back of the mouth is called the pharynx. Between 

 the pharynx and the stomach (refer to body manikin) 

 is this tube (35) called the oesophagus. By the 

 action of the muscles of the pharynx and the oesopha- 

 gus, the food is moved into the stomach. This is 

 deglutition. 



We have now traced the course of the 



$toniah th ^ ooc ^ * n * * ne ma ^ n or g an of digestion 



the stomach. Here its greatest change 



is to be produced. The position of the stomach 



