198 THE MOUTH. 



court-plaster, where they meet after passing around the tube, 

 lay the three kinds of cord, each frayed out at one end, the 

 frayed ends resting upon the tube. Moisten the court-plaster, 

 and press the layers firmly together. The court-plaster should 

 now adhere so closely to the tube as hardly to be seen ; and 

 the two layers should seem as one, in which appear the cords 

 representing the arteries, veins, and lacteals. 



The Organs of Digestion. The organs of digestion are 

 the digestive tube and the accessory parts, the masticatory 

 organs, the glands in, and alongside of, the walls of the tube. 



The parts of the digestive tube are the mouth, the pharynx, 

 the gullet (or esophagus), the stomach, the small intestine, the 

 large intestine. 



The Mouth. In studying the mouth and contained or- 

 gans, the student should not content himself with mere read- 

 ing, but should carefully examine his own mouth cavity by 

 means of a hand glass. 



We are apt to think of the mouth as a cavity of consid- 

 erable size, as indeed it is when fully opened ; but we are not 

 so likely to think how completely the cavity is obliterated 

 when the mouth is closed. If one notes the sensations from 

 the mouth when it is closed, he will perceive that the tongue 

 almost entirely fills the space, touching the roof of the mouth, 

 and the teeth in front and at the sides. 



The tongue consists chiefly of muscles, extending in differ- 

 ent directions, thus giving the tongue a variety of motions. 

 The tongue is the chief organ of taste, and is therefore (with 

 the sense of smell) the gatekeeper of the digestive tube. The 

 tongue has also a keen sense of touch (the keenest of any 

 part of the body), and so is useful in detecting and removing 

 any food particles that may remain on the teeth after a meal. 

 During mastication the tongue, with the lips and cheek, keep 

 the food between the teeth. When the morsel of food is 



