1 62 PHYSIOLOGY. 



of the 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 Mouth. In studying the mouth and contained 

 organs, the student should not content himself with mere 

 reading, 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 considerable 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. The tongue consists chiefly of muscles, 

 extending in different 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 gate- 

 keeper 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 

 sufficiently masticated, the tongue pushes it back into the 

 pharynx to be swallowed. 



The Teeth. The teacher can usually obtain a lot of 

 teeth from the dentist for the asking. These should be 

 cleaned before using them in the class. Use pearline 



