104 



OUR BODIES AND HOW WE LIVE 



Next in order, after the bicuspids, come the largest and 

 strongest teeth, which do the hardest work. They are 

 called molars, or grinders. There are six of them in each 

 jaw. They have broad crowns, with four or five cusps 

 or ridges for grinding. The last molars are commonly 

 called the "wisdom teeth," because they do not usually 



appear before the age 

 of twenty, or the " age 

 of wisdom" (Sec. 178). 



Experiment 28. Get a 



specimen of each kind of 

 tooth if possible. A den- 

 tist friend will give you 

 what you need. Use a 

 very fine saw to cut a per- 

 fect molar in two length- 

 wise. If need be, crack 

 the tooth with a hammer. 



Note its structure in a 

 general way, its crown, 

 cusps, roots, enamel, den- 

 tine, pulp cavity, etc. 



Make a blackboard 

 sketch of a tooth on a 

 large scale, using colored 

 crayon to make plain the 

 various parts (Fig. 65). 



Experiment 29. With the help of a mirror, let each pupil locate 

 his own teeth. Note the incisors, eye teeth, bicuspids, molars, and 

 wisdom teeth, if any. In the same way, note the teeth of some 

 schoolmate. 



150. The Salivary Glands. While the food is being 

 chewed it is moistened by the saliva, or spittle, which flows 

 into the mouth from six little glands. They are known as 

 the salivary glands. There are three of them on each side. 



SUBMAXILLARY 

 CLANO 



FIG. 66. BLACKBOARD SKETCH. 

 Salivary Glands of the Right Side. 



