THE CUPOLA. 81 



STRUCTURE OF THE TEETH. Each tooth 

 consists of three parts the crown, the neck, 

 and the fang. The fang or root is the part 

 which is set firmly in the jaw-bone, as if it 

 were driven in like a nail. The neck is close 

 to the edge of the jaw, where the thin skin or 

 membrane which covers the jaw-bone joins to 

 the tooth and adheres to it. (It is this mem- 

 brane which the dentist separates from the 

 tooth with his lancet, when he is going to 

 extract it.) The tooth is a little smaller here, 

 like a neck, or as if a cord had been tied 

 tightly around, and indented it. The crown 

 or body of the tooth is that part which we see 

 above the gum. Every tooth has blood, and 

 feeling in it ; but of this I cannot tell you the 

 particulars now. You will find more about it 

 in another chapter. 



Now to prevent the teeth from wearing out, 

 as a piece of common bone would, this crown 

 is coated all over with something much harder 

 than any bone in the human body. It is 

 called enamel. 



USES OF THE TEETH. Hard as it is, how- 

 ever, enamel will wear out in time. It will 



