TEETtf. 39 



parts in which they lie completely and firmly imbedded. 

 Within each root there exists a canal leading 

 up into the crown where they all terminate 

 in a common cavity, as you may see in this 

 figure, in which they are represented by the 

 black space. In these canals are enclosed 

 the nerves and blood vessels which serve 

 for the nourishment of the tooth. 

 Emily. It is when this cavity is exposed by disease, 

 I presume, that we experience that distressing affliction, 

 the tooth ache, which too often obliges us to resort to the 

 soothing properties of cold iron. Could not the pain be 

 prevented, and the tooth preserved by destroying the 

 nerve in some way or other, as I have sometimes heard 

 proposed ? 



J}r t J5. And supposing you could succeed in the 

 operation of destroying the nerve, what would it avail 

 you in the end ? Do you imagine that the nerve is placed 

 there for no other purpose than to give pain, and that 

 the tooth can do perfectly well without it ? 



Emily. I see iny mistake now, but I never before 

 saw the subject in that light. The tooth then requires 

 its proper nerves as well as other parts, without which it 

 tends to decay and death. 



Dr. B. The teeth, you observe, differ considerably 

 in their form and size. In the front of the mouth you 

 see four in each jaw, rather flat and terminating in a 

 sharp edge. These are called the incisors or cutting 

 teeth, and are the first to make their appearance in the 

 young child. Behind these in both jaws and on each 

 side you may observe one distinguished from the incis- 

 ors by superior length and by terminating in a point. 

 They are called canine or dog teeth, irom the circum- 

 stance of their being very conspicuous in the dog when 

 he raises his lips under the influence of anger. The 

 other teeth are much larger, their faces are terminated 

 by a few blunt points, and he roots are two or three and 

 sometimes four iq number. They are called molares or 



