VII 



DIGESTION 



79 



repair itself. We should be very careful not to crack 

 or in any way injure the enamel. 



FIG. 39. Showing how the upper and lower teeth fit together. (From 

 Hopkins' " Care of the Teeth." D. Appleton Co.) 



There is a large space in the middle of the dentine, 

 called the pulp cavity, that is filled with connective 

 tissue, blood vessels, and 

 nerves. At the very tip of 

 the root we find a small open- 

 ing, through which the blood 

 vessels and nerves enter the 

 tooth. It is by means of these 

 vessels that the central por- 



Crown 

 Neck 



/foot 



FIG. 40. Showing the structure 

 of a tooth (Zinns). 



