POSITION AND STRUCTURE OF HORSE 29 



down into the heart of the crown. The nature 

 of this peculiar structure may be best understood 

 by taking the finger of a kid glove, and, after 

 fillino- it with soft wax, pushing in the summit 

 by means of a fine pencil to a depth of an inch or 

 so. This will give an exact representation of a 

 horse's incisor, more especially if we smear the 

 lower part of the outer surface of the finger with 

 sealing-wax, as we shall then have representatives 

 of the three constituents of the tooth. Thus the 

 sealing-wax will represent the outer coat, or cement, 

 the elove the middle element, or enamel, and the 

 soft wax the inner constituent, technically known as 

 the ivory or cement. 



In this condition the wax-filled glove-finger 

 with the pit, or "mark," at the tip, will represent 

 the unworn incisor of the horse ; but if we snip off 

 with a pair of scissors half an inch from the summit, 

 we shall have a model of the tooth after it has been 

 in use for some time, and h;is had its tip ground 

 away by wearing against its fellow in the opposite 

 jaw. On looking at the section of the summit of 

 the cut glove-finger, it will be seen that the original 

 pit now forms an island in the middle of the soft 

 wax ( = dentine) bounded by a ring of kid ( = enamel). 

 By carrying the experiment one stage further, and 

 cutting off another three-quarters of an inch from 

 the summit, we shall have the model of an incisor 

 of an old horse. In this state the pit, or "mark," 



