THE HORSE S TEETH, AND HOW TO TEI,L HIS AGE. 115 



finally be not more than halt an inch in length, and the breadth 

 decreases in about the same proportion. There is this difference, how- 

 ever, between the teeth of the foal and those of the horse. The thick- 

 ness and breadth of the foal's teeth are constantly decreasing from the 

 grinding surface or enameled part ^jward the root, while the teeth of the 

 horse decrease by contraction. The grinding surface of a nipper, which 

 has not been used, is three times as broad as it is thick, and is hollowed 

 from the top downward, the hollow having two sharp edges inclosing it. 

 This hollow is called the mark. In the center of this mark the kernel is 

 seen. This is a tube commencing at the end of the root, and contains 

 the nerve, which must not be confounded with the mark. The mark is 

 the outer depression, lying next to the sharp edges. The inner cavity is 

 a funnel shaped socket of enamel, a hard shell. Around this, and in- 

 side the outer shell, is a thick fluid, which remains as long as the tooth 

 retains sensibility, but becomes by degrees a gray matter. Figure y, ou 

 the chart, will illustrate this. 



Again, the outer edge of an incisor (nipper) always risen a line or two 

 - -a line is the twelfth part of an inch — above the inner edge. Ttius, at 

 first, only the outer edges of the upper and lower nippers meet, and the 

 inner edges do not touch until the outer edges are sufficiently worn to al- 

 low them to meet, or until they are of an e(|ual height. Horse-teeth 

 reach this condition in about a year. When the colt is two-and-a-half 

 years old, the teeth begin to shed, and the permanent or horse-teeth be- 

 gin to appear. The chart. Fig. 7, A, will explain this gro^vth, and Fig. 

 7, B, will show still further development and Avear. 



The grinders have but little to do in determniing the age of a horse, 

 but still they assist thereto. The crowns of the grinders are entirely 

 covered with enamel on the top and sides, but the grinding of the food 

 wears it away from the top and there remains a compound surface of al- 

 ternate layers of crusted enamel and ivory, which serve, in grinding the 

 food, to fit it for the stomach. Nature has therefore made an additional 

 [)rovision to render them strong and enduring. 



To illustrate this we represent a grinder sawed 

 across. The fine dark spots show bony matter. The 

 shaded portions show the enamel, while the white 

 spaces represent a strong bony cement uniting the 

 other parts of the teeth. In the dental formula at the 

 beginning of this chapter we have given 40 as the 

 number of teeth for the stallion, and 36 for the mare, 

 the stallion having 4 hook teeth, or tushes {canines), 

 which the mare lacks. Sometimes, however, the mare has imperfect 

 teeth in the portion of the mouth corresponding to that of the tushes in 



