148 



BEGINNINGS IN ANIMAL HUSBANDRY 



Fig. 75. 3M years old. 



Some time between the sixth 

 and ninth month, two more ap- 

 pear, one by the side of each 

 outer tooth. These six pairs are 

 called nippers. They are the 

 milk teeth, and are only tem- 

 porary. They are not all equally 



level with one another at first, but in the course of 12 

 months or so they become uniform on the surface. The 

 outside of the tooth is a very hard, white enamel. This 

 covers a hard, ivory-like bone, 

 while at the center is a soft, 

 bony substance which more 

 easily wears away, but is con- 

 stantly renewed. The ends of 

 the teeth have a ridged cutting 

 surface, forming at the centers 

 small depressions, or "cups," 

 marks by which the age is deter- 

 mined. The cups in the central 

 pair of nippers at first are 

 dark of center; in the second 



year they begin to wear light in color, and these cups 

 become smaller than those of the other four. Similar 



changes follow in order in the 

 other pairs. 



At three years of age, per- 

 manent incisors or nippers be- 

 gin to appear. These teeth are 

 larger than the first ones, which 

 were small but suited to the 

 mouth of the colt. The first or 



Fig. 77. 5 years old. 



Fig. 76. 4 years old. 



