32 



JUDGING FARM ANIMALS 



Pig. 12. — Two and one-half years of age. 



iside of the two al- 

 • ready present. 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 temporary. They are not all equally level with 

 one another at first, but in the course of twelve months or so 

 they become uniform on the surface. The outside of the 

 tooth is very hard, white enamel. This covers a hard, 

 ivory-like bone, at the center of which is a softer sub- 

 stance which more easily wears away, but is constantly 

 renewed. The ends of the teeth have a ridged cutting 

 surface, forming at the centers small depressions, or 

 "cups," by which the age is determined. The cups in the 

 central pair of nippers at first are wide and somewhat dark ; 

 in the second year, with use, they appear lighter in color, 

 and become smaller than those of the other four. Similar 

 changes follow in order in the other pairs. 



At two and one-half to three years of age permanent 

 incisors or nippers appear. These teeth are larger than the 

 first ones, which 

 were small but 

 suited to the 

 mouth of the 

 colt. The first 

 or central pair 

 of temporary 

 teeth is pushed 

 out by the pair 

 of larger per- 

 manent ones. 

 At three and 



one-half to four fflS- is.— Three and one-half years of age. 



