STRUCTURE OF THE OX. 



627 



distinct in the central, or two central pairs — and which, at eight years, has 

 spread over the six central incisors. 



At eight years, a change takes place which cannot be mistaken. The 

 process of absorption has again commenced in the central incisors ; it is 

 slow, and is never carried to the extent seen in the milk teeth, but is 

 sufficicnLy plain, and the two central teeth are evidently smaller than 

 their neighbors. A considerable change has also taken place on the 

 surface of the teeth ; the two dark marks are worn into one in all but the 

 corner teeth. 



HOLSTEIN-FRIESIAN COW, SEGIS L\KA. 



At ten years old the four central incisors are diminished in size, and 

 the mark is becoming smaller and fainter, as shown in figure 14. At 

 eleven years the six central incisors are smaller, and, at twelve, all of 

 them are very considerably diminished ; but not to the same extent as in 

 the young animal. The mark is now nearly obliterated, except in the 

 corner teeth, and the inside edge is worn down to the gum. 



From the age of twelve years and onward, the teeth diminish more and 

 more, so that the animal cannot properly gather or grind the food. There 

 are many instances, however, of cows breeding, and remaining good 

 ;nilkers, up to twenty years of age and over. But in this day of early 

 development, no careful farmer will keep a cow breeding after the age of 

 twelve years, except, perhaps, in the case of some extraordinary milker, 

 or an exceptional cow, of great physical powers, and excellent breeding 

 ♦lualities, whose stock it may be desirable to perpetuate. 



