36 THE farmer's veterinarian 



The mark in the tooth is occasioned by the food 

 blackening the hollow pit. This is formed on the 

 surface by the bending in of the enamel, which 

 passes over the surface of the teeth, and, by the 

 gradual wearing down of the enamel from friction, 

 and the consequent disappearance of it, the age can 

 be determined for a period of several years. 



When a horse has attained his sixth year the 

 mark on the central or middle incisors or nippers 



LUMPY JAW 



The disease is caused by the ray fungus. The result is local 

 tumors in the bones and other tissues. 



of the lower jaw will be completely worn off, leav- 

 ing, however, a little difference of color in the cen- 

 ter of the teeth. The cement which fills the hole 

 produced by the dipping in of the enamel will be 

 somewhat browner than that of the other portions 

 of the tooth, and will exhibit evident proofs of the 

 edge being surrounded by enamel. 



At seven years the marks in the four middle in- 

 cisors are worn out and are speedily disappearing 

 in the corner ones. These disappear entirely at the 



