SIFTING THE FEED. 171 



animals, for it is a substance that is gradually worn 

 off by mastication ; but the violence which has caused 

 fracture of the enamel, may at the same time have 

 caused such an amount of injury to the dentine that 

 it dies, and progressively becomes decomposed. In 

 man it seems there should be death of the dentine and 

 acidity of the oral fluids before caries can take place, 

 test-paper applied to a carious tooth invariably show- 

 ing the presence of free acid, and* a very small perfora- 

 tion in the enamel may coexist with a considerable 

 amount of disease in the dentine." 



Surgeon T. W. G owing, of London, a well-known 

 inventor of dental instruments (veterinary), in an 

 " Essay on the Diseases of the Teeth of the Horse," 

 which was printed in "The Veterinarian" for 1851 

 (p. 632), in substance says: 



" I am aware that the cause of disease of the teeth 

 must to a certain extent always remain a mystery ; yet 

 from observation and reflection we may be able to de- 

 duce conclusions which practice will confirm. 



" Let us consider the two classes of horses that we 

 are principally called upon to attend, namely, the cart 

 or draft-horse, and the hack or carriage-horse. So far 

 as my observations have led me, the latter class are 

 less liable to diseases of the teeth than those of a 

 coarser breed. Now, may not this be caused by the 

 better care they receive in the stable? The good and 

 efficient groom regularly sifts the provender previous 

 to feeding his horses, and thus rids it of stones, glass, 

 &c. The cart-horse and the machine-horse of our 

 London omnibus proprietors, not receiving this atten- 

 tion, are more subject to diseases of the teeth. Be- 

 sides, it is a common practice with carters to sprinkle. 



