36 Veterinary Elements. 



is forced into the mouth by the pressure of the air, such 

 a process constitutes the act of sucking. Iii the mature 

 animal, pumping is the method employed, the lips are 

 immersed below the water, a small opening is made 

 between them, the tongue withdrawn and a vacuum 

 formed, the air pressure forcing the water into the 

 mouth. 



The Teeth. In the mouth cavity those important or- 

 gans, the teeth, are found. It has been said, and with a 

 great deal of truth, "no foot, no horse," the substitution 

 of tooth for foot would make another adage as significant 

 as the old one and just as true, whether referred to the 

 horse, ox or sheep, as on the condition of the teeth 

 depends the health and consequent ability to do work or 

 make gains. Every hofse, and for that matter, the 

 other animals, have two sets of teeth, the milk or colt 

 (temporary) teeth, which are shed at different periods 

 in the early life of the animal, smaller and whiter than 

 the permanent, which are intended to last the animal 

 the balance of its life. In sheep the front (incisors) 

 permaneuts tend to fall out at from 8 to 10 years, in cat- 

 tle rarely so, while in horses the front teeth remain, the 

 grinders ^(molars) are, however, quite often diseased, 

 necessitating their removal. Although a simple looking 

 object a tooth is composed of bony materials, the hardest 

 in the animal body. The visible part of the tooth (the 

 crown) is formed of dentine (an ivory-like substance) 

 which is covered by a layer more or less thick of a white, 

 still harder substance, the enamel. The invisible part 

 of the tooth (the fang) consists of a comparatively thin 

 layer of crusta petrosa, and is chiefly made up of dentine. 



