74(3 



THE EXTERIOR OF THE HORSE. 



Fig. 323.— Right molar arcades of a very old hor,se. 

 (The inferior jaw i.s to the left of the figure.) 



Fig. 323 there are nine. 

 Thus, as we have said d, 

 propos of their structure, 

 when the wear has reached 

 this point there is formed 

 around the dental stumps 

 a thiclv layer of cement, 

 A\hich, by consolidating 

 them into the alveoli and 

 augmenting the area of the 

 dental tables, permits them 

 still to fulfil their func- 

 tion.s. 



However, we would 

 make a great mistake 

 were we to believe that 

 these functions are 

 formed with the 

 perfeetit)n as when 

 anijnal ' is young, 

 surfaces of friction, 

 ing lost their bands of 

 enamel, are smooth, round, 

 and deprived of all rough- 

 nesses. Mastication be- 

 comes incomplete, irregu- 

 lar, and the alimentary 

 substances pass through 

 most of the digestive ap- 

 paratus without yielding 

 anvthino; like the sum total 

 of their nutritive princi- 

 ples. Hence nutrition is 

 impaired ; the animal be- 

 comes languid, emaciated, 

 and, little by little, in- 

 capable of working. 



b. Superior Jaw. — 

 What we have just now 

 said can, in all respects, be 

 applied to the teeth of the 



per- 



same 



the 



The 

 hav- 



