TEETH. 159 



bones, which is always going forward as age advances, does not necessi- 

 tate the power of growth should in early life be largely exhibited. 



With almost every form of being, as years accumulate, the ability to 

 masticate becomes enfeebled. It is with the horse as it is with other 

 animals. The thin coating of enamel does not extend to the ultimate 

 root of the fang, so that in advanced age the power of the molars is 

 almost destroyed by the absence of the cutting agent upon the grinding 

 surface. The chief component, moreover, or the dentine, diminishes in 

 quantity as in solidity ; the last portions of the molar, therefore, could 

 not fill the socket, only for that ability to increase with which the crusta 

 petrosa is gifted. Upon the extreme roots of the grinders, taken from 

 the jaws of very old horses, this substance is always found in great 

 abundance. In illustration of this fact, a sketch made from the tooth of 

 an aged quadruped is here inserted ; the body has been sawn asunder, 

 to exhibit the proportions and the substances that 

 entered into its composition. The reader will re- P^ 

 mark certain dark lines upon the dentine. These 

 indicate the places where existed the cavity of the 

 pulp, which once served to nourish the organ ; but 

 it is lost as vitality lessens with the advance of V i \ j'lJ 



senility. Does not the reader, as he inspects the ^li3ak>>*' ^'Wi^ 



engraving, perceive the wickedness and the folly ''''™'' ''iooih."^'* '""'^ 

 of placing harsh and dried food before a creature 

 which nature, in age, deprives of ability to comminute such a form of 

 sustenance ? 



The permanent incisors are not cut after the same manner as the 

 molars. The nippers being merely emploj^ed to bite the grass, a wide 

 vacancy does not necessarily incapacitate the other portions of the ex- 

 cising apparatus. A blade can cut, even though a large notch exist upon 

 its edge. Whereas the points which are developed upon the upper sur- 

 faces of the newly cut molars must render the grinders entirely useless ; 

 although the short period of enforced abstinence, which announces the 

 appearance of a fresh double tooth, may be nature's own medicine to 

 quiet a feverish system, burning with morbid excitement. 



The front milk teeth have fangs when they appear in the mouth ; but 

 no fang exists when the primary members are shed. The root of the 

 temporary organ, when perfect, however, resembles that of the perma- 

 nent incisor. It is only sufficient to fit the member for its purposes. In 

 the same canal as was occupied by the milk tooth, the permanent in- 

 cisor generally appears. Much suffering must attend the absorption of 

 bone ; yet, during the time the huge permanent nipper is forcing its way 

 through the narrow channel, which held firmly the diminutive milk 



