594 THE EXTERIOR OF THE HORSE. 



The general aspect of the body, the state of the organization, and 

 his particular mode of functional activity furnish, in most instances, 

 the indications that cannot deceive a practised eye, but they are not 

 infallible in practice, and are subject to variation according to the 

 rational or abusive employment which has been given to the animals. 



It is necessary, therefore, to have recourse to other sources to 

 establish the basis of a precise determination of the characters indi- 

 cative of the age of the horse. 



Now, of all the organs which receive and preserve with the 

 greatest accuracy the marks of time, the teeth of solipeds are, without 

 doubt, those which register them, so to speak, in ineffaceable signs. 

 Admirably adapted to the needs of the organism, instruments con- 

 structed in view of the mode of alimentation, and presenting a series 

 of landmarks whose successive disappearance marks the trace of the 

 years, the teeth appear, develop, wear oif, change their external form, 

 are shed, and succeed each other with a regularity which veterinarians 

 have learned to recognize and determine scientifically. 



Hence we will commence the study of the age of the horse by a 

 minute description of the dental apparatus, in order to place the 

 reader in a situation to understand fully the characteristics upon which 

 it is based. 



PART I. 



THE TEETH. 



Definition ; Number ; Distribution. " The teeth are mechan- 

 ical instruments, harder than bone, placed, in vertebrate animals, at the 

 entrance of the alimentary canal, to seize, cut, tear, and bruise the nu- 

 tritive substances before their transmission from the mouth into the 

 oasophagus. They can also serve the animal as weapons of defence 

 and oifence." * 



In the adult animal of the equine species the teeth number from 

 thirty-six to forty, 2 and are designated by names which recall their use 

 (Fig. 270) : 



1 G. Cuvier, Lecons d'anatomie compared, t. iv., Ire partie, p. 197. 



2 This number should be considered as absolute, but we will call attention to some variations 

 which it presents, according to the individual. 



