604 



THE EXTERIOR OF THE HORSE. 



Whence it follows that the external dental cavity is deeper, all things being 

 equal, in the superior incisors, and that, in each jaw, its depth is greatest in the 

 intermediates. It may also be added, as a differential characteristic relative to 

 this cavity, that this part of the tooth extends closer to the posterior face of the 

 incisors of the inferior jaw. 



FIG. 278. Longitudinal section of a permanent 

 incisor that has been used. 



FIG. 279. Eccentric and longitudinal sec- 

 tion of the superior and inferior interme- 

 diates of the adult, showing the different 

 characters of the external dental cavity. 



The incased extremity or root presents a large opening which leads into a 

 cavity in the interior of the tooth, in which the dental pulp is lodged. This is 

 the internal dental or pulp cavity. 



The preceding details apply in a general manner to all the incisor teeth. 

 They nevertheless present some slight modifications if each individual tooth be 

 examined in particular. Hence we have presented in Fig. 280 antero-posterior 

 longitudinal sections of three superior and inferior incisors of the same side, 

 obtained from the jaws of a five-year-old horse, in order that the reader may 

 view for himself the modifications of which we speak. 



Successive Forms of the Dental Table. From the con- 

 tinual friction and rubbing against each other, the incisors progressively 

 level their crowns, which gives to the extremity of the latter the aspect 

 of a plane surface, known under the name of dental table. The form 

 of this table, which changes more and more as we approach the root 

 of the tooth, necessarily varies with the age of the animal. This can 

 be proved by following, in the horse, its successive modifications during 

 several years. 



