600 



THE EXTERIOR OF THE HORSE. 



second dentition, we will study with the latter the modifications in the dental 

 table from wear. 



As to the' embedded extremity, it is provided with an opening, the orifice of 

 the iiiternal dental or pulp cavity, d, in which the papilla or pulp of the tooth 

 is contained. 



B 



Fig. 273.— a deciduous pineer. 

 A. Posterior face. | B. Anterior face. | 



C. Profile. 



But, as the young animal advances in age, the milk-teeth increase in length 

 by growth at their roots, while their pulp cavities diminish in size in a great 



Fig. 274.— Magnified longitudinal section of a superior virgin pineer of the iirst dentition, seen 



in its alveolus. 



measure. The maxillary bones at the same time become thicker and the perma- 

 nent incisors are being formed in their thickness. The latter are situated behind 

 and within the deciduous teeth, from which they are at first separated by the 



