Ixvi INTRODUCTION. 



by some branches from the division of the nerve that afterwards 

 escapes by the foramen mentale, and from this plexus the cancellous 

 tissue of the bone and the vascular gums are supplied. 



In the Dog and other Carnivora the nerve of the laniary tooth 

 is conspicuous from its size ; that which supplies the still more 

 developed analogous tooth or tusk of the Boar, is still larger having 

 relation also to the continual reproduction of the matrix at the 

 base of the tusk.(l) 



In the lower jaw of the Porcupine the nerve of the great incisor 

 is given off from the dental nerve near the middle of its course 

 through the osseous canal, and returns at an acute angle to penetrate 

 the cavity at the base of the scalpriform tooth, and supply its 

 persistent pulp. (2) This recurrent course indicates the progressive 

 change in the relative position of the pulp to the origin of its nerve. 

 Besides the branches for the molar teeth, many smaller filaments 

 penetrate the spongy texture of the bone, and form a rich plexus 

 from which the gum derives its filaments. 



The maxillary plexus is most developed, in the Horse, 

 above and between the alveoli of the three premolar teeth ; it is 

 less complex where it supplies the molar teeth, their alveoli and the 

 gums. In the lower jaw of the Horse a very rich plexus begins 

 to be formed in the cancellous substance of the bone by branches 

 of the dental nerve, soon after its entry into the canal. 



The intercommunications between the dental and gingival 

 nerves, and those supplied to the osseous tissue from the supra- 

 maxillary and infra-maxillary plexuses explain the sympathies 

 manifested in neuralgy and rheumatic pains between the teeth and 

 the osseous cavities in which they are implanted. 



I have been represented as having arrived at the conclusion 



(1) PI. 140, fig. 2. (2) PL 104, fig. 1, 1». 



