140 THE PATHOLOGY OF THE TEETH. 



number of permanent teeth than should naturally 

 exist. In the latter case it is necessary to admit the 

 existence of a greater number of dental bulbs than is 

 normal. We saw some time ago, at the consultation 

 of the Veterinary College in Alfort,* a horse which, to 

 use the words of its owner, ' had a double row of teeth 

 in the upper jaw.' 



" Sometimes the supernumerary tooth is situated in 

 one or the other jaw, in front of the normal range of 

 grinders, without having a corresponding tooth in the 

 opposite jaw ; at other times it is situated either within 

 or without the arcade. The latter anomaly is caused 

 more frequently by the deviation of a normal than by 

 the addition of a supernumerary tooth. In the first 

 instance it is not long before mastication is interfered 

 with. The tooth, by its growth, which is not counter- 

 acted by wear, finally reaches the opposite jaw, lacera- 

 ting the mucous membrane and contusing and some- 

 times fracturing the bone itself. In the second in- 

 stance, the tooth, if within the arcade, is an obstacle 

 to the tongue; if without, to the cheek. Besides these 

 evil effects, supernumerary teeth cause irregularity in 

 the arcades, and consequently prevent the exact appo- 

 sition of the normal teeth. They interfere also with 

 the action of the lower jaw. Hence irregularity in the 

 friction and wear of the teeth follows, the result being 

 that the performance of the all-important function of 

 mastication is almost stopped. 



"^. Anoftialies in the Form of the Arcades. — The 

 upper rows of grinder teeth form two curves, opposed 

 by their concavities, while the lower rows form two 



* A city of France — Prof. Boulev's home. Surgeon Ferguson, 

 an Englishman, was attached to the Paris British Legation. 



