788 MAMMALIA. 







has already taken its office. There is, therefore, no absorption of the 

 roots of these teeth, but they are ground down from the crown to the 

 stump. 



(2276.) The new tooth that thus advances from behind is always of 

 larger dimensions than that to which it succeeds, because the animal 

 itself has grown in the interval, and the jaws have become proportionally 

 developed. 



(2277.) The Elephant in this way may have a succession of seven or 

 eight teeth on each side in both jaws, or from twenty- eight to thirty- 

 two in all ; and nevertheless, seeing that the anterior ones successively 

 fall out, there are never more than two visible at once above the gums 

 on each side, or eight in all ; generally, indeed, there is only one visible 

 at a time. Every successive tooth is composed of more laminae than that 

 which immediately preceded it, and a longer time is required to perfect 

 its growth. 



(2278.) Nearly the same account of this process was found in the 

 Manuscripts of John Hunter *, who lucidly accounts for such an aberra- 

 tion from the ordinary course of proceeding. " These creatures," says 

 that distinguished observer of Nature, " do not shed their teeth as other 

 animals do that have more than one ; for those that have more than one 

 tooth can afford to be for some time without some of their teeth : there- 

 fore the young tooth comes up in many nearly in the same place with its 

 predecessor, and some exactly underneath ; so that the shedding tooth 

 falls sometimes before the succeeding tooth can supply its uses. But 

 this would not have answered in the Elephant ; for if the succeeding 

 tooth had formed in the same situation with respect to the first, the 

 animal would have been for some time entirely deprived of a tooth on 

 one side, or, at least, if it had one on the same side in the opposite jaw, 

 that one could have been of no use ; and if this process took place in 

 both sides of the same jaw, and in either jaw, the animal would have 

 been entirely deprived of any use of the two remaining." 



(2279.) The teeth of Mammalia being thus adapted to so many 

 various offices, and serving, under different circumstances, to hold, to 

 bruise, to cut, to tear, or to grind alimentary substances, we must natu- 

 rally expect the movements of which the lower jaw is capable to be in 

 correspondence with the nature of the dental apparatus. 



(2280.) In MAN, as the student well knows, in consequence of the 

 laxity of the ligaments that connect the inferior maxilla with the tem- 

 poral bone, and the thickness of the articular cartilage that is interposed 

 between the convex surface of the condyle and the shallow glenoid 

 cavity, every kind of motion is permitted, in conformity with the omni- 

 vorous habits of the human race ; and the temporo-maxillary articula- 

 tion is no longer a mere hinge, but the teeth can be made to act upon 



* Descriptive and Illustrated Catalogue of the Physiological Series of Comparative 

 Anatomy in the Museum of the Royal College of Surgeons of London, Parti, p. 100. 



