276 TEETH OF THE ELEPHANT. 



bones and teeth of Siberia, published in the Philosophical 

 Transactions for 1787, No. 446, tusks are cited which 

 weighed two hundred pounds each, and "are used as 

 ivory to make combs, boxes, and such other things, being 

 but little more brittle, and easily turning yellow by wea- 

 ther and heat." From that time to the present there has 

 been no intermission in the supply of ivory, furnished by 

 the tusks of the extinct elephants of a former world. 



The mnsket-balls and other foreign bodies which are 

 occasionally found in ivorj^, are immediately surrounded 

 by osteo-dentine in greater or less quantity. It has often 

 been a matter of wonder how such bodies should become 

 completely imbedded in the substance of the tusk, some- 

 times without any visible apertnre, or how leaden bullets 

 may have become lodged in the solid centre of a very 

 large tusk without having been flattened. The explana- 

 tion is as follows : a musket-ball, aimed at the head of 

 an elephant, may penetrate the thin bony socket and the 

 thinner ivory parietes of the wide conical pulp-cavity 

 occupying the inserted base of the tusk ; if the projectile 

 force be there spent, the ball will gravitate to the opposite 

 and lower side of the pulp-cavity, as indicated in Fig. 73. 

 The presence of the foreign body exciting inflammation 

 of the pulp, an irregular course of calcification ensues, 

 which results in the deposition around the ball of a cer- 

 tain thickness of osteo-dentine. The pulp then resuming 

 its healthy state and functions, coats the surface of the 

 osteo-dentine inclosing the ball, together with the rest of 

 the conical cavity into which that mass projects, with 

 layers of normal ivory. 



The portions of the cement-forming capsule surround- 

 ing the base of the tusk, and the part of the pulp, which 

 were perforated by the ball in its passage, are soon re- 



