ENCLOSED IN THE TUSKS OF THE ELEPHANT. 59 



enough those instances in which uo such cicatrices exist, and 

 concludes by denying the power of the ivor\' to throw out 

 ossific matter, as asserted by Bluraenbach. 



The author of the Osscmens Fossiles, in his chapter on the 

 Structure, Development, and Diseases of the Tusks of the 

 Elephant, after stating that gi-ooves and notches on the sur- 

 faces of the tusks never fill up, and only disappear from the 

 effects of friction, allows that musket-balls are found in ivory 

 without any apparent hole by which they could have entered. 

 He does not believe that the holes are filled up with ossific 

 deposition, as Haller and Blumenbach supposed ; but main- 

 tains that they are never obliterated. He states that the ivory 

 on the outside of the ball is natural, and tliat it is only the 

 bone surrounding it which is iiTegular. The phenomena are 

 to be explained, he says, by supposing the balls to penetrate 

 the very thin bases of tusks in young elephants, so as to enter 

 the pidps when still in a growing state. 



There appear, then, to be two circumstances, regarding 

 which great doubts still exist — first, whether a shot-hole is 

 ever closed up ; and, secondly, how this is accomplished in a 

 non-vascidar substance like ivory. 



In proceeding to consider this subject, two facts must be 

 borne in mind in reference to a tusk. The first is, that the 

 two substances of which it is composed, ivory and cement, 

 undergo no change of form or an'angement from vital action, 

 after they are once deposited ; the second, that it is an organ 

 of double gi'owth — it is endogenous as well as exogenous, the 

 ivory being formed from without inwards, the cement from 

 within outwards. 



As there are certain processes which invariably commence 

 when a foreign body passes through or lodges in the pulp, it 

 will facilitate the conception of the mode in which a bidlet is 

 inclosed if these be described first Recent researches have 

 proved that the regular ivory of teeth is formed by the cells 



