64 ON THE MODE IN WHICH MUSKET-BALLS BECOME 



ossification of the pulp surrounding the ball, and the ultimate 

 application of the mass to the hole in the ivory, and, as the 

 latter is necessarily at this part of its extent very thin, the hole 

 is closed ; second, the application to the hole in the ivory and 

 to the surface of the ossified pulp in it, of cement formed by 

 the internal surface of the tusk-follicle. For although the ball 

 may have removed, or at least torn, the follicle opposite the 

 hole in the ivory, yet, as the tooth advances in the socket, the 

 ball will in time arrive at a sound portion of the latter. 

 One of the specimens exhibited to the Society proves that 

 the wounded portion of the follicle may perform this duty 

 sufficiently well. In it the external surface of the cement 

 exhibits a longitudinal fissure, with smooth rounded edges, 

 resulting from the defective formation of cement in the 

 situation of a longitudinal rent or wound in the membrane 

 of the follicle, through which the ball had entered the 

 ivory. The hole in the ivory then being plugged up ex- 

 ternally by cement, and internally by ossified pulp, the case 

 proceeds as in the last class of wounds the ossified portion 

 of the pulp surrounding the ball becoming enclosed in true 

 ivory. 



Third. When the foreign body enters from above, without 

 wounding the tusk, the pulp ossifies round it, and true ivory 

 envelopes the mass in the usual manner. I have not seen 

 any morbid ivory which could be referred to wounds of the 

 class now under consideration ; but a very interesting account 

 is given by Mr. Comb in the Philosophical Transactions, 1801, 

 of a tusk in which a spear-head was found, and which could 

 only have entered the cavity from the base of the pulp. Mr. 

 Comb describes and figures the ossified portion of the pulp, and 

 the manner in which it had attached itself to the ivory, and 

 become covered by it, so as to obliterate partially and to alter 

 the relative width of the pulp-cavity. 



The description I have now given of the changes which 



