EXPLANATION OF THE PLATES. xi 



Fig. 9. Tlie cavity of reserve Bending (iff the pulp and sac of 



the wisdom tooth. 

 Fig. 10. The sac of the wisdom tooth advanced al(jng a cufvlmI line 



into the niaxilhiry tiiljL-rosity or corouoid process. 

 Fig. 11. The sac of the wisdom tooth returned to the e.vtremity of 



the dent;d i-iUige. 



MUSKET-BULLETS IN TUSKS OF ELEPHANTS. 

 Plate IL page 56. 



Fig. 1. A portion of a section of a wounded tusk ; a cement ; h regular 

 ivory deposited previous to the wound ; c irregular ivory 

 di'positL'd alter the wound. 



Fig. 2. A diagram illustrative of the mode of connection hotwecn the 

 Ketzian tubes of tlie primary and secondaiy regular ivory, 

 and the cells and Retziau tubes of the different inosculating 

 systems of the irregular ivory, after inclosure of a ball ; a 

 cement with its osseous corpuscles ; h primary regular ivory 

 with its Retzian tubes ; c the ball ; d the irregular ivory 

 with its systems of tubes and cells ; e secondary regular ivory 



Fig. 3. A copper ball inclosed in a sphere of irregular ivory, on the 

 surface of which are the orifices of Haversian canals. Some 

 of the orifices have closed, and present the appearance of 

 irregular projections. The mass has begun to be attached to 

 the regular ivory of the tu>k, and would in time have been 

 inclosed in it. The ball must either have passed across from 

 the opi)osite side of the tusk, or must have sunk below the 

 level of the hole by which it entered. 



Fig. 4. Section of a tusk across the cavity of which a ball has pa.ssed, 

 and become inclosed in the ivoiy of the wall opposite the 

 hole by which it entered. Tlie hole is fdled with irregidar 

 ivory, coated externally with cement. The cement over the ball 

 has been disiirranged by the shock. This section proves that 

 the track of a ball across the pulp is not necessarily ossified. 



Fig. .^>. Section of a tusk across the base of which a spear-head has 

 penetrated and remained in the M'ound. Tlie weapon ha.s 

 tlierefore been sejiarated from the pulp by deposition of 

 irregular ivory in the U>vn\ of a tube ; a cement ; b b ir- 

 regular ivory dfjiosited previous to the wound ; c c regular 

 ivory deposited after the wound ; d irregular ivory inclosing 

 a vaciuit space e, the seat of an abscess or sinus, imd con- 

 tinuous with the Ciivity of t\ a mass of irregular ivory (coated 

 with regular ivory) in the form of a tube surrounding the 

 foreign body. As irregular ivory always contract."* in drying, 

 more than any other kiiul of dental substance, that portion 

 of the section marked 7 </ has been l>ent outwards. 



Fig. 6. Tlie siime section viewed in piolUe ; a the broken shaft of the 



