18 PHYSIOLOGY AND TOXICOLOGY 



auchylosed portion ; if it be broken off by violence, the freedom of the pseiido socket 

 is accomplished by the same means. And now the first tooth of reserve is urged 

 forwards into a recess in the maxillary bone directly adjacent to, and on the inner 

 side of the fallen fang ; and the requisite advancement is brought about by the 

 developmental vis a tergo of the remaining reserve pulps, and probably also by the 

 traction in front, exerted by the cicatrizing parts. It is evident that the fang 

 emerges from its capsule, and that the point and crown repose in the den, but 

 the base is closely invested with the capsular remains under the form of a perios- 

 teal expansion, which is the mediate bond of union between the base and the new 

 and shallow socket of the maxilla. 



" As may be perceived, upon examination at this stage, two sockets co-exist in 

 the same jaw. The inner, new one, suj^portiug the recently promoted fang, and 

 the outei", old, and now vacant one, which is fast being disencumbered of the ves- 

 tiges pertaining to its former resident. In this maxilla, the new fang occupies the 

 innermost part, having the old socket on the outer side, while in the opposite max- 

 illa, the older venom fang may be discovered in its normal situation, leaving the 

 recess to its inner side vacant, for the temporary lodgment of its successor. Or, 

 both fangs being recently fixed to the jaw, the vacuities will both be formed on 

 the outside, and all the reserve fangs will appear to follow backwards and outwards 

 in direct line. 



" Now let us look at the situation of the poison duct, and examine into the mode 

 by which it is brought into relation with the fang. 



" The venom duct arising from the gland makes a bend upwards, immediately 

 beneath the eye, then advances forwards under the skin, as far as the crotaline 

 fossette, and lying upon the maxilla externally, plunges downw.ards, and pierces 

 the gum in front of the fang, where it terminates in a papilla, which projects 

 slightly into the pi'oximal aperture of the tooth. In this position, it is maintained 

 by the gum which clasps the base laterally and in front, with considerable firmness, 

 its inferior or distal edge, encompassing the annular enlargement already alluded 

 to. Nor is there any other than a mediate application of the poison papilla against 

 the fang, for as the whole venom canal of each tooth is really upon the outside of 

 the organ, no special membrane lines it which might be continuous with the duct 

 that discharges into the upper aperture. 



" Such is the condition of things in an old fang, occupying its normal exterior 

 position. But when the tooth drops out, or is broken, the gum is left entire; or, 

 if its exodus has been forced, the gum escapes with laceration only. In either 

 case, however, the gum remains as a barrier, limiting the progress of the advancing 

 reserve fang; and while the latter is establishing itself provisionally, the gum 

 encircles it, clasps it tenaciously, and brings the poison papilla in apposition with 

 its dental aperture. As time passes, the new fang moves gradually outwards to its 

 permanent seat; the inner maxillary recess is restored, and the first fang of reserve 

 is again discovered on the inner side of its senior, resting with its pulp attachment 

 in the bottom of the recess. 



" Thus, the reserve fang has become an adult functioning fang, nor does its pulp 



