SUCCESSION OE THE POISON-FANGS OF SNAKES. 
383 
There is nothing noteworthy about the dentinal pulps of poison-fangs ; but their 
manner of attachment to the bone merits a word or two of notice. 
Looking with the naked eye at the bone which carries the poison-fangs, to which they 
are anchylosed by their bases, there is seen to be a sort of hood or parapet of bone 
rising up in front of the fangs. This would appear to add to their strength, as the 
tendency of the blow struck by the snake would be to displace the tooth forwards. This 
parapet of bone is seen in section in fig. 4 and fig. 3 (m). The firm attachment of the 
tooth is likewise secured by the form of its own base, which is convoluted (see figs. 
4 & 5) and recalls the structure of labyrinthodont teeth at that point in the crown 
where their complexity of structure first commences ; this convolution of the dentine at 
the base of a tooth which is attached by anchylosis is quite common in the teeth of both 
fishes and reptiles. The dentine interdigitates with the supporting bone, the line of 
junction consisting of a cloudy opaque calcified tissue, in which, without the use of acids, 
no definite structure can be seen. Immediately outside this there is very coarse bone, 
with very large irregular lacunae, which gradually merges into the regular fine-textured 
bone of the snake’s jaw. 
When the new tooth is about to become attached, a sort of network or scaffolding of 
new bone is thrown out, which meets and interdigitates with the convoluted dentine, 
which is being simultaneously calcified. This new bone, coarse in texture and very 
rapidly developed, springs up outside the tooth-sac, and takes its origin from the surface 
of the old bone ; it constitutes that “ bone of attachment ” to which I have elsewhere 
called attention as being invariably present where a tooth becomes fixed in place by the 
process of anchylosis. This “ bone of attachment,” present in large quantity both in 
the cobra and in viperine snakes, is specially developed for every tooth, and is removed 
when the tooth is shed, a fresh scaffolding being put forth for its successor. 
The duct of the poison-gland was formerly supposed to become enclosed within the 
tube of the poison-fang by the process of the latter growing around it. This, however, 
does not happen ; for that part of the tooth in which the groove has its lips closed, so 
as to form a tube, is completed before the tooth moves into place upon the maxillary 
bone. 
That portion which is not thus completed is very short, and is impressed by an open 
groove only. Moreover the new tooth comes by the side of the old one, and does not 
occupy the same spot, so that such an arrangement would be all but impossible. 
The poison-duct opens close above the base of the tooth, where the groove in which 
the upper end of the poison-tube terminates is situated. The close apposition of the 
hood of mucous membrane which covers the poison-fangs in secures a large proportion 
of the poison passing down it, but no more absolute communication than this takes 
place. In longitudinal section the remnant of the enamel-organ within the tube has 
a superficial resemblance to a duct within the tooth, and by this I was at first deceived. 
Examination of specimens in more perfect preservation, however, has rendered me certain 
that no sort of duct with soft walls exists within any part of the tube in the poison-fang. 
