228 
MAMMALIA. 
[Chap. VII. 
to break them off short. 1 I have never heard of the 
teeth themselves being so affected, and it is just pos- 
sible that the operation of shedding the subsequent 
decay of the milk-tushes, may have in some instances 
been accompanied by incidents that gave rise to this 
story. 
At the same time the probabilities are in favour of its. 
being- true. Cuvieii committed himself to the statement 
that the tusks of the elephant have no attachments to 
connect them with the pulp lodged in the cavity at 
their base, from which the peculiar modification of 
dentine, known as " ivory, " is secreted 2 ; and hence, by 
inference, that they would be devoid of sensation. 
But independently of the fact that ivory is permeated 
by tubes so fine that at their origin from the pulpy 
cavity they do not exceed yy^-th part of an inch in 
diameter, Owen had the tusk and pulp of the great 
elephant which died at the Zoological Gardens in 
London in 1847 longitudinally divided, and found that, 
" although the pulp could be easily detached from the 
inner surface of the cavity, it was not without a certain 
resistance ; and when the edges of the co-adapted pulp 
and tusk were examined by a strong lens, the filamen- 
tary processes from the outer surface of the former 
could be seen stretching, as they were drawn from the 
dentinal tubes, before they broke. These filaments are 
so minute, he adds, that to the naked eye the detached 
surface of the pulp seems to be entire ; and hence Cuvier 
was deceived into supposing that there was no organic 
1 See a paper entitled " Ttecollec- 1805. p. 94, and Ossemens Fossiles, 
tions of Ceylon" in 'Eraser's Mag a- quoted by Owen, in the article on 
zine for December, 1860. " Teeth," in Todd's Cyclop, of 
2 Annates du Museum F. viii. Anatomy, fe. } vol. iv. p. 929. 
