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. Cuvier 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 Yj-^o"oth 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 Cuviek 

 was deceived into supposing that there was no organic 



1 See a paper entitled " Rccollec- 1805. p. 94, and Ossemens Fossiles, 



Hons of Ceylon" in Fr user's Mag a- quoted by Owen, in the article on 



zine for December, 1860. "Teeth," in Todd's Cyclop, of 



* Annalcs du Museum F. viii. Anatomy, $c, vol. iv. p. 929. 



