But independently of the fact that ivory in permeated by tubes so fine that at their origin from the pulpy cavity they do not exceed 1/15000th 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 filamentary 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 connexion between the pulp and the ivory. But if, as there seems no reason to doubt, these delicate nervous processes traverse the tusk by means of the numerous tubes already described, if attacked by caries the pain occasioned to the elephant would be excruciating. As to maintaining a stud of elephants for the purposes to which they are now assigned in Ceylon, there may be a question on the score of prudence and economy. In the rude and unopened parts of the country, where rivers are to be forded, and forests are only traversed by jungle paths, their labour is of value, in certain contingencies, in the conveyance of stores, and in the earlier operations for the construction of fords and rough bridges of timber. But in more highly civilised districts, and wherever macadamised roads admit of the employment of horses and oxen for draught, I apprehend that the services of elephants might, with advantage, be gradually reduced, if not altogether dispensed with. The love of the elephant for coolness and shade renders him at all times more or less impatient of work in the sun, and every moment of leisure he can snatch is employed in covering his back with dust, or fanning himself to diminish the annoyance of the insects and heat. From the tenderness of his skin and its liability to sores, the labour in which he can most advantageously be employed is that of draught; but the reluctance of horses to meet or pass elephants renders it difficult to work the latter with safety on frequented roads. Besides, were the full load which an elephant is capable of drawing, in proportion to his muscular strength, to be placed upon waggons of corresponding dimension, the to the roads would be such that the wear and tear of the highways and bridges would prove too costly to be borne. On the other hand, by restricting it to a somewhat more manageable quantity, and by limiting the weight, as at present, to about _one ton and a half_, it is doubtful whether an elephant performs so much more work than could be done by a horse or by bullocks, as to compensate for the greater cost of his feeding and attendance.