Page:Encyclopædia Britannica, Ninth Edition, v. 13.djvu/545

 IVORY 521 ends bound with metal to prevent their splitting; and, as the tusk is continually growing by the conversion of fresh portions of vascular pulp into ivory, the operation has to be repeated. When this is done at intervals of ten years, the segment cut off is valuable, and is sold as ivory ; some prefer, however, to cut the tusks much more frequently. In a young elephant the vascular pulp extends beyond the portion of the tusk implanted in the jaw, while in the older animal it does not reach so far ; its probable extent has to be borne in mind in shortening the tusk, as if it be encroached upon much suffering is entailed on the animal. Yet the vascular formative pulp of an elephant s tooth is singularly tolerant of injury without having its function of ivory formation destroyed, and hence it happens that foreign bodies which have got access into the pulp chamber become solidly enclosed in ivory. The growing end of the tusk is widely open, and its edges are not much thicker than paper ; the cavity which contains the pulp is of conical form, tapering to a point, which is situated at a distance down the tusk, varying, as has been before stated, with the age of the animal. The tusk grows by the con version of successive portions of the surface of the conical mass of pulp into ivory, whilst fresh pulp is added at the flat base or open end of the tusk. The tusks are deeply implanted in curved bony sockets, which run nearly verti cally upwards, so that the open growing ends of the tusks are brought up to about the level of the eyes. Hence it is not a rare occurrence for a sportsnfan s bullet, intended to pierce the elephant s brain, to penetrate the tusk near to its growing end, where the walls of the pulp cavity are quite thin, and to lodge in the &quot;nerve&quot; of its tooth. Indeed sportsmen remark that the forehead shot 13 less fatal to African than to Asiatic elephants, owing to the size and position of their tusks. The amount of disturb ance produced by a bullet in the nerve is variable ; some times the conversion of pulp into ivory goes on with but little interruption, so that the bullet comes to be imbedded in ivory, which fits closely up against it, instead of in pulp as it was at first. Generally the pulp immediately around it has been so disintegrated by its impact, or by subsequent inflammation, that it is incapable of conversion into normal ivory, and in its place there is a more or less irregular de velopment of nodular secondary dentine. And sometimes there is a failure to produce even this less highly organized tissue in the immediate proximity of the bullet, which then ultimately comes to lie loose in an irregular cavity com pletely surrounded by secondary dentine. Of a similar nature is the so-called &quot; abscess in ivory &quot;; this was really an abscess in the formative pulp surrounded by a limiting membrane ; as the conversion of the pulp into ivory went on, calcification passed all round the abscess and enclosed this, pus, membrane, and all, in solid ivory ; and there it is discovered by the ivory cutter as an empty hole lined by a thin dried skin, the old abscess sac. African natives sometimes spear elephants to death when they have been surrounded by an extemporized barrier of twisted creepers, and for this purpose some of them climb into trees ; they also set traps made of a very heavy piece of wood shod with an iron spearhead, arranged to fall upon the elephant as he passes along a track beneath (Du Chaillu); elsewhere lances of extreme length are used in the same way. The open base of the tooth, containing the formative pulp, looking directly upwards, a spear from above intended to fall upon the head or to &quot; pith &quot; the animal might easily enter it, and break away, leaving the point in the tooth pulp. In a specimen now in the museum of the Odonto- logical Society, London, such a spear head remained without stopping the further growth of the tusk, and came to be solidly enclosed in ivory and secondary dentine, although it measures no less than 7J by 1|- inches. Not a trace of its presence was discernible upon the exterior of the tusk, and it was only discovered when the tooth was sawn up. This specimen is not unique, there being said to be another, which has been turned into a cup with the imbedded spear head as its stem ; and there is a specimen of a javelin head firmly built in by ivory in the museum of the lloyal College of Surgeons. But that an elephant is not wholly indifferent to a large foreign body in the nerve of his tooth is proved by the fact that a notoriously fierce and dangerous &quot; rogue &quot; elephant in Ceylon was found when killed to have been suffering from inflammation and suppuration consequent upon the presence of a bullet in the pulp of a tooth ; the supposed madness of the famed elephant of Exeter Change was also found to have been due to the pain of a diseased tooth. A common result of injury to a growing tusk is the conversion of a portion of the pulp into irregular globular masses of secondary den tine, sometimes enclosed solidly in the midst of normal ivory, sometimes forming loose masses as big as hen eggs in the pulp cavity, and sometimes stalagmite-like append ages to its walls. Of course such deviations from normal structure seriously injure its value for industrial purposes, and they are specially apt to occur in domesticated animals whose tusks are being repeatedly shortened, the cut not being invariably made at a sufficient distance from the apex of the living pulp. But under no circumstances is the ivory from domesticated elephants so highly esteemed as that from the wild animal. The large balls of secondary dentine appear on section as a conglomerate of spherical masses bound together by softer and looser-textured materials ; they are sometimes beautiful, but cannot be made much use of. Small spots of globular dentine sometimes occur in the midst of normal ivory, for which no cause can be detected. Malformed tusks are far from rare ; the College of Surgeons pos sesses one about 2 feet in length, the base of which is an irregular mass of osteodentine nearly as large as a man s head. Spiral tusks are also met with, and are almost always the result of some disease of one side of the pulp, leading to a slower growth on the one side than on the other. Much of the ivory of such tusks will be faulty ; they should not be purchased except as curiosities. The Board of Trade returns for 1879 give as the total weight of ivory imported into England during the year 9414 cwts., of the value of 400,927 ; l but nearly half this quantity appears again amongst the exports. By far the larger portion of the ivory is entered as coming from African ports, and less than one-fourth from India, while from this fourth a further reduction must be made in esti mating the quantity produced by the country, as a consider able weight of African ivory from Zanzibar, &c., is shipped from Bombay. About 1080 cwts. is entered as &quot;from other countries.&quot; 2 The best ivory is the African, and the first quality of that comes from near the equator ; much is brought down by natives by land from the interior, whilst in other districts expeditions are organized by Europeans to go into the interior, and collect the stores gathered by native&quot; tribes ; 20,000 K&amp;gt;, valued at Khartoum at 4000, would be considered a good result for a season s expedition with one 1 The imports vary considerably from year to year. In 1875 they amounted to 16,258 cwt,, valued at 772,371. 2 Westendarp states that Africa exports on an average about 15,550 cwt. a year, which would be worth from 600,000 to 750,000, and that the ivory trade is steadily growing, especially on the West Coast. He estimates that in the west not less than 51,000 elephants are killed annually, and anticipates their becoming less numerous. Although the export from India only reached in 1875-7 from 9000 to 17,000 R&amp;gt; a year, a considerably larger quantity of ivory is used in India for arm rings, &c., and for decorative and ornamental purposes. China also deals in ivory, exporting most of it after it Las been carved. XIII. 66