196 ON HORX-GROWi'H IN A CASTRATED PRONGBUCK. [Mar. 21, 



slieaths united by a solid central core. The proximal, or fifth, is 

 separated from the f oitrth by a deep cleft extending moie than half 

 way round the sheath. It measures li inches, and presents on its 

 concave (morphologically anterior) side a small but distinct and. 

 sharp tubercle representing the prong. The fourth, measuring 

 1| inches, is itself subdivided into two by a deep cleft, suggesting 

 that it may represent two short, partially-separated sheaths. 

 The third, which is marked off externally from the fourth by a 

 deep but narrow cleft, measures 1| inches. Neither the foui-th 

 nor the third shows a trace of the prong. The second, measuring 

 1^ inches, has, however, a very pronounced tubercle ; it is 

 sepai-ated from the third by a deep cleft completely encii'cling 

 the sheath. A similar complete cleft also marks the divisional 

 line between the second and first, which is curved as in the right 

 horn-sheath and measures about 2 inches. 



In longitudinal section this sheath is also like that of the light 

 side. The individual components are firmly welded together by 

 the solid central core, and the cortical layer is subdivided by 

 oblique clefts, some of which fall short of the periphery of the 

 sheath and are visible only in section, v^^hile others are carried 

 through to the surface and mai-k the spaces between the sheaths. 

 The lengths of the latter from base to apex, as shown in section, 

 are as follows : — Nos. 5-2 about 2^ inches, no. 1 about 2^ inches. 



The left horn I removed from the animal's head myself. It 

 was loose, and the fibres at its base were easily laiptured by 

 rotation. The sheath came partially away from the horn-core, 

 leaving it covered with a horny cap, the last-formed sheath. 

 This cap, however, Avas firmly united apically to the angle of the 

 socket of the antecedent sheath by a solid horny strand con- 

 tinuous with the central core ti'aversing the length of the 

 composite horn-sheath and binding its constituents together. 

 This strand (text-fig. 29, A) had to be severed with a knife before 

 the sheath could be removed. The presence of this horny cap 

 upon the left horn-core and the naked and bleeding condition of 

 the right one sufiiciently explain the presence of six horn-sheaths 

 in the right and five in the left detached composite sheath. 



The effects of castration on the hoi-ns of the Prongliuck may 

 thus be summarised as follows : — 



1. Modification of the Horn-cores. — These are shortened and bent 



obliquely forwards and outwards at the apex, causing the 

 sheath to project in the direction of the nose. 



2. Modifications of the Horn-sheath: — 



a. Shedding of the sheath does not take place. 



6. The first-formed sheath is normal in shaj^e, and at the time 

 for shedding breaks away from the second except at the 

 point where the a.pex of the latter joins the angle of the 

 cup of the former. A similar partial severance separates 

 the succeedina; sheaths from each other. 



