892 THE SHAPES OF HORNS [ch. 



or is very slightly, manifested. There are very distinct traces of 

 the phenomenon in the horns of certain antelopes, but the reason 

 why it is not a more conspicuous feature of the antelope's horn or 

 of the ram's is apparently a very simple one: namely, that the 

 presence of the bony core within tends to check that deformation 

 which is perpendicular, while it pfermits that which is parallel, to 

 the axis of the horn. 



Uf deer's antlers 



But let us return to our subject of the shapes of horns, and con- 

 sider briefly our last class of these structures, namely the bony 

 antlers of the elk and deer*. The problems which these present to 

 us are very different from those which we have had to do with in 

 the antelope or the sheep. 



With regard to its structure, it is plain that the bony antler corre- 

 sponds, upon the whole, to the bony core of the antelope's horn; 

 while in place of the hard horny sheath of the latter, we have the 

 soft "velvet," which every season covers the new growing antler, 

 and protects the large nutrient blood-vessels by help of which the 

 antler grows -f. The main difference hes in the fact that in the 

 one case the bony coTe, imprisoned within its sheath, is. rendered 

 incapable of branching and incapable also of lateral expansion, and 

 the whole horn is only permitted to grow in length while retaining 

 a sectional contour that is identical with (or but little altered from) 

 that which it possesses at its growing base : but in the antler on the 

 other hand no such restraint is imposed, and the living, growing 

 fabric of bone is free to expand into a broad flat plate over which 

 the blood-vessels run. In the immediate neighbourhood of the main 

 blood-vessels growth will be most active, in the interspaces between 

 it may wholly fail: with the result that we may have great notches 

 cut out of the flattened plate, or may at length find it reduced to the 



* For an elaborate study of antlers, see A. Rorig, Arch. f. Entw. Mech. x, 

 pp. 525-644, 1900; xi, pp. 65-148, 225-309, 1901; C. Hoffmann, Zur Morpholdgie 

 der rezenten Hirsche, 75 pp., 23 pis., 1901; also Sir V^ictor Brooke, On the 

 classification of the Cervidae, P.Z.S. 1878, pp. 883-928. For a discussion of the 

 development of horns and antlers, see H. Gadow, P.Z.S. 1902, pp. 206-222, and 

 works quoted therein. 



t Cf. L. Rhumbler, Ueber die Abhangigkeit des Geweihwachsturas der Hirsche, 

 speziell des Edelhirsches, vom Verlauf der Blutgefasse im Kalbengeweih, Zeitsckr. 

 f. Forst. und Jagdwesen, 1911, pp. 295-314, 



