628 THE SHAPES OF HORNS [ch. 



such stems are especially susceptible of torsion ; and (2) that the 

 effect of torsion will be to intensify any such peculiarities of 

 sectional outline which they may possess, though not to initiate 

 them in an originally cylindrical structure. In the leaf-climbers 

 the case does not present itself, for there, as w^e have seen, torsion 

 itself is not, 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 permits that 

 which is parallel, to the axis of the horn. 



Of Deer^s Antlers. 



Bulrlet us return to our subject of the shapes of horns, and 

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

 antlers of the various species of 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 

 corresponds, 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 lies in the fact 

 that, in the one case, the bony core, 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 : 



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

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

 der rezenten Hirschen, 75 pp., 23 pis., 1901 : also Sir Victor Brooke, On the 

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

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

 works quoted therein. 



f Cf. Rhumbler, L., Ucber die Abhangigkeit des Geweihwachstums der Hu'sche, 

 speziell des Edelhirsches, vom Verlauf der Blutgefasse im Kolbengeweih, Zeitschr. 

 /. Forst. mid Jagdwesen, 1911, pp. 295-314. 



