322 THE PHYSIOLOGY OF REPRODUCTION 



the complete development of the antlers, these are shed prematurely 

 and are replaced in the next season by incomplete antlers with a 

 tendency towards peruke formation, and these, on being thrown off, 

 are not renewed. Partial castration in the immature stag is said t<> 

 result in a weaker horn formation ; but the effect is general, and 

 shows no restriction to the side on which the testis is wanting. 1 



The results of castration in the fallow deer have been investigated 

 by Fowler, 2 who summarises his results under five headings : 

 (1) Complete castration at birth limits the horn formation to the 

 development of single dugs ; (2) Castration in mature life tends to 

 produce asymmetry in the growtli of the horns ; (8) The antlers 

 of castrated deer are often shed prematurely if the operation is 

 performed after they have lost the velvet, but antlers which have 

 grown after castration may be retained for over two years ; (4) 

 Incomplete castration shortly after birth is followed by a weak 

 development of the antlers, which are otherwise normal; (5) One- 

 sided castration may result in the abnormal or incomplete develop- 

 ment of one antler, the other antler being nearly normal. The last 

 point would seem to require confirmation. 3 



In the prong-buck (Antilocapra americana), which is the only 

 hollow-horned Kuininant that periodically sheds its horns, the effects 

 of castration are also quite distinct. The horns, instead of rising 

 vertically as in normal individuals, curve forwards from the roots, 

 and then bend downwards and backwards so as to terminate in 

 incurved points in the close vicinity of the eyes. The anterior tine 

 is almost completely suppressed. The horn-sheath is never shed, 

 and as a consequence a composite sheath is developed, and this 

 seems to go on growing as long as new sheaths are formed from the 

 horn-core. 4 



It is interesting to note that in the eland, in which both sexes 

 possess horns, the development of these structures is not appreciably 

 affected by castration. A similar statement may be made about some 

 horned cattle, in which (in common with other cattle) castration in 



1 These statements are based chiefly-upon the results of Caton's experiments 

 with Wapiti and Canadian deer (Caton, Antelope and Deer of America, 

 2nd Edition, New York, 1881. See also Holdich, "Exhibition of Antlers of 

 Deer showing Arrest of Development due to Castration," Proc. Zool. Soc., 

 1905). Some further examples of sexual correlation are given in Chapter I. of 

 this work. (See Morgan, loc. cit.) Professor Seligman informs me that stags 

 which fail to grow antlers (i.e. occasional " sports ") have well-developed testicles. 



2 Fowler, "Notes on some Specimens of Antlers of the Fallow Deer, etc.," 

 Proc. Zool. Soc., 1894. 



3 MacEwen (The Growth and Shedding of the Antlers of the JJeer, Glasgow, 1920) 

 refers to another case of one-sided castration being followed by asymmetrical 

 horn growth. 



4 Pocock, "The Effects of Castration on the Horns of the Prong-buck," 

 Proc. Zool. Soc., 1905. It is to be noted that horns are occasionally pi'esent 

 in the female prong-buck. 



