288 THE ZOOLOGIST. 





variable presence or absence in the females of genera and species 

 whose males possess them, universally requires explanation from 

 the standpoint of the previous argument. A solution of the 

 problem will be found in the physiological antagonism between 

 growth and reproduction, which seems to have been overlooked 

 by the theory of sexual selection, but which nevertheless, in the 

 higher mammalian organisation, lies at the root of all the more 

 distinctively sexual characters. In the organic economy of the 

 male the sum of vital force is expended on self-maintenance, and 

 growth continues till expenditure nearly balances nutrition ; in 

 the organic economy of the female there is a reserve of vital force 

 to meet the cost of reproduction, and growth is arrested " while 

 there is yet a considerable margin of nutrition, for otherwise there 

 could be no offspring" (Herbert Spencer). I think it probable that 

 frontal weapons of a simple type and for the common purpose of 

 defence were aboriginally developed without distinction of sex, 

 though not necessarily by both sexes and not necessarily by either; 

 but I think it certain that the development of such weapons must 

 have been differently modified from the outset by the physiological 

 organisation proper to either sex. In females the recurrent strain 

 of parturition, suckling, and anxious maternity would tend to 

 arrest the development of cranial structures necessitating for their 

 effective maintenance a large expenditure of vital force; would 

 tend, in the continuously severer struggles for life, to promote 

 their loss by retrogression consequent upon the paramount claim 

 and higher utility of rearing vigorous offspring ; and would tend, 

 in any case, to throw the burden of protection primarily upon the 

 males, to the development of whose weapons, whether horns or 

 antlers, physiology would offer no check and natural selection 

 would afford a constant stimulus, the calibre of the weapon being 

 directly conditioned by the struggle for life. Female horns and 

 antlers therefore represent a compromise between conflicting 

 forces, maternal and self-protective, whose variable incidence, 

 according to the reaction of diverse constitutions upon diverse 

 conditions of life, has produced a variable resultant, and added a 

 new factor to the problem ; so that the quesion, whether protectve 

 weapons are profitable to the female sex, becomes subordinate to 

 the further inquiry, how far the development of such weapons 

 may have been compatible with the complete fulfilment of the 

 maternal functions ? 



