314 SEXUAL selection: mammals. PartIL 



without the aid of selection. But when the colours are 

 diversified and strongly pronounced, when they are not 

 developed until near maturity, and when they are lost 

 after emasculation, we can hardly avoid tlie conclusion 

 that they have been acquired through sexual selection for 

 the sake of ornament, and have been transmitted exclu- 

 sively, or almost exclusively, to the same sex. When 

 both sexes are coloured in the same manner, and the 

 colours are conspicuous or curiously arranged, ^Yithout 

 being of the least apparent use as a protection, and 

 especially when they are associated with various other 

 ornamental appendages, we are led by analogy to the 

 same conclusion, namely, that they have been acquired 

 through sexual selection, although transmitted to both 

 sexes. That conspicuous and diversified colours, whether 

 confined to the males or common to both sexes, are as 

 a general rule associated in the same groups and sub- 

 groups with other secondary sexual characters, serving 

 for war or for ornament, wdll be found to hold good if 

 we look back to the various cases given in this and 

 the last chapter. 



The law of the equal transmission of characters to 

 both sexes, as far as colour and other ornaments are 

 concerned, has prevailed far more extensively with 

 mammals than with birds; but in regard to weapons, 

 such as horns and tusks, these have often been trans- 

 mitted either exclusively, or in a mucli higher degree 

 to the males than to the females. This is a surprising 

 circumstance, for as the males generally use their 

 weapons as a defence against enemies of all kinds, 

 these weapons would have been of service to the fe- 

 male. Their absence in this sex can be accounted for, 

 as far as we can see, only by the form of inheritance 

 which has prevailed. Finally with quadrupeds the 



