258 THE PRINCIPLES OF Part II. 



possessed by the males for fighting with and driving 

 away their rivals — their courage and pugnacity — their 

 ornaments of many kinds — their organs for producing 

 vocal or instrumental music — and their glands for 

 emitting odours; most of these latter structures serv- 

 ing only to allure or excite the female. That these 

 characters are the result of sexual and not of ordinary 

 selection is clear, as unarmed, unornamented, or un- 

 attractive males would succeed equally well in the 

 battle for life and in leaving a numerous progeny, if 

 better endowed males were not present. We may infer 

 that this would be the case, for the females, which are 

 unarmed and unornamented, are able to survive and 

 procreate their kind. Secondary sexual characters of 

 the kind just referred to, will be fully discussed in the 

 following chapters, as they are in many respects in- 

 teresting, but more especially as they depend on the 

 will, choice, and rivalry of the individuals of either sex. 

 When we behold two males fighting for the possession 

 of the female, or several male birds displaying their 

 gorgeous plumage, and performing the strangest antics 

 before an assembled bodv of females, we cannot doubt 

 that, though led by instinct, they know what they are 

 about, and consciously exert their mental and bodily 

 powers. 



In the same manner as man can improve the breed 

 of his game-cocks by the selection of those birds which 

 are victorious in the cockpit, so it appeal's that the 

 strongest and most vigorous males, or those provided 

 with the best weapons, have prevailed under nature, 

 and have led to the improvement of the natural breed 

 or species. Through repeated deadly contests, a slight- 

 degree of variability, if it led to some advantage, how- 

 ever slight, would suffice for the work of sexual selec- 

 tion ; and it is certain that secondarv sexual characters 



