Ohap. VI II. Sexual Selection. 24 1 



as by acquiring bright colours, which would render them con- 

 spicuous to their enemies, or by acquiring structures, such as 

 great horns, which would expend much vital force in their 

 development. Variations of this kind occurring in the young 

 males would almost certainly be eliminated through natural 

 selection. With the adult and experienced males, on the other 

 hand, the advantages derived from the acquisition of such 

 characters, would more than counterbalance some exposure to 

 danger, and some loss of vital force. 



As variations which give to the male a better chance of 

 conquering other males, or of finding, securing, or charming tho 

 opposite sex, would, if they happened to arise in the female, be 

 of no service to her, they would not be preserved in her through 

 sexual selection. We have also good evidence with domesticated 

 animals, that variations of all kinds are, if not carefully selected, 

 soon lost through intercrossing and accidental deaths. Conse- 

 quently in a state of nature, if variations of the above kind chanced 

 to arise in the female line, and to be transmitted exclusively in 

 this line, they would be extremely liable to be lost. If, however, 

 the females varied and transmitted their newly acquired 

 characters to their offspring of both sexes, the characters which 

 were advantageous to the males would be preserved by them 

 through sexual selection, and the two sexes would in consequence 

 be modified in the same manner, although such characters were of 

 no use to the females ; but I shall hereafter have to recur to these 

 more intricate contingencies. Lastly, the females may acquire, and 

 apparently have often acquired by transference, characters from 

 the male sex. 



As variations occurring late in life, and transmitted to one 

 sex alone, have incessantly been taken advantage of and accumu- 

 lated through sexual selection in relation to the reproduction of 

 the species ; therefore it appears, at first sight, an unaccountable 

 fact that similar variations have not frequently been accumu- 

 lated through natural selection, in relation to the ordinary 

 habits of life. If this had occurred, the two sexes would often 

 have been differently modified, for the sake, for instance, of 

 capturing prey or of escaping from danger. Differences of this 

 kind between the two sexes do occasionally occur, especially in 

 the lower classes. But this implies that the two sexes follow 

 different habits in their struggles for existence, which is a rare 

 circumstance with the higher animals. The case, however, is 

 widely different with the reproductive functions, in which respect 

 the sexes necessarily differ. For variations in structure which 

 are related to these functions, have often proved of value to one 

 sex, and ^rom having arisen at a late period of life, have been 



