SEXUAL SELECTION. 207 



while in the Argus-pheasant the secondary quills are 

 so enormously lengthened and broadened as to have 

 become almost useless for flight. Now it is easily 

 conceivable, that during this process of development, 

 inequalities in the distribution of colour may have arisen 

 in different parts of the same feather; and that spots and 

 bands may thus have become broadened out into shaded 

 spots or ocelli, in the way indicated by Mr. Darwin, 

 much as the spots and rings on a soap-bubble increase 

 with increasing tenuity. This is the more probable, 

 because in domestic fowls varieties of colour tend to 

 become symmetrical, quite independently of sexual 

 selection. (Descent of Man, p. 424.) 



If now we accept the evidence of Mr. Darwin's most 

 trustworthy correspondents, that the choice of the female, 

 so far as she exerts any, falls upon the " most vigorous, 

 defiant, and mettlesome male ; " and if we further 

 believe, what is certainly the case, that these are as a 

 rule the most brightly coloured and adorned with the 

 finest developments of plumage, we have a real and not 

 a hypothetical cause at work. For these most healthy, 

 vigorous, and beautiful males will have the choice of the 

 finest and most healthy females ; will have the most 

 numerous and healthy families ; and will be able best to 

 protect and rear those families. Natural selection, and 

 what may be termed male selection, will tend to give 

 them the advantage in the struggle for existence ; and 

 thus the fullest plumage and the finest colours will be 

 transmitted, and tend to advance in each succeeding 

 generation. 



Theory of Display of Ornaments by Males. The full 

 and interesting account given by Mr. Darwin of the 



