138 NATURAL SELECTION 



greater danger to which she is exposed and her greater im- 

 portance to the existence of the species ; and this she always 

 acquires, in one way or another, through the action of natural 

 selection. 



In his Origin of Species, fourth edition, p. 241, Mr. Darwin 

 recognises the necessity for protection as sometimes being a 

 cause of the obscure colours of female birds ; 1 but he does not 

 seem to consider it so very important an agent in modifying 

 colour as I am disposed to do. In the same paragraph (p. 

 240) he alludes to the fact of female birds and butterflies 

 being sometimes very plain, sometimes as gay as the males ; 

 but, apparently, considers this mainly due to peculiar laws of 

 inheritance, which sometimes continue acquired colour in the 

 line of one sex only, sometimes in both. Without denying 

 the action of such a law (which Mr. Darwin informs me he 

 has facts to support), I impute the difference, in the great 

 majority of cases, to the greater or less need of protection in 

 the female sex in these groups of animals. 



This need was seen to exist a century ago by the Hon. 

 Daines Barrington, who, in the article already quoted (see p. 

 104), after alluding to the fact that singing birds are all small, 

 and suggesting (but I think erroneously) that this may have 

 arisen from the difficulty larger birds would have in conceal- 

 ing themselves if they called the attention of their enemies by 

 loud notes, goes on thus : " I should rather conceive it is for 

 the same reason no hen bird sings, because this talent would 

 be still more dangerous during incubation, which may possibly 

 also account for the inferiority in point of plumage." This is a 

 curious anticipation of the main idea on which this essay is 

 founded. It has been unnoticed for near a century, and my 

 attention was only recently called to it by Mr. Darwin himself. 



Conclusion 



To some persons it will perhaps appear that the causes to 

 which I impute so much of the external aspect of nature are 

 too simple, too insignificant, and too unimportant for such a 

 mighty Ayork. But I would ask them to consider that the 

 great object of all the peculiarities of animal structure is to 

 preserve the life of the individual, and to maintain the exist- 

 1 This passage is omitted in the sixth edition. 



