Darwin s Theory of Sexual Selection 199 



The male Argus pheasant has a remarkable series of spots, 

 or ocelli, on the secondary wing-covers. They are concealed 

 until the male displays them before the female. Darwin 

 states that, while it may seem incredible that such elegant 

 shading and exquisite patterns could have been the outcome 

 of the taste of the female, yet the extraordinary attitude 

 assumed by the male during courtship appears entirely pur- 

 poseless, unless it be supposed that he is attempting to charm 

 the female by a display of his ornamentation. 



Let us pass to the second class of cases, in which both 

 sexes are similarly and brightly colored, and in which the 

 young have a plumage different from the adults. For exam- 

 ple, the male and the female of the splendid scarlet ibis are 

 alike, whilst the young are brown. The males and females of 

 many finely colored herons are ornamented alike, and this 

 plumage, Darwin admits, has a nuptial character. He even 

 tries to explain this by the curious assumption, that while the 

 color has been acquired through the selection of the males 

 by the females, the results attained in this way have been 

 transmitted to both sexes. We find here another example of 

 the method so often employed by Darwin. When he meets 

 with facts that are not in conformity with the theory, he pro- : 

 ceeds to make a new assumption without establishing its \ 

 validity. Thus, to assume that in all cases where the sexes : 

 are colored differently, the characters acquired by the males 

 have been transmitted only to the same sex, and in those 

 cases where the sexes are colored alike the transmission has 

 been to both sexes, is most arbitrary. 



In other cases, which are commoner than the last, the male 

 and female have the same color, and the young in their first 

 plumage resemble the adults. Darwin admits that here the 

 facts are so complex that his conclusions are doubtful. The 

 following account of the tree-sparrow shows how vague are 

 the principles involved in the entire discussion in relation to 

 transmission : — 



