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 :— 
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