720 The Colors of Animals and Plants. [ December, 
and black, while the females are orange, yellow, and black, and 
so banded and spotted as exactly to, resemble species of Heli- 
conidæ. Mr. Darwin admits that these females have acquired 
these colors as a protection ; but as there is no apparent cause 
for the strict limitation of the color to the female, he believes 
that it has been kept down in the male by its being unattractive 
to her. This appears to me to be a supposition opposed to the 
whole theory of sexual selection itself. For this theory is, that 
minute variations of color in the male are attractive to the fe- 
male, have always been selected, and that thus the brilliant 
male colors have been produced. But in this case he thinks that 
the female butterfly had a constant aversion to every trace of 
color, even when we must suppose it was constantly recurring 
during the successive variations which resulted in such a marvel- 
ous change in herself. But if we consider the fact that the fe- 
males frequent the forests where the Heliconidz abound, while 
the males fly much in the open, and assemble in great numbers 
with other white and yellow butterflies on the banks of rivers, 
may it not be possible that the appearance of orange stripes or 
patches would be as injurious to the male as it is useful to the 
female, by making him a more easy mark for insectivorous birds 
among his white companions ? This seems a more probable sup- 
position than the altogether hypothetical choice of the female, 
sometimes exercised in favor of and sometimes against every new 
variety of color in her partner. 
_ The full and interesting account given by Mr. Darwin of the 
colors and habits of male and female birds (Descent of Man, 
chapters xiii. and xiv.) proves that in most, if not in all, cases 
the male birds fully display their ornamental plumage before the 
` females, and in rivalry with each other; but on the essential 
point of whether the female’s choice is determined by minute 
. differences in these ornaments or in their colors, there appears to 
be an entire absence of evidence. In the section on Preference 
for Particular Males by the Females, the facts quoted show m- 
difference to color, except that some color similar to their own 
seems to be preferred. But in the case of the hen-canary, who 
chose a greenfinch in preference to either chaffinch or goldfinch, 
gay colors had evidently no preponderating attraction. There 
do, choose their mates, but none whatever that the choice is de- 
termined by difference of color; and no less than three eminent e 
breeders informed Mr. Darwin that they “did not believe that Z : 
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is some evidence adduced that female birds may, and probably — 
