by the preference of the females, the more ornamented males becoming the
parents of each successive generation." "Darwinism," 1889, page 285. See
also Letters 442, 443, 449, 450, etc.)

Down, April 15th, [1868].

I have been deeply interested by your admirable article on birds' nests. I
am delighted to see that we really differ very little,--not more than two
men almost always will. You do not lay much or any stress on new
characters spontaneously appearing in one sex (generally the male), and
being transmitted exclusively, or more commonly only in excess, to that
sex. I, on the other hand, formerly paid far too little attention to
protection. I had only a glimpse of the truth; but even now I do not go
quite as far as you. I cannot avoid thinking rather more than you do about
the exceptions in nesting to the rule, especially the partial exceptions,
i.e., when there is some little difference between the sexes in species
which build concealed nests. I am not quite satisfied about the incubating
males; there is so little difference in conspicuousness between the sexes.
I wish with all my heart I could go the whole length with you. You seem to
think that male birds probably select the most beautiful females; I must
feel some doubt on this head, for I can find no evidence of it. Though I
am writing so carping a note, I admire the article thoroughly.

And now I want to ask a question. When female butterflies are more
brilliant than their males you believe that they have in most cases, or in
all cases, been rendered brilliant so as to mimic some other species, and
thus escape danger. But can you account for the males not having been
rendered equally brilliant and equally protected? (440/2. See Wallace in
the "Westminster Review," July, 1867, page 37, on the protection to the
female insect afforded by its resemblance either to an inanimate object or