ely,

C. DARWIN.

I do not know whether you will care to read this scrawl.

P.S.--I heard yesterday that my photograph had been sent to your London
address--Westbourne Grove.

* * * * *

_Down, Bromley, Kent, S.E. May 5, 1868._

My dear Wallace,--I am afraid I have caused you a great deal of trouble
in writing to me at such length. I am glad to say that I agree almost
entirely with your summary, except that I should put sexual selection as
an equal or perhaps as even a more important agent in giving colour than
natural selection for protection. As I get on in my work I hope to get
clearer and more decided ideas. Working up from the bottom of the scale
I have as yet only got to fishes. What I rather object to in your
articles is that I do not think anyone would infer from them that you
place sexual selection even as high as No. 4 in your summary. It was
very natural that you should give only a line to sexual selection in
the summary to the _Westminster Review_, but the result at first to my
mind was that you attributed hardly anything to its power. In your
penultimate note you say: "In the great mass of cases in which there is
_great_ differentiation of colour between the sexes, I believe it is due
_almost wholly_ to the need of protection to the female." Now, looking
to the whole animal kingdom I can at present by no means admit this
view; but pray do not suppose that because I differ to a certain extent,
I do not thoroughly admire your several papers and your admirable
generalisation on birds' nests. With respect to this latter point,
however, although following you, I suspect that I shall ultimately look
at the whole case from a rather different point of view.

You ask what I think about the gay-coloured females of Pieris:[70] I
believe I quite follow you in believing that the colours are wholly due
to mimicry; and I further believe that the male is not brilliant from
not having received through inheritance colour from the female, and from
not himself having varied; in short, that he has not been influenced by
Selection.

I can make no answer with respect to the elephants. With respect to the
female reindeer, I have hitherto looked at the horns simply as the
consequence of inheritance _not_ having been limited by sex.

Your idea about colour being concentrated in the smaller males seems
good, and I presume that you will not object to my giving it as your
suggestion.--Believe m