LETTER 452. TO A.R. WALLACE.
Down, October 6th [1868].

Your letter is very valuable to me, and in every way very kind. I will not
inflict a long answer, but only answer your queries. There are breeds
(viz. Hamburg) in which both sexes differ much from each other and from
both sexes of Gallus bankiva; and both sexes are kept constant by
selection. The comb of the Spanish male has been ordered to be upright,
and that of Spanish female to lop over, and this has been effected. There
are sub-breeds of game fowl, with females very distinct and males almost
identical; but this, apparently, is the result of spontaneous variation,
without special selection. I am very glad to hear of case of female Birds
of Paradise.

I have never in the least doubted possibility of modifying female birds
alone for protection, and I have long believed it for butterflies. I have
wanted only evidence for the female alone of birds having had their colour
modified for protection. But then I believe that the variations by which a
female bird or butterfly could get or has got protective colouring have
probably from the first been variations limited in their transmission to
the female sex. And so with the variations of the male: when the male is
more beautiful than the female, I believe the variations were sexually
limited in their transmission to the males.


LETTER 453. TO B.D. WALSH.
Down, October 31st, 1868.