WCP1974

[1]

Down,

Beckenham, Kent.

Railway Station

Orpington. S.E.R

Aug[ust] 31 77

My dear Wallace,

I am very much obliged to you for sending your article; which is very interesting & appears to me as clearly written as it can be. You will not be surprised that I differ altogether from you about sexual colours. That the tail of the peacock & his elaborate display of it should be due merely to the vigour, activ[2]ity, & vitality of the male is to me as utterly incredible as my views are to you. Mantegazza published a few years ago in Italy a somewhat similar view. I cannot help doubting about recognition through colour: our horses dogs, fowls, & pigeons seem to know their own species however differently the individuals may be coloured. I wonder whether [3] you attribute the odoriferous & sound producing organs, when confined to the males to their greater vigour &c. I could say a good deal in opposition to you, but my arguments would have no weight in your eyes & I do not intend to write for the public anything on this or any other difficult subject. By the way I doubt whether the term voluntary in relation to [4] sexual selection ought to be employed: when a man is fascinated by a pretty girl it can hardly be called voluntary, & I suppose that female animals are charmed or excited in nearly the same manner by the gaudy males.

Three essays have been published lately lately in Germany which would interest you: one by Weismann who shows that the coloured stripes on the caterpillars of sphinx are beautifully protective: & birds were frightened away from their feeding place by a caterpillar [5] with large eye-like spots on the broad anterior segments of the body. Fritz Müller has well discussed the first steps of mimicry with butterflies, & comes to nearly or quite the same conclusions as you, but supports it by additional arguments.

Fritz ^Müller also has lately shown that the males alone of certain butterflies have odoriferous glands on their wings (distinct from those [6] which secrete matter disgusting to birds) & where these glands are placed, the scales assume a different shape making little tufts.

Farewell— I hope that you find Dorking a pleasant place? I was staying lately at Abinger Hall & wished to come over to see you but driving tires me so much that my courage failed.

Yours very sincerely | Chas. Darwin [signature]