Chapter 61

W. [March 6th, 1868].

I have come here for a few weeks, for a little change and rest. Just as I was leaving home I received your first note, and yesterday a second; and both are most interesting and valuable to me. That is a very curious observation about the goldfinch's beak (435/1. "Descent of Man," Edition I., Volume I., page 39. Mr. Weir is quoted as saying that the birdcatchers can distinguish the males of the goldfinch, Carduelis elegans, by their "slightly longer beaks."), but one would hardly like to trust it without measurement or comparison of the beaks of several male and female birds; for I do not understand that you yourself assert that the beak of the male is sensibly longer than that of the female. If you come across any acute birdcatchers (I do not mean to ask you to go after them), I wish you would ask what is their impression on the relative numbers of the sexes of any birds which they habitually catch, and whether some years males are more numerous and some years females. I see that I must trust to analogy (an unsafe support) for sexual selection in regard to colour in butterflies. You speak of the brimstone butterfly and genus Edusa (435/2. Colias Edusa.) (I forget what this is, and have no books here, unless it is Colias) not opening their wings. In one of my notes to Mr. Stainton I asked him (but he could or did not answer) whether butterflies such as the Fritillaries, with wings bright beneath and above, opened and shut their wings more than Vanessae, most of which, I think, are obscure on the under surface. That is a most curious observation about the red underwing moth and the robin (435/3. "Descent of Man," Edition I., Volume I., page 395. Mr. Weir describes the pursuit of a red-underwing, Triphoena pronuba, by a robin which was attracted by the bright colour of the moth, and constantly missed the insect by breaking pieces off the wing instead of seizing the body. Mr. Wallace's facts are given on the same page.), and strongly supports a suggestion (which I thought hardly credible) of A.R. Wallace, viz. that the immense wings of some exotic lepidoptera served as a protection from difficulty of birds seizing them. I will probably quote your case.

No doubt Dr. Hooker collected the Kerguelen moth, for I remember he told me of the case when I suggested in the "Origin," the explanation of the coleoptera of Madeira being apterous; but he did not know what had become of the specimens.

I am quite delighted to hear that you are observing coloured birds (435/4. "Descent of Man," Edition I., Volume II., page 110.), though the probability, I suppose, will be that no sure result will be gained. I am accustomed with my numerous experiments with plants to be well satisfied if I get any good result in one case out of five.

You will not be able to read all my book--too much detail. Some of the chapters in the second volume are curious, I think. If any man wants to gain a good opinion of his fellow-men, he ought to do what I am doing, pester them with letters.