Dear Darwin

Thanks for your kind note. I could not persuade Mr. Macmillan to cut more than 25 copies for my own friends, & he even seemed to think this a sign of most strange and barbarous taste.¹

Mr. Weir’s paper on the kinds of larvæ &c. eaten or rejected by insectivorous birds, was read at the last meeting of the Entomological Society & was most interesting & satisfactory.² His observations & experiments, so far as they have yet gone, confirm in every instance my hypothetical explanation of the colours of catterpillars. He finds that all nocturnal feeding obscure coloured catterpillars, all green & brown and mimicking catterpillars, are greedily eaten by almost every insectivorous bird. On the other hand every gaily coloured spotted or banded species, which never conceal themselves, & all spiny & hairy kinds are invariably rejected, either without or after trial.³

He has also come to the curious & rather unexpected conclusion, that hairy & spiny catterpillars are not protected by their hairs,—but by their nauseous taste, the hairs being merely an external mark of their uneatableness, like the gay colours of others— He deduces this from two kinds of facts—1st. That very young catterpillars before the hairs are developed are equally rejected,—and 2nd—that in many cases the smooth pupæ & even the perfect insect of the same species, are equally rejected.

His facts it is true are at present not very numerous, but they all point one way. They seem to me to lend an immense support to my view of the great importance of protection in determining colour,—for it has not only prevented the eatable species from ever acquiring bright colour spots or markings injurious to them, but it has also conferred on all the nauseous species distinguishing marks to render their uneatableness more protective to them than it would otherwise be.

When you have read my book I shall be glad of any hints for corrections if it comes to another edition— I was horrified myself by coming accidentally on several verbal inelegancies after all my trouble in correcting, & I have no doubt there are many more important errors.

Believe me Dear Darwin | Yours very truly | Alfred R. Wallace