Dear Sir

I thank you for your very interesting letter,² & I should have greatly regretted not to have received it. By an odd chance my eldest son (at whose house I am now staying, & which fact will account for the delay in acknowledging your letter) about a year ago told me of a pony coloured exactly as you describe & which he was almost certain changed colour in the same manner during winter.³ He has since observed the pony carefully & finds that it is so.

With these two cases, I think I may now fully rely on the fact, so that it would be superfluous to write to any paper for the chance of receiving an answer.—

With respect to the hairs on the human body I am much surprised at what you say— I had always fancied that goose-skin & the erection of the scattered hairs were part of the same phenomenon, & so it is generally stated in books. It is very strange that the cold & hot water sh^d. have induced goose-skin in your case & not the erection of the hair.

I imagine that the muscles to the hairs on the body of man must be tending to a rudimentary condition. That they will act in some cases I must believe from the statement of so careful an observer as Lister who states that tickling the surface will cause the erection of the hairs on the closely adjoining surface.⁴

I daresay there is much truth in what you say about the influence of colour & temperature, which I quite over⁠⟨⁠l⁠⟩⁠ooked; & your account of the effects of heat on the different parts of the skin of your hands is very remarkable.⁵

With very cordial thanks for your valuable letter, pray believe me Dear Sir | Yours faithfully & obliged | Ch. Darwin