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Darwin Correspondence Project

From Frank Chance   31 July – 7 August 1873

Burleigh House, Sydenham Hill,

July 31, 1873,

My dear Sir,

In your work on the “Descent of Man” (ed. 1871) ii. 298, 299, in speaking of the change of colour of mammals in the winter, you quote a statement from Pallas that in Siberia the coat of the domestic horse becomes paler in the winter, though even there it does not appear to become quite white.1 I infer from this that you are not aware that in England any change of colour has ever been observed to take place in the horse in winter; and therefore, as an undoubted case has come under my notice in which the coat of a pony in England has not only become paler in the winter but has actually turned quite white, I venture to communicate this case to you. About two years ago, an acquaintance of mine, a farmer living in Northamptonshire, called my attention to a pony behind which I was at the moment sitting. This pony was then (it was in the summer) of a dark cream colour as its owner called it, though to my mind the tint was rather that of the French café au lait, and its mane and tail were quite white. I frequently see ponies of this colour in the neighbourhood of London and they seem almost always to have white manes and tails, though I have seen one with a mane & tail of much the same colour as its body. The Northamptonshire pony however, to which my attention was called, was stated by its owner to have the peculiarity that in winter its coat habitually became white like the mane and tail. This change of colour could not, its owner said, be attributed in any way to age, though the pony was some twelve years old, for he had had it when it was only three or four, and its coat was then subject to the same change of colour in the winter.

I have never indeed myself seen this pony in the winter, but a short time (2 or 3 months perhaps) after I had seen it, and when I thought it might very likely be changing its coat, I wrote to a friend who knew the pony well & asked him to procure and send me samples of the hair from its body, & tail. He wrote to me in answer on the 10th. Oct. 1871, enclosing the hair asked for & the following is an extract from his letter: “The hair from the body is from the back; the pony is much lighter in colour than he was a month ago. I suppose it will be more than another month before he becomes quite white. They have had him 8 or 9 years; he is entire and has changed colour every year since they have had him. The pony is about twelve years old.”

I enclose specimens of the hair*2 then sent me, and if you take interest in the case & the pony is still alive & you would like to have specimens of the hair as it is in the summer and when it is in a more advanced stage of change than that enclosed, I shall be most happy to procure for you what you require, as also any further details which you would like to have.

It is evident from what I have said above that there are many ponies of this café au lait colour with white manes & tails in England, and it does not seem to me at all likely that the pony which I have seen should be the only one in which this change to white takes place in winter. Would it not be well to address a letter to “Land and Water” or some other periodical, or to some sporting paper, requesting any one who knows of a similar case to be kind enough to communicate it to you, or to me if you would prefer that I should write this letter.


In the same work (11. 298) you say “no one has ever doubted that the quadrupeds which inhabit snow-clad regions have been rendered white to protect them from their enemies or to favour their stealing on their prey. In regions where snow never lies long on the ground, a white coat would be injurious; consequently species thus coloured are extremely rare in the hotter parts of the world”.3 Now, though it may be doubted whether these quadrupeds were rendered white for these two purposes, and it may be urged that the absence of colour is due in a greater degree to the absence of heat and consequent absence of pigment than to the influence of natural selection.— Still there cannot be the least doubt that the white colour does confer upon its possessor the two advantages which you mention. I cannot, however, keep thinking it to be probable that the white coat also keeps the animal warmer than the darker coat would do. Just as heat develops pigment and this pigment (as in the negro) protects from the very heat which develops it, so the absence of pigment induced by cold (i.e., the diminution of heat) ought to shield from cold. The presence of pigment prevents the penetration of heat; the absence of pigment should favour the penetration of that small amount of heat which is left in the arctic regions & which is termed cold.* But as this view of mine is based merely upon analogy & not upon observed facts, I will say no more about it. It would be interesting, however, to observe whether, when the coat becomes white, the subjacent skin also becomes paler.4

Of the protective power of pigment I have had a singular illustration in my own person. Some 18 or 19 years ago, the skin of the back of my hands began to undergo irregular pigmentation in the hotter months of the year. Instead of the whole skin assuming one uniform darker tint as in ordinary sun-burn, one part of my skin became of a yellowish colour similar to that of freckles only slightly darker and in large patches not in spots, whilst the rest of the back of the back of my hands remained of its original hue or if anything became a little lighter. In the colder months, the discolouration disappeared again, or at any rate subsided to such an extent as to be distinguishable only upon close inspection. This irregular pigmentation has continued ever since, though every year brings changes in the distribution of the pigment & I have now I am glad to say, less than I have had for a long time. Now, if I go and fish (without gloves) in an unusually hot sun as has happened to me two or three times of late years (the last time two years ago), the unpigmented portion of the skin of the back of my hands becomes very red, very hot, very much swollen and at last vesicles form upon the surface & two or three days pass before the inflammation subsides. But this takes place only where there is no undue amount of pigment. Where the pigment is, there there is not the slightest redness, there is not the slighest heat, there is not the slightest swelling, and of course there is no vesication. And yet this pigmented skin is but of a pale yellow colour, hardly as dark as the skin of a chinese. The inflammation never crosses the border— the line of demarcation is most sharply defined.

I am afraid you will be tired long before you reach this point in my letter, yet I venture to trouble you with a few remarks upon another passage in one of your works, emboldened by my belief that you are one of the very few authors who really like to receive criticisms upon what they have written.

In your “Expressions of the Emotions”, when speaking of the influence of fear in the case of man, you say (p. 290), “The hairs also on the skin stand erect”. A year ago, I should have allowed this statement to pass unchallenged, but since then I have been accidentally led to devote some attention to the matter & I have been brought to the conclusion that in the case of my own body at least, the minute hairs on my skin (I do not include my scalp), and much more the longer ones, are incapable of erection. Some months ago, I suffered somewhat from pain in the region of the bladder & I sought to relieve it and did relieve it, by sitting in water of about 105o or 106o Fahr. I noticed that this unusually hot water produced a well marked goose skin on my thighs (I was sitting in a hip bath with only the upper part of my thighs in the water) & this extended beyond the limits of the water. After that, I sat, I dare say, 50 or 60 times in water varying from 60o to 113o, in order to make observations with regard to this goose skin. I did not take notes at the time & I cannot therefore give you such an accurate account as I should like, but I found that water at 60o (and very likely a few degrees higher) would constantly produce goose skin & I found that water above 100o & I believe a few degrees below it also) would likewise constantly produce the same effect. The hotter the water, the more marked the goose skin, & no doubt the same would hold good with regard to cold water, but I have not tried this. I have a good deal of hair about my body, more than most men, and I was naturally led to examine whether the hairs on my thighs became erect whilst the goose skin lasted; and, in order that I might not be deceived, I several times made use of a large magnifying glass. On no one occasion, was I able to detect the very smallest movement in a single hair!

I see that Dr. Hassall in his “Microscopic Anatomy” 1. 275 says “Man, to a certain extent, and many animals in a considerable degree, possess the power of erecting the hairs. This power in man is limited to the hairs of the head, in many animals it is much more general”, so that he too seems to have been aware or to have been of opinion that the hairs of the body are in man incapable of erection.5 And yet strangely enough Kòlliker tells us (Handb. d. bewebelehre 3rd. Ed. p. 102) that the little muscles which are attached to the hair sheaths & called “arrectores pili” are twice as thick in some parts of the body (as on the pubes) as on the scalp.6 The hairs of the head ought, therefore, independently of their length, to be still less capable of erection than those of the body & yet you give instances in which such erection has undoubtedly occurred (though apparently only in the case of the insane) & Dr Hassall also states (though without giving his authority) that the hair of the head is capable of erection to a certain extent, though not to such an extent as “to stand on end”.7 I suppose the real truth is that it is only in certain people that the hair of the head is capable of erection & that in even in them this erection takes place only when they are insane. It would be interesting to learn whether in the insane the hairs of the skin ever bristle up also.

At all events, to the causes of goose skin which you enumerate in the same work p. 101,8 may now be added heat*, for I do not suppose that my skin differs in this respect from that of my neighbours.


I must once more apologize for the inordinate length to which I have spun out my letter & indeed I think I ought to apologize for troubling you at all. I have had misgivings as to whether I ought to send this letter and the interval of some days between the date of the first & second half is partly due to this. And if at length I have determined to send you what I have written, it is because I feel that I have almost entirely confined myself to facts* and that therefore my letter will require no answer from you; and because I think that these facts may possibly be made use of by you, whilst I myself can do nothing with them.

Believe me, | my dear Sir, | Yours very truly | F. Chance

C. Darwin Esqr.

* I see that some few of the hairs in the tail have a brownish tinge.

* 7/8/73 I think this is very badly expressed & that I should have done better to say simply—the presence of pigment prevents (or diminishes) the penetration of heat; the absence of pigment prevents (or diminishes) the penetration of cold—or in other words prevents (or diminishes) the abstraction of heat. White radiates heat much less than black & would therefore retain the heat of the body better.

* I should perhaps say hot water, for with regard to a dry heat I have determined nothing.

* No one who reads your works can fail to see that you welcome information from every quarter.

CD annotations

1.1 In your … tail. 1.17] crossed pencil
4.2 and it … letter. 4.7] crossed pencil
7.6 of the back of my] ‘of the back’ cancelled blue crayon
7.11 Now, if … vesication. 7.18] scored red crayon
9.1 In … Emotions”,] scored pencil


The reference in Descent 2: 298–9 n. 36 is to Pallas 1778, p. 7.
Samples of hair from the pony’s body, mane, and tail and a page of notes in CD’s hand are in DAR 142: 59–60. Chance had previously written to CD enclosing samples from his hair and beard to show that his beard was darker than his scalp hair, an exception to the usual pattern as described in Descent 2: 319 (see Correspondence vol. 19, letter from Frank Chance, [before 25 April 1871]). The hair and beard samples are in DAR 142: 59–60.
Descent 2: 298.
CD had dismissed the action of light and temperature in different climates as a major determinant of colour in the races of humans in Descent 1: 241–2.
Chance refers to Arthur Hill Hassall and Hassall 1849, 1: 275.
Chance refers to Rudolf Albert von Kölliker and Kölliker 1859, p. 102.
Hassall 1849, 1: 276.
Expression, p. 101.


Gives some observations on ponies’ becoming white in winter;

on skin pigmentation and the effects of heat;

on the bristling of the hair in man.

Letter details

Letter no.
Frank Chance
Charles Robert Darwin
Sent from
Sydenham Hill
Source of text
DAR 53.1: 2–5
Physical description
7pp †

Please cite as

Darwin Correspondence Project, “Letter no. 8993,” accessed on 14 December 2017,

Also published in The Correspondence of Charles Darwin, vol. 21