Dear Sir

I do not know how to thank you enough for your MS. observations on expression.¹ They contain exactly and fully the information which I wanted; and besides being of the greatest use to me, are most interesting and so graphic as to be almost painful.

You kindly say that you are willing to give me further information. I may premise that my object is to make out to a limited extent the causes of the movement of certain muscles under various emotions in man and the lower animals. Your answers are distinct and amply sufficient about the hair “standing on end”; and before receiving them, I felt doubtful whether this expression was not a mere poetic licence. With mammals of all orders, the hair (and in birds the feathers) are erected both under fear and anger; and I think especially when these emotions are combined. Now from your account it seems that with man the hair is erected under both terror and rage;² but I understand from one of your remarks, and from what you say about the hair under acute melancholia and hypochondria that the erection often occurs without any emotion either of terror or rage being felt; Is this the case? As any habitual expression seems ultimately to affect the features, is it conceivable that frequent paroxysms of terror and rage might give a tendency to the hair to stand on end without at the time any such emotion being excited? I suppose however that this notion is too improbable.

Your remark on the sterno-cl.-mast.-muscle³ leads me to ask for information on one point, about which I have long been extremely curious. Duchenne (whose great work on expression perhaps you know) gives photographs of persons with the platysma myoides contracted by galvanism, which wrinkles the skin of the neck transversely, and draws a very little downwards the cheeks near the corners of the mouth.⁴ These photographs when tested by showing them to many persons without any explanation and asking what they meant, seem well to exhibit extreme fear; but whether the contraction of the platysma plays so important a part as Duchenne thinks, I wish to ascertain.⁵ Would you kindly observe patients suffering under extreme fear, with widely distended eyes, open mouth and erect hair, whether you can observe the contraction of this muscle? Gratiolet says it contracts under severe dyspnœa: a good observer denies this: another surgeon says he has seen it contracted during violent screaming by a patient who was quite insensible from an injury on the head.⁶

Altogether this muscle has quite perplexed me. If it does contract under terror, one might suspect that it partook of the contraction of the homologous scalp muscles.⁷ Your description of the grinning and exposure of the canine teeth under furious rage is excellent.⁸ I presume that you would not object to my quoting, if I require it, some of your words, as well as giving your general results. I fear that you will think me quite unreasonable, but I should very much like to hear whether the “grief muscles” (see query 5) act frequently and in a prolonged manner with patients who are suffering from extreme depression and anxiety.⁹ I should expect that it would be oftenest observed in women. I enclose a poor photograph of a girl who could voluntarily (and this is not common) contract these muscles; but as I have no other copy, having sent the remainder to distant countries I must beg you to return it some time hence.¹⁰ I have noticed the “grief muscles” in action with girls who were pretending to be in distress and by girls who could not voluntarily bring them into action.

I must not write any more, or I shall weary you; but I will add that I should be grateful for any hints from so excellent an observer on any points, such as Query 10 or 9 or 2.¹¹ Mr. Paget has been observing for me with respect to blushing, but has never seen a blush extend lower down than the clavicles, except a few irregular blotches.¹² I am however assured that some savages who go nearly naked blush over a much more extended surface.¹³ I am led to suppose that you must long have felt some interest in Expression; and this leads me to ask whether you have seen Duchenne’s great work in folio with numerous photographs.¹⁴ If you would like to see it I would send it by rail, and you could keep it for a couple of months; but the plates are hardly intelligible without reading the text, and this perhaps would be hardly worth your while, even if you had spare time. With the most cordial thanks for your great kindness, and apologies for the length of this letter

I remain dear Sir | Yours very faithfully | Charles Darwin

P.S. In about a month’s time a new Edit. of my Origin of Species will appear and for the chance of your liking to have a copy I will direct the publisher to send one¹⁵