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Darwin Correspondence Project

To Michael Foster   16 April 1871

Down. | Beckenham | Kent. S.E.

Ap. 16. 1871

Dear Sir

I hope that you will forgive the liberty which I take in asking the favour of some information on a subject, to which I know from having read your admirable lecture before the R. Institution, (as translated in the Revue des Cours) that you have closely attended.—1

I enclose two questions, neither of which you may be able to answer, especially the second one; but it will be of great use to me to know that they cannot be answered under our present state of knowledge, or to hear what you think most probable. You will perceive by my manner of framing my 2nd query, how ignorant I am on the subject—2

Hoping that you will grant me this favour I remain | dear Sir | with much respect | yours faithfully | Charles Darwin



When a man stands before a fire & his face redden,— does the heat act directly on the nerves or muscles of the capillaries— or do centripetal nerves transmit some effect from the heat on the surface, to the vaso-motor ganglia, & these by reflex action cause the capillaries to dilate?— If this latter contingency be the true one, & the sympathetic nerves of the face were cut before they entered any ganglia, the face would not redden before the fire, or conversely grow pale from cold.—

Secondly: if we think of any part of our body, we become conscious of its existence; & if we think intentely on it odd sensations (Sir H. Holland) are then felt this then may be muscular;4 but its path appear that some direct effect is often & thus locally produced, as in the case of glands & the uterus in the sharpening of the senses &c.— In other cases, where glands are not concerned Can it be supposed in that effect as produced by closer attention to that part extending through the vaso-motor ganglia, modifying the capillary circulation of the spot? In the case of glands I infer from I from Pagets writing that nerve power probably acts directly on the scaly cells, as well as on the capillary circulation.—5 Now, & this is my special query when I think intently on for [instance] the top of my little finger, & become conscious of its existence physiologists believe that some power is sent along the nerves to their point; & if so pray what sort of nerves? It seems at first a rash view that my attention being directed to my little finger may stimulate some part of my sensorium & make it pass sensations along away from little finger but at other times unnoticed; but such a view does not seem compatible with [2 words illeg] effects being produced by the mind’s attention on other parts & organs


In Expression, p. 344, CD referred to a lecture Foster gave before the Royal Institution of Great Britain on involuntary movements in animals, with particular reference to the heart, in February 1869 (Athenæum, 9 January 1869, p. 38). It was translated in the Revue des cours scientifiques (Foster 1869).
Foster replied in his letter of 4 June [1871].
The text of the enclosure has been transcribed from a draft of the enclosure sent to Foster.
CD refers to Henry Holland and Holland 1858; see also letter to William Turner, 28 March [1871] and n. 13.
The two sentences running from ‘In other cases’ to ‘circulation.—’ are written on a separate page (DAR 195.1: 13), with numbers indicating the appropriate point of insertion for the text. James Paget discussed the influence of the mind on the nutrition of particular parts of the body in J. Paget 1853, 1: 39. CD quoted this in Expression, pp. 339–40. Scaly cells are squamous cells, the outermost layer of some organs or parts of the body.


Athenæum. 1844. A few words by way of comment on Miss Martineau’s statement. No. 896 (28 December): 1198–9.

Expression: The expression of the emotions in man and animals. By Charles Darwin. London: John Murray. 1872.

Foster, Michael. 1869. Mouvements involuntaires chez les animaux. Revue des Cours scientifiques de la France et de l’étranger 6 (1869): 677–85 and 712–20.

Holland, Henry. 1858. Chapters on mental physiology. 2d edition. London: Longman, Brown, Green, Longmans, & Roberts.

Paget, James. 1853. Lectures on surgical pathology delivered at the Royal College of Surgeons of England. 2 vols. London: Longman, Brown, Green, and Longmans.


Encloses two questions he hopes MF can answer: the mechanism of transmission by nerves; and the mechanism by which contemplating part of our body, we become conscious of its existence

Letter details

Letter no.
Charles Robert Darwin
Michael Foster
Source of text
Natural History Museum, Library and Archives (General Special Collections DC AL 1/16); DAR 195.1: 11–13
Physical description
3pp & 6pp

Please cite as

Darwin Correspondence Project, “Letter no. 7689G,” accessed on 1 December 2021,

Also published in The Correspondence of Charles Darwin, vol. 19