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Darwin Correspondence Project

To Erasmus Wilson   29 March [1871]1

Dear Sir

The kindness with which you received my former note makes me think that you will excuse me troubling again.—2 But the chances are a 100 to 1 that you cannot aid me.— I am anxious to learn whether the mind by being long & intently directed on any portion of the skin, acts on the capillary circulation, so as to cause their dilatation of the [illeg].— It occured to me as just possible, though improbably, that it might be known to you, that by thinking much about any cutaneous disorder (not on the face, for annoyance & shame with blushing might here possibly come in) that irritation was incurred, & the surface temporarily reddened.— In case you can throw no light on the point, I beg you not to think of acknowledging this note, but if you can aid me, I shd be most grateful for any information.—3

Pray excuse & believe me | with sincere respect | Dear Sir | Yours faithfully

I suppose that you have not noticed the violent contraction of the orbicular causing an effluence of tears when a person violently scratches an intolerably itchy place

March 29th.


The year is established by the relationship between this letter and the letter from Erasmus Wilson, 3 February 1871.
In Expression, pp. 339–40, CD discussed the effect of directing attention to a particular part of the body, but did not refer to Wilson.


Wonders whether correspondent might possibly know of any cases in which intense concentration of the mind on one portion of the skin produces dilation of the capillary vessels and hence reddening of the area.

Letter details

Letter no.
Charles Robert Darwin
William James Erasmus (Erasmus) Wilson
Sent from
Source of text
DAR 96: 99
Physical description
Adraft 2pp

Please cite as

Darwin Correspondence Project, “Letter no. 7639,” accessed on 19 February 2019,

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