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Darwin Correspondence Project

From J. W. Clark   16 September 1875

18 High Street | Southampton

Sept 16. 1875.

Dear Sir,

As promised by my letter of yesterday I forward a few instances briefly described—respecting the dilation of the pupils of animal’s eyes when suffering from fear.1 The appearance is that of Gratiolet quoted in the “Expression of the Emotions”—as if “gazing into profound darkness”—but with associated actions & appearances it also conveys to my mind most distinctly the impression of fear or dread.2

Should I be able to get any more opinions or observations I shall make note of them & should you desire it shall be happy to forward them to you at any time.

Believe me I remain dear Sir, yours very truly, | J W Clark

P.S. Any further inquiries or suggestions you have to make respecting my experiments on the Drosera I shall esteem an honour.3


Clark’s letter to CD of 15 September 1875 has not been found, but see the letter from J. W. Clark, 25 June 1875.
The quotation from Louis Pierre Gratiolet’s De la physionomie et les mouvements d’expression (Gratiolet [1865]) is in Expression, p. 304. The observations sent with this letter have not been found, but a note added in the second edition of Expression, which was published after CD’s death, suggests that they may have concerned a cat (Expression 2d ed., p. 321 n. 37).
Clark published on Drosera (sundew) in September 1875 (J. W. Clark 1875). CD had published Insectivorous plants, the first part of which was devoted to Drosera, in July 1875 (CD’s ‘Journal’ (Appendix II)).


Clark, Joseph Warner. 1875. On the absorption of nutrient material by the leaves of some insectivorous plants. Journal of Botany, British and Foreign n.s. 4: 268–74.

Expression 2d ed.: The expression of the emotions in man and animals. By Charles Darwin. 2d edition. Edited by Francis Darwin. London: John Murray. 1890.

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

Gratiolet, Pierre. [1865.] De la physionomie et des mouvements d’expression. Paris: J. Hetzel.

Insectivorous plants. By Charles Darwin. London: John Murray. 1875.


Examples of pupillary dilation.

Letter details

Letter no.
Joseph Warner Clark
Charles Robert Darwin
Sent from
Source of text
DAR 161: 155
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 10158,” accessed on 21 October 2021,

Also published in The Correspondence of Charles Darwin, vol. 23