Ɛpsilon

To J. W. Clark   9 February 1875

Down, | Beckenham, Kent.

Feb 9 75

Dear Sir

I am very much obliged to you for so kindly sending me the information on the action of fear in the iris.,—a subject about which I formerly felt great doubts1

Dear Sir | Yrs faithfully | Ch. Darwin

LS

1
In Expression, pp. 303–4, CD discussed claims that fear caused the pupils to dilate, but admitted he did not have much evidence of the phenomenon. A note was added to Expression 2d ed., p. 321 n. 37, referring to information received from T. W. Clark of Southampton in letters of 25 June and 16 September 1875 on the dilation of dogs’ and cats’ pupils due to fear. The writer was, in fact, Joseph Warner Clark; see letters from J. W. Clark, 25 June [1875] and 16 September 1875.

Please cite as “DCP-LETT-9847,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-9847