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Darwin Correspondence Project

From E. B. Baxter   8 July 1874

King’s College | London

July 8/74

Dear Sir

On p.41 of your work on The Expression of the Emotions, you state that “the iris is not known to ⁠⟨⁠be⁠⟩⁠ under the conscious control of the will in any animal.”

The following sentence which I came across the other day in Virchow’s Gedächtnissrede über Johannes Müller, seems to be of some interest in this connexion.1 It is the only instance of the kind I have ever seen alluded to and,—unless it be an example of carefully veiled irony—it should be a trustworthy one, since its subject was ⁠⟨⁠an⁠⟩⁠ eminent physiologist, personally ⁠⟨⁠fa⁠⟩⁠miliar to Professor Virchow.

“Denn mann weiss es ja, dass Müller es gelernt hatte, fast jeden einzelnen Muskel seiner Willkür zugänglich zu machen,—dass er die Iris, die Ohren, selbst die Gehörknöchelchen willkürlich bewegte.” (Gedächtnissrede, p: 45).2

I remain | Your obedient Servant | E B Baxter.


Baxter refers to Rudolf Carl Virchow and Virchow’s eulogy of Johannes Peter Müller delivered at the University of Berlin (Virchow 1858; an English translation appeared in the Edinburgh Medical Journal 4 (1858–9): 452–63, 527–44).
The German quotation is from a footnote that described Müller’s physical appearance. The passage reads: ‘It is very well known that Müller had learnt to make almost every single muscle subject to his control,—that he could voluntarily move his iris, his ears, even his auditory ossicle.’ Since the auditory ossicles are tiny bones in the middle ear that are not externally visible, it is likely that the comment was at least somewhat ironic.


Sends quotation from R. C. Virchow which contravenes CD’s statement in Expression that there is no voluntary control of the iris.

Letter details

Letter no.
Evan Buchanan Baxter
Charles Robert Darwin
Sent from
King’s College, London
Source of text
DAR 160: 96
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 9538,” accessed on 16 October 2021,

Also published in The Correspondence of Charles Darwin, vol. 22