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Darwin Correspondence Project

From Herbert Spencer   11 November 1874

38 Queen’s Gardens | Bayswater W

11 Nov. 74

Dear Darwin

Unless I am mistaken you have somewhere given the story of a dog which, on a breezy day, growled when he saw an opened umbrella moved by the wind. I want to make use of the instance, but cannot find it. Can you tell me where it is?1

I yesterday referred to your work on the Cirrhipedia for the purpose of seeing whether you said anything about their sensitiveness to passing shadows. I find that you have noted it in respect of individuals in the water with their cirrhi expanded.2 You do not say, however, that it is noticeable with those which are left exposed by the retreating tide, and which, having their valves but loosely closed, close them tightly when a shadow is cast on them. Have you ever observed this?3

Sincerely yours | Herbert Spencer


CD gave this story in Descent 1: 67, as an instance of the assumption by dogs and early humans that movement must be produced by a living agent. Spencer used it in his discussion of ideas of the animate and the inanimate in his Principles of sociology (Spencer 1876–96, 1: 140–1).
In Living Cirripedia (1851), pp. 51 and 242, and Living Cirripedia (1854), p. 94, CD gave instances of cirripedes responding to shadows.
Spencer mentioned this phenomenon as evidence of a general response, even in unintelligent creatures like cirripedes, to an ‘indication of adjacent life’ in Spencer 1876–96, 1: 138–9.


Wishes to know where, in his works, CD refers to some particular behaviour in dogs.

Mentions the sensitivity of cirripedes to passing shadows.

Letter details

Letter no.
Herbert Spencer
Charles Robert Darwin
Sent from
Source of text
DAR 177: 233
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 9716,” accessed on 27 June 2019,

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