From Charles Lyell   [22 November 1859]1

201 Rattle of snake

The reader is here tantalized to enquire what can be your explanation of the rattle2

It would relieve him if you have no guess could you say so—

Qy. Why do moths & certain gnats fly into candles & why are they not all on their way to the moon, at least when the moon is in the horizon—

I formerly observed that they fly very much less at candles on a moon-light night. Let a cloud pass over & they are again attracted to the candle—

211. l. 7 from bottom

The passing over imperfect instincts tantalizing—

qy flies mistaking the odour of the (Drossera?) for carrion & getting caught— one or two sentences might do—an example wanted because the ignorance so great & the optimists sure to be up in arms—

Afterwards at p. 218 the ostrich is given—but an earlier example would interest.

CD annotations

1.1 201 Rattle … so— 3.1] crossed pencil
4.1 Qy.] ‘Mistaken Instinct’ added pencil
4.1 Qy… . moon-light night. 5.1] triple scored pencil; ‘Ch X’3 added brown crayon
6.1 211… . interest. 9.2] crossed pencil
1
The correspondent and the date are given by CD’s reference in his letter to Charles Lyell, 24 [November 1859], to ‘a letter dated 22d.’.
2
The sentence to which Lyell refers (Origin, p. 201) reads: It is admitted that the rattlesnake has a poison-fang for its own defence and for the destruction of its prey; but some authors suppose that at the same time this snake is furnished with a rattle for its own injury, namely, to warn its prey to escape.
3
CD’s annotation refers to chapter 10 of Natural selection, on the mental powers and instincts of animals. The topics cited by Lyell were drawn from the corresponding chapter on instinct in Origin (chapter 7).

Please cite as “DCP-LETT-2551,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-2551