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Darwin Correspondence Project

To Jeffries Wyman   3 February [1861]1

Down Bromley Kent

Feb. 3d.

My dear Sir

I have been extremely much interested by your letter on Rattle-snakes.—2 The subject has always rather fascinated me. By the way can there be any truth in the many accounts of Rattle-snakes fascinating their prey?3 Do they rattle when gazing at their prey & can the poor animals be paralised by fear?— I never could understand from drawing, the rattle, till seeing yours, which makes it quite clear. If not known, is it not a shame that you do not publish your diagram?4 The whole contrivance & structure is much more complex than I expected; & I fear it will be impossible to show amongst other snakes any gradation except the vibrating the tail (I did not know of your Black snake having this habit, & am glad to hear it) & the little knob at the end of tail of Trigonocephalus. Nevertheless I will have a look some day at the tails of the Viperidæ in B. Museum for bare chance of any vestige of the concentric ridges which seem to play an important part in retaining the rattle. I presume each new rattle adheres closely to the “matrix” till the period of moulting.— It certainly is a very curious structure; & odiously wonderful to me if it serve merely to warn prey & so injure its possessor.—5

With respect to Electrical organs, have you seen M’Donnel’s article in the new Nat. Hist. Review? the discovery (if proved) of these organs in head of Skates seems very interesting.—6

Thank you much for telling me your observations on the marks on the face of Vespidæ:7 I will show your sketch & consult our great authority on these insects F. Smith of B. Museum.8 I shall be curious to know whether anything analogous occurs with our wasps. I particularly value such cases of variation & have already got a large series of cases, & very important they seem to me. Those who believe in creation, will have to say this mark in this animal was thus created; in this other animal that very same mark is due to Variation.

With cordial thanks for your most interesting letter. Believe me, my dear Sir | Yours sincerely C. Darwin

CD note:9

In accounting for origin of rattle snake no difficulty if it cd be shewn, rattle of any use and intermediate forms.

*Do they go in pairs?? [interl in CD’s hand] Those that think that an animal admirably provided to find its own sustenance shall purposely have a structure rendering such provision partly futile must yet be startled that other snakes quite as venomous & I believe incomparably more active & again others equally inactive have no rattle. Now [after del ‘Now I have shewn’] from habits of trigonocephalus we may suspect that the vibration of tail & consequent rattle is somehow useful, & in the minute terminal button we have first indication of intermediate form *as I long ago remarked [interl]. Has not rattle snake wide range— A small argument for utility of rattle or more properly that it is not injurious otherwise other venomous genera wd have beaten this out of the field.


Dated by the relationship to the letter from Jeffries Wyman, 8 January 1861.
Wyman subsequently published a short account on this subject (Wyman 1861). See also Dupree 1951.
See Origin, p. 201. See also CD note, above.
M’Donnell 1861. CD mentioned this discovery to Wyman in his letter of 3 December [1860] (Correspondence vol. 8).
The remarks were apparently made in the concluding section of Wyman’s letter of 8 January 1861, which is now missing.
Frederick Smith, a specialist on the Hymenoptera, was employed in the zoological department of the British Museum.
The undated note is in DAR 205.5: 212. It is in Emma Darwin’s hand except for one addition by CD.


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 27 vols to date. Cambridge: Cambridge University Press. 1985–.

Dupree, Anderson Hunter. 1951. Some letters from Charles Darwin to Jeffries Wyman. Isis 42: 104–10. [Vols. 8,9]

M’Donnell, Robert. 1861. On an organ in the skate which appears to be the homologue of the electrical organ of the torpedo. Natural History Review n.s. 1: 57–60. [Vols. 8,9]

Origin: On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. By Charles Darwin. London: John Murray. 1859.

Wyman, Jeffries. 1861. On the mode of formation of the rattle of the rattlesnake. Boston Society of Natural History 8 (1861–2): 121.


Can there be any truth in account of rattlesnakes fascinating their prey? Structure of rattle complex.

Fears it will be impossible to show gradation among other snakes.

Has JW seen Robert McDonnell’s article on electrical organ in skate ["On an organ in the skate", Nat. Hist. Rev. (1861): 57–60]?

Thanks for observations on Vespidae. Particularly values such cases of variation.

Letter details

Letter no.
Charles Robert Darwin
Jeffries Wyman
Sent from
Source of text
Harvard Medical Library in the Francis A. Countway Library of Medicine (Jeffries Wyman papers H MS c12)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 3056,” accessed on 20 October 2021,

Also published in The Correspondence of Charles Darwin, vol. 9