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Darwin Correspondence Project

From Frederick Smith   10 November 1857

British Museum.

10 Novr. 1857

My dear Sir

Some time ago you asked me to furnish you with remarkable instances of desparity in form etc—in workers of Insects living in community—1 As one is apt to forget these things at the moment they are asked for I send you one that is a truly remarkable instance— In my Monograph on the Genus Cryptocerus I figured & described a species as C. discocephalus—2 some time subsequent I received a letter from Mr. H. W. Bates from Brazil—3 he said—“I have met with your curious species C. discocephalus— the creature figured is only the large size of the worker of the species— I send you both the workers taken from several nests constructed in dead branches of shrubs—”

☿ major ☿ minor Cryptocerus discocephalus

I send you tracings of the creatures in relative proportion— dont trouble to reply to this but tell me what you think of it when you are next time at the Museum4 and believe me

Yours very truly | Fredk Smith Chas. Darwin Esqre

CD annotations

Top of letter: ‘Ch. 8’5 brown crayon


Smith, an assistant in the zoological department of the British Museum, was an authority on social insects. In a discussion of the origin of neuter insects in his species book, CD stated in a note: ‘I am greatly indebted to Mr. F. Smith of the British Museum, one of the highest authorities on Hymenoptera, for much valuable information on all points in the following discussion.’ (Natural selection, p. 364 n.1).
Henry Walter Bates had accompanied Alfred Russel Wallace to the Amazon in 1849 and remained in Brazil to continue his researches and the collection of specimens (DNB).
This letter was attached by CD to a page in the manuscript of his species book relating to neuter insects, part of chapter 8 on ‘Difficulties on the theory of natural selection’ (see Natural selection, pp. 368 and 574). In this chapter, CD attempted to explain how natural selection could bring about changes in the structure of neuter (or worker) forms of ants and bees, which cannot propagate their kind. Certain ants, like those of the genus Cryptocerus, which, as Smith’s letter indicates, have two kinds of workers, were to CD ‘the acme of difficulty on our principle of natural selection’ (Natural selection, p. 371). For CD’s explanation of the possible advantages accruing to parent-ants if they produce some sterile offspring, see Natural selection, pp. 370–4.
CD refers to chapter 8 of his species book (see n. 4, above).


DNB: Dictionary of national biography. Edited by Leslie Stephen and Sidney Lee. 63 vols. and 2 supplements (6 vols.). London: Smith, Elder & Co. 1885–1912. Dictionary of national biography 1912–90. Edited by H. W. C. Davis et al. 9 vols. London: Oxford University Press. 1927–96.

Natural selection: Charles Darwin’s Natural selection: being the second part of his big species book written from 1856 to 1858. Edited by R. C. Stauffer. Cambridge: Cambridge University Press. 1975.

Smith, Frederick. 1854. Essay on the genera and species of British Formicidæ. [Read 4 December 1854.] Transactions of the Entomological Society of London n.s. 3 (1854–6): 95–135.


Sends drawings of two forms of workers of Cryptocerus discocephalus in response to CD’s request for examples of insects whose workers show disparity of form.

Letter details

Letter no.
Frederick Smith
Charles Robert Darwin
Sent from
British Museum
Source of text
DAR 11.2: 65a
Physical description
4pp † sketch

Please cite as

Darwin Correspondence Project, “Letter no. 2167,” accessed on 24 September 2021,

Also published in The Correspondence of Charles Darwin, vol. 6