To J. D. Hooker   31 May [1866]¹

The year is established by the relationship between this letter and the letter from J. D. Hooker, 29 May 1866.

CD went to Leith Hill Place in Surrey, the home of his sister Caroline and his brother-in-law Josiah Wedgwood III, on 29 May; he returned to Down on Saturday 2 June 1866 (Emma Darwin’s diary (DAR 242)).

William Robert Grove had asked Hooker for recent evidence supporting CD’s theory for use in preparing his presidential address for the British Association for the Advancement of Science. See letter from J. D. Hooker, 29 May 1866 and nn. 3 and 4.

In 1864, John William Dawson identified samples taken from pre-Silurian strata in eastern Canada as fossilised Foraminifera, single-celled protists with shells; he named the species Eozoon canadense, the ‘Dawn animal from Canada’ (Dawson 1864). Further samples were sent to William Benjamin Carpenter, an expert on Foraminifera, who confirmed Dawson’s interpretation (Carpenter 1864). CD added information on the discovery of Eozoon canadense to Origin 4th ed., p. 371, as substantiating his claim, made in Origin, p. 307, that life existed before the Silurian period. The interpretation of the samples as pre-Silurian fossils remained controversial, however (see, for example, Carpenter 1866, and King and Rowney 1866); and by the end of the century, comparisons with similar, more recent, formations indicated that the samples were mineral in origin (see Schopf 2000).

Archaeopteryx, a Jurassic fossil bird with reptilian features, was discovered in Bavaria in 1861 and described by Richard Owen (Owen 1862). For CD’s interest in the discovery, see Correspondence vol. 11, letters to Hugh Falconer, 5 [and 6] January [1863] and 20 [January 1863]. In Origin 4th ed., p. 367, CD noted the discovery of Archaeopteryx as evidence against the view that the whole class of birds had suddenly come into existence during the Eocene period.

F. Müller 1864c, a study of the Crustacea, was supportive of CD’s theory of transmutation. For CD’s enthusiasm about the book, see Correspondence vol. 13.

In his letter of 25 May [1866], John Murray had informed CD that the printing of the fourth edition of Origin was nearly completed. Grove’s address included discussions of Eozoon canadense and Fritz Müller’s work (W. R. Grove 1866, p. lxxiv); it did not mention Archaeopteryx, or CD’s work on orchids or Primula. See also letter from J. D. Hooker, 29 May 1866, n. 9.

CD met Grove in London on 29 April (see letter to W. R. Grove, [26 April 1866] and n. 3).

CD refers to Henry Walter Bates and Bates 1860, which discussed the variability of different species of butterflies, Bates 1861, and J. D. Hooker 1860a. See letter from J. D. Hooker, 29 May 1866, nn. 7 and 8.

CD refers to Variation. CD referred to J. D. Hooker 1860a in Variation 2: 256.

A review in the London Review of Politics, Society, Literature, Art, and Science, 28 April 1866, pp. 482–3, of the first two volumes of Richard Owen’s On the anatomy of vertebrates (Owen 1866–8) claimed that even though Owen repudiated Darwinian views, he made ‘a significant though partial admission …  of the truth of the principles of Natural Selection’; the reviewer quoted what he found to be the relevant passage in Owen’s book. In a letter to the editor of the London Review, 5 May 1866, p. 516, Owen confirmed the ‘essential identity of the passage cited with the basis of that [Darwinian] theory, the power, viz., of species to accommodate themselves, or bow to the influences of surrounding circumstances’; he added that the cited statement in his recent book was almost identical to that expressed in his 1850 paper on the Dinornis (Owen 1850), and that if he was thought to have followed the view of Darwin’s Origin, the fact that he had published this work in 1850 actually placed CD in the position of ‘adoptor’. Following Owen’s letter, the editor wrote: ‘So far as we can gather … [Owen] denies the Darwinian doctrine, admits the accuracy of its basis, and claims to be the first to point out the truth of the principle on which it is founded.’ CD revised his discussion of Owen’s work in the historical sketch in the fourth edition of Origin, including the following passage (p. xviii): Professor Owen now believes that he promulgated the theory of natural selection in a passage read before the Zoological Society in February, 1850. … This belief in Professor Owen that he then gave to the world the theory of natural selection will surprise all those who are acquainted with the several passages in his works, reviews, and lectures, published since the ‘Origin,’ in which he strenuously opposes the theory; and it will please all those who are interested on this side of the question, as it may be presumed that his opposition will now cease. It should, however, be stated that the passage above referred to in the ‘Zoological Transactions,’ as I find on consulting it, applies exclusively to the extermination and preservation of animals, and in no way to their gradual modification, origination, or natural selection. CD considerably modified this passage in the fifth edition (see Peckham ed. 1959, p. 66). See also Rupke 1994, pp. 246–7.

In an unsigned review of Origin, Asa Gray had stated that Owen might have been harbouring ‘some transmutation theory of his own conceiving’, which might yet see the light ([A. Gray] 1860, p. 115). See also Correspondence vol. 11, letters from Asa Gray, 26 May 1863 and 21 July 1863. For a discussion of Owen’s views on evolution, see Rupke 1994, pp. 220–58.

Robert Caspary had visited CD at Down on 27 May 1866 (Emma Darwin’s diary (DAR 242)).