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Darwin Correspondence Project

From J. D. Hooker   [16? October 1864]1



Dr. Darwin

Harvey will answer you categorically from Dublin whither he goes on Thursday.2

I thought Huxley’s article splendid:3—the best in the number   Thomson wrote the article on Agardh,4 it is well done, but too favorable; Agardhs book is very curious, but full of paradox & mistakings of analogy for affinity,5 & so horridly jumbled that it is impossible to make any use of it, if use it has. The article fails to show that the book contains any really valuable novel matter.

I am not up in Oxlips, what is the true O. & what the Badsfield?.—6 What is the use of your making the Cowslip & Primrose good species by results of crossing, if Scott finds that red & yellow var: of Cowslip won’t breed!.7 We fall back on the idea of difference of species being only practicably defineable by morphological difference;—but then morphological species are d— —d uninteresting things compared with Physiological species!8

Ever yr affec | J D Hooker.

CD annotations9

Top of letter: ‘Lyell | Asa Gray | (Tyndall)’ pencil . Paragraph 3, line 2: ‘Badsfield’ sic, but in N4404, replying to this letter, CD seems to write . Bardsfield, CB Both are wrong. Bardfield is correct. FHB. (Noted for indexer.) . Who wrotte ‘Sept’ at top? ASB . Original, 3.2.95, ASB


The date is conjectured from the relationship between this letter and the letters to J. D. Hooker, 8 October [1864] and 22 October [1864]; in 1864, 9 and 16 October were the intervening Sundays. Given the date of CD’s reply to this letter, it is probable that the sixteenth was the day this letter was written.
The reference is to William Henry Harvey, from whom CD had been seeking information on climbing plants from South Africa. Harvey was returning to Dublin following a visit to Hooker at Kew (see letter from J. D. Hooker, [28 September 1864] and n. 7).
See letter to J. D. Hooker, 8 October [1864] and n. 4. Hooker refers to Thomas Henry Huxley’s article in the October 1864 issue of the Natural History Review ([T. H. Huxley] 1864a). See also letter to T. H. Huxley, 3 October [1864], and letter from T. H. Huxley, 5 October 1864.
See letter to J. D. Hooker, 8 October [1864] and n. 6. Hooker refers to Thomas Thomson’s anonymous review of Agardh 1858 ([Thomson] 1864).
The terms analogy and affinity were applied in a number of different ways by taxonomists at this time (see Macmillan dictionary of the history of science). For a discussion of early-nineteenth-century classification see Correspondence vol. 4, Appendix II, and McOuat 1996. CD discussed the importance of ‘real affinities and analogical or adaptive resemblances’ in classification in Origin, pp. 427–34. For a discussion of Jacob Georg Agardh’s taxonomic system, see DSB.
CD had informed Hooker that his crossing experiments indicated that the cowslip and the primrose were different species (see letter to J. D. Hooker, 8 October [1864] and n. 11). CD had drawn Hooker’s attention to Scott’s experiments with cowslips in his letter to Hooker of 13 September [1864] (see also letter to Asa Gray, 13 September [1864] and n. 13, and Scott 1864a, pp. 106–8). For CD’s reply, see letter to J. D. Hooker, 22 October [1864] and n. 8.
The term ‘physiological species’ had been coined by Huxley to refer to a definition of species based on reproductive barriers between life-forms (T. H. Huxley 1863b, pp. 106–8). See also letter to Asa Gray, 13 September [1864] and n. 13.
CD’s annotations are notes for his letter to J. D. Hooker, 22 October [1864].


Agardh, Jacob Georg. 1858. Theoria systematis plantarum; accedit familiarum phanerogamarum in series naturales dispositio, secundum structuræ normas et evolutionis gradus instituta. Lund, Sweden: C. W. K. Gleerup.

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

Macmillan dictionary of the history of science. Edited by W. F. Bynum et al. London and Basingstoke, Hampshire: Macmillan Press. 1981.

McOuat, Gordon R. 1996. Species, rules and meaning: the politics of language and the ends of definitions in nineteenth century natural history. Studies in the History and Philosophy of Science 27: 473–519.

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.

[Thomson, Thomas]. 1864. Agardh’s classification of plants. [Review of Theoria systematis plantarum, by J. G. Agardh.] Natural History Review n.s. 4: 536–51.


Morphological differences only partly define species; physiological differences, e.g., incompatibility results in Primula, are far more interesting.

T. Thomson’s review of Agardh’s muddled book ["Agardh’s classification of plants", Nat. Hist. Rev. (1864): 536–51].

Letter details

Letter no.
Joseph Dalton Hooker
Charles Robert Darwin
Sent from
Source of text
DAR 101: 246, 246a
Physical description
3pp †

Please cite as

Darwin Correspondence Project, “Letter no. 4638,” accessed on 22 February 2020,

Also published in The Correspondence of Charles Darwin, vol. 12