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Darwin Correspondence Project

To J. D. Hooker   22 October [1864]1


Oct 22d

My dear Hooker.

You will perhaps like to see second page of enclosed:2 please return it sometime.— Thanks about Harvey, from whom I shall doubtless hear.—3

The Lyells have been here4 & were extremely pleasant, but I saw them only occasionally for 10 minutes & when they went I had an awful day of vomiting; but I am now slowly getting up to my former standard.— I shall soon be confined to a living grave & a fearful evil it is.—

I suppose you have read Tyndall—5 I have now come round again, to Ramsay’s view for third or fourth time; but Lyell says when I read his discussion in the Elements6 I shall recant for fifth time.— What a capital writer Tyndall is!—

In your last note you ask what the Bardsfield oxlip is— it is P. elatior of Jacq. which certainly looks when growing to common eyes different from common oxlip.7 I will fight you to the death, that as Primrose & Cowslip are different in appearance (not to mention odour, habitat & range) & as I can now show that when they cross, the intermediate offspring are sterile like ordinary Hybrids, they must be called as good species as a man & a Gorilla.— I agree that if Scotts Red Cowslip grew wild or spread itself & did not vary into common cowslip (& we have absolutely no proof of primrose or cowslip varying into each other) & as it will not cross with cowslip, it would be a perfectly good species.—8

The power of remaining for a good long period constant, I look at as the essence of a species, combined with an appreciable amount of difference; & no one can say there is not this amount of difference between Primrose & Cowslip.—

Yours affectionately | C. Darwin

Do not go on purpose; but if you walk through Orchid House & see any Stanhopea in flower send me 2 or 3 pollen-masses— I want them for special purpose to cross a plant of mine which will be in flower in 2 or 3 days.—9


The year is confirmed by the relationship between this letter and the letter from J. D. Hooker, 26[–8] October 1864.
CD enclosed the letter from Asa Gray, 3 October 1864 (see letter from J. D. Hooker, 26[–8] October 1864); the second page begins with the words ‘time to write, or think,’ and ends with ‘than carries any other’, and discusses the progress of the American Civil War.
Charles and Mary Elizabeth Lyell stayed at Down from 15 to 17 October 1864 (Emma Darwin’s diary, DAR 242).
CD refers to John Tyndall’s paper entitled ‘On the conformation of the Alps’ (Tyndall 1864c), in which he presented evidence supporting Andrew Crombie Ramsay’s theory of the glacial origin of mountain rock-basins (Ramsay 1862). See also letter from J. D. Hooker, 16 September 1864 and nn. 14 and 15. CD had long been a supporter of Ramsay’s theory (see Correspondence vol. 10, letter to A. C. Ramsay, 5 September [1862], and letter to Charles Lyell, 14 October [1862], and this volume, letter to A. C. Ramsay, 12 July [1864], and letter from J. B. Jukes, 10 August 1864 and n. 2). However, he had also been impressed by Roderick Impey Murchison’s critique of the theory (Murchison 1864b; see letter from R. I. Murchison, 19 August 1864, and letter to J. D. Hooker, [23 August 1864]).
Lyell favoured the view that great rock-basins had been formed by gradual movements of upheaval and subsidence and believed that glaciers lacked sufficient force to carve out deep rock-basins (see C. Lyell 1863a, pp. 309–19). Lyell’s opposition to Ramsay’s glacial-erosion theory (Ramsay 1862) was reiterated in the sixth edition of Lyell’s Elements of geology (C. Lyell 1865, pp. 168–74). There is an annotated copy of C. Lyell 1865 in the Darwin Library–Down (Marginalia 1: 524–5).
CD described the characteristics of Primula elatior, or the Bardfield oxlip, in ‘Specific difference in Primula, p. 449, and Forms of flowers, p. 32.
For CD’s and Hooker’s discussion of whether primroses and cowslips are different species, and of John Scott’s crossing experiments with red and yellow cowslips, see letter to J. D. Hooker, 8 October [1864] and n. 11, and letter from J. D. Hooker, [16? October 1864] and n. 7. See also Forms of flowers, pp. 224–8.
CD had been carrying out experiments on Stanhopea oculata pollination in his hothouse in early September 1864 (see his notes in DAR 70: 115–6, and letter to J. D. Hooker, 3 November [1864] and nn. 23 and 24).


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 26 vols to date. Cambridge: Cambridge University Press. 1985–.

Forms of flowers: The different forms of flowers on plants of the same species. By Charles Darwin. London: John Murray. 1877.

Lyell, Charles. 1865. Elements of geology, or the ancient changes of the earth and its inhabitants as illustrated by geological monuments. 6th edition, revised. London: John Murray.

Marginalia: Charles Darwin’s marginalia. Edited by Mario A. Di Gregorio with the assistance of Nicholas W. Gill. Vol. 1. New York and London: Garland Publishing. 1990.

‘Specific difference in Primula’: On the specific difference between Primula veris, Brit. Fl. (var. officinalis of Linn.), P. vulgaris, Brit. Fl. (var. acaulis, Linn.), and P. elatior, Jacq.; and on the hybrid nature of the common oxlip. With supplementary remarks on naturally produced hybrids in the genus Verbascum. By Charles Darwin. [Read 19 March 1868.] Journal of the Linnean Society (Botany) 10 (1869): 437–54.


To Lyell’s chagrin, CD has come round again to A. C. Ramsay’s glacial theory.

On primrose and cowslip, CD maintains they are good species, notwithstanding Scott’s work.

CD defines species by power of remaining constant for a good long time and showing appreciable amount of difference from close species.

Letter details

Letter no.
Charles Robert Darwin
Joseph Dalton Hooker
Sent from
Source of text
DAR 115: 252
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 4642,” accessed on 18 November 2019,

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