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Darwin Correspondence Project

To J. D. Hooker   12 [December 1862]

Down Bromley Kent


My good old friend,

How kind you have been to give me so much of your time! Your letter is of real use & has been & shall be well considered.1 I am much pleased to find that we do not differ as much as I feared. I begin my book with saying that my chief object is to show inordinate scale of variation;2 & I have especially studied all sorts of little variations of the individual. On crossing I cannot change; the more I think, the more reason I have to believe that my conclusion would be agreed to by all practised breeders.3 I, also, greatly doubt about variability & domestication being at all necessarily correlative; but I have touched on this in Origin.—4 Plants being identical under very different conditions has always seemed to me a very heavy argument against what I call direct action.

I think perhaps I will take case of 1000 pigeons as means to sum up my volume.5 I will not discuss other points; but as I have said I shall recur to your letter. But I must just say that if sterility be allowed to come into play—if long-beaked be in least degree sterile with short beak, my whole case is altered.6 By the way my notions on hybridity are becoming considerably altered by my dimorphic work: I am now strongly inclined to believe that sterility is at first a selected quality to keep incipient species distinct.7 If you have looked at Lythrum, you will see how pollen can be modified merely to favour crossing; with equal readiness it could be modified to prevent crossing.—8 It is this which makes me so much interested with dimorphism &c.— One word more: when you pitched me head over heels by your new way of looking at the back side of Variation,9 I received assurance & strength by considering monsters,—due to law, but so horribly strange as they are. I looked at some Plates;10 the monsters were alive till at least when born. They differ at least as much from parent as any one mammal from another.—

I have just finished a long weary chapter on simple facts of variation of cultivated Plants; & am now refreshing myself with paper on Linum for Linn. Soc.y.—11

I paid Bonafous & other Books to London, but could not pay to Kew.—12

I have just ordered one of the Glass cases, which are warmed by dish of hot-water twice a day, & I hope I shall then be able to keep Oxalis sensitiva.13 I see a book mentioned which I have ordered   Cohn on contractile tissue in plants;14 I suspect he has been at work like, but far fuller, mine on Drosera.15 I am reading Dutrochet’s work, which seems extremely clever, but, I know not why, does not convince me about the swelling of cells by endosmose of fluid & of oxygen.!16

If you know, do please tell me who is John Scott of Bot. Garden of Edinburgh; I have been corresponding largely with him: he is no common man.—17 I enclose one other request to be added to awful number, which you already have.—18 I shall be anxious to know whether I can have a Begonia frigida with the strange flowers to cross.19

You once told me that I shd. be executed for Origin in Edinburgh;20 but I received the other day Diploma of Medical Soc. with signatures of 37 Edinburgh big-wig medicals; so I must be rather up with at least heretical Doctors.21

I hardly know whether the enclosed letter of Gray’s is worth sending, for as it is not answered, I must have it back. & for References.— —22

My dear Hooker | Yours ever most truly | C. Darwin.


Hooker’s letter, presumably a reply to the letter to J. D. Hooker, [after 26] November [1862], has not been found.
According to his ‘Journal’ (Correspondence vol. 8, Appendix II), CD wrote a draft of the introduction to Variation in the spring of 1860. In the published version he began by stating his intention to provide, ‘under the head of each species’, those facts that he had been able to collect or observe ‘showing the amount and nature of the changes which animals and plants have undergone whilst under man’s dominion, or which bear on the general principles of variation’ (Variation 1: 1).
CD discussed variation under domestication in the first chapter of Origin (pp. 7–43). He began by observing (p. 7) that individuals of the same variety or sub-variety of older cultivated plants and animals ‘generally differ much more from each other than do the individuals of any one species or variety in a state of nature’, suggesting that this greater variability was ‘simply due to our domestic productions having been raised under conditions of life not so uniform as, and somewhat different from, those to which the parent-species have been exposed under nature.’ In particular, he gave some countenance to the view, suggested by Thomas Andrew Knight, that ‘this variability may be partly connected with excess of food.’
CD made a note to this effect on 18 December 1862; the note is preserved in DAR 205.7: 163 (see Correspondence vol. 10, Appendix VI).
See Correspondence vol. 10, Appendix VI.
In his letter to J. D. Hooker, 24 [November 1862], CD sent a diagram illustrating what he believed to be the sexual relations between the three forms of flower in Lythrum salicaria.
Possibly a reference to the plates in Geoffroy Saint-Hilaire 1832–7, an extensively annotated copy of which is in the Darwin Library–CUL (see Marginalia 1: 306–16).
According to his ‘Journal’ (Correspondence vol. 10, Appendix II), CD wrote a draft chapter on ‘Facts of variation of Plants’, which became chapters 9 and 10 of Variation, between 7 October and 11 December 1862. The journal also records that he wrote his paper, ‘Two forms in species of Linum, between 11 and 21 December.
The reference is to copies of Bonafous 1836 and volumes 6 and 7 of the London Journal of Botany that had been sent to CD from the Royal Botanic Gardens, Kew, possibly also with volume 1 of the Technologist (see letter from J. D. Hooker, [15 and] 20 November [1862], and letter from Daniel Oliver, 25 November 1862).
See letter to Pickard & Stoneman, 1 December [1862]. CD required the plant case so that he could work with temperature-sensitive plants like Oxalis sensitiva (a synonym of Biophytum sensitivum; see letter from J. D. Hooker, 26 November 1862, and letter to J. D. Hooker, [after 26] November [1862]).
CD had begun his experiments with the insectivorous plant Drosera rotundifolia in 1860 (see Correspondence vol. 8). He had hoped to continue and complete the experiments in the summer of 1861, but subsequently decided to postpone them (see Correspondence vol. 9, letter to J. D. Hooker, 4 February [1861], and letter to Daniel Oliver, 11 September [1861]). After experimenting further with the plant in September 1862, CD had come to the conclusion that it must have ‘diffused matter, in organic connection, closely analogous to the nervous matter of animals’, in which view Cohn had preceded him (see letter to J. D. Hooker, 26 September [1862], and letter to T. H. Huxley, 7 December [1862]).
CD refers to Dutrochet 1837. According to his library catalogue (DAR 240), CD owned a copy of this work; however, only the atlas of plates is in the Darwin Library–CUL. See also Correspondence vol. 4, Correspondence vol. 10, Appendix IV, *119: 2v. In Dutrochet 1837, 1: 534–73, Réné Joachim Henri Dutrochet discussed the mechanism by which he believed sensitive plants to move. He explained the movements in mechanical terms, distinguishing two antagonistic causes for the depression and elevation of petioles. He claimed that the former was caused by the flexing of fibrous tissues owing to oxygenation, while the latter was caused by the distention of cellular tissue owing to ‘endosmis’. Dutrochet had pioneered the study of what he termed ‘endosmis’ and ‘exosmis’ (in modern terms, osmosis and diffusion). See DSB.
John Scott was foreman of the propagating department at the Royal Botanic Garden, Edinburgh; he began to correspond with CD on 11 November 1862 (see letter from John Scott, 11 November 1862).
The enclosure has not been found; it apparently contained a request for specimens of the wild gooseberry (see letter from J. D. Hooker, [14 December 1862] and n. 10).
The reference has not been identified.
See Correspondence vol. 10, Appendix IX. The Royal Medical Society of Edinburgh is a student society, founded in 1737, and closely associated with the Edinburgh Medical School (J. Gray 1952).


Bonafous, Matthieu. 1836. Histoire naturelle, agricole et économique du maïs. Paris and Turin.

Cohn, Ferdinand Julius. 1860. Ueber contractile Gewebe im Pflanzenreiche. [Read 1 November 1860.] Abhandlungen der Schlesischen Gesellschaft für vaterländische Cultur. Abtheilung für Naturwissenschaften und Medicin 1 (1861): 1–48.

Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.

Dutrochet, Henri. 1837. Mémoires pour servir à l’histoire anatomique et physiologique des végétaux et des animaux. 2 vols. and atlas. Paris: J.-B. Baillière.

Geoffroy Saint-Hilaire, Isidore. 1832–7. Histoire générale et particulière des anomalies de l’organisation chez l’homme et les animaux, ouvrage comprenant des recherches sur les charactères, la classification, l’influence physiologique et pathologique, les rapports généraux, les lois et les causes des monstruosites, des variétés et des vices de conformation, ou traité de tératologie. 3 vols. and atlas. Paris: J. B. Baillière.

Gray, James. 1952. History of the Royal Medical Society, 1737–1937. Edited by Douglas Guthrie and with a foreword by Robert Hutchison. Edinburgh: Edinburgh University Press. [Vols. 10,11]

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.

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.

‘Two forms in species of Linum’: On the existence of two forms, and on their reciprocal sexual relation, in several species of the genus Linum. By Charles Darwin. [Read 5 February 1863.] Journal of the Proceedings of the Linnean Society (Botany) 7 (1864): 69–83. [Collected papers 2: 93–105.]

Variation: The variation of animals and plants under domestication. By Charles Darwin. 2 vols. London: John Murray. 1868.


Maintains his view on crossing. Thinks practical breeders would agree with him; doubts that variability and domestication are at all necessarily correlative.

Identical plants in different conditions a heavy argument against "direct action" [of physical conditions].

His 1000-pigeon case is altered if long-beaked are in least degree sterile with short-beaked.

His work on dimorphism inclines him to believe that sterility is at first a selected quality to keep incipient species distinct.

Case of easy modification of Lythrum pollen to favour or prevent crossing.


Has just finished chapter on variations of cultivated plants.

Edinburgh doctors have sent him Diploma of Medical Society.

Letter details

Letter no.
Charles Robert Darwin
Joseph Dalton Hooker
Sent from
Source of text
DAR 115: 176
Physical description
ALS 6pp

Please cite as

Darwin Correspondence Project, “Letter no. 3855,” accessed on 1 March 2024,

Also published in The Correspondence of Charles Darwin, vol. 10