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Darwin Correspondence Project

From H. C. Watson to J. D. Hooker   4 January 1861

Thames Ditton S.W.

19 Jnry. 61

My dear Hooker,

Better late than never; and where there is ample reason for lateness, there can be none for complaint. Many thanks for your letter de convergentibus &c.—1 How much outside the botanical circles,—or, at any rate the great circle,—not even to have heard that you had been beyond seas again!2 Was there ever a botanist who had seen so much of the earth & its vestments?3

How vastly I should have enjoyed the run over Syria with you! And yet if I had chanced to be away from England those eight weeks, inconveniences to myself & others would have been so incurred, that might hardly have been removed in as many years. I seem always called on to give time & thought to things no wise botanical, while wishing to give them to matters that are botanical, or connected with botany.4

I can hardly conceive you & Mr. Bentham employed more serviceably than on a ‘Genera Plantarum’.5 So many qualifications & advantages concentrate in you two, towards such an undertaking, that the accomplishment of your task ought to date as a new formation in the series of botanical strata—& doubtless will do so.— Can a list of species under each genus be compassed, if only single names?6

You have not yet grasped the whole idea of convergence, as I conceive of it whether rightly or erroneously.7 No wonder. If Darwin had sought to explain his notions of divergence & selection in compass of a letter sheet, he might have got further or fuller than I could do with its (presumed) counterpoise, & yet done it most imperfectly.

Darwin watches minutesimal variations; & he supposes that these may & do accumulate into any extent of diversity in long time.— I suspect that we should all have said, that is pure fancy or pure absurdity, if geology had not shown the fact, that enormous differences do exist between the present & the past, & must have come about somehow.8

I watch minutesimal variations also; & I suppose that these may & do accumulate into any degree of similarity in long time. But, seeing that we know not the future, and cannot compare the present therewith, we lack corroboration. And we (i.e. you &c.) do think convergence to such a degree mere fancy or absurdity.

You & Darwin seem to me at present something like an Astronomer endeavouring to account for the planetary system by a centrifugal force alone, without taking into account a centripetal force, or recognising it only as occasional, anomalous, trifling.9 Darwin’s idea that similitudes must be always inherited from some predecessor, common ancestor of all that so resemble, if pushed to its logical consequences, would concentrate all organic characters in the dozen (or single) original types;—and that surely is a real as well as logical absurdity?10

Observe,—every the smallest possible change in a plant, which to that extent renders it more like another plant, (whether that other plant be the nearest, or the most remote otherwise) is a step in convergence. Advergence would perhaps be a better term. Can you point out divergences in any plants, which are certainly not advergences towards some other plants?

You will be ready to cry, ‘Hold enough’. And I will not inflict on you a criticism of the various ideas in your letter;—some of which indeed I quite admit the force of; though I think that the arguments against ad/convergence are not proof against reply.—

The Indian specimens you kindly sent some time ago are still kept apart, awaiting some other introductions into my herbarium, before trying how closely I can concur with your labels of European identity.11 Unlike you, I have to go through all the mechanical processes, such as washing over with poison, glueing to paper, & so forth,—sadly time-consuming.12

Writing with back to the fire, I still have to keep rubbing fingers, or the pen would fall from their cold benumbed trembling guidance—

Glad to have so favorable an account of your Father—13

Ever faithly | Hewett C. Watson

Dr J. D. Hooker


The letter from Hooker to Watson has not been found.
Hooker had taken part in an expedition to Syria from mid-September to mid-November 1860 (L. Huxley ed. 1918, 1: 528; see also Correspondence vol. 8).
For details of Hooker’s wide-ranging travels, see, for example, R. Desmond 1999.
Watson was active as a politician (DNB). By 1861, he travelled rarely and was engaged in philanthropic activity (Frank Egerton, personal communication).
Hooker’s collaboration with George Bentham on Genera plantarum is documented in Stearn 1956, and Hooker’s work on the volume began in earnest in March 1860 (see Correspondence vol. 8, letter to J. D. Hooker, 12 March [1860] and n. 4). The aim of the work was to describe all known genera of flowering plants and gymnosperms from specimens in the herbarium at the Royal Botanic Gardens, Kew, and to include all known synonyms. The first part of the first volume was published in 1862 (Bentham and Hooker 1862–83).
Bentham and Hooker 1862–83 did not contain lists of species. However, Hooker and Benjamin Daydon Jackson’s Index Kewensis, financed by a bequest from CD and first published in 1893, provided such a list.
Watson’s views on ‘convergence’ were summarised in a memorandum to CD (Correspondence vol. 8, letter from H. C. Watson, [3? January 1860]). Hooker wrote to CD on the subject in his letter of [11 May – 3 December 1860] (this volume, Supplement), and in the missing fragment of his letter of [26 November – 4 December 1860] (Correspondence vol. 8; see also Correspondence vol. 8, letter to J. D. Hooker, 4 December [1860] and n. 6). CD referred to Watson’s criticism in the revised American edition of Origin and in the third and later editions of Origin (see, for example, Origin 3d ed., pp. 141–3).
CD referred to the geological record in support of his transmutation theory in Origin, chapters 9 and 10.
Hooker had previously described centripetal and centrifugal models of variation (Correspondence vol. 3, letter from J. D. Hooker, 1 February 1846); however, Watson and Hooker evidently understood the terms centripetal and centrifugal somewhat differently. For Watson, centripetal variation afforded a mechanism for the convergence of species (see also this volume, Supplement, letter from J. D. Hooker, [11 May – 3 December 1860]). Hooker used centripetal variation to designate variations that were prone to revert to a parental type. CD objected to Hooker’s notion, arguing that Gnaphalium species tended to ‘revert to more than one centre or type’ (Correspondence vol. 3, letter to J. D. Hooker, [16 April 1846]). Hooker used centrifugal variation to designate variation that accompanied extensive geographical distribution, as in Senecio (Hooker 1844–7, p. 315), while Watson used it to signify the mechanism of divergence. CD disapproved of Hooker’s use of the word centrifugal (Correspondence vol. 7, letter to Charles Lyell, 31 [October 1859] and n. 3).
The correspondence between CD and Watson on ‘convergence’ is in Correspondence vol. 8 (letters from [H. C. Watson], [3? January 1860] and 10 May 1860, and letter to H. C. Watson, [5–11 January 1860]). See also this volume, Supplement, letter from J. D. Hooker, [11 May – 3 December 1860].
Hooker had been on a botanical expedition to India from November 1847 to January 1851 (R. Desmond 1999, pp. 96–177). Hooker had presumably asked for comparisons between his Indian specimens and specimens in Watson’s herbarium of British plants (DNB).
These processes are stages in the preparation of herbarium specimens. For more on preparation of specimens, see Oliver 1881, pp. 269–73. Watson had private means and worked from home (DNB).
Watson refers to William Jackson Hooker.


Comments on the travels of JDH.

Genera plantarum a most worthy undertaking.

Criticisms of the Darwin–Hooker understanding of HCW’s views of convergence.

Letter details

Letter no.
Hewett Cottrell Watson
Joseph Dalton Hooker
Sent from
Thames Ditton
Source of text
Royal Botanic Gardens, Kew, DC 105 (205)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 3041A,” accessed on 25 March 2019,

Also published in The Correspondence of Charles Darwin, vol. 13 (Supplement)