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Darwin Correspondence Project

From H. C. Watson   10 May 1860

Thames Ditton | Kingston—S.W.

10 May 1860

My dear Sir

I return by same post the four notices of ‘Origin’ which you kindly sent.— Gradually, the various arguments, objections, cavils, etc. on the grand subject are growing into a sort of conglomerate in my recollections; who said this, & who said that, getting pretty much confused together. I hope you can keep them mentally distinct.

Pictet goes a good way,1—farther perhaps than he himself clearly knows,—   on page 15, where you pencil the no. 12,2 your difficulty is & will be to lead zoologists & botanists, those who look to existing “species”, so far as Pictet “believes”. Until a faith in certain impassable barrier between existent species becomes thoroughly shaken, naturalists will resist your views, & hail difficulties as if conclusive arguments on the contra side.

Differently as these unseen barriers are traced or placed, they are believed in about as strongly by almost all. Let the subjoined numerals represent botanical forms, & the lines be the barriers as placed by different botanists;

Jordan3 1 2 3 4 5 6 7 8 9 0 Babington4 1 2 3 4 5 6 7 8 9 0 Bentham5 1 2 3 4 5 6 7 8 9 0 Hooker6 1 2 3 4 5 6 7 8 9 0 at any rate, previous to 1859.

This represents an approximate uniformity which is not always found; the differences lying only in the more numerous barriers of J e B, as compared with B e H.— But these transpositions sometimes occur;

Hooker 1 2 3 4 — One species Smith7 1 2 3 4 — Two species Babn. 1 4 2 3 — Two (other) species

Shall I bore you with a simple illustration of convergence?8 You have at any rate the option not to read it. Take two plants, nore or less unlike in all other respects than these three characters:—

1. Glabrous — Leaves linear — Flowers white. 2. Pubescent — Leaves oval — Flowers blue 1 varies with leaves lanceolate — Flowers pink. 2 varies with Leaves lanceolate — Flowers pink.

Then let one (1) become pubescent, or the other (2) glabrous; & the convergence is completed so far as the three characters go.—

Accumulate similar convergences, in your way of accumulating divergences, and though you may never actually change two distant species into each other, you still may counterpoise endless divergence. Now, as facts in nature, the changes from pubescent to glabrous,—from linear or oval to lanceolate,—from white or blue to pink,—are ordinary, & excite no surprize singly. And yet those three characters would be held (as a rule) amply sufficient to justify a separation of 1 e 2 as perfectly distinct species, tho‘ all other technical characters should agree.

I presume you would say that some ancestors of 1 e 2 had lanceolate leaves & pink flowers, which had diverged into linear & white, oval & blue. But you can at best only suppose this lanceolate & pink fore-parent. And if you try to account for all converging variations in the like manner, your original adam or dozen of adams must surely have combined every character in one? Unless you believe that diverging characters are novelties, while converging are restorations only?

Sincerely yours | Hewett Cl. Watson

C. Darwin | Esqe

CD annotations

2.1 Pictet … knows,—] double scored pencil
5.1 Shall … divergence. 8.3] ‘The variations wd have to be [illeg] else one form wd blend the other if living together; if separate not likely same organic & inorganic conditions’; ‘Have 2 varieties ever produced an identical variety.—’ added ink
Top of first page: ‘Ch VI’9 brown crayon
End of letter: ‘I think it possible or even probably that offspring of 2 species might & vary & converge so as to be classed as vars. as one.’; ‘In cultivated vars I daresay many would be placed in wrong groups from converging variation.—’ ink


Pictet de la Rive 1860. CD’s copy of the review is in the Darwin Pamphlet Collection–CUL.
CD’s copy of Pictet de la Rive 1860 has been marked with the numbers 1 to 15, sometimes in an unidentified hand. Two passages are marked ‘12’. The one on p. 15, indicated in the letter, reads: Je crois que la longue série des temps géologiques peut lui avoir donné un peu plus de portée, et lui a permis, par l’accumulation de résultats analogues, de faire naître d’une même espèce quelques espèces très-voisines. [I believe that the long sequence of geological time could have given him a longer period of gestation, making it possible, by the accumulation of analogous results, for one species to give birth to other, closely related species.]
Alexis Jordan was renowned for his tendency to classify plants as distinct species that other botanists might consider varieties of a single species. Watson had made a similar comparison between taxonomic ‘splitters’ and ‘lumpers’, also citing Jordan, in letters to CD in 1855. See Correspondence vol. 5, letters from H. C. Watson, 13 August 1855, 2 October 1855, and 8 November 1855.
Charles Cardale Babington was also known as a ‘splitter’. See Correspondence vol. 7, letters to C. C. Babington, 22 February [1858], and to J. D. Hooker, 28 February [1858].
George Bentham.
Joseph Dalton Hooker.
James Edward Smith.
Watson had sent CD a long memorandum on the problem of convergence in species earlier in the year. See letter from H. C. Watson, [3? January 1860].
CD’s annotation refers to chapter 6 of Origin, entitled ‘Difficulties on theory’. CD inserted a discussion of Watson’s point in both the revised American edition and in the German translation of Origin. See letters to Asa Gray, 8 March [1860], and to H. G. Bronn, 21 March [1860].


Returns reviews of Origin.

F. J. Pictet [Arch. Sci. Phys. & Nat. n.s. 7 (1860): 231–55] goes further than he himself realises.

Naturalists will resist CD’s views until faith in certain "impassable" barriers between existent species is shaken.

Gives CD an instance of convergence.

Letter details

Letter no.
Hewett Cottrell Watson
Charles Robert Darwin
Sent from
Thames Ditton
Source of text
DAR 47: 160–1
Physical description
4pp †

Please cite as

Darwin Correspondence Project, “Letter no. 2793,” accessed on 19 March 2019,

Also published in The Correspondence of Charles Darwin, vol. 8