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Darwin Correspondence Project

To Hewett Cottrell Watson   [17 July 1861]1


Begin by saying that I have but little information on variation— Bronn & Mr Maw state often or generally mingled.—2

The difficulty to know what to call vars & what species,—hopeless—3 But your suggested plan to take list of forms which some call vars & some species print list?—4

Now most valuable information to know how far down to be called incipient species, not only for my object but generally to know how to settle this work, if habits & distribution of these were well attended to.—

Point. does each pair or two in any district familiar to observer grow mingled or separate & in what stations.5 Or does one grow in one country & one in another? Where they mingle are they equally distinct   Cause effects of condition or crossing. About the frequency.— Forms such as albinoes or monstrosities not apparently propagated to be excluded.—

Then about polymorphic genera, about the vars of these make perhaps a distinct case.— but it would be interesting to know range & station of these extremely varying forms.—

Any facts about rare var. being known in same locality for period, ie if propagated by seedlings—


The date is given by a note written by Watson on a copy he made of part of the letter received from Darwin, of which the draft is printed here. Watson wrote on a slip tipped into his presentation copy of the first edition of Origin: ‘C Darwin in lre of July 17. 1861’ (see n. 5, below). The book is in the collection of Texas Tech University Library, Lubbock, Texas. Watson also refers to ‘your letter of 17th.’ in the letter from H. C. Watson, 24 July 1861.
In his review of Origin, George Maw stated that varieties were usually found mingled with their parent forms, just as different genera are closely associated ‘without engaging in that mutually extirpating struggle upon which Mr. Darwin’s theory of progression so much depends.’ (Maw 1861a, p. 7600). In his criticism of CD’s theory included as the final chapter of his translation of Origin, the German palaeontologist Heinrich Georg Bronn pointed out that variations used to distinguish different varieties of a species are not generally clearly marked but consist of several different deviating characters (Bronn trans. 1860, p. 503).
Since the publication of Origin, Watson and CD had been corresponding concerning various aspects of the theory. Although Watson accepted natural selection as the mechanism for species change, he argued that in addition to CD’s principle of the divergence of species from the original type, there also appeared to have been a ‘convergence’ of species. According to Watson, this principle was necessary in order to limit the vast numbers of different specific types that would otherwise proliferate. See Correspondence vol. 8, letters from H. C. Watson, [3? January 1860] and 10 May 1860. CD responded to Watson’s points in the new material added to the third edition of Origin, pp. 141–3.
See the earlier correspondence between CD and Watson on this topic, especially the letter from H. C. Watson, [after 23 March 1858] (Correspondence vol. 7). See also letter from H. C. Watson, 24 July 1861.
The part of the original letter discussing this point has survived in a copy Watson made under the heading ‘Distribution of closely allied species or subspecies’ (see n. 1, above). The text reads: The point I should so much like to see discussed, is how often do such allied forms (held species by some, vars. by other botanists) live mingled in same spot,—& how often in same district, but in different stations,—& how often in different geographical districts. I presume you could discuss these points only in a few cases. It has surprized me how little information I have been able to find on such subjects with respect to very closely allied forms.— The habitats & range of the forms in the protean or polymorphous genera, such as Rubus &c, might, I should think, be discussed in comparison with the somewhat more clearly defined forms—


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

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.


Difficulty of distinguishing varieties and species. Did HCW suggest a printed list that might help?

Polymorphic genera.

Letter details

Letter no.
Charles Robert Darwin
Hewett Cottrell Watson
Sent from
Source of text
DAR 185: 49
Physical description
Adraft 2pp

Please cite as

Darwin Correspondence Project, “Letter no. 1616,” accessed on 5 December 2020,

Also published in The Correspondence of Charles Darwin, vol. 9