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Darwin Correspondence Project

From A. R. Wallace   16 August [1868]1

9, St. Mark’s Crescent | N.W

August 16th.

Dear Darwin

I ought to have written before to thank you for the copies of your papers on “Primula” and on “Cross Unions of Dimorphic plants &c.”2 The latter is particularly interesting and the conclusion most important; but I think it makes the difficulty of how these forms, with their varying degrees of sterility, originated, greater than ever. If “natural selection” could not accumulate varying degrees of sterility for the plant’s benefit, then how did sterility ever come to be associated with one cross of a trimorphic plant rather than another? The difficulty seems to be increased by the consideration that the advantage of a cross with a distinct individual is gained just as well by illegitimate as by legitimate unions. By what means then did illegitimate unions ever become sterile? It would seem a far simpler way for each plant’s pollen to have acquired a prepotency on another individual’s stigma over that of the same individual, without the extraordinary complication of three differences of structure and eighteen different unions with varying degrees of sterility!.

However the fact remains an excellent answer to the statement, that sterility of hybrids proves the absolute distinctness of the parents.

I have been reading with great pleasure Mr. Bentham’s last admirable address, in which he so well replies to the gross misstatements of the Athenæum;, & also says a word in favour of Pangenesis.3 I think we may now congratulate you on having made a valuable convert, whose opinions on the subject, coming so late & being evidently so well considered will have much weight.

I am going to Norwich on Tuesday to hear Dr. Hooker, who I hope will boldly promulgate “Darwinianism” in his address.4 Shall we have the pleasure of seeing you there?

I am engaged in negociations about my book.5

Hoping you are well & getting on with your next volumes6 | Believe me | Yours very faithfully | Alfred R. Wallace—


The year is established by the reference to Joseph Dalton Hooker’s presidential address at the annual meeting of the British Association for the Advancement of Science in Norwich (see n. 4, below).
‘Specific difference in Primula and ‘Illegitimate offspring of dimorphic and trimorphic plants’ were published in the June 1868 issue of the Journal of the Linnean Society of London (Botany).
Hooker was president of the British Association, which held its annual meeting at Norwich from 19 to 26 August 1868 (Report of the 38th meeting of the British Association for the Advancement of Science, p. lvii).
The Malay archipelago … a narrative of travel, with studies of man and nature (A. R. Wallace 1869) was an account of Wallace’s time in the Malay Archipelago between 1854 and 1862.
Wallace probably refers to work that was published as Descent and Expression.


Descent: The descent of man, and selection in relation to sex. By Charles Darwin. 2 vols. London: John Murray. 1871.

‘Illegitimate offspring of dimorphic and trimorphic plants’: On the character and hybrid-like nature of the offspring from the illegitimate unions of dimorphic and trimorphic plants. By Charles Darwin. [Read 20 February 1868.] Journal of the Linnean Society of London (Botany) 10 (1869): 393–437.

‘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.


The problem of sterility, and its relation to natural selection.

George Bentham’s support of Darwinism.

Letter details

Letter no.
Alfred Russel Wallace
Charles Robert Darwin
Sent from
London, St Mark’s Crescent, 9
Source of text
DAR 106: B63–4
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 6318,” accessed on 22 September 2021,

Also published in The Correspondence of Charles Darwin, vol. 16