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Darwin Correspondence Project

To Francis Galton   7 November [1875]1


Nov. 7th

My dear Galton.—

I have read your essay with much curiosity & interest, but you probably have no idea how excessively difficult it is to understand.2 I cannot fully grasp, only here & there conjecture, what are the points on which we differ.— I daresay this is chiefly due to muddy-headiness on my part but I do not think wholly so.— Your many terms not defined, “developed germs”—“fertile” & “sterile germs” (the word “germ” itself from association misleading to me) “stirp”—“sept” “residue” &c &c quite confounded me.3 If I ask myself how you derive & where you place the innumerable gemmules4 contained within the spermatogen formed by a male animal during its whole life I cannot answer myself.— Unless you can make several parts clearer I believe (though I hope I am altogether wrong) that very few will endeavour or succeed in, fathoming your meaning.

I have marked a few passages with numbers,5 & here make a few remarks & express my opinion, as you desire it, not that I suppose it will be of any use to you.—

(1) If this implies that many parts are not modified by use & disuse during the life of the individual, I differ widely from you, as every year I come to attribute more & more to such agency.

(2) This seems rather bold, as sexuality has not been detected in some of the lowest forms, though I daresay it may hereafter be.

(3) If gemmules (to use my own term) were often deficient in buds I cannot but think that bud-variations wd be commoner than they are in a state of nature: nor does it seem that bud-variations often exhibit deficiencies which might be accounted for by absence of the proper gemmules. I take a very different view of the meaning or cause of sexuality.

(4) I have ordered Fraser’s Mag. & am curious to learn how twins from a single ovum are distinguished from twins from 2 ova.6 Nothing seems to me more curious than the similarity & dissimilarity of twins.—

(5) Awfully difficult to understand.

(6) I have given almost the same notion.

(7) I hope that all this will be altered. I have received new & additional cases, so that I have now not a shadow of doubt.—7

(8) Such cases can hardly be spoken of as very rare, as you wd say if you had received half the number of cases which I have.—

I am very sorry to differ so much from you but I have thought that you wd desire my open opinion.— Frank is away; otherwise he shd have copied my scrawl.

I have got a good stock of pods of Sweet Peas, but the autumn has been frightfully bad; perhaps we may still get a few more to ripen.8

My dear Galton | Yours very sincerely | Ch Darwin


The year is established by the relationship between this letter and the letter from Francis Galton, 5 November 1875.
Galton had sent CD a proof copy of his essay, ‘A theory of heredity’ (Galton 1875b; see letter from Francis Galton, 5 November 1875).
Galton used the term ‘germs’ to refer to the hereditary material stored in each organism and transmitted to offspring; he defined ‘stirp’ as the sum total of the germs in a newly fertilised ovum or bud (Galton 1875b, p. 81). According to Galton’s theory, some germs developed, giving rise to all of an individual’s characteristics, such as eye-colour; however, most germs remained dormant. He argued that the developed germs were rendered ‘sterile’ by their activity in the organism, and so exerted little or no influence on offspring; whereas the inactive germs (also referred to as the ‘residual germs’) were concentrated in the sexual elements and transmitted to offspring unmodified (ibid., pp. 82, 88). ‘Septs’ were divisions or aggregations of germs within the stirp (ibid., p. 89).
‘Gemmules’ was CD’s term for the material of heredity and development: they were minute granules dispersed throughout an organism and thrown off by its various parts, as well as concentrated in the reproductive organs (Variation 2d ed. 2: 374).
The proof copy of Galton 1875b with CD’s marks has not been found, so that it is not possible to identify what passages CD is referring to.
Galton’s article on twins was published in Fraser’s Magazine (Galton 1875a). Some of the results of this study are discussed in Galton 1875b, p. 87.
CD is probably referring to cases in which injuries to a parent were apparently transmitted to offspring (see letter to Francis Galton, 4 November [1875] and n. 4). Galton questioned the evidence for such cases (Galton 1875b, pp. 92–3).
Galton asked CD and other friends to experiment with sweetpeas (see letter to Francis Galton, 22 September 1875 and n. 6).


Variation 2d ed.: The variation of animals and plants under domestication. By Charles Darwin. 2d edition. 2 vols. London: John Murray. 1875.


Comments on FG’s paper ["A theory of heredity"]. Finds essay difficult to understand. Objects that FG’s theory conflicts with phenomenon of use and disuse. Conflicts also with rarity of bud-variations in nature.

Says he has ordered FG’s article ["The history of twins", Fraser’s Mag. 92 (1875): 566–76; revised in J. Anthropol. Inst. 5 (1876): 391–406].

Letter details

Letter no.
Charles Robert Darwin
Francis Galton
Sent from
Source of text
UCL Library Services, Special Collections (GALTON/1/1/9/5/7/19)
Physical description
ALS 3pp

Please cite as

Darwin Correspondence Project, “Letter no. 10245,” accessed on 27 February 2024,

Also published in The Correspondence of Charles Darwin, vol. 23