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Darwin Correspondence Project

To George Bentham   25 November [1869]1

Down. | Beckenham | Kent. S.E.

Nov. 25

My dear Mr Bentham

I was greatly interested by your address, which I have now read thrice, & which I believe will have much influence on all who read it. But you are mistaken in thinking that I ever said you were wrong on any point. All that I meant was that on certain points, & these very doubtful points, I was inclined and had to differ from you.2 And now, on further considering the point, on which even 2 or 3 months ago I felt most inclined to differ, viz on isolation,3 I find I differ very little. What I have to say is really not worth saying, but as I shd be very sorry not to do whatever you asked, I will scribble down the slightly dissentient thoughts which have occurred to me. It wd be an endless job to specify the points in which you have interested me; but I may just mention the relation of the extreme W. flora of Europe (some such very vague thoughts have crossed my mind, relating to the Glacial period) with S. Africa4—& your remarks on the contrast of passive & active distribution.—5

p. Lxx. I think the contingency of a rising isld, not as yet fully stocked with plants, ought always to be kept in mind, when speaking of colonisation.—6

p. Lxxiv. I have met with nothing which makes me in the least doubt, that large genera present a greater number of vars. relatively to their size, than do small genera.— Hooker was formerly convinced by my data, never as yet published in full, only abstracted in the Origin.—7

p. Lxxviii.— I dispute whether a new race or species is necessarily, or even generally, descended from a single or pair of parents: the whole body of individuals, I believe, becomes altered together—like our race-horses, and like all domestic breeds which are changed through “unconscious selection” by man.8

p. do. When such great lengths of time are considered, as are necessary to change a specific form, I greatly doubt whether more or less rapid powers of multiplication have more than the most insignificant weight.9 These powers, I think, are chiefly related to greater or less destruction in early life.

p. Lxxix. I still think you rather underrate the importance of isolation. I have come to think it very important from various grounds; the anomalous and quasi-extinct forms on islands &c. &c. &c.10 With respect to areas with numerous “individually durable” forms, can it be said that they generally present a “broken” surface with “impassible barriers”? This no doubt is true in certain cases, as Teneriffe.11 But does this hold with S.W. Australia and the Cape? I much doubt. I have been accustomed to look at the cause of so many forms, as being partly an arid or dry climate (as De Candolle insists) which indirectly leads to diversified conditions, and, secondly to isolation from the rest of the world during a very long period, so that other more dominant forms have not entered, and there has been ample time for much specification and adaptation of character.12

Lxxx.— I suppose you think that the Restiaceae, Proteaceae, etc. etc. once extended over the world, leaving fragments in the South.13

You in several places speak of distribution of plants, as if exclusively governed by soil and climate: I know that you do not mean this, but I regret whenever a chance is omitted of pointing out that the struggle with other plants (and hostile animals) is far more important.14 I told you that I had nothing worth saying, but I have given you my thoughts.

How detestable are the Roman numerals. why should not the President’s addresses, which are often, & I am sure in this case, worth more than all the rest of the Number, be paged with Christian figures?—

My dear Mr. Bentham | Your’s very sincerely | Ch. Darwin

Footnotes

The year is established by the relationship between this letter and the letter from George Bentham, 23 November 1869.
For CD’s comments on Bentham 1869b, see the letters to J. D. Hooker, 22 June [1869] and 13 November [1869].
See Bentham 1869b, p. lxxxvii.
See Bentham 1869b, pp. xcv–xcvi.
See Origin 5th ed., pp. 466–7 and 472.
CD discussed the greater number of varieties in large genera (genera containing many species) in Origin, pp. 55–6. In Bentham 1869b, p. lxxiv, Bentham suggested that Joseph Dalton Hooker’s similar opinion expressed in On the flora of Australia, its origin, affinities, and distribution; being an introductory essay to the flora of Tasmania (J. D. Hooker 1859) had probably since changed.
See Origin, pp. 355–6. CD discussed ‘unconscious selection’ in Origin, pp. 34–40.
See, for example, Origin, pp. 302–3.
CD discussed the role of isolation, including isolation on islands, in forming new species in Origin, pp. 104–7. CD made some additions to this section in the fifth edition of Origin; see Peckham ed. 1959, p. 196.
For contemporary knowledge of the botany of Tenerife, one of the Canary Islands, see C. J. F. Bunbury 1855; see also Correspondence vol. 15.
CD refers to south-western Australia and the Cape of Good Hope in South Africa. Alphonse de Candolle referred to isolation in dry climates several times in Géographie botanique raisonnée (A. de Candolle 1855); see, for example, vol. 1, p. 562.
Bentham mentioned these and additional names of southern hemisphere families in Bentham 1869b, p. lxxiii, in reference to possible ancient connections between their representatives in South Africa and Australia. Restiaceae is roughly equivalent to the modern family Restionaceae.
CD mentions the importance of interaction with other plants and animals in determining the range of a species in, for example, Origin, p. 175.

Bibliography

Bunbury, Charles James Fox. 1855. Remarks on the botany of Madeira and Teneriffe. [Read 6 March and 3 April 1855.] Journal of the Proceedings of the Linnean Society (Botany) 1 (1857): 1–35.

Candolle, Alphonse de. 1855. Géographie botanique raisonnée ou exposition des faits principaux et des lois concernant la distribution géographique des plantes de l’époque actuelle. 2 vols. Paris: Victor Mason. Geneva: J. Kessmann.

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

Hooker, Joseph Dalton. 1859. On the flora of Australia, its origin, affinities, and distribution; being an introductory essay to the flora of Tasmania. London: Lovell Reeve.

Origin 5th ed.: On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. 5th edition, with additions and corrections. By Charles Darwin. London: John Murray. 1869.

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.

Summary

CD finds GB’s address interesting; assures him that he has never said GB was wrong on any point, but that there were differences between them, which he now thinks are not great.

Comments on specific parts of the address [see 6793]: colonisation, variability of large and small genera, descent from a single parent or pair of parents, rapid multiplication and change in species, isolation.

Letter details

Letter no.
DCP-LETT-7011
From
Charles Robert Darwin
To
George Bentham
Sent from
Down
Source of text
Royal Botanic Gardens, Kew (GEB/1/3)
Physical description
8pp

Please cite as

Darwin Correspondence Project, “Letter no. 7011,” accessed on 20 February 2020, https://www.darwinproject.ac.uk/letter/DCP-LETT-7011.xml

Also published in The Correspondence of Charles Darwin, vol. 17

letter