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Darwin Correspondence Project

To J. D. Hooker   15 March [1857]1

Down Bromley Kent

My dear Hooker

I have thought you would like to see enclosed which please return.2 & I shd. have sent it earlier, but I sent the last page to H. C. Watson for advice.—3 The pencil scores mean nothing.—

I asked A. Gray whether he cd. tell me about Trees in U. States; & I told him that I had expected they wd have sexes tending to be separate from theoretical notions, & I told him result for Britain & N. Zealand from you.—4

I have been thinking over your casual remarks at the Club, versus “accidental” dispersal, in contradistinction to dispersal over land more or less continuous;5 & your remarks do not quite come up to my wishes; for I want to hear whether plants offer any positive testimony in favour of continuous land.— Your remarks were that the dispersal & more especially non-dispersal could not be accounted for by “accidental” means; which of course I must agree to & can say only that we are quite ignorant of means of trans-oceanic transport. But then all these arguments seem to me to tell equally against “continuous more or less” land; & you must say that some were created since separation on mainlands, & some extinct since on island.— Between these excuses on both sides, there seems not much to choose, but I prefer my answer to yours.—6

The same remark, seems to me applicable to your observation on the commonest species not having been transported; for it seems bold hypothesis to suppose that the commonest have been generally last created on the mainland or soonest extinguished on the island.— But I shd. like to hear whether you are prepared on reflexion to uphold this doctrine of the commonest being least widely disseminated on outlying islds.— I know it holds in New Zealand & feebly owing to distance in Tristan d’Acunha., but generally I shd. have taken from De Candolle a different impression:—7 I am referring only to identical species in these remarks.—

What I shd. call positive evidence would be if proportions of Families had been exactly same on island with mainland.— If all plants were common to some mainland & island (as in your Raoul Isd.)8 more especially if some other main-land was nearer.— If soundings concurred with any great predominance of species from any country—or any other such argument of which I know nothing.

Do not answer me, without you feel inclined, but keep this part of subject before your mind for some future essay. I have written at this length that you may see, what I for one shd. like to see discussed. But I will stop for I could go on prosing for another hour.—

I hope to get a feeble ray of light on Protean genera from A. Gray: how infinitely kind he has been to me.

I have just heard from H. C. Watson with whom I have been corresponding on protean genera; & I find I shall have to send back to Gray the latter half—of his letter,9 which I daresay you wd. not care to see.

So adios | Ever yours | C. Darwin March 15th.—


Dated by the references to Hewett Cottrell Watson’s letters about protean genera (see n. 3, below).
CD had sent Watson the last page of Asa Gray’s letter, which contained a list Gray had prepared of protean genera. See letter from H. C. Watson, 10 March 1857 and letter from H. C. Watson to Asa Gray, 13 March 1857.
CD and Hooker had discussed means of geographical dispersal when they met at a meeting of the Philosophical Club in February (see letter to J. D. Hooker, [after 20 January 1857]).
CD summarised the botanical relations that led Hooker to believe in a former land-mass connecting New Zealand, Kerguelen Land, Tristan d’Acunha, and Tierra del Fuego in Natural selection, pp. 560–5. There he also discussed his own view of the agencies that may have accounted for these particular relationships.
In a paper on the botany of Raoul Island, Hooker stated: ‘The most interesting circumstance connected with the vegetation of Raoul Island is the identity of most of the flowering plants, and all but one of the ferns, that have been collected upon it, with those of New Zealand.’ (J. D. Hooker 1857, p. 126). Hooker found this difficult to explain by assuming accidental transportation, for the island lies 450 miles north-west of New Zealand.
See n. 2, above.


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.

Natural selection: Charles Darwin’s Natural selection: being the second part of his big species book written from 1856 to 1858. Edited by R. C. Stauffer. Cambridge: Cambridge University Press. 1975.


Separation of sexes in trees [U. S.].

Do plants offer positive evidence for "continuous land" theory?

Protean genera.

Letter details

Letter no.
Charles Robert Darwin
Joseph Dalton Hooker
Sent from
Source of text
DAR 114: 193
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 2066,” accessed on 29 September 2021,

Also published in The Correspondence of Charles Darwin, vol. 6