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Darwin Correspondence Project

To J. D. Hooker   [22 July – 19 August 1845]1

Down Bromley Kent


My dear Hooker

I am particularly obliged for your facts about solitary islands having several species of peculiar genera: it knocks on the head some analogies of mine: the point stupidly never occurred to me to ask about.— I am amused at your anathemas against variation & co; whatever you may be pleased to say, you will never be content with simple species, “as they are”—I defy you to steel your mind to technicalities, like so many of our brother naturalists.— I am much pleased that I thought of sending you Forbes article: I confess I cannot make out the evidence of his time-notions in distribution, & I cannot help suspecting that they are rather vague.2 Lyell preceded Forbes in one class of speculation of this kind; for instance in his explaining the identity of the Sicily Flora with that of S. Italy, by its having been wholly upraised within the recent period;3 & so I believe with mountain-chains separating floras.— I do not remember Humboldts fact about the Heath regions.— Very curious the case of the broom; I can tell you something analogous on a small scale: my Father when he built his house sowed many broom-seed, on a wild bank which did not come up, owing, as it was thought, to much earth having been thrown over them: about 35 years afterwards, in cutting a terrace, all this earth was thrown up, & now the bank is one mass of broom.—4

I see we were in some degree talking to cross purposes; when I said I did much believe in hybridising to any extent,5 I did not mean at all to exclude crossing. It has long been a hobby of mine to see in how many flowers such crossing is probable: it was, I believe Knights view, originally that every plant must be occasionally crossed:6 I find, however, plenty of difficulty in showing even a vague probability of this; especially in the Leguminosæ, though their structure is inimitably adapted to favour crossing, I have never yet met with but one instance of a natural mongrel (nor mule?)7 in this family

I shall be particularly curious to hear some account of the appearance & origin of the Ayshire Irish Yew. And now for the main object of my letter; it is to ask, whether you would just run your eye over the proof of my Galapagos Chapter, where I mention the plants, to see that I have made no blunders or spelt any of the scientific names wrongly.8 As I daresay you will so far oblige me, will you let me know a few days before, when you leave Edinburgh & how long you stay at Kinnordy, so that my letter might catch you.—

You ought to find out if possible, on what part of Albemarle Isd. Macræ landed; it could not have been on the sterile northern part where I did: the SW. end is high & green. I am not surprised at my collection from James isld differing from others, as the damp upland district (where I slept 2 nights is 6 miles from the coast, & no naturalist except myself probably ever ascended to it. Cuming had never even heard of it—. Cuming tells me that he was on Charles, James & Albemarle islands, & that he cannot remember from my description, the Scalesia, but thinks he could if he saw a specimen.—

I have no idea of origin of the distribution of the Galapagos shells, about which you ask: I presume (after Forbes’ excellent remarks on the facilities by which embryo-shells are transported)9 that the Pacific shells have been borne thither by currents; but the currents all run the other way.—

Farewell, my dear Hooker with many thanks for your long letter, always most interesting to me. Ever yours | C. Darwin


Probably E. Forbes 1843. Forbes discusses the distribution of marine invertebrates through time on pp. 173–5. See also letter to J. D. Hooker, [8 September 1844]. It is unlikely that CD is referring to E. Forbes 1845, since this was available only in abstract form in the Athenæum (see letter to J. D. Hooker, [11–12 July 1845], n. 15).
C. Lyell 1830–3, 3: 115–16. In his annotated copy of C. Lyell 1837, 3: 445, CD has marked the passage and added ‘Capital!’. Both works are in the Darwin Library–CUL.
CD has apparently omitted the word ‘not’. See letter to J. D. Hooker, [11–12 July 1845], in which CD claims he does not believe in hybridisation to any great extent.
Knight 1799.
CD is distinguishing between crossing varieties (mongrels) and species (mules).
Journal of researches 2d ed., ch. 17.
E. Forbes 1844, p. 326.


Thanks for facts on solitary islands having several species of peculiar genera; "it knocks on the head some analogies of mine".

Has long been trying to discover in how many flowers crossing is probable, but finds it difficult to show "even a vague probability of this".

Will JDH proof-read Galapagos chapter of Journal of researches?

Gives information on his Galapagos collection; explains why it differs from others.

Letter details

Letter no.
Charles Robert Darwin
Joseph Dalton Hooker
Sent from
Source of text
DAR 114: 37
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 892,” accessed on 26 March 2019,

Also published in The Correspondence of Charles Darwin, vol. 3