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Darwin Correspondence Project

From J. D. Hooker   9 August 1866


Aug 9/66

My dear Darwin

If my letters did not génér you,1 it is impossible that you should suppose that your’s were of no use to me! I would throw up the whole thing were it not for correspondence with you; which is the only bit of silver in the affair. I do feel it disgusting to have to make a point of a speciality in which one cannot see one’s way—a bit further than I could before I began.—2 To be sure I have a very much clearer notion of the pros & cons on both sides—(though these were rather forgotten facts than rediscoveries) I see the sides of the well further down & more distinctly but the bottom is as obscure as ever—3

I think I know Origin by heart in relation to the subject.—& it was reading it that suggested the queries about Azores boulders & Madeira bird: the former you & I have talked over, & I thought I remembered that you wanted it confirmed.4 The latter strikes me thus— Why should plants & insects have been so extensively changed & Birds not at all? I perfectly understand & feel the force of your argument—in reference to Birds per se but why do these not apply to insects & plants?5

Can you not see, that this suggests the conclusion, that the plants are derived one way & the Birds another!

I certainly did take it for granted that you supposed the stocking by occasional transport to be something even more than a “well established hypothesis”—but disputants seldom stop to measure the strength of their antagonists opinion.6

I shall be with you on Saturday week I hope.7 I should have come before, but have made so little progress that I could not. I am now at St Helena, & shall then go to & finish with, Kerguelen’s Land.8

Cape Roch to St. Michaels 741 Cape Race to Flores 1035.9

Azores to nearest temperate State is nearly double the distance—but to my mind does not mend the matter.—for I do not ask why Azores have even proportionally (to distance) smaller number of American plants, but why they have none, seeing the winds & currents set that way.10

The Bermudas are all American in Flora—but from what Col Munro11 informs me, I should say they have nothing but common American weeds & the Juniper. (Cedar)12—no changed forms—yet they are as far from America as Azores from Europe. I suppose they are modern & out of the pale.13

You say (“Coral Reefs” 205) that they “ought to have been colored red”— but you do not say on what map. I do not find them on 3.14

There is this, to me, astounding difference between certain Oceanic Islands which were stocked by continental extension & those stocked by immigration (following in both definitions your opinion)—that the former do contain many types of the more distant continent, the latter do not any!!!! Take Madagascar with it’s many Asiatic Genera unknown in Africa;—Ceylon with many Malayan types not Peninsula Indian.— Japan with many non Asiatic American types—15

Baird’s fact of Greenland migration I was aware of since I wrote my Arctic paper—16 I wish I was as satisfied either of continental or of transport means, as I am of my Greenland hypothesis! oh dear me what a comfort it is to have a belief—(sneer away—)17

Ever yr affec | J D Hooker

CD annotations

2.6 but why … & plants?] scored pencil; ‘because not introduced in body at same time or so finally [one word illeg]added pencil
5.1 I shall … hope] scored pencil
6.3 yet they … the pale. 6.4] scored pencil
7.1 You say … map. 7.2] scored pencil
7.2 3.] underl pencil; ‘I do not understand’ added pencil


‘Gêner’: to embarrass or to annoy (French).
Hooker refers to the writing of his lecture on insular floras (J. D. Hooker 1866a) and to recent correspondence with CD on the subject of the geographical dispersal of plants to oceanic islands.
Hooker refers to the alternative hypotheses of occasional trans-oceanic transport and continental extension. For more on these hypotheses, see Origin, pp. 357–65. See also letter from J. D. Hooker, [24 July 1866] and letter to J. D. Hooker, 30 July [1866] and n. 7.
Hooker had questioned CD about the veracity of reports of erratic boulders in the Azores (see letter from J. D. Hooker, 7 August 1866). In his letter of 4 August 1866, Hooker had informed CD that he had written to Philip Lutley Sclater for information on the birds of Madeira. In Origin, CD considered the erratic boulders of the Azores on page 363 and the birds of Madeira on page 391. On CD’s prediction of erratic boulders in the Azores, and their subsequent discovery, see Correspondence vol. 7, letter to J. D. Hooker, 26 [April 1858].
CD recognised that there were no endemic species of birds on Madeira, whereas there were numerous endemic species of insects and land shells (Origin, p. 391). On the plants and insects of oceanic islands, see Origin, pp. 389–402.
In his letter of 8 August [1866], CD denied that he regarded occasional transport as a ‘well established hypothesis’ but expressed his belief that it was far more probable than continental extension as the means by which islands had become colonised by plants. On occasional transport, see letter to J. D. Hooker, 30 July [1866], n. 7. See Correspondence vol. 6, letter to Charles Lyell, 25 June [1856], for CD’s rejection of Edward Forbes’s hypothesis of continental extension.
In 1866, the second Saturday after 9 August was 18 August. Hooker visited CD at Down on that date (see letters from J. D. Hooker, [17 August 1866] and 18 August 1866).
In the first part of his lecture, Hooker described in turn the principal features of the floras of the Madeiran, Canarian, Azorean, and Cape Verde islands, followed by St Helena, Ascension and Kerguelen’s Land (J. D. Hooker 1866a).
Cape Roche is on the south-western coast of Spain, São Miguel (St Michael’s) is an island in the south-eastern Azores, Cape Race is at the south-eastern extremity of Newfoundland, and Flores is the most westerly island in the Azores (Times atlas). For Hooker’s earlier approximation of the distances in miles between America and the Azores and between the Azores and Europe, see the letter from J. D. Hooker, 7 August 1866 and n. 3.
In his letter of 8 August [1866], CD suggested that Hooker measure the distance from the Azores to the more temperate southern states of North America rather than to Newfoundland. See also letter to J. D. Hooker, 5 August [1866] and n. 5.
For many years, William Munro had provided Hooker with information on botany from the different continents in which he served as an army officer (see L. Huxley ed. 1918).
The common name of the Bermudan native Juniperus bermudiana is Bermuda cedar (Bailey and Bailey 1976).
CD had noted that the Bermuda islands were fringed by coral reefs (Coral reefs, p. 205), and presented evidence that islands with ‘fringing reefs’ had been formed more recently than other islands (ibid., pp. 131–8). Hooker implies that there had not been time for endemic species to develop on Bermuda by the action of natural selection.
Plate 3 in Coral reefs distinguishes three different classes of coral islands by colour; however, the West Indies appear at the edge of the plan, which consequently shows no Atlantic islands lying east of Barbados. In Coral reefs, p. 205, CD wrote that the Bermuda islands ‘ought to have been coloured red’ owing to their fringing reefs (see n. 13, above), but that they were left uncoloured because they had some features in common with another class of coral island, the lagoon island or atoll.
For CD’s general views on the derivation of the flora and fauna of oceanic islands from continents, see Origin pp. 388–406. On the affinity between the floras of Madagascar and islands of the Indian Ocean, see Correspondence vol. 9, letter to J. D. Hooker, 7 November [1861]). The identity of elephants in Ceylon (now Sri Lanka) and India had been used as evidence that Ceylon and India were once connected by dry land (Falconer 1863, pp. 94–6). CD also believed that Japan was once similarly joined to mainland China (Correspondence vol. 7, letter to Asa Gray, 11 August [1858]).
Hooker refers to Baird 1865–6 and J. D. Hooker 1860a. See letter to J. D. Hooker, 8 August [1866] and nn. 4 and 5.
In his essay ‘Outlines of the distribution of Arctic plants’ Hooker hypothesised that Greenland represented the western boundary of the European flora, owing to the predominance of European species and lack of Asiatic and American species (J. D. Hooker 1860a, p. 252). Hooker also endorsed CD’s theory of plant migrations southward from the Arctic during a former cold period (see Origin, pp. 365–82), and argued that Greenland has an anomalous flora, because of its lack of a former southward connection to land on which migration could have proceeded (J. D. Hooker 1860a, p. 254). Hooker and CD subsequently discussed continental extension and occasional transport in relation to the flora of Greenland (Correspondence vol. 10). See also Correspondence vol. 13, letter to J. D. Hooker, 15 [February 1865] and n. 6.


Bailey, Liberty Hyde and Bailey, Ethel Zoe. 1976. Hortus third: a concise dictionary of plants cultivated in the United States and Canada. Revised and expanded by the staff of the Liberty Hyde Bailey Hortorium. New York: Macmillan. London: Collier Macmillan.

Coral reefs: The structure and distribution of coral reefs. Being the first part of the geology of the voyage of the Beagle, under the command of Capt. FitzRoy RN, during the years 1832 to 1836. By Charles Darwin. London: Smith, Elder & Co. 1842.

Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.

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.

Times atlas: ‘The Times’ atlas of the world. Comprehensive edition. 9th edition. London: Times Books. 1992.


More on continental extension vs transport [or migration] hypothesis. New questions raised. On Madeira, why were insects and plants changed so much, birds hardly at all?

Erratic boulders of the Azores.

Letter details

Letter no.
Joseph Dalton Hooker
Charles Robert Darwin
Sent from
Source of text
DAR 102: 94–7
Physical description
ALS 7pp †

Please cite as

Darwin Correspondence Project, “Letter no. 5186,” accessed on 26 September 2022,

Also published in The Correspondence of Charles Darwin, vol. 14