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Darwin Correspondence Project

To J. D. Hooker   [10–11 November 1844]

Down Bromley Kent


My dear Hooker

I had intended writing to you today, had I not received yesterday’s enclosure to remind me. Many thanks for the seed & for sending me your curious account of the antarctic ice, which no doubt, together with your notes on Infusoria, Ehrenberg wd be very glad to see.— I sent my last parcel through Mr Taylor of Fleet St. or rather, (I believe) through Mr Francis, who lives with him.— The homogeneous manner in which the brash1 is coloured, certainly appears very curious; I presume you consider the quantity too great for snow; with respect to its rising from the bottom, I shd rather doubt it, though in fresh running water, it is well known that icy matter, I suspect like your brash, rises from the bottom, & brings with it stones. There has been much argument about cause of this, in which even Arago has joined:2 the best explanation offered, as it appeared to me, was that the bottom of the stream lost its heat by radiation & and the water froze on it. Should you feel much interest on this subject, I could look you up, (I think) some references. One wd doubt, whether the bottom of the sea would lose its heat by radiation through several hundred feet of thickness of water, & the whole body of water would have to be cooled to the freezing point of sea-water. On other hand Simpson & Deane (I think) found the bottom of shallow arctic sea hard frozen:3 off Spitzbergen masses of ice suddenly rise from the bottom, I have fancied they were remnants of fixed & grounded icebergs.

What a curious, wonderful case is that of the Lycopodiums; I suppose you would hardly have expected them to be more varying than a phanerogamic plant. I trust you will work the case out & even if unsupported publish it, for you can surely do this with due caution. I have heard of some analogous facts, though on the smallest scale, in certain insects being more variable in one district than in another; & I think the same holds with some land-shells. By a strange chance, I had noted to ask you in this letter an analogous question, with respect to genera, in lieu of individual species4 —that is, whether you know of any case of a genus with most of its species being variable (say Rubus) in one continent, having another set of species in another continent non-variable or not in so marked a manner.5 Mr Herbert incidentally mentioned in a letter to me, that the Heaths at the C. of Good Hope were very variable, whilst in Europe they are (?) not so (?); but then the species here are few in comparison, so that the case, even if true, is not a good one.—6 In some genera of insects the variability appears to be common in distant parts of the world: in shells, I hope hereafter, to get much light on this question through fossils. If you can help me, I shd be very much obliged: indeed all your letters are most useful to me.

Monday— Now for your first long letter & to me quite as interesting as long. Several things are quite new to me in it, viz for one, your belief that there are more extra-tropical than intratropical species. I see that my argument from the Arctic regions is false, & I shd not have tryed to argue against you, had I not fancied that you thought that equability of climate was the direct cause of the creation of a greater or lesser number of species: I see you call our climate equable, I shd have thought it was the contrary; anyhow the term is vague, & in England will depend upon whether a person compares it with the United States or T. del Fuego.— In my Journal, (p. 342) I see I state that in South Chiloe at height of about 1000 ft the forest had a Fuegian aspect: I distinctly recollect, that at sea-level in middle of Chiloe, the forest had almost a tropical aspect. I shd. like much to hear, if you make out, whether the N. or S. boundaries of a plant are the most restricted; I shd have expected that the S. would be, in the temperate regions, from the number of antagonist species being greater. (N.B. Humboldt, when in London, told me of some river in N. E. Europe, on the opposite banks of which the Flora was, on the same soil & under same climate, widely different!)7 I forget my last letter, but it must have been a very silly one, as it seems I gave my notion of the number of species being in great degree governed by the degree to which the area had been often isolated & divided;; I must have been cracked to have written it, for I have no evidence, without a person be willing to admit all my views, & then it does follow; but in my most sanguine moments, all I expect, is that I shall be able to show even to sound Naturalists, that there are two sides to the question of the immutability of species;—that facts can be viewed & grouped under the notion of allied species having descended from common stocks. With respect to Books on this subject, I do not know of any systematical ones, except Lamarck’s, which is veritable rubbish; but there are plenty, as Lyell,8 Pritchard9 &c, on the view of the immutability. Agassiz lately has brought the strongest arguments in favour of immutability.10 Isidore G. St. Hilaire has written some good Essays, tending towards the mutability-side, in the “Suites à Buffon”, entitled “Zoolog: Generale”.11 Is it not strange that the author of such a book, as the “Animaux sans Vertebres”,12 shd have written that insects, which never see their eggs, should will, (& plants, their seeds) to be of particular forms so as to become attached to particular objects.13 The other, common (specially Germanic) notion is hardly less absurd, viz that climate, food, &c shd make a Pediculus formed to climb Hair, or woodpecker, to climb trees.— I believe all these absurd views, arise, from no one having, as far as I know, approached the subject on the side of variation under domestication, & having studied all that is known about domestication.— I was very glad to have your criticisms on island-floras & on non-diffusion of plants: this subject is too long for a letter; I cd. defend myself to some considerable extent, but I doubt whether successfully in your eyes, or indeed in my own.

I shd be much obliged for a loan of the Tasmanian Journal with Revd: Clarke’s Paper: I suspect, however, it will turn out to be the same with a paper read by him before the Geolog: Soc: on the same subject.—14 I shall be in town on the 20th.: could you leave it for me at the Athenæum (Have you your name down for this club? I think you wd find it worth while, if you have not) or at the Geolog: Soc:—

Is there any chance of your being able to pay us a visit here soon; it would give Mrs. Darwin & myself real pleasure. I shd have written sooner, had not my own plans, owing to a visit to my Fathers now paid, been rendered uncertain. We cd send to meet you to Croydon; or you cd come by Coach from the Bolt-in-tun Fleet St.— We are wholly disengaged, except on 19, 20, 21, when I must be in London on business.

Once again, thanks for your Botanical letters & believe me, my dear Hooker, | Very truly yours | C. Darwin

Will you tell Sir William, that the Deodar, which he gave me, is doing famously.

I am really ashamed how infamously this letter is written.—


Brash-ice, fragments of crushed ice.
Dease and Simpson 1838, pp. 218, 220.
See CD’s annotations to the letter from J. D. Hooker, 28 October 1844.
CD was to repeat this question to Hooker and other naturalists. For example, on 28 December 1853, CD noted: Hooker went through the N. Zealand & Tasmanian Flora, & he thinks that all the genera which are variable in Europe are quite as variable in these localities. Hence I must [‘clearly’ del ] give up this kind of generic variability, as any aid in transmutation (DAR 45: 5).
See Correspondence vol. 2, letter from William Herbert, [c. 27 June 1839].
CD met Alexander von Humboldt in January 1842 and made the following note: Jan. 29t h. /42/. Humboldt descanted on remarkable fact (as observed by Gmelin & Pallas) that the *banks of the [interl ] River Oby separates two Floras—on one side 810 of plants same as in Germany with 210 Asiatic—on other side reversed large proportion of Asiatic.— Remarked a similar case with respect to the distribution of oaks in some place, I did not catch up—with Astacus in all the brooks on one side & not on the other: says Bellis perennis extends to a certain limit & then ceases, but it is not the cold, for this plant will flower, [‘far’ del ] within the limits of snow on some mountains— On the Oby there is no geological change——prepossession *of soil [interl ] must here have done much.— [reverse question mark].Have two Floras marched from opposite sides & met here??—strange case.— (DAR 100: 167).
Annotations on CD’s copy of C. Lyell 1837 (Darwin Library–CUL) are discussed in S. Smith 1960.
CD’s copy of Prichard 1836–7 is annotated (Darwin Library–CUL).
Agassiz 1842.
CD’s copy of I. Geoffroy Saint-Hilaire 1841 is annotated (Darwin Library–CUL).
Lamarck 1815–22. CD’s copies of this and the second edition (Lamarck 1835–45) are in the Darwin Library–CUL.
CD’s copy of Lamarck 1830 (volume one only) is in the Darwin Library–CUL. This particular opinion is not found there, but see pp. 223, 235, and 268, where CD has marked Lamarck’s discussion of insect reproduction. See also Notebook C: 63.
Clarke 1842, which was a longer version of a paper read to the Geological Society in 1839 (Clarke 1839).


Arago, Dominique François Jean. 1833. On the ground-ice or the pieces of floating ice observed in rivers during winter. Edinburgh New Philosophical Journal 15: 123–37.

Clarke, William Branwhite. 1839. A notice of showers of ashes which fell on board the Roxburgh, at sea, off the Cape de Verd islands, February, 1839. [Read 6 November 1839.] Proceedings of the Geological Society of London 3 (1838–42): 145–6.

Clarke, William Branwhite. 1842. On the occurrence of atmospheric deposits of dust and ashes; with remarks on the drift pumice of the coasts of New Holland. Tasmanian Journal of Natural Science 1: 321–41.

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

Geoffroy Saint-Hilaire, Isidore. 1841. Essais de zoologie générale, ou mémoires et notices sur la zoologie générale, l’anthropologie, et l’histoire de la science. Paris: Librairie Encyclopédique de Roret.

Lamarck, Jean Baptiste Pierre Antoine. 1830. Philosophie zoologique, ou exposition des considérations relatives à l’histoire naturelle des animaux; à la diversité leur organisation … et les autres l’intelligence de ceux qui en sont doués. New edition. 2 vols. Paris: J. B. Baillière.

Lamarck, Jean Baptiste Pierre Antoine de Monet de. 1815–22. Histoire naturelle des animaux sans vertèbres, présentant les caractères généraux et particuliers de ces animaux, leur distribution, leurs classes, leurs familles, leurs genres, et la citation des principales espèces qui s’y rapportent; précédée d’une introduction offrant la détermination des caractères essentiels de l’animal, sa distinction du végétal et des autres corps naturels, enfin, l’exposition des principes fondamentaux de la zoologie. 7 vols. Paris: Verdière [and others].

Lamarck, Jean Baptiste Pierre Antoine de Monet de. 1835–45. Histoire naturelle des animaux sans vertèbres. 2d ed. 11 vols. Paris.

Notebook C. See de Beer 1960; de Beer and Rowlands 1961; de Beer, Rowlands, and Skramovsky 1967; Notebooks.

Prichard, James Cowles. 1836–7. Researches into the physical history of mankind. 3d edition. 2 vols. London: Sherwood, Gilbert and Piper.

Smith, Sydney. 1960. The origin of ‘The Origin’ as discerned from Charles Darwin’s notebooks and his annotations in the books he read between 1837 and 1842. The Advancement of Science 16: 391–401.


Origin of Antarctic brash ice.

Further on case of Lycopodium: does JDH know any genera of plants whose species are variable in one continent but not in another? Discussion on variations between floras as regards species richness, and factors affecting geographical distribution. On species, CD expects "that I shall be able to show even to sound naturalists that there are two sides to the question of the immutability of species; – that facts can be viewed and grouped under the notion of allied species having descended from common stocks". Mentions books and papers for and against species mutability. CD believes past absurd ideas arose from no one’s having approached subject on side of variation under domestication.

Would like to see Clarke’s paper

and would welcome visit from JDH.

Letter details

Letter no.
Charles Robert Darwin
Joseph Dalton Hooker
Sent from
Source of text
DAR 114: 19
Physical description
ALS 7pp

Please cite as

Darwin Correspondence Project, “Letter no. 789,” accessed on 23 April 2024,

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