To J. D. Hooker [10 February 1846]1
Down Bromley Kent.
My dear Hooker
I ought to have written sooner to say that I am very willing to subscribe £1s1 to the African man (though it be murder on a small scale) & will send you a Post-office-order payable to Kew, if you will be so good as to take charge of it.2
Thanks for your information about the Antarctic Zoolog. I got my numbers when in town on Thursday: wd it be asking your publisher to take too much trouble to send your Botany to the Athenæum Club: he might send two or three numbers together: I am really ashamed to think of your having given me such a valuable work; all I can say is that I appreciate your present in two ways, as your gift & for its great use to my species-work.— I am very glad to hear that you mean to attack this subject some day: I wonder whether we shall ever be public combatants: anyhow, I congratulate myself in a most unfair advantage of you, viz in having extracted more facts & views from you than from any one other person.
I daresay your explanation of polymorphism on volcanic islds. may be the right one: the reason I am curious about it, is, the fact of the birds on the Galapagos being in several instances very fine-run species;—that is comparing them, not so much one with another, as with their analogues from the continent.— I have somehow felt like you, that an alpine form of a plant is not a true variety; & yet I cannot admit that the simple fact of the cause being assignable ought to prevent its being called a variety: every variation must have some cause so that the difference would rest on our knowledge in being able or not to assign the cause. Do you consider that a true variety should be produced by causes acting through the parent? but even taking this definition are you sure that alpine forms are not inherited for one, two or three generations? Now would not this be a curious & valuable experiment, viz to get seeds of some alpine plant, a little more hairy &c &c than its lowland fellow, & raise seedlings at Kew: if this has not been done, could you not get it done? Have you anybody in Scotland from whom you cd. get the seeds.?
I cannot answer your question about the Purpura or about the currents: western currents flow strongly across the southern half of the group: I have not heard of the observations on the temperature of the sea in the different channels; but I know it varies wonderfully.—
I don’t believe a Cactus ever was seen at the Galapagos 40 ft. high.— 20 or wd be nearer the mark.—
I have been interested by your remarks on Senecio & Gnaphalium: would it not be worth while (I shd. be very curious to hear the result) to make a short list of the generally considered variable or polymorphous genera, as Rosa, Salix Rubus &c &c, & reflect whether such genera are generally mundane & more especially whether they have distinct or identical (or closely allied) species in their different & distant habitats.—
Don’t forget me, if you ever stumble on cases of the same species being more or less variable in different countries.—
With respect to the word “sterile” as used for male or polleniferous flowers, it has always offended my ears dreadfully, on the same principle that it would to hear a potent stallion ram or Bull called sterile, because they did not bear, as well as beget, young.
With respect to your geological-map suggestion, I wish with all my heart I cd follow it, but just reflect on the number of measurements requisite; why at present it could not be done even in England, even with the assumption of the land having simply risen any exact number of feet..— But subsidence in most cases has hopelessly complexed the problem: see what Jordan-hill-Smith says of the dance up & down, many times, which Gibraltar has had all within the recent period.3 Such maps as Lyell has published of sea & land at the beginning of the Tertiary periods4 must be excessively inaccurate: it assumes that every part on which Tertiary beds have not been deposited, must have then been dry land;—a most doubtful assumption.—
I have been amused by Chambers V. Hooker on the K. Cabbage:5 I see in the Explanations6 (the spirit of which, though not the facts, ought to shame Sedgwick)7 that Vestiges considers all land animals & plants to have passed from marine forms; so Chambers is quite in accordance. Did you hear Forbes when here,8 giving the rather curious evidence (from a similarity in error) that Chambers must be the author of the Vestiges: your case strikes me as some confirmation.—9
I have written an unreasonably long & dull letter, so farewell. C. Darwin
Did you extract anything about J. Fernandez from Gay?
Do you take in the Hort. Journal;10 I want much to see first Number.—
Thinks JDH’s explanation of polymorphism on volcanic islands is probably correct.
Proposes experimental test to see whether alpine form of a plant is inherited like a true variety.
Please cite as
Darwin Correspondence Project, “Letter no. 951,” accessed on 20 February 2017, http://www.darwinproject.ac.uk/DCP-LETT-951