From J. D. Hooker 2 [March] 1846
Feby 2 1846.2
You are very good to send me Forbes’ letter, which I return with many thanks I am exceedingly glad to have seen it, especially as I could not be at the lecture. Between ourselves I cannot say that the things being put in black & white has tended to fix my ideas: though as you make no comment I may be differently acted upon to what I ought.
It is a notable fact that of all the Irish Flora, only some 10 or 15 are peculiar to that portion of the U.K., & it is the more singular that 10 of those inhabiting the W. coast should be Asturian plants, the majority of them peculiar to the W. of Ireland & Asturias or that part of the Peninsula.3 I cannot account for this by any known probable laws of migration, nor on the other hand was I aware of the xtensive system of changes his theory invoked. It looks exceedingly pretty on paper, but would look more so, if any more of the said 10 plants inhabited the Azores & Madeira, except one. Now though Botanical evidence is in favor of some theory that will bring Asturias &, W. Ireland into closer connection, the same evidence appears to me against bringing Azores & Madeira into the same category, for those Islands ought to possess more than one of these 10 plants. It is true they possess hundreds of other things instead & that their Floras are Mediterranean, but these other things are not Irish & all that argument for their previous connection by land is overwhelmed by their wanting what their mountains ought to have retained & were as likely to have received as those of W. Ireland. I do not know how far my disconnecting the Islands from the same theory that includes Ireland will affect the whole question. I am still inclined to admit any theory that will appear so Botanically reasonable as that proposing the existence of land between Asturias & Ireland the apparent proof of which is drawn from the fact of the very 10 plants which would be likely to have availed themselves of this bridge being found at its opposite ends. But it is Botanically unreasonable to suppose that Azores & Madeira if Island in the same circumstances did not receive the same plants & retain them.
I have little doubt but that the V. D. L. plants found at Illawarra migrated thither from V. D. L. but I should not think so many species would have done so had ocean alone intervened. I may tell you candidly that my mind becomes more made up to be a migrationist than ever, that I have changed in so far that my previous indecision was the other way; but I cannot get over what perhaps you cannot so fully feel, that the only plants peculiar to the W of Ireland are all Asturian, & some of them confined to Asturia. I wish I could talk with you on this subject for I am sure you cannot understand what I have written above.
As for the rest.— Schouw’s 3d Bot. region is very good & proper.4 The Canaries are the transition between that & the Nubian Abyssinian & Sengambia Flora, including the C. D. V.5 To that succeeds the Asiatic Flora xtending from W. Tropical Africa to Java at least; & again to that the Cape Flora.
It is not a very good remark that there is no relation between the Alpine Flora’s N. & S. of the dotted line, (I speak from memory), the fact is, there is little relation between the Alpine Floras of any of the N. Atlantic Islds & those of Europe & that is the worst part I fear of the whole theory. Till we know the Atlas Flora it is dangerous to meddle with the Azores & Madeira. The Mt. Floras of widely separated spots are more similar than the low land ones, & so the Mt. Plants of these Islds. shd be more Spanish than the others, but I fear it is not so, & that whilst the Alpigeni have come from Africa (Atlas) the lowlanders have come from Europe.
As to the great Sargassian bed, that is “all my eye” & I fear will tend to throw discredit on the rest of Forbes work. The idea that it indicates a previously existing line of coast is surely preposterous, & untenable, nor do I think it has the form he gives it in longitude, certainly not in Latitude. The fact is that floating weeds are found all the way between the Sargasso sea & England, & as soon as you enter (on leaving Sargasso) the cold current (from the Newfoundland Banks), abundance of the F. nodones & serratus & canaliulatus are found, & I think I found a bit of one of these (eminently cold country) algæ in company with the Sargassum, certainly very little to the Northward of it. I never doubted but that the Sargassum was floated off from a continent & retained in the “meeting of the waters” at the Sargasso Sea, There is however much to be done regarding that Sargasso sea, there is little doubt but that it is rapidly decreasing, if not changing its place very remarkably, or both. I would like to collect statistics regarding it: please retain any thing you may see.— I cannot object to the Azores being peopled with Europæan plants by means of the Miocene (or Post-Miocene I hardly understand which) land, that may once have united them, but am inclined to look upon their Mt: Floras as of a much more recent nature than those of the Mts. of Spain. Do not however take this as my decided opinion, the question as a Botanical one requires detailed study, which I cannot now give it.
My ideas of my future duties as Bot. Surveyor are so undefined that I cannot say whether I may or may not make an opportunity of going down to Kent, few things would give me so much pleasure as accepting your hearty invitation. As I told Henslowe I took all duplicates from the Gal. Coll. that I dared. If you have nothing else to do with them I would ask them to go to the Paris Herb., who liberally gave me every scrap they could spare of their Galap. scraps. I now remember well that my views of the Sicily flora are Lyells & no doubt unconsciously borrowed from him. I am so apt to take what I read & forget, for my own, when I do remember it, that I cannot doubt Forbes doing so too, but he that publishes must remember. The Appenine fact I long have known & have lately seen it stated by a man of the name of Alexander (I think) a monied dabbler in Europæan Botany, who travels much. 6
Bentham who desires his very kind remembrances, has been talking about Polymorphism with me & we certainly do conclude wholly against Bory. I must define the term Polymorphism as applied to a Flora or genus, as indicating one whose species are difficult of separation & definition. It is in such genera & groups that Volcanic Islds are lamentably deficient, in comparison to continents. Take any Isld. or group of Islds. as St Helena, J. Fernandez, Tasmania even, Sandwich, Galapagos, & their species are admirably defineable & distinct, take the Flora of the same area as any of those occupys’ out of a continent, & in most cases there will be some dozen genera that will drive you crazy. I do think that I may safely dismiss the question but pray do not let me do so if you have any doubt. I have too much respect for nature to force a Botanical hypothesis if at variance with evidence derived from other branches of Nat. Hist.
I am sorry for Cuming, though he has behaved abominably to Botanists & particularly to my Father who paid him once upwards of £700 for himself & friends & with my Mother’s & my aid distributed 13 sets of his S. American plants at no expense to himself, of between 2000 & 3000 species each. I hope that it is not a little that would induce me to think so very ill of anyone as I in common with all Botanists do of Cuming’s meanness to give it the most lenient term. I am truly glad he behaved better about shells & since I heard it have not failed to couple that with my bad opinion of him, when asked.
I have a sister to be married about the 24th in Norfolk,7 which will take me away from my work here earlier that I expected: she is to splice a Scotch Presbyterian clergyman8 to whom she has been long attached & our friends being all in Norfolk, it will take place there, whence she will go to Glasgow for her future abode.
I hope I may congratulate you on your fathers restoration to his usual health & the continuance of your own & Mrs Darwin’s.
Ever most truly Yours | Jos D Hooker
Thanks for Edward Forbes’s letter. Botanical evidence conflicts with parts of his theory but supports others. Is becoming more of a migrationist.
Bentham agrees with JDH on polymorphism.
Please cite as
Darwin Correspondence Project, “Letter no. 958,” accessed on 10 December 2016, http://www.darwinproject.ac.uk/DCP-LETT-958