My dear Darwin

I had the pleasure of receiving your last welcome letter the morning after my arrival & thank you much for it. Wilkes you may return at your convenience, either sending it to Hiscock’s Kew boat Hungerford Stairs, or by Parcel’s delivery Co^y., the former is, if any thing, the most convenient, but it makes little matter. I quite agree with you in your opinion of (what I have read of) Forbes’ Alps, it is written in a vigorous & manly style, he appears at once the naturalist & traveller & though personally unacquainted either with him or his friends, I look forward with much pleasure to making his acquaintance in Edinbro’. His glacier theory¹ is I believe much disputed, especially by Sedgewick & Hopkins of Cambridge,² at least I judge so from what a young Cambridge friend told me some time back; true or false it has the merit of great originality & certainly it is “not a bad idea”.— D’Urville you shall have the moment it arrives, the more willingly because I do not like a new bought book to be idle, & I have no time to look into it myself; how foolish I must look to you for having bought books I have no time to read, but my present circumstances must be plead as some excuse.

With regard to Morphology (Vegetable) the best work I know is S^t. Hilaire’s “Lecons de Botanique comprenant principalement la Morph. Veg. &c” Paris 2 Parts.—P. J. Loss. 10 Rue Hautefeuille—1841.³ I shall send you a little pamphlet on the Doctrine, written by the man “Murray”, which will I hope have a salutary effect on your course of study..⁴ I see it will go by post & so it will prepare you for the subject. By the bye, Decaisne of Paris wrote to Lindley asking him about the transmutation of Cerealia, & the latter wrote back word that he did not believe in the change at all.. this rather surprized me I must confess, for though Lindley has never actually avowed himself a believer, the tenor of his communications apparently shewed him to be one, & this full recantation to a foreigner makes me think him not very candid to us his country men.

From all that I heard at Leyden, the Indian Islands seem not only to be peculiarly rich in species, but also to present many curious facts regarding the distribution of the individuals & species in the different localities. I talked much with Schlegel,⁵ who appears a very nice fellow, he is strongly in favor of a multiple creation & against migration, & as he drew most of his arguments from Zoological grounds, I could not follow him well, he says he has long studied the subject & has come to that conclusion after a full consideration of the number of cases, in which a species is common to two narrow areas seperated by large tracts equally capable to all appearance of supporting the said species: from what I know of the Botany of these regions I incline decidedly to the migration principle, the number of dispersed species being very great & belonging to very transportable orders. Blume⁶ told me that the Bos (bubalus?) of Java is decidedly the same as that of India, but that the species is nowhere found (not even fossil) in Sumatra, the high road to Java if it migrated: this is to me startling but Blume may be mistaken, or Bos may have been imported by the Javanese, a very different & more energetic people I suppose than the Sumatrans: I did not think of this latter explanation when with Blume, but Horsfield⁷ would doubtless solve the difficulty.

The Holland Botanists are Miquel of Rotterdam, a most agreeable person & accomplished Botanist,⁸ Blume of Leyden who has published a most beautiful work & knows the plants of Java well,⁹ & de Vriese of Amsterdam,¹⁰ all these, & to the first I attach some importance, are strong anti-migrationists. I do not think however that the subject has engrossed much of their attention— I have set Miquel to collect facts for you, which will probably lead to the modification of his own opinions, as a similar course did of mine. Certainly the further I trace a diffused species, the more natural its voyages seem & there are remarkably few plants that inhabit all countries, they are the exceptions. Schouw was one of the first, I think, who proposed a double creation amongst plants, & attributed the reappearance of a species in a remote spot to similar momenta cosmica (or some such name) influencing both spots, or rather producing the same form in both.¹¹ Unfortunately for his theory, besides these plants being the exceptions in the flora of a country, we further have dispersed species abounding under circumstances where all the momenta that we can appreciate are opposite. Except S^t. Helena & the Galapagos there are few spots not largely indebted to neighbouring lands for their vegetable productions. I do not know Owens opinion upon these subjects, nor do I like to ask him, for I never propose such subjects to these master minds without being soon convinced of the feebleness of my own reasoning in such matters: indeed my own opinion is wholly formed upon the arguments of others & I shall be quite content to be a gatherer of facts for you to work with. I advanced the subject with great trepidation to Brown the other day, & found him a strong migrationist, he quoted Schouw & shewed the folly of his reasoning by adducing the opposite characters of the vegetation of the temperate regions of the 2 hemispheres, though the momenta cosmica were similar, whilst at the same time there were so many species common to the two as to render it probable that had their appearance been owing to such a cause the whole vegetation would naturally have followed the impulse. he further alluded to the borowed nature of the flora of the S. Sea Islands & the plants of the coral reefs being such as are the most easily transported by birds winds & waves. I certainly cannot account for plants which put themselves to the trouble of going from the American Continent to New Zeald & L^d. Auckland group, not also visiting Tasmania; but there is no accounting for tastes!—

I shall not go N.¹² till the beginning of May I hope, & have quite a month full of work before that, Graham & Brown are trying to get me appointed as Assist. & Successor.¹³

S^t. Hilaire is perhaps too much upon pure Morphology for you, I will look out for a book on Monsters which is I suppose what you want, such things are generally the subject of detached monographs, of which there are several in the Ann. Sc. Nat. of considerable interest. if I was going to stay at home I would hunt them up by degrees. At present I do not see how we are to get your mss from Ehrenberg & the blocks from Devilbach but must wait a little, I expect to hear from Klotssczch soon & perhaps Schomburgk will take charge of them.. Reinwardt¹⁴ at Leyden asked most particularly after you, as did Schlegel, but I could tell neither of them how you are.—Why?

Ever your’s most truly | Jos D Hooker.

My pamphlet on variations of species has not yet arrived from Paris where I left it.. ¹⁵