To J. D. Hooker 24 December 
My dear Hooker.
I am going to amuse myself by scribbling a bit to you about your last long letter.1 But first you must congratulate me in your mind when you hear that I have sent M.S. (such an awful, confounded pile, two volumes I much fear) of “Domestic Animals & Cult. Plants” to Printers.2 I am now writing concluding chapter, & shall perhaps insert, but am much perplexed on this head, a Chapt. on Man; just to say how I think my views bear on him.—3
We have all the Boys at home & are very jolly, & William has come for 3 days.4 He has brought back the Introduction to Australian Flora, after having read it over three times & liked it extremely. I mention this because it shows how interesting & valuable a book you might produce for general readers on Insular Floras.5 I feel, however, sure that you will grapple with this work now.— I see in Müllers letter that I assumed without any grounds that the Adenanthera was a native Brazilian plant:6 it is not worth enquiring in India about, though it is a perplexing case, for I can hardly admit your wriggle of the seeds being devoured by birds with weak gizzards: at least soaking for 10 hours in a little warm water got out hardly anything soluble from one of the seeds. Yet I must believe that they hang long on the tree & look so gaudy to attract birds.—7
I read aloud your simile of H. Spencer to a thinking pump, & it was unanimously voted first-rate, & not a bit the worse for being unintelligible.8
One word more about about the flora derived from supposed pleistocene Antarctic Land, requiring land intercommunication, this will depend much, as it seems to me, upon how far you finally settle whether Azores, Cape de Verdes, Tristan d’Acunha, Galapagos Juan Fernandez &c &c &c have all had land intercommunication. If you do not think this necessary might not New Zealand &c have been stocked during intervening glacial period by occasional means from Antarctic Land?9 As for lowlands of Borneo being tenanted by a moderate number of temperate forms during Glacial period, so far from appearing a “frightful assumption”, that I am arrived at that pitch of bigotry that I look at it as proved!10
I had another letter from Fritz Müller yesterday & in one day’s collecting he found six genera of dimorphic plants! One is a Plumbago.—11 Now have you seed of any species; I see none are on sale in Carter’s list.12 I want a second favour; could you lend me for short time a recent number of Revue Horticole, with an account by Carrière of curious effect of grafting an Aria, given in last Gard. Chronicle.—13
Yours affect | C. Darwin
Has finished Variation. May insert a chapter on man.
Still puzzled by seeds of Adenanthera.
New Zealand and Borneo flora problems continued.
Fritz Müller found six genera of dimorphic plants in one day.
Please cite as
Darwin Correspondence Project, “Letter no. 5321,” accessed on 26 May 2016, http://www.darwinproject.ac.uk/DCP-LETT-5321