To J. D. Hooker   28 January [1859]

My dear Hooker

Thanks about Glaciers. It is a pleasure & profit to me to write to you, & as in your last you have touched on naturalised plants of Australia, I suppose you would not dislike to hear what I can say in answer. At least I know you would not wish me to defer to your authority, as long as not convinced.—

I quite agree to what you say about our agragrian ¹ plants being accustomed to cultivated land & so no fair test: Buckman has I think published this notion with respect to N. America.—² With respect to road-side plants I cannot feel so sure that these ought to be excluded, as animals make roads in many wild countries.—

I have now looked & found passage in F. Müllers letter to me, in which he says In the wildernesses of Australia some Europaean perennials are “advancing in sure progress” “not to be arrested” &c.— he gives as instances (so I suppose there are other cases) eleven species. viz 3 Rumex Poterium sanguisorba— Potentilla anserina, Medicago sativa, Taroxicum officinale, Marubium vulgare. Plantago lanceolata P. major, Lolium perenne.— All these are seeding freely.—³

Now I remember years & years ago your discussing with me how curiously easily plants, get naturalised on uninhabited isl^d, if ships ever touch there: I remember we discussed packages being opened with old hay or straw &c.— Now think of Hides & wool (& wool exported largely over Europe) & plants introduced & samples of corn; & I must think that if Australia had been the old country, & Europe had been the Botany Bay very few, very much fewer Australian plants would have run wild in Europe, than have now in Australia.— The case seems to me much stronger between La Plata & Spain.— Nevertheless I will put in my one sentence on this head, illustrating the greater migration during Glacial period from N. to S. than reversely, very humbly & cautiously.—⁴

I am very glad to hear you are making good progress with your Australian Introduction.— I am, thank God, more than half through my Ch. on Geograph. Distrib. & have done the abstract of Glacial part.—

I am disgusted at A. De Candolle. How a man can think a begged honour, worth having I cannot understand! I sh^d. have thought his claims above A. Grays; but of course do not hesitate a second after what you say, & if consulted by anyone, will so express myself.—⁵

I never did pick anybody’s pocket, but whilst writing my present chapter I keep on feeling, (even when differing most from you!) just as if I were stealing from you, so much do I owe to your writings & conversations; so much more than mere acknowledgments show.—

Farewell my dear Hooker | Yours ever | C. Darwin

With respect to Nilgherri it is not worth explaining—but I sh^d. look at an Australian plant settling in the great northern temperate Workshop, as a greater victory than on a mountain-summit or mere island on the land—but this is perhaps mere hair-splitting—

I have been skimming through Griffiths Indian Travels, which are too purely & technically Botanical for me.⁶ And I have been astounded at his admiration of Swainson; says he will get his Rules framed & follow them implicitly—that number is everything.—⁷ This is “humbling” with a vengeance.—