To J. D. Hooker   [16 April 1846]

My dear Hooker

It would give me great pleasure to help you even in the construction of a sentence, though if you knew what a bad hand I am in building my own, you would apply to some better workman.— I find I am more disabled than usual in this instance from not knowing the precise facts.— In many respects I like your expression centrifugal, & it is a striking one which is a great advantage; I would use “centrifugally” & avoid the word force.— I doubt more about “centripetal”, as it appears that the Gnaphaliums tend to revert to more than one centre or type. I presume in the case of Senecio you actually mean that the species differ in rough proportion to the distance from some one country inhabited by your typical form; if you mean that the groups of species differ in different countries in proportion to their distances apart, I w^d certainly altogether avoid “centrifugal”, as it irresistibly leads the mind to one type & tends to the notion of one central spot whence the species have spread; in this case one naturally wishes to know what is your typical form, & what is its country.— The whole case strikes me as eminently curious.— Shall you elsewhere enlarge on Gnaphalium? I do not quite understand why you state that the species return in each country to a few typical forms, instead of supposing that the same typical forms have been originally widely spread, & have in each country varied a little.—¹

I wish with all my heart I could aid you; I am often myself driven half-desperate over a paragraph.— I have made one or two most trifling pencil suggestions: I do not understand what you mean by “its recognized states”.—

I shall be proud to append my name to your certificate on Wednesday.—² I shall not be able to return your Books quite so quickly as I anticipated, as Bailliere has no copy of M. Tandon.³

Ever yours | C. Darwin

Would it not be adviseable when you remark on the confined ranges of species of Senecio, though belonging to a genus, of univers⁠⟨⁠al⁠⟩⁠ diffusion & numerous in species,—to point out why this is remarkable, viz in as much as the species of most genera which are large in number & have very wide ranges have themselves wide ranges.—⁴