My dear Hooker

I cannot aid you much or at all.¹ I sh^d. think that no one could have thought on the modification of species, without thinking of representative species.— But I feel sure that no discussion of any importance had been published on this subject before the Origin; for if I had known of it, I sh^d. assuredly have alluded to it in the Origin, as I wished to gain support from all quarters. I did not then know of Von Buchs view (alluded to in my Historical Introduction in all the later editions). Von Buch published his “Isles Canaries” in 1836 & he here briefly argues that plants spread over a continent & vary, & the varieties in time come to be species.² He also argues that closely allied species have been thus formed in the separate valleys of the Canary Islands, but not on the upper & open parts.

I have not Baer’s papers, but as far as I remember the subject is not fully discussed. by him.—³

I quite agree about Wallace’s position on the Ocean & Continent question.—⁴

To return to Geograph. Distribution: As far as I know no one ever discussed the meaning of the relation between representative species, before I did & as I suppose Wallace did in his paper before Linn. Soc.⁵ Von Buch’s is the nearest approach to such discussion, known to me.

Ever yours | Ch. Darwin

I could lend you Von Buchs Book if you like: I have just consulted passage