My dear Hooker

Many thanks about the Lupine. Your letter has interested me extremely & reminds me of old times.¹ I suppose by your writing, you would like to hear my notions. I cannot admit the Atlantis connecting Madeira & Canary Islands without the strongest evidence & all on that side: the depth is so great; there is nothing geologically in the islands favouring the belief; there are no endemic mammals or batrachians;² did not Bunbury shew that some orders of plants were singularly deficient?³ But I rely chiefly on the large amount of specific distinction in the insects & land-shells of P. Santo & Madeira; surely Canary & Madeira c^d not have been connected if Mad. P. Santo had long been distinct.⁴ If you admit Atlantis, I think you are bound to admit or explain the difficulties.

With respect to cold temperate plants in Mad: I of course know not enough to form an opinion; but admitting Atlantis I can see their rarity is a great difficulty; otherwise seeing that the latitude is only a little N. of the Persian Gulph & seeing the long sea transport for seeds, the rarity of N. plants does not seem to me difficult.⁵ The immigration may have been from a Southerly direction & it seems that some few African, as well as coldish plants are common to the M^ts to the South.⁶

Believing in occasional transport, I cannot feel so much surprize at there being a good deal in common to Mad. & Canary; These being the nearest points of land to each other.⁷ It is quite new & very interesting to me what you say about the endemic plants being in so large a proportion rare Species. From the greater size of the workshop (i.e. greater competition & greater number of individuals &c) I sh^d expect that continental forms, as they are occasionally introduced, w^d always tend to beat the insular forms; & as in every area there will always be many forms more or less rare tending towards extinction, I sh^d certainly have expected that in Islands a large proportion of the rarer forms w^d have been insular in their origin.⁸ The longer the time any form has existed in an island, into which continental forms are occasionally introduced, by so much the chances will be in favour of it’s being peculiar or abnormal in nature, & at the same time scanty in numbers. The duration of its existence will also have formerly given it the best chance, when it was not so rare, of being widely distributed to adjoining archipelagos. Here is a wriggle; the older a form is the better the chance will be of its having become developed into a tree!⁹ An island from being surrounded by the sea will prevent free immigration & competition, hence a greater number of ancient forms will survive on an island than on the nearest continent whence the island was stocked; & I have always looked at Clethra & the other extra-european forms as remnants of the tertiary flora which formerly inhabited Europe.¹⁰ This preservation of ancient forms in islands appears to me like the preservation of ganoid fishes in our present fresh waters.¹¹

You speak of no northern plants on mountains south of the Pyrenees; does my memory quite deceive me that Boissier published a long list from the mountains in southern Spain?¹²

I have not seen Woollaston’s catalogue but must buy it, if it gives the facts about rare plants which you mention.¹³

And now I have given more than enough of my notions which I well know will be in flat contradiction with all yours. Remember that you have to come here if you possibly can before Nottingham.¹⁴

Wollaston in his Insecta Maderiensis 4^to. p. xii & in his Variation of Species p. 82– 87 gives case of Apterous insects, but I remember I worked out some additional details. I think he gives in these same works the proportion of European insects.—¹⁵

I sh^d be most grateful for loan of Book with enclosed Title, if you have it; for I presume I could no how else see it—¹⁶

Yours affect | C. Darwin