Origin of Species Variorum

one part to another of the arctic and antarctic regions; ... and during the Glacial period from one part of the now temperate regions to another. In the Azores, from the large number of ... plants common to Europe, in comparison with the species in the other Atlantic islands which stand nearer to the mainland, and (as remarked by Mr. H. C. Watson) from their somewhat northern character ... in comparison with the latitude, I suspected that these islands had been partly stocked by ice-borne seeds, during the Glacial epoch. At my request Sir C. Lyell wrote to Mr. Hartung to inquire whether he had observed erratic boulders on these islands, and he answered that he had found large fragments of granite and other rocks, which do not occur in the archipelago. Hence we may safely infer that icebergs formerly landed their rocky burthens on the shores of these mid-ocean islands, and it is at least possible that they may have brought thither the seeds of northern plants.

Considering that these several .. means of transport, and that several other means, which without doubt remain to be discovered, have been in action year after year, for .. tens of thousands of years, it would I think be a marvellous fact if many plants had not thus become widely transported. These means of transport are some-times called accidental, but this is not strictly correct: the currents of the sea are not accidental, nor is the direction of prevalent gales of wind. It should be observed that scarcely any means of transport would carry seeds for very great distances; for seeds do not retain their vitality when exposed for a great length of time to the action of sea-water; nor could they be long carried in the crops or intestines of birds. These means, however, would suffice for occasional transport across tracts of sea some hundred miles in breadth, or from island to island,