336 THE ORIGIN OF SPECIES 



migrate — for instance, the millions of quails across the Mediter- 

 ranean — must occasionally transport a few seeds embedded in 

 dirt adhering to their feet or beaks? But I shall have to recur to 

 this subject. 



As icebergs are known to be sometimes loaded with earth and 

 stones, and have even carried brushwood, bones, and the nest of 

 a land-bird, it can hardly be doubted that they must occasionally, 

 as suggested by Lyell, have transported seeds from one part to 

 another of the arctic and antarctic regions; and during the Gla- 

 cial period from one part of the now temperate regions to another. 

 In the Azores, from the large number of plants common to Eu- 

 rope, in comparison with the species on the other island of the 

 Atlantic, 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-born seeds during the Glacial 

 epoch. At my request Sir C. Lyell wrote to M. Hartung to in- 

 quire whether he had observed erratic bowlders 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 burdens on 

 the shores of these mid-ocean islands, and it is at least possible 

 that they may have brought thither some few seeds of Northern 

 plants. 



Considering that these several means of transport, and that 

 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 cur- 

 rents 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, or from a continent to 

 a neighboring island, but not from one distant continent to an- 

 other. The floras of distant continents would not by such means 

 become mingled; but would remain as distinct as they now are. 

 The currents, from their course, would never bring seeds from 

 North America to Britain, though they might and do bring seeds 



