4l€ ORIGIN OF SPECIES 



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

 terranean — 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 

 form one part to another of the arctic and antarctic regions ; 

 and during the Glacial period from one part of the now tem- 

 perate regions to another. In the Azores, from the large 

 number of plants common to Europe, in comparison with the 

 species on the other islands of the Atlantic, which stand 

 nearer to the mainland, and (as remarked by Mr. H. C. 

 Watson) from their somewhat northern character in com- 

 parison 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 M. 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 archi- 

 pelago. 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 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 sometimes 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, or from a continent to a 



