GEOGRAPHICAL DISTRIBUTION 157 



imbedded 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 thej must occasionally, as suggested by 

 Lyell, have transported seeds from 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 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 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 0. Lyell wrote to M. Hartung 

 to inquire 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 ice- 

 bergs 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 dis- 

 covered, 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 trans- 

 ported. These means of transport are sometimes called 

 accidental, but this is not strictly correct: the currents 



