326 ON THE ORIGIN OF SPECIES 



Although the beaks and feet of birds are generally 

 quite clean, I can show that earth sometimes adheres 

 to them : in one instance I removed twenty-two grains 

 of dry argillaceous earth from one foot of a partridge, 

 and in this earth there was a pebble quite as large as 

 the seed of a vetch. Thus seeds might occasionally be 

 transported to great distances ; for many facts could be 

 given showing that soil almost everywhere is charged 

 with seeds. Reflect for a moment on the millions of 

 quails which annually cross the Mediterranean ; and can 

 we doubt that the earth adhering to their feet would 

 sometimes include a few minute seeds ? But I shall 

 presently 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, I can hardly doubt 

 that they must occasionally have transported seeds from 

 one part to another of the arctic and antarctic regions, 

 as suggested by Lyell ; and during the Glacial period 

 from one part of the now temperate regions to another. 

 In the Azores, from the large number of the species 

 of plants common to Europe, in comparison with the 

 plants of other oceanic islands nearer to the mainland, 

 and (as remarked by Mr. H. C.Watson) from the some- 

 what northern character of the flora 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 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 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 the several above means of trans- 

 port, and that several other means, which without 

 doubt remain to be discovered, have been in action 

 year after year, for centuries and tens of thousands of 



