158 THE ORIGIN OF SPECIES 



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 another. The floras of distant 

 continents would not by such means become mingled; 

 but would remain as distinct as they now are. The cur- 

 rents, from their course, would never bring seeds from 

 North America to Britain, though they might and do 

 bring seeds from the West Indies to our western shores, 

 where, if not killed by their very long immersion in salt 

 water, they could not endure our climate. Almost every 

 year, one or two land -birds are blown across the whole 

 Atlantic Ocean, from North America to the western 

 shores of Ireland and England; but seeds could be 

 transported by these rare wanderers only by one means, 

 namely, by dirt adhering to their feet or beaks, which is 

 in itself a rare accident. Even in this case, how small 

 would be the chance of a seed falling on favorable soil, 

 and coming to maturity! But it would be a great error 

 to argue that because a well-stocked island, like Great 

 Britain, has not, as far as is known (and it would be 

 very difficult to prove this), received within the last few 

 centuries, through occasional means of transport, immi- - 

 grants from Europe or any other continent, that a " 

 poorly-stocked island, though standing more remote from 



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