SOME AMERICAN COLONISTS. 227 



seeds in this country, propagating entirely by its lissom 

 floating rootless branches. Still, the area over which it 

 has made its way, and the centres from which it started 

 - Yorkshire, Leicestershire, Berwick, and Edinburgh 

 clearly show (what is otherwise well known) that it 

 owes its introduction to human means : while the spon- 

 taneous occurrence of the other water-plants in a few 

 lonely portions of the western coasts equally suggests 

 that they owe their transplantation solely to birds or 

 ocean-currents. 



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