SO.][E AMERICAN COLONISTS. 227 



seeds in this countr>^ 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. 



Q2 



