GEOGRAPHICAL VICISSITUDES OF PLANTS. 293 



Period did not extend southward much, if any, be- 

 yond what is now the Thames ; and also because 

 they find in the mild winters of Cornwall, Devon, 

 and the Channel Islands, a climate similar to that 

 they originally enjoyed, and under whose influence 

 they were perhaps evolved. 



Therefore these southern plants belong to an 

 earlier period. They are " ancient Britons " by com- 

 parison with the northern or Arctic plants ; and 

 even the latter are of much higher antiquity than 

 the main flora of our fields, meadows, and green 

 lanes, which did not occupy England until the 

 Glacial Period had passed away, with its severe 

 cold, and the present climate had been instituted. 

 The area now occupied by the German Ocean was 

 then dry land, through which the river Thames 

 made its way, to be eventually joined by the Rhine, 

 into the North Sea off the Scottish coasts. It was 

 by way of this dry -land connection with Holland 

 and Belgium that our lowland flora reached us from 

 Germany. So that the main army of our common 

 flowering plants are new-comers. They occupy the 

 richest soils, whence they ousted the older and less 

 fitly adapted species — ^just as the Normans possessed 

 themselves of Saxon lands, and the Saxons of the 

 earlier British possessions. It is on our hills and 

 mountains that we find the older Arctic flora of the 

 Glacial Period protected from invasion ; precisely 

 in the same spots that the remnants of the ancient 



