6o Flowers and their Pedio;rees. 



passed av/ay. For the ice had driven man and beast, 

 herb and tree, southward before it ; and even if there 

 was a Httle fringe of what is now Southern Britain not 

 wholly glaciated, yet its condition must have been 

 like that of the little habitable fringe in Greenland, 

 and its plants and animals (if any) must have been of 

 thoroughly Arctic types. But as the glaciers cleared 

 away again, with the return of the sun to the northern 

 hemisphere after its long cold cycle, the southern and 

 eastern plants and animals must have followed the 

 retreating ice-sheet from year to year ; till at last the 

 species which used to inhabit Kent and the Isle of 

 Wight found their permanent home in Lapland, and 

 those which used to inhabit Greece and Italy found 

 their permanent home in Holland, Denmark, and 

 Great Britain. 



This sufficiently accounts for the presence in 

 England and Scotland of the central European and 

 Scandinavian elements ; but it does not account for 

 the presence of my hairy spurge and of all the other 

 south-western species, belonging to the Pyrenean and 

 Italian region. Clearly, the ordinary plants of Eastern 

 England are plants which once spread uninterruptedly 

 from Warwickshire to Central L^urope, when the belt 

 of land over the German Ocean was still entire ; and 

 clearly, too, the ordinary plants of the North and of 



