THE BEGIITSIXGS OF SPKING. 23 



northward again as the ice melted. When the connect- 

 ing lands were washed away by the waves, or submerged 

 by alterations of level, the arbutus, the lobelia, and the 

 scented heath would be stranded, so to speak, in a few 

 warm corners of England, Wales, or Ireland, and would 

 be separated by many miles from all other specimens of 

 their race elsewhere. In some cases, no doubt, they 

 would be killed off by the intrusive Scandinavian forms, 

 which always show a singular power of living down all 

 opposition ; and as still warmer types would finally oc- 

 cupy the lowlands of southern France, when the ice age 

 was .quite over, it happens now that these insulated plants 

 live in the mountain districts only the Pyrenees, Au- 

 vergne, and the Mediterranean islands, as well as in the 

 hill regions .of Kerry and Cornwall. The warmth de- 

 rived from the Gulf Stream and the insular position has 

 put the west coasts of our islands on a practical equality 

 with mountain-countries many degrees south of them. 

 The same climatic peculiarities which make the horse- 

 chestnuts bud a month earlier in the valley below me 

 than on the east coast have enabled the hairy spurges to 

 live on for ages among the combes and dells of this 

 broken oolitic down, in spite of their total separation 

 from the main body of their congeners elsewhere. Warm 

 nooks like Bath and Bournemouth, in fact, form as it 

 were climatic islands in the midst of our average British 

 temperature ; while in the sheltered spots of the Isle of 

 Wight the Italian arum and the woodland calamint live 

 on as wild plants, whereas they have long since been 

 totally extinguished by the cold in all the rest of Eng- 

 land. 



