96 HIGH LIFE. 



northward toward the pole in great abundance. Now, 

 how did this little colony of chilly insects get separated 

 from the main body, and islanded, as it were, on a 

 remote mountain-top in far warmer New Hampshire ? 



The answer is, they were stranded there at the end of 

 the Glacial epoch. 



A couple of hundred thousand years ago or there- 

 abouts don't let us haggle, I beg of you, over a few 

 casual centuries the whole of northern Europe and 

 America was covered from end to end, as everybody 

 knows, by a sheet of solid ice, like the one which 

 Frithiof Nansen crossed from sea to sea on his own 

 account in Greenland. Eor many thousand years, with 

 occasional warmer spells, that vast ice-sheet brooded, 

 silent and grim, over the face of the two continents. 

 Life was extinct as far south as the latitude of New 

 York and London. No plant or animal survived the 

 general freezing. Not a creature broke the monotony of 

 that endless glacial desert. At last, as the celestial 

 cycle came round in due season, fresh conditions 

 supervened. Warmer weather set in, and the ice began 

 to melt. Then the plants and animals of the sub-glacial 

 district were pushed slowly northward by the warmth 

 after the retreating ice-cap. As time went on, the cli- 

 mate of the plains got too hot to hold them. The summer 

 was too much for the glacial types to endure. They 

 remained only on the highest mountain peaks or close to 

 the southern limit of eternal snow. In this way, every 

 isolated range in either continent has its own little 

 colony of arctic or glacial plants and animals, which still 

 survive by themselves, unaffected by intercourse with 



