228 MYSTERIES OF THE FLOWERS 



and moved southward before the icy invasion, just 

 as the peoples of Europe fled before the invasion 

 of the Huns, but those Arctic j^lants inured to the 

 cold, and loving the proximity of ice and snow, re- 

 treated in a more orderly fashion and formed a 

 rear-guard against the advance. 



When the Glacial Epoch Avas passing, and the 

 frontier of ice and snow was withdrawing north- 

 ward, the Arctic flora followed closely upon the 

 line of retreat, or climbed to the cool peaks of moun- 

 tains. The 23lants of more tender habits sj)read 

 around the bases of these mountains and followed 

 as far as climate would permit. Thus colonies of 

 Arctic stock were isolated on mountains, yet 

 through long ages keep their close resemblance to 

 kin on distant ranges, or polar plains. The less 

 hardy plants which had moved southward could 

 not, on returning, traverse high and cold mountain 

 barriers. Hence, we see in Europe that the Alps 

 and Apennines, running East and West, were a bar 

 to progress northward, whilst in the United States, 

 where mountain chains run from North to South, 

 no such barriers are opposed and we can thus under- 

 stand why we possess so much richer and more 

 varied flora. 



The epic of flower-wanderings has not yet been 

 written. We should like to know how it came about 



