--^these remnants of a past multitudinous vegeta- 

 tion, ever since they were allowed to exist and 

 perpetuate their kind, have been obliged to wage 

 war upon neighbors from generation to generation, 

 in order to gain or retain a foothold, resorting to 

 changes of ground, of character, or weapons, in 

 order to win in the incessant battle of life. 



PROOFS OF DOUBLE MIGRATION. 



That the plants have made the double journey 

 described is plainly proved by the characters of 

 alpine plants on high peaks of the North Temper- 

 ate Zone. They are found to be identical with 

 Arctic plants. Now they could not have passed 

 from northern regions directly to these summits 

 during the southern flight, for the reason that both 

 Arctic regions and these mountain tops were being 

 slowly covered simultaneously, with snow, soon 

 becoming permanent ice. Manifestly cold-loving 

 plants our Alpine plants could ascend mountains 

 only when fleeing from torrid heat, and exactly 

 that condition was experienced on the return 

 journey; so here on all the peaks of the North 

 Temperate Zone are stranded Arctic species of 

 plants, with less northern families established 

 on the slopes of the mountains. 



GREAT FOREST OF THE NQRTHWEST. 



It has been stated that Europe and Asia were 

 deprived of their quota of plants by the many long 

 transverse ranges of mountains preventing the 

 passing of plants north or south, except through 

 the wide gaps between ranges; while North Amer- 



(10) 



