THE ALPINE FAUNA. 347 



was to lower the vertical height of the zones of 

 vegetation by from one to two thousand feet." He 

 acknowledges that there was probably a moderate 

 diminution of the mean temperature of Europe with 

 an increased snowfall, so as to cause a great extension 

 of glaciers on all the mountains of Northern Europe. 

 "But that the clim.ate of Middle Europe was such that 

 the plants of the high Alps could spread across the 

 plains seems to me an improbable supposition" 

 (p. 584). 



On the Continent, also, some botanists seem to 

 feel that Forbes's theories of the origin of the 

 Alpine flora, which were at first hailed with such 

 delight, and accepted by almost every naturalist as 

 the final verdict, must be modified in - the light 

 of recent researches. Professor Krasan believes that 

 many plants which now live in the high Alps 

 flourished in pliocene times at sea-level (p. 37). 

 " Especially the evergreen species exhibit the im- 

 pression of an originally mild climate of a climate 

 without winter frosts for otherwise the plants 

 would have developed into species with deciduous 

 leaves." To the favourable conditions, consisting in 

 periodic snowfalls and high summer temperature, 

 must be attributed the fact that in the highlands so 

 many more species from Tertiary times have survived 

 than in the plains. The temperature was probably 

 much higher during the Glacial period than is 

 generally believed. The climate was more moist, 

 thus contributing to an abundant snowfall, while the 



