344 HISTORY OF THE EUROPEAN FAUNA. 



a Mediterranean one. The last element is a survival 

 of the Tertiary flora of the Central European plateau 

 (p. 53 2 )- The plants were driven down to the shores 

 of the Mediterranean, and it is only after the retreat 

 of the glaciers that a few of them have been able to 

 regain their ancient territory. The incoming Asiatic 

 and North American flora likewise retired at the end 

 of the Glacial period to the Alps and the Arctic 

 countries, and left isolated traces of its former 

 abundance on the North European plain. The 

 bulk of the Arctic or Alpine flora is held to be 

 of Asiatic origin. Since Siberia shows little trace 

 of having been glaciated, owing to the dryness of the 

 climate, a rich flora was able to develop there, which 

 spread into Europe as soon as the vanishing glaciers 

 made room for it. 



These are the views of Professor Engler and Dr. 

 Christ. They agree in so far as both of them main- 

 tain that the bulk of the Alpine flora is post-glacial 

 that is to say, that it has developed quite 

 recently, or migrated to the Alps after the glaciers 

 had retreated from the plain to the mountain 

 recesses. It is assumed by Dr. Christ that while 

 Europe was practically uninhabitable, a rich flora 

 survived in Northern Asia, because the climate there 

 was too dry for the development of glaciers. Due 

 consideration in this interesting speculation, however, 

 is not given to the fact which he himself emphasised, 

 that Alpine plants are particularly prone to suffer 

 from a dry climate. Even a moderately dry cold 



