290 SAGACITY AND MORALITY OF PLANTS. 



mountains would be permanently covered with what 

 had been an Arctic flora of the plains, now converted 

 into an Alpine flora. The ancient habitats down 

 below would gradually be occupied by plants better 

 fitted for the changed warmer conditions. They would 

 swarm in like a vegetable tide, to relieve the over- 

 crowding of their metropolitan areas. Such a 

 country might then be subjected to a geological 

 alteration of level, and be completely surrounded by 

 the sea. In which case its mountain sides and hill 

 tops would be occupied by growing Alpine plants of 

 the same species as those found living at the sea- 

 level in higher latitudes, and its plains would be 

 crowded by new-comers which disliked extreme 

 cold, and which had streamed in from quite a dif- 

 ferent quarter to that whence the Arctic flora origin- 

 ally started on a similar invasion, to oust warmth- 

 loving plants of a higher antiquity still ! 



This need not be regarded as a series of mere 

 suppositions. It is a brief but definite outline of the 

 geological and climatal changes through which our 

 English flowering plants have passed since the 

 commencement of the Miocene Period. There are 

 numerous plants, with which most ordinary botanists 

 are familiar, which illustrate both the later geological 

 periods and each of the later geographical changes 

 as well. 



Professor Edward Forbes, long ago, showed that 

 our British flora had come to us from several points 



