GEOGRAPHICAL STATISTICS OF THE EUROPEAN FLORA. 211° 
The comparison indicates that very few of our present Alpine species 
can have been in existence before the glacial age, for if they had then 
fontished, along with the Arctic-alpine species in the circumpolar 
area, We should find them now equally widely spread over the moun- 
tains of the temperate zone. Of 101 Arctic-alpine species 72 (or 71 
per cent.) are found in all the Northern Continents, and 44 (or 43 per 
cent.) are common to the mountains of the Old and New Worlds; but 
of Alpine plants none are ‘‘universal,’”’ and only 2 (or + per cent.) 
are found on both sides the Atlantic. With the exception of these 
two species, and possibly some few others which extend from the Alps 
to the Himalayas, or even to the Baikal mountains, Alpine species 
are of so limited a range that we cannot conceive their existence 
before the ae age. Again, if they came into sper ela 
is in the other. ‘I'he comparison between gave now found only 
Species. Average. 
404 Alpine, above cereal line . é . Begs by of 
4752 Sonthern, below cereal line . ‘ cae 
This betokens that at any rate a great many of the Alpine species 
have originated since the isolation of the mountain ranges. . 
however, are common to the Alps eo BE as or to the Alps and 
the mountains of E. Europe and Asia Minor, or even occur on all. 
Respecting these wider rangers three Keoniseenbe suggest themselves :— 
1. They may have originated while the climate - S. Europe was still 
oe severe to admit of their ranging over the low country, 
ing there with the older Arctic-alpine eis which had come 
Stim we - th Returning warmth would drive them upwards o 
to the , where they may have succeeded in entablishing 
themselves, ‘ot have failed to accomplish the longer journey n north- 
ards. That some such extinctions would d take place amongst the 
tents to the North is but natural, “! they would be 
a 
been ee ae ssgtialicoc pg 
Which of these three explanations is the correct - 1 will not 
ie 
