HISTORY OF PLANTS. 3843 
of flat countries. Wherever primitive rocks sur- 
round a plain country, we find all the plants of this at 
their root and even at their summits. But after ascend- 
ing and descending on the opposite side, we find a 
different vegetation, which again extends as far as 
the next mountainous chain. ‘The lists of plants of 
the different countries of Europe and other parts of 
the globe will be of great service to us to prove 
this fact. Now, who will doubt, that all the plants 
. of flat countries, which were formed at a later pe- 
riod, came from the high mountains, and that the 
primitive mountains of our globe, were the chiet 
sources, aS it were, of the floras of different coun- 
tries. Hence America is so full of plants, because 
from the North Pole to the South, high mountainous 
chains, with numberless intermediate branches, in- 
tersect it. Hence Canada produces different plants 
from Pennsylvania, this again from Virginia, this 
again different plants from Carolina, and Carolina 
from Florida, &c. Hence the north-west coast of 
North America produces plants which totally differ 
from those of the north-east coast, the south-west 
coast different plants from those of the south-east. 
Islands which are quite flat, have all the plants of 
the neighbouring continent, but if they are sur- 
rounded by high mountains, many quite peculiar 
plants are to be found in them. 
It would appear from these facts, that the vege- 
table kingdom did not suffer materially from all 
those very violent catastrophes. Perhaps those 
changes took place only gradually, and several 
thousands of years, 1f not more, elapsed before all 
things 
