Warm, dank, low-lying lands,
bathed by warm oceans and steeped in their vapours, are the
picture suggested-- as we shall see more closely--to the minds of
all geologists. In those happy conditions the primitive life of
the earth erupts into an abundance and variety that are fitly
illustrated in the well-preserved vegetation of the forest. And
when the earth has at length flooded its surface with this
seething tide of life; when the air is filled with a thousand
species of insects, and the forest-floor feels the heavy tread of
the giant salamander and the light feet of spiders, scorpions,
centipedes, and snails, and the lagoons and shores teem with
animals, the Golden Age begins to close, and all the
semi-tropical luxuriance is banished. A great doom is pronounced
on the swarming life of the Coal-forest period, and from every
hundred species of its animals and plants only two or three will
survive the searching test.
CHAPTER X. THE PERMIAN REVOLUTION
In an earlier chapter it was stated that the story of life is a
story of gradual and continuous advance, with occasional periods
of more rapid progress. Hitherto it has been, in these pages, a
slow and even advance from one geological age to another, one
level of organisation to another.
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