latitudes. Many European species of plants
and animals would probably perish in consequence, because the mean
temperature would be greatly lowered; and others would fail in America,
because it would there be raised. On the other hand, in places where the
mean annual heat remained unaltered, some species which flourish in
Europe, where the seasons are more uniform, would be unable to resist
the greater heat of the North American summer, or the intenser cold of
the winter; while others, now fitted by their habits for the great
contrast of the American seasons, would not be fitted for the _insular_
climate of Europe. The vine, for example, according to Humboldt, can be
cultivated with advantage 10 degrees farther north in Europe than in North
America. Many plants endure severe frost, but cannot ripen their seeds
without a certain intensity of summer heat and a certain quantity of
light; others cannot endure a similar intensity either of heat or cold.

It is now established that many of the existing species of animals have
survived great changes in the physical geography of the globe. If such
species be termed modern, in comparison to races which preceded them,
their remains, nevertheless, enter into submarine deposits many hundred
miles in length, and which have since been raised from the deep to no
inconsiderable altitude. When, therefore, it is shown that changes in
the temperature of the atmosphere may be the consequence of such
physical revolutions of the surface, we ought no longer to wonder that
we find the distribution of existing species to be _local_, in regard to
_longitude_ as well as latitude. If all species were now, by an exertion
of creative power, to be diffused uniformly throughout those zones where
there is an equal degree of heat, and in all respects a similarity of
climate, they would begin from this moment to depart more and more from
their original distribution. Aquatic and terrestrial species would be
displaced, as Hooke long ago observed, so often as land and water
exchanged places; and there would also, by the formation of new
mountains and other changes, be transpositions of climate, contributing,
in the manner before alluded to, to the local extermination of
species.[184]

If we now proceed to consider the circumstances required for a _general_
change of temperature, it will appear, from the facts and principles
already laid down, that whenever a greater extent of high land is
collected in the p