nts is the same as
that of different degrees of latitude; and the slope of a high mountain
in the Tropics, from base to summit, presents, in a condensed form, an
epitome, as it were, of the same kind of gradation in vegetable growth
that may be observed from the Tropics to the Arctics. At the base of
such a mountain we have all the luxuriance of growth characteristic
of the tropical forest,--the Palms, the Bananas, the Bread-trees, the
Mimosas; higher up, these give way to a different kind of growth,
corresponding to our Oaks, Chestnuts, Maples, etc.; as these wane, on
the loftier slopes comes in the Pine forest, fading gradually, as it
ascends, into a dwarfish growth of the same kind; and this at last gives
way to the low creeping Mosses and Lichens of the greater heights, till
even these find a foothold no longer, and the summit of the mountain is
clothed in perpetual snow and ice. What have we here but the same series
of changes through which we pass, if, travelling northward from the
Tropics, we leave Palms and Pomegranates and Bananas behind, where the
Live-Oaks and Cypresses, the Orange-trees and Myrtles of the warmer
Temperate Zone come in, and these die out as we reach the Oaks,
Chestnuts, Maples, Elms, Nut-trees, Beeches, and Birches of the colder
Temperate Zone, these again waning as we enter the Pine forests of
the Arctic borders, till, passing out of these, nothing but a dwarf
vegetation, a carpet of Moss and Lichen, fit food for the Reindeer and
the Esquimaux, greets us, and beyond that lies the region of the snow
and ice fields, impenetrable to all but the daring Arctic voyager?

I have thus far spoken of the changes in the vegetable growth alone as
influenced by altitude and latitude, but the same is equally true of
animals. Every zone of the earth's surface has its own animals, suited
to the conditions under which they are meant to live; and with the
exception of those that accompany man in all his pilgrimages, and are
subject to the same modifying influences by which he adapts his home and
himself to all climates, animals are absolutely bound by the laws of
their nature within the range assigned to them. Nor is this the case
only on land, where river-banks, lake-shores, and mountain-ranges might
be supposed to form the impassable boundaries that keep animals within
certain limits; but the ocean as well as the land has its faunae and
florae bound within their respective zooelogical and botanical provinces