of such antiquity. Like nations,
the assemblage may be perpetual, while the members that compose it are
constantly perishing, and leaving their places to be supplied by others
of more recent origin. Probably the earth does not contain forests in
which any tree exceeds a thousand years of age, though the oldest forest
extant may be as ancient as the Chinese Empire; for the oldest trees
are not found in dense assemblages, but are probably such as have grown
singly in isolated situations. As soon as a tree in a forest begins to
feel the infirmities of age, its place is usurped by some young and more
vigorous neighbor, and it is gradually deprived of subsistence in this
unequal contest. The tempests and tornadoes, it may be added, which
occasionally sweep over a country, commonly make the oldest and tallest
trees their victims; for events seem to follow the same course in a
forest as in human society. The most vigorous growers at any period
continue to flourish a certain length of time at the expense of others;
but when they have risen above the common level, they become marks for
destruction,--they fall before certain inimical forces that do not reach
their more humble companions.

It was the opinion of Humboldt, that, if any tract of wooded country
deserves to be considered a part of the great "primeval forest", it is
"that boundless district which, in the torrid zone of South America,
connects the river-basins of the Amazon and the Orinoco." This tract,
unequalled in extent by any other forest in the world, occupies an area
of more than a thousand miles square. In this vast chaos of teeming
vegetation, trees of the largest dimensions are connected by an
undergrowth of vines and shrubbery which is almost impenetrable. Immense
rivers and their tributaries intersect the forest in all directions, and
constitute the only avenues of commercial intercourse. This impervious
thicket is like a huge wall, separating near neighbors, rendering them,
as it were, inhabitants of distant regions, and obliging them to make
long and circuitous river journeys before they can hold communication.

Here the leaves of the trees are always green, and flowers appear in
constant succession; but the surface of the ground is without herbage,
for the darkness of the wood is fatal to all humble vegetation. The
small plants are mostly parasites, thousands inserting their roots into
the bark of trees and garlanding them with beauty. Those that take roo