than any of the other forms of animated life, which, like him, are
nourished at the table of bounteous nature.

In the rudest stages of life, man depends upon spontaneous animal and
vegetable growth for food and clothing, and his consumption of such
products consequently diminishes the numerical abundance of the species
which serve his uses. At more advanced periods, he protects and
propagates certain esculent vegetables and certain fowls and quadrupeds,
and, at the same time, wars upon rival organisms which prey upon these
objects of his care or obstruct the increase of their numbers. Hence the
action of man upon the organic world tends to derange its original
balances, and while it reduces the numbers of some species, or even
extirpates them altogether, it multiplies other forms of animal and
vegetable life.

The extension of agricultural and pastoral industry involves an
enlargement of the sphere of man's domain, by encroachment upon the
forests which once covered the greater part of the earth's surface
otherwise adapted to his occupation. The felling of the woods has been
attended with momentous consequences to the drainage of the soil, to the
external configuration of its surface, and probably, also, to local
climate; and the importance of human life as a transforming power is,
perhaps, more clearly demonstrable in the influence man has thus exerted
upon superficial geography than in any other result of his material
effort.

Lands won from the woods must be both drained and irrigated; river-banks
and maritime coasts must be secured by means of artificial bulwarks
against inundation by inland and by ocean floods; and the needs of
commerce require the improvement of natural and the construction of