stlings, are destroyed by birds and
beasts of prey; we do not always bear in mind that though food may be
now superabundant, it is not so at all seasons of each recurring year.

I should premise that I use this term in a large and metaphorical sense,
including dependence of one being on another, and including (which is
more important) not only the life of the individual, but success in
leaving progeny. Two canine animals, in a time of dearth, may be truly
said to struggle with each other which shall get food and live. But a
plant on the edge of a desert is said to struggle for life against the
drought, though more properly it should be said to be dependent on the
moisture. A plant which annually produces a thousand seeds, of which
only one on an average comes to maturity, may be more truly said to
struggle with the plants of the same and other kinds which already
clothe the ground. The mistletoe is dependent on the apple and a few
other trees, but can only in a far-fetched sense be said to struggle
with these trees, for if too many of these parasites grow on the same
tree, it languishes and dies. But several seedling mistletoes, growing
close together on the same branch, may more truly be said to struggle
with each other. As the mistletoe is disseminated by birds, its
existence depends on them; and it may metaphorically be said to struggle
with other fruit-bearing plants, in tempting the birds to devour and
thus disseminate its seeds. In these several senses, which pass into
each other, I use for convenience's sake the general term of Struggle
for Existence.

THE GEOMETRICAL RATIO OF INCREASE

From 'Origin of Species'

A struggle for existence inevitably follows from the high rate at which
all organic beings tend to increase. Every being which during its
natural lifetime produces several eggs or seeds must suffer destruction
during some period of its life, and during some season or occasional
year; otherwise, on the principle of geometrical increase, its numbers
would quickly become so inordinately great that no country could
support the product. Hence, as more individuals are produced than can
possibly survive, there must in every case be a struggle for existence,
either one individual with another of the same species, or with the
individuals of distinct species, or with the physical conditions of
life. It is the doctrine of Malthus applied with manifold force to the
whole animal and vegetable kingdoms; for