se. Most vegetable organisms remain
stationary, while some possess organs of locomotion, and swim about
in the water in a manner much resembling the movements of certain
animals. Most vegetables obtain their nutriment from the earth and the
air, while animals subsist on living matter. A few plants seem to take
organic matter for food, some even catching and killing small insects.

It is found impossible to draw the precise line between animals and
vegetables, for the reason just mentioned. The two kingdoms blend so
intimately that in some cases it is impossible to tell whether a certain
microscopic speck of life is an animal or a vegetable. But since these
doubtful creatures are usually so minute that several millions of them
can exist in a single drop of water, it is usually of no practical
importance whether they are animal or vegetable, or sometimes one and
sometimes the other, as they have been supposed to be by some
biologists.

All living creatures are _organized_ beings. Most possess a structure
and an organism more or less complicated; but some of the lowest forms
are merely little masses of a transparent, homogeneous jelly, known
as protoplasm. Some of the smallest of these are so minute that one
hundred millions of them could occupy the space of a cube one-thousandth
of an inch on each side; yet each one runs its course of life as regularly
as man himself, performing its proper functions even more perfectly,
perhaps.

Life Force.--To every thinking mind the question often recurs, What
makes the fragrant flower so different from the dead soil from which
it grows? the trilling bird, so vastly superior to the inert atmosphere
in which it flies? What subtle power paints the rose, and tunes the
merry songster's voice? To explain this mystery, philosophers of olden
time supposed the existence of a certain peculiar force which is called
life, or vital force, or vitality. This supposition does nothing more
than furnish a name for a thing unknown, and the very existence of which
may fairly be doubted. In fact, any attempt to find a place for such
a force, to understand its origin, or harmonize its existence with that
of other well-known forces, is unsuccessful; and the theory of a
peculiar vital force, a presiding entity present in every living thing,
vanishes into thin air to give place to the more rational view of the
most advanced modern scientists, that vital force, so-called, is only
a manifestation of the ordi