decay, ferment, but do not putrefy, and which, on
being subjected to analysis, furnish an excess of carbon and no
nitrogen. The powers of chemistry, and of the microscope, however,
instead of confirming these views, tend more and more to show that a
still closer affinity exists between plants and animals; for it is now
ascertained that nitrogen, which was believed to be present only in
animals, enters largely into the composition of plants also. When the
microscope is brought to aid our powers of observation, we find that
there are organized bodies belonging to the vegetable kingdom which
possess very evident powers of locomotion, and which change about in so
very remarkable a manner, that no other cause than that of volition can
be assigned to it." Thus it would seem that, in this particular at
least, some vegetables bear a very close resemblance to animal life; and
when we consider the manner in which they are supplied with nourishment,
and perform the functions of their existence, the resemblance would seem
still closer. If, for example, we take a thin transverse slice of the
stem of any plant, or a slice cut across its stem, and immerse it in a
little pure water, and place it under a microscope, we will find that it
consists principally of cells, more or less regular, and resembling
those of a honeycomb or a network of cobweb. The size of these varies in
different plants, as it does in different parts of the same plant, and
they are sometimes so minute as to require a million to cover a square
inch of surface. This singular structure, besides containing water and
air, is the repository or storehouse of various secretions. Through it,
the sap, when produced, is diffused sideways through the plant, and by
it numerous changes are effected in the juices which fill its cells. The
forms of the cells are various; they are also subject to various
transformations. Sometimes a number of cylindrical cells are laid end to
end, and, by the absorption of the transverse partitions, form a
continuous tube, as in the sap-vessels of plants, or in muscular and
nervous fibre; and when cells are thus woven together, they are called
cellular tissue, which, in the human body, forms a fine net-like
membrane, enveloping or connecting most of its structures. In pulpy
fruits, the cells may be easily separated one from the other; and within
the cells are smaller cells, commonly known as pulp. Among the
cell-contents of some plants are beautiful