the phenomena of organic nature as at present displayed. The general
result of our investigations might be summed up thus: we found that the
multiplicity of the forms of animal life, great as that may be, may be
reduced to a comparatively few primitive plans or types of construction;
that a further study of the development of those different forms
revealed to us that they were again reducible, until we at last brought
the infinite diversity of animal, and even vegetable life, down to the
primordial form of a single cell.

We found that our analysis of the organic world, whether animals or
plants, showed, in the long run, that they might both be reduced into,
and were, in fact, composed of, the same constituents. And we saw that
the plant obtained the materials constituting its substance by a
peculiar combination of matters belonging entirely to the inorganic
world; that, then, the animal was constantly appropriating the
nitrogenous matters of the plant to its own nourishment, and returning
them back to the inorganic world, in what we spoke of as its waste; and
that finally, when the animal ceased to exist, the constituents of its
body were dissolved and transmitted to that inorganic world whence they
had been at first abstracted. Thus we saw in both the blade of grass and
the horse but the same elements differently combined and arranged. We
discovered a continual circulation going on,--the plant drawing in the
elements of inorganic nature and combining them into food for the animal
creation; the animal borrowing from the plant the matter for its own
support, giving off during its life products which returned immediately
to the inorganic world; and that, eventually, the constituent materials
of the whole structure of both animals and plants were thus returned to
their original source: there was a constant passage from one state of
existence to another, and a returning back again.