s therefore had an effect on their organs of generation.

This division into "Animal" and "Vital" functions recalls Buffon's and
Bichat's distinction of the "animal" and the "vegetative" lives.
Cuvier apparently took this idea from Buffon, for he says that a plant
is an animal that sleeps.[42] But the idea is as old as Aristotle, who
discusses the "sleep" of embryos and of plants in the last book of the
_De Generatione animalium_. The distinction between animal and
vegetative life is, of course, based for Aristotle in the difference
between the [Greek: psyche aisthetike] and the [Greek: psyche
threptike]. Cuvier, like Aristotle, Buffon, and Bichat, makes the
heart the centre of the "vegetative" organs.

It is important to note that Cuvier puts function before structure,
and infers from function what the organ will be. "Plants," he writes,
"having few faculties, have a very simple organisation."[43] It is only
after having discussed and classified functions that Cuvier goes on to
examine organs.

First his views on the composition of the animal body. Aristotle
distinguished three degrees of composition--the "elements," the
homogeneous parts, and the heterogeneous parts or organs. Cuvier does
the same. Some small advance has been made in the two thousand years'
interval, due in the first place to the progress of chemistry, and in
the second to the invention of the microscope. To the first
circumstance Cuvier owes his knowledge that the inorganic substances
forming the first degree of composition are principally C, N, H, O,
and P, combined to form albumen, fibrine, and the like, which are in
their turn combined to form the solids and fluids of the body. To the
latter circumstance Cuvier owes the statement that the finest
fragments into which mechanical division can resolve the organism are
little flakes and filaments, which, joined up loosely together, form a
"cellulosity." The discovery of the true cellular nature of animal
tissues did not come till much later, till some years after Cuvier's
death in 1832. Knowledge of histological detail was, however,
considerable by the beginning of the 19th century. Cuvier knew, for
example, that each muscle fibre has its own nerve fibre. But he gives
no elaborate account of the homogeneous parts, no detailed histology.
On the other hand his treatment of the heterogeneous parts or organs
is detailed and masterly.[44]

The main systems of organs are, in order of importance, the nerv