equilibrium is established, and thus this vital turgescence disappears. The reaction of the internal principle is diminished in old age, while the action of external bodies remains the same; thus life languishes and advances insensibly towards that natural term, which must happen when all proportion has ceased.
The measure of life then, in general, is the difference which exists between the effort of external powers, and of internal resistance. The excess of the former announces its weakness; the predominance of the latter is an indication of its strength.
SECTION I.
Division of Life into Animal and Organic.
Such is life considered in the whole; examined more minutely, it offers to our view two remarkable modifications. The one is common to vegetable and animal, the other is peculiar to the last. Let us cast our eyes, for example, on an individual of each of these living kingdoms: we shall see that the one exists only within itself, having no other relation to what surrounds it, than as it respects nutrition, that it springs up, flourishes, and dies, in the spot which received its germe; that the other has, in addition to this internal life which it enjoys in a higher degree, an external life which establishes numerous relations between it and surrounding objects, that its existence is entwined with that of every other being, that it avoids or approaches these according to its fears or wants, and thus appears to appropriate every thing in nature to its exclusive use.
It may be said that the vegetable is the rough sketch, the canvas of the animal; and that to form this last, no-
