e. Of these
none are complete embryon animals, but form an embryon by their
reciprocal conjunction.

There hence appears to be an analogy between generation and nutrition,
as one is the production of new organization, and the other the
restoration of that which previously existed; and which may therefore
be supposed to require materials somewhat similar. Now the food taken
up by animal lacteals is previously prepared by the chemical process
of digestion in the stomach; but that which is taken up by vegetable
lacteals, is prepared by chemical dissolution of organic matter
beneath the surface of the earth. Thus the particles, which form
generated animal embryons, are prepared from dead organic matter by
the chemico-animal processes of sanguification and of secretion; while
those which form spontaneous microscopic animals or microscopic
vegetables are prepared by chemical dissolutions and new combinations
of organic matter in watery fluids with sufficient warmth.

It may be here added, that the production and properties of some kinds
of inanimate matter, are almost as difficult to comprehend as those of
the simplest degrees of animation. Thus the elastic gum, or
caoutchouc, and some fossile bitumens, when drawn out to a great
length, contract themselves by their elasticity, like an animal fibre
by stimulus. The laws of action of these, and all other elastic
bodies, are not yet understood; as the laws of the attraction of
cohesion, to produce these effects, must be very different from those
of general attraction, since the farther the particles of elastic
bodies are drawn from each other till they separate, the stronger they
seem to attract; and the nearer they are pressed together, the more
they seem to repel; as in bending a spring, or in extending a piece of
elastic gum; which is the reverse to what occurs in the attractions
of disunited bodies; and much wants further investigation. So the
spontaneous production of alcohol or of vinegar, by the vinous and
acetous fermentations, as well as the production of a mucus by
putrefaction which will contract when extended, seems almost as
difficult to understand as the spontaneous production of a fibre from
decomposing animal or vegetable substances, which will contract when
stimulated, and thus constitutes the primordium of life.

Some of the microscopic animals are said to remain dead for many days
or weeks, when the fluid in which they existed is dried up, and
quickly to r