sfy
their needs without moving, since they find their food in the environing
_milieux_. But it is not the same with animals, which are obliged to
move about to procure their sustenance. Moreover, most of them have
other wants to satisfy, which require other kinds of movements and
acts." This matter is discussed in the author's often leisurely and
prolix way, with more or less repetition, which we will condense.

The lowest animals--those destitute of a nervous system--move in
response to a stimulus from without. Nature has gradually created the
different organs of animals, varying the structure and situation of
these organs according to circumstances, and has progressively improved
their powers. She has begun by borrowing from without, so to speak--from
the environment--the _productive force_, both of organic movements and
those of the external parts. "She has thus transported this force [the
result of heat, electricity, and perhaps others (p. 307)] into the
animal itself, and, finally, in the most perfect animals she has placed
a great part of this force at their disposal, as I will soon show."

This force incessantly introduced into the lowest animals sets in motion
the visible fluids of the body and excites the irritability of their
contained parts, giving rise to different contractile movements which we
observe; hence the appearance of an irresistible propensity (_penchant_)
which constrains them to execute those movements which by their
continuity or their repetition give rise to habits.

The most imperfect animals, such as the _Infusoria_, especially the
monads, are nourished by absorption and by "an internal inhibition of
absorbed matters." "They have," he says, "no power of seeking their
food, they have not even the power of recognizing it, but they absorb it
because it comes in contact with every side of them (_avec tous les
points de leur individu_), and because the water in which they live
furnishes it to them in sufficient abundance."

"These frail animals, in which the subtile fluids of the environing
_milieux_ constitute the stimulating cause of the orgasm, of
irritability and of organic movements, execute, as I have said,
contractile movements which, provoked and varied without ceasing by this
stimulating cause, facilitate and hasten the absorptions of which I have
just spoken." ...

_On the Transportation of the force-producing Movements in the Interior
of Animals._

"If nature were confined t