disappearance of the
nervous system. Since, in such a case, the progress of organization must
have localized all the conscious activity in nervous centres, we may
conjecture that consciousness is even weaker in animals of this kind
than in organisms much less differentiated, which have never had nervous
centres but have remained mobile.

How then could the plant, which is fixed in the earth and finds its food
on the spot, have developed in the direction of conscious activity? The
membrane of cellulose, in which the protoplasm wraps itself up, not only
prevents the simplest vegetable organism from moving, but screens it
also, in some measure, from those outer stimuli which act on the
sensibility of the animal as irritants and prevent it from going to
sleep.[54] The plant is therefore unconscious. Here again, however, we
must beware of radical distinctions. "Unconscious" and "conscious" are
not two labels which can be mechanically fastened, the one on every
vegetable cell, the other on all animals. While consciousness sleeps in
the animal which has degenerated into a motionless parasite, it probably
awakens in the vegetable that has regained liberty of movement, and
awakens in just the degree to which the vegetable has reconquered this
liberty. Nevertheless, consciousness and unconsciousness mark the
directions in which the two kingdoms have developed, in this sense, that
to find the best specimens of consciousness in the animal we must
_ascend_ to the highest representatives of the series, whereas, to find
probable cases of vegetable consciousness, we must _descend_ as low as
possible in the scale of plants--down to the zoospores of the algae, for
instance, and, more generally, to those unicellular organisms which may
be said to hesitate between the vegetable form and animality. From this
standpoint, and in this measure, we should define the animal by
sensibility and awakened consciousness, the vegetable by consciousness
asleep and by insensibility.

To sum up, the vegetable manufactures organic substances directly with
mineral substances; as a rule, this aptitude enables it to dispense with
movement and so with feeling. Animals, which are obliged to go in search
of their food, have evolved in the direction of locomotor activity, and
consequently of a consciousness more and more distinct, more and more
ample.

* * * * *

Now, it seems to us most probable that the animal cell and the ve