also, is the consciousness that accompanies
them. But neither this mobility nor this choice nor consequently this
consciousness involves as a necessary condition the presence of a
nervous system; the latter has only canalized in definite directions,
and brought up to a higher degree of intensity, a rudimentary and vague
activity, diffused throughout the mass of the organized substance. The
lower we descend in the animal series, the more the nervous centres are
simplified, and the more, too, they separate from each other, till
finally the nervous elements disappear, merged in the mass of a less
differentiated organism. But it is the same with all the other
apparatus, with all the other anatomical elements; and it would be as
absurd to refuse consciousness to an animal because it has no brain as
to declare it incapable of nourishing itself because it has no stomach.
The truth is that the nervous system arises, like the other systems,
from a division of labor. It does not create the function, it only
brings it to a higher degree of intensity and precision by giving it the
double form of reflex and voluntary activity. To accomplish a true
reflex movement, a whole mechanism is necessary, set up in the spinal
cord or the medulla. To choose voluntarily between several definite
courses of action, cerebral centres are necessary, that is, crossways
from which paths start, leading to motor mechanisms of diverse form but
equal precision. But where nervous elements are not yet canalized, still
less concentrated into a system, there is something from which, by a
kind of splitting, both the reflex and the voluntary will arise,
something which has neither the mechanical precision of the former nor
the intelligent hesitations of the latter, but which, partaking of both
it may be infinitesimally, is a reaction simply undecided, and therefore
vaguely conscious. This amounts to saying that the humblest organism is
conscious in proportion to its power to move _freely_. Is consciousness
here, in relation to movement, the effect or the cause? In one sense it
is the cause, since it has to direct locomotion. But in another sense it
is the effect; for it is the motor activity that maintains it, and, once
this activity disappears, consciousness dies away or rather falls
asleep. In crustaceans such as the rhizocephala, which must formerly
have shown a more differentiated structure, fixity and parasitism
accompany the degeneration and almost complete