erception, or so little that nothing comes
of it, the movements of the foetus, such as they are, being rather
mechanical than dependent on sensation and will.

"Whatever the matter may be which serves as the vehicle of perception,
and produces muscular movement, it is certain that it is propagated
through the nerves, and that it communicates itself instantaneously from
one extremity of the system to the other. In whatever manner this
operation is conducted, whether by the vibrations, as it were, of
elastic cords or by a subtle fire, or by a matter resembling
electricity, which not only resides in animal as in all other bodies,
but is being continually renewed in them by the movements of the heart
and lungs, by the friction of the blood within the arteries, and also by
the action of exterior causes upon our organs of sense--in whatever
manner, I say, the operation is conducted, it is nevertheless certain
that the nerves and membranes are the only parts in an animal body that
can feel. The blood, lymphs, and all other fluids, the fats, bone,
flesh, and all other solids, are of themselves void of sensation. And
so also is the brain; it is a soft and inelastic substance, incapable
therefore of producing or of propagating the movement, vibrations, or
concussions which, result in perception. The meninges, on the other
hand, are exceedingly sensitive, and are the envelopes of all the
nerves; like the nerves, they take rise in the head; and, dividing
themselves like the branches of the nerves, they extend even to their
smallest ramifications: they are, so to speak, flattened nerves; they
are of the same substance as the nerves, are nearly of the same degree
of elasticity, and form a necessary part of the system of sensation. If,
then, the seat of the sensations must be placed in the head, let it be
placed in the meninges, and not in the medullary part of the brain,
which is of an entirely different substance."[95]

If this is so, it appears from what will follow as though the meninges
must be the "stock" rather than the diaphragm.

"What perhaps has given rise to the opinion that the seat of all
sensations and the centre of all sensibility is in the brain, is the
fact that the nerves, which are the organs of perception, all attach
themselves to the brain, which has hence come to be regarded as the one
common centre which can receive all their vibrations and impressions.
This fact alone has sufficed to indicate the brain as th