anic
nature. [Footnote: Dr. Berthold has shown that Leibnitz had sound views
regarding the conservation of energy in inorganic nature.] The
vegetable world, though drawing all its nutriment from invisible
sources, was proved incompetent to generate anew either matter or
force. Its matter is for the most part transmuted gas; its force
transformed solar force. The animal world was proved to be equally
uncreative, all its motive energies being referred to the combustion
of its food. The activity of each animal, as a whole, was proved to
be the transferred activity of its molecules. The muscles were shown
to be stores of mechanical energy, potential until unlocked by the
nerves, and then resulting in muscular contractions. The speed at
which messages fly to and fro along the nerves was determined by
Helmholtz, and found to be, not, as had been previously supposed,
equal to that of light or electricity, but less than the speed of
sound--less even than that of an eagle.

This was the work of the physicist: then came the conquests of the
comparative anatomist and physiologist, revealing the structure of
every animal, and the function of every organ in the whole biological
series, from the lowest zoophyte up to man. The nervous system had
been made the object of profound and continued study, the wonderful
and, at bottom, entirely mysterious controlling power which it
exercises over the whole organism, physical and mental, being
recognised more and more. Thought could not be kept back from a
subject so profoundly suggestive. Besides the physical life dealt
with by Mr. Darwin, there is a psychical life presenting similar
gradations, and asking equally for a solution. How are the different
grades and orders of Mind to be accounted for? What is the principle
of growth of that mysterious power which on our planet culminates in
Reason? These are questions which, though not thrusting themselves so
forcibly upon the attention of the general public, had not only
occupied many reflecting minds, but had been formally broached by one
of them before the 'Origin of Species' appeared.

With the mass of materials furnished by the physicist and physiologist
in his hands, Mr. Herbert Spencer, twenty years ago, sought to graft
upon this basis a system of psychology; and two years ago a second and
greatly amplified edition of his work appeared. Those who have
occupied themselves with the beautiful experiments of Plateau will
rememb