living world. Consider why is the skeleton of this horse capable of
supporting the masses of flesh and the various organs forming the living
body, unless it is because of the action of the same forces of cohesion
which combines together the particles of matter composing this piece of
chalk? What is there in the muscular contractile power of the animal but
the force which is expressible, and which is in a certain sense
convertible, into the force of gravity which it overcomes? Or, if you go
to more hidden processes, in what does the process of digestion differ
from those processes which are carried on in the laboratory of the
chemist? Even if we take the most recondite and most complex operations
of animal life--those of the nervous system, these of late years have
been shown to be--I do not say identical in any sense with the
electrical processes--but this has been shown, that they are in some way
or other associated with them; that is to say, that every amount of
nervous action is accompanied by a certain amount of electrical
disturbance in the particles of the nerves in which that nervous action
is carried on. In this way the nervous action is related to electricity
in the same way that heat is related to electricity; and the same sort
of argument which demonstrates the two latter to be related to one
another shows that the nervous forces are correlated to electricity; for
the experiments of M. Dubois Reymond and others have shown that whenever
a nerve is in a state of excitement, sending a message to the muscles or
conveying an impression to the brain, there is a disturbance of the
electrical condition of that nerve which does not exist at other times;
and there are a number of other facts and phenomena of that sort; so
that we come to the broad conclusion that not only as to living matter
itself, but as to the forces that matter exerts, there is a close
relationship between the organic and the inorganic world--the difference
between them arising from the diverse combination and disposition of
identical forces, and not from any primary diversity, so far as we can