le not setting any limits to the possible
extension of knowledge, are not prepared to dogmatize about it, it is
still necessary to draw a line. A dualism remains, name and fact alike
abhorrent to the completely logical philosophic mind. On the one hand
the ordinary laws of physical science are constantly extending their
sphere; on the other, the fact of life still remains unexplained by
them, and becomes in itself more and more marvellous as we investigate
it. The general position remains much as Johannes Mueller expressed it
about the middle of the last century, himself sometimes described as the
central figure in the history of modern physiology. 'Though there
appears to be something in the phenomena of living beings which cannot
be explained by ordinary mechanical, physical, or chemical laws, much
may be so explained, and we may without fear push these explanations as
far as we can, so long as we keep to the solid ground of observation and
experiment.' Since this was written the double process has gone on
apace. The chemistry and physics of living matter are being sketched,
and biologists are more and more inclined to study the mechanical
expression of the facts of life. Mr. Bateson, for instance, tells us
that the greatest advance that we can foresee will be made 'when it is
possible to connect the geometrical phenomena of development with the
chemical'. The process of applying physical laws to life follows, it
would seem, the reverse order of their original development. First the
chemistry of organic matter was investigated, then the physical
attraction of their molecules, and now their geometry is in question.
So, says Professor Bateson, the 'geometrical symmetry of living things
is the key to a knowledge of their regularity and the forces which cause
it. In the symmetry of the dividing cell the basis of that resemblance
which we call Heredity is contained'.

But such work as this is still largely speculative and in the future. It
does not solve the secret of life. It does not affect the fact of
consciousness which we are free to conceive, if we will, as the other
side of what we call matter, evolving with it from the most rudimentary
forms into the highest known form in man, or still further into some
super-personal or universal form. This, however, is philosophy or
metaphysics. We are here concerned with the progress of science, in one
of its two great departments, i.e. knowledge about life and all its
known man