talism, and who has tried to show by analogies and
illustrations what is necessarily implied in vital activity.(82) The
mechanical reduction of vital phenomena to physico-chemical forces, he
says, is impossible, and becomes more and more so as our knowledge
deepens. He brings forward a series of convincing examples of the way in
which apparent mechanical explanations have broken down. The absorption of
the chyle through the walls of the intestine seemed to be a mechanically
intelligible process of osmosis and diffusion. But in reality it proves to
be rather a process of selection on the part of the epithelial cells of
the intestine, analogous to the selection and rejection exercised
elsewhere by unicellular organisms. In the same way the epithelial cells
of the mammary glands "select" the suitable substances from the blood. It
is impossible to explain in a mechanical way the power which directs the
innumerable different chemical and physical processes within the organism,
whether they be the bewilderingly purposeful reactions in the individual
life of the cell, which seem to point to psychic processes within the
plasm, or the riddles of development and of inheritance in particular; for
how can a spermatozoon, so small that 500 millions can lie on a cubic
line, be the bearer of all the peculiarities of the father to the son?

In Lecture III. Bunge defines his attitude towards the law of the
conservation of energy. In so doing he unconsciously follows the lines
laid down by Descartes. All processes of movement and all functions
exhibited by the living substance are the results of the accumulated
potential energies, and the sums of work done and energy utilised remain
the same. But the liberation and the direction of these energies is a
factor by itself, which neither increases nor diminishes the sum of
energies. "_Occasiones_" and "_causae_" are brought into the field once
more. The energies effect the phenomena, but they require "_occasiones_"
to liberate them--thus a stone may fall to the ground by virtue of the
potential energies stored in it at the time of its suspension, but it
cannot fall until the thread by which it hangs has been cut. The function
of the "_occasio_" itself is something quite outside of and without
relation to the effect caused; it is a matter of indifference whether the
thread be cut gently through with a razor or shot in two with a cannon
ball.

Kassowitz(83) is an instructive example of how much