With all these assertions we may agree,
though we cannot with that which follows, namely, that energy is
creative, for that such is impossible in any true sense of that word we
have already tried to show.

We have now to ask ourselves in what way this energy conception of life
differs from, or goes beyond, the two theories of life--mechanistic and
vitalistic, which have hitherto been supposed to have exhausted the
possibilities of explanation. In order to do this we must analyse the
author's idea of energy and its relationship to biological processes a
little more closely. He begins his study of life and its evolution by
considering how nutrition and the derivation of energy can have taken
place before chlorophyl had come into existence; and he very pertinently
points to the _prototrophic_ bacteria as probably representing "the
survival of a primordial stage of life chemistry." Thus a "primitive
feeder," the bacterium _Nitrosomonas_, "for combustion ... takes in
oxygen directly through the intermediate action of iron, phosphorus or
manganese, each of the single cells being a powerful little chemical
laboratory which contains oxidising catalysers, the activity of which
is accelerated by the presence of iron and manganese. Still, in the
primordial stage, _Nitrosomonas_ lives on ammonium sulphate, taking its
energy (food) from the nitrogen of ammonium and forming nitrates. Living
symbiotically with it is _Nitrobacter_, which takes its energy (food)
from the nitrates formed by _Nitrosomonas_, oxidising them into
nitrates. Thus these two species illustrate in its simplest form our law
of the _interaction of an organism_ (_Nitrobacter_) _with its life
environment_ (_Nitrosomonas_)" (p. 82, author's italics).

Once one has got to this stage, it is _ex hypothesi_ easy to ascend
through the vegetable and animal worlds and to formulate the various
laws which appear to have shaped the evolution of life and of species.
We are then "within the system," but to arrive at anything worthy of the
name of an explanation we have first to _get_ within the system. Even
then there remains over the task of explaining how the system comes to
be there to get inside of. The writer talks of his example as "the
simplest form." Yet, in his own words, it is a "_powerful little
chemical laboratory_," well stocked with catalysers and other potent
means for carrying on its work. "Simple"! Well, no doubt comparatively
simple, but in reality complex alm