impossible in systems which retarded change at every step
and never proceeded in any direction but in that of dissipation.
Once created, indeed, it is conceivable that, as heat engines,
they might have dragged out an existence of alternate life and
death; life in the hours of sunshine, death in hours of darkness:
no final death, however, their lot, till their parts were simply
worn out by long use, never made good by repair. But the
sustained and increasing activity of organized nature is a fact;
therefore some other order of events must be possible.

[1] The law of Least Action, which has been applied, not alone in
optics, but in many mechanical systems, appears physically based
upon the restraint and retardation opposing the transfer of
energy in material systems.

66

GENERAL DYNAMIC CONDITIONS ATTENDING ANIMATE ACTIONS

What is the actual dynamic attitude of the primary organic
engine--the vegetable organism? We consider, here, in the first
place, not intervening, but resulting phenomena.

The young leaf exposed to solar radiation is small at first, and
the quantity of radiant energy it receives in unit of time cannot
exceed that which falls upon its surface. But what is the effect
of this energy? Not to produce a retardative reaction, but an
accelerative response: for, in the enlarging of the leaf by
growth, the plant opens for itself new channels of supply.

If we refer to "the living protoplasm which, with its unknown
molecular arrangement, is the only absolute test of the cell and
of the organism in general,[1] we find a similar attitude towards
external sources of available energy. In the act of growth
increased rate of assimilation is involved, so that there is an
acceleration of change till a bulk of maximum activity is
attained. The surface, finally, becomes too small for the
absorption of energy adequate to sustain further increase of mass
(Spencer[2]), and the acceleration ceases. The waste going on in
the central parts is then just balanced by the renewal at the
surface. By division, by spreading of the mass, by

[1] Claus, _Zoology_, p. 13.

[2] Geddes and Thomson, _The Evolution of Sex_, p. 220.

67

out-flowing processes, the normal activity of growth may be
restored. Till this moment nothing would be gained by any of
these changes. One or other of them is now conducive to
progressive absorption of energy by the organism, and one or
other occurs, most generally the best of them, subdivi