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This is the dynamic basis for a "struggle for existence." The
organism being a material system responding to accession of
energy with fresh demands, and energy being limited in amount,
the struggle follows as a necessity. Thus, evolution guiding' the
steps of the energy-seeking organism, must presuppose and find
its origin in that inherent property of the organism which
determines its attitude in presence of available energy.
Turning to the factor, "adaptation," we find that this also must
presuppose, in order to be explicable, some quality of
aggressiveness on the part of the organism. For adaptation in
this or that direction is the result of repulse or victory, and,
therefore, we must presuppose an attack. The attack is made by
the organism in obedience to its law of demand; we see in the
adaptation of the organism but the accumulated wisdom derived
from past defeats and victories.
Where the environment is active, that is living, adaptation
occurs on both sides. Improved means of defence or improved means
of attack, both presuppose activity. Thus the reactions to the
environment, animate and inanimate, are at once the outcome of
the eternal aggressiveness of the organism, and the source of
fresh aggressiveness upon the resources of the medium.
As concerns the "survival of the fittest" (or "natural
selection"), we can, I think, at once conclude that the organism
which best fulfils the organic law under the circumstances of
supply is the "fittest," _ipso facto._ In many
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cases this is contained in the commonsense consideration, that to
be strong, consistent with concealment from enemies which are
stronger, is best, as giving the organism mastery over foes which
are weaker, and generally renders it better able to secure
supplies. Weismann points out that natural selection favours
early and abundant reproduction. But whether the qualifications
of the "fittest" be strength, fertility, cunning, fleetness,
imitation, or concealment, we are safe in concluding that growth
and reproduction must be the primary qualities which at once
determine selection and are fostered by it. Inherent in the
nature of the organism is accelerated absorption of energy, but
the qualifications of the "fittest" are various, for the supply
of energy is limited, and there are many competitors for it. To
secure that none be wasted is ultimately the object of natural
selection, deciding among the eager competitors what is best for
each.
In short, the facts and generalisations concerning evolution must
presuppose an organism endowed with the quality of progressive
absorption of energy, and retentive of it. The continuity of
organic activity in a world where supplies are intermittent is
evidently only possible upon the latter condition. Thus it
appears that the dynamic attitude of the organism, considered in
these pages, occupies a fundamental position regarding its
evolution.
We turn to the consideration of old age and death, endeavouring
to discover in what relation they stand to the innate
progressiveness of the organism.
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