ment is profoundly altered, though external physical conditions
remain practically the same. If we represent the relatively static
environment by the symbols A, B, C, D ... M, the actual
dynamic environment will be A, B, C, E ... Mx (x signifying
the modification wrought by the habit); for if the animal find
food in its arboreal excursions, more will be left on the ground
for others and new conditions will arise. If the habit become
permanent, and if through imitation (which the organic selectionists emphasize) or similar pressure of external conditions, others
acquire the habit through successive generations, variations may
arise favoring continued adaptation to the new mode of life, and
these will be selected.
Thus by slow increments of change in the environment of the individual the general average of individuals constituting the species is a moving average; and in turn the species, always ultimately through the individual, modifies its environment. The latter is never practically fixed and static, but a moving and dynamic influence. And it is environment solely in this sense that is significant in our use of the term natural selection, an environment whose constituent factors can never be fully exhibited in their joint influence.
Now it is admitted that natural selection signifies fitness for survival, the fitness being determined by environment through natural selection, which tends to group individuals about a mean or general average. As the environment is constantly changing, it is this changing environment which determines the standard of survival. But, contrariwise, this dynamic environment, of constantly increasing complexity, is regarded by the evolutional ethicist as something which is merely superadded or superimposed upon a permanent environment, one that determines through natural selection the elemental instincts and qualities of the organism, and with regard to these, the standard or criterion, alike of organic and human evolution. Let us, say they, find the laws which are common to man and the amœba and we shall have the clue to human progress in the future. It is this static conception of environment which occasions the evolutionist attitude expressed in the statement that "we must interpret the
