Page:Popular Science Monthly Volume 82.djvu/168

164 pre-arranged plan, that at the beginning everything was determined in detail and that all life is now following out the lines of that plan. Comparing this with the other two theories, the rabbits have long hind legs according to the Neo-Lamarckians because of the exercise they received when running to escape the fox; their ears likewise became longer because of the intentness with which they must guard against enemies. To the Neo-Darwinian the elongate ears and hind legs are due to changes in this direction in the germ cell, which changes nature selected by means of the fox who ate all individuals failing to make this change. To the teleologist it was planned in the beginning that as the fox became swifter the rabbit should likewise become swifter and more acute of hearing so that a proper balance should always be preserved between them.

Bergson's view of creative evolution is vitalistic in that it, with teleology, postulates a psychical force, which he calls the life impetus. But it differs from teleology especially in its belief that life is not bound by any prearranged plan, that it is free at all times to modify its course, to change its direction. Life, according to this view, is like a shell bursting as it flies, each fragment again bursting, and so on. The life impetus is thus continually dividing. Just as the way a shell bursts depends both upon the explosive force of the powder and the resistance of the metal surrounding it, so the direction of life depends upon the unstable balance of tendencies which it bears within itself and the resistance it meets with from inert matter. It is as if the vital impetus were trying to graft on the invariableness of matter the largest possible amount of instability.

According to the view of creative evolution, then, environment is a force evolution must reckon with, but not its cause, as with the mechanists, while adaptation of the organism to its environment will explain the sinuosities of the course of evolution, but not the general direction and still less the cause of the movement itself.

The problem confronting this vital impetus as it enters matter is somewhere to gather energy with which to counteract the retarding force of matter. At the surface of this earth the most available source of energy is the sun's rays. So the problem before life was this—to store this energy in suitable reservoirs so that it could be drawn upon at any time and for any need such as movement or reproduction. It succeeded in this by causing the kinetic power of the sun's rays to break up the inorganic compounds into their separate elements and then recombine them into the potential energy of organic foodstuffs. At first, doubtless, an organism thus gathered for itself the energy which it later expended in free movements; this form may be symbolized in a crude way by the infusorian, Euglena. This organism expends kinetic energy in motion like any animal, but in addition to the ordinary animal