Page:Popular Science Monthly Volume 82.djvu/167

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HE French philosopher Henri Bergson has most appropriately chosen as the title of his book on development the name "Creative Evolution." As the name implies, to the inevitableness, the invariability of evolution as developed through physico-chemical laws, this philosophy adds the spontaneity, the indetermination of creation. The English translation of this book by Arthur Mitchell is a masterpiece of such work, and he is to be highly commended for the sympathetic manner in which the translation has been carried through.

All views of evolution divide naturally into two groups, the mechanistic—that all life can be accounted for through the application of the laws of physics and chemistry—and the vitalistic—that while the laws of physics and chemistry explain much, they do not explain all.

The principal radical views of these two groups are the following:

The Neo-Lamarckians hold that characters acquired during the lifetime of an individual are transmitted to its offspring. The Neo-Darwinians deny this utterly, holding that the germ cell, the reproductive tissue, is set apart for its generative work while the animal is in its embryonic state, that is, the reproductive tissue is not the product of the animal's own soma cells, but of its parents' germ cells. This school of Neo-Darwinians explains evolution by the theory that the germ cells are continually changing in every possible direction permitted by their stage of development and that those of these changes shown forth in the adult animal or plant which are beneficial to the organism are selected by nature for preservation. To the adherents of the former school, environment gives rise to variations; to the adherents of the latter it merely selects. To the former the long neck of the giraffe is due to the necessity that successive generations get their food from higher and higher bushes, a process of stretching illustrated by the animals in Kipling's "Just So Stories"; to the latter, those changes in the germ cell leading to neck elongation in the adult were selected by nature in times of drought.

Teleology in its most radical form holds that life is carrying out a