Page:Popular Science Monthly Volume 79.djvu/460

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This, however, does not give a mechanical reason for it; not more so than for the left-handed spirals of snail-shells. In the Rocky Mountains I have often noticed this peculiar tendency in the uniform twisting of the fibers of the Lodge Pole pine.

The plain appearance of geometric configurations and relations is, of course, not limited to plant life alone; mineralogy, zoology and geology also offer many examples of this kind.

The forms of crystals, for instance, may be derived abstractly from certain considerations in the theory of groups.

Mendel's law of heredity has in recent years become of extreme importance as a powerful means of research. The abstract form of this law is derived from combinatory analysis, as will appear from the following experiment of L. Cuénot. All individuals of the offspring resulting from the crossing of the ordinary gray mouse with the albino mouse are gray; the gray element G dominates, while the white element W is hidden by the gray. Crossing individuals of the offspring, among the new offspring there will be gray and white specimens, and the ratio