ABSTRACT
The changes which are induced in the plant or the animal during its lifetime, spoken of as the effects of its environment, that is, produced by variations in temperature, by good food or bad, by exercise or the lack of it,—all such changes are mere fluctuations, and are not passed along in heredity to the next generation. A wheel by its turning is never seen to work up more and more speed, or more and more energy of rotation, merely by its turning, and by itself. It takes some external force even to keep it going. And it seems to be one of the best established principles of biology that the effects of the environment are never passed along from one generation to the next, unless in a few ambiguous cases which are clearly cases of degeneracy. In the next generation two wholly new types appeared or were separated out, as the Mendelians say.
