Note 208 — Chapter XIV

In Dr. Weismann's essay on "Heredity," already referred to, he considers it not improbable that changes in organisms produced by climatic influences may be inherited, because, as these changes do not affect the external parts of an organism only, but often, as in the case of warmth or moisture permeate the whole structure, they may possibly modify the germ-plasm itself, and thus induce variations in the next generation. In this way, he thinks, may possibly be explained the climatic varieties of certain butterflies, and some other changes which seem to be effected by change of climate in a few generations.