Page:Popular Science Monthly Volume 76.djvu/54

50 two great modes of progress., choosing such methods of biological improvement as may help rather than hinder civilization, and, where this can not be done, judging carefully in any specific case between social and biological values.

That the modern preachers of eugenics are quick to recognize their unity of interest with the workers for social and institutional progress is shown by Dr. Francis Galton:

Before coming to a decision upon radical schemes for race improvement, it is of vital necessity that we consider first the factors of human evolution, and second the possibility and means of their control, with the relations of these means to progress that is social rather than biological. We must ascertain from biology those factors which are actively producing change in other organisms, and then determine to what extent they are potent in human beings as well.

Natural selection, though a dominating factor, is not the sole one in evolution, determinate variation and the direct influence of environment being also of great importance. Of these two the former is noncontrollable, and affects eugenics only in so far as its presence may make our work easier or more difficult; so we may confine our interest at present to natural selection and the direct influence of environment.

The latter factor brings us at once to the time-honored controversy over the "inheritance of acquired characteristics." The dispute seems to have ended in a drawn battle, one party having established its claim that modifications of the body are not inherited in kind, while the other has proved that the environment is able to originate certain inheritable characteristics, provided only the action in question is able to penetrate to the germ cells themselves. This modification of the germ cells caused by environment is called blastophthory by Forel, and is thus described (p. 35, "The Sexual Question"):

An illustration of this direct influence is afforded by the experiments of Professor Wm. Tower, at the University of Chicago. It was found