Page:Popular Science Monthly Volume 16.djvu/191

 the altruistic—the one concerned only about the well-being of self, the other about the well-being of the race. These correspond each to each. Traced to its deepest physiological roots, the one in its last analysis is connected with the nutritive functions and the appetite for food, the other with the reproductive functions and the sexual appetite.

It seems to me not inappropriate to draw passing attention to the fact that that form of woman's rights which would assimilate as much as possible the two sexes is certainly in direct conflict with the law of evolution which we have been tracing. If founded in nature at all, we must seek for its justification in a higher law than that of animal evolution.

—Are there still further differentiations and still better results possible? Yes; by judicious crossing of varieties. Groups of individuals of both sexes, under the influence of differing environment, become different. This difference may be slight (slight varieties), or decided (strong varieties), or still more decided (races), or may become in time so great as to constitute distinct species. Now, it has been found that the indefinite interbreeding of individuals subject to identical conditions (close-breeding) produces weakness and degeneracy; and, on the contrary, the judicious crossing of slight varieties produces improved results. The reason is apparently this: Among all the qualities, good and bad, strong and weak, inherited from both sides by the offspring, there is a kind of struggle for life, and a survival of the best and the strongest qualities. It is probable that this improvement is more decided in the psychical than in the physical nature, and therefore is more conspicuous in man than in animals. Too close breeding—i. e., the interbreeding in isolated communities of individuals subject to identical conditions, and therefore with identical customs, habits, feelings, thoughts—tends to deteriorate the mind and character, even when the physique is unimpaired; tends to petrify the communal character and destroy that plasticity on which all progress depends.

Now, it is quite certain that within certain limits the improved results of crossing increase with the diversity of the crossing varieties. But mark, only within certain limits, beyond which they again decrease until deterioration is reached; and the deterioration increasing with the increasing divergence, when the crossing varieties reach a divergence represented by the term species, Nature practically forbids the ban. Thus, when species cross, there is either (a) no fertilization, and therefore no offspring; or (b), the offspring is an infertile hybrid, and therefore perishes in the next generation; or (c), if the offspring be fertile, the progeny is feeble, and perishes in the struggle for life in a few generations, or (d) is absorbed by crossing with the stronger parent species. If this were not so, species, in many cases at least, could not exist. Many species of oak or of pine grow in the same grove; the air is full of the pollen of many species; the conditions