Page:Popular Science Monthly Volume 75.djvu/465

Rh warranted? We can not say until we have examined the present status of the problem of inheritance; but whether or not we are pessimistic as regards the future of the race, we must agree that the sudden and increasing burden which culture places upon the human mind raises this problem to the first rank of importance.

Suppose that we look, then, at the grounds of belief in the hereditary transmission of mind. The belief itself stands among the feed convictions of common sense. In our every-day thinking we take it for granted. The child, we maintain, inherits its father's bad temper just as it inherits its mother's good looks. We consider twice before we adopt the foundling, which may be of dull or vicious parentage. We shake our heads over the wayward son, remembering that his father "sowed his wild oats," and we observe "like father like son," or "blood will tell." We expect to find talent in the children of the gifted, thrift or dwarfed intellect or high purpose, according as these qualities are "bred in the bone." The folk-tale of paupered prince or stolen princess who never, though reared as swineherd or scullion, loses regal bearing and courtly demeanor, the wide respect for royal blood, and the easy belief in the "born criminal," alike testify to the common and venerable persuasion that minds, and even morals, are subject to hereditary transmission.

It is only when we stop to inquire precisely what is inherited in all these instances, and how it is conceivable that mind should pass from parent to offspring, that we leave the highway of common sense and enter the more difficult path of critical observation and induction. It is obvious that a clear statement of the problem and a forecast of method are of the first importance.

Inasmuch as the notion of "inheritance" involves both the process and the products of transmission, the inheriting and the thing inherited, a choice of methods is at once suggested. Shall we—that is to say—seek to describe the mechanism of inheritance, or to discover the like qualities that have actually appeared in successive generations of blood-relatives? It is quite impossible to state the alternatives without adverting to the fact that biology has, for a half-century, been absorbed in the parallel investigation of physical inheritance. Nor are we likely to forget, in the midst of our commemoration of Darwin's birth and of "The Origin of Species," that the whole doctrine of organic evolution rests upon the facts of heredity. Whatever the factors that determine racial descent—fluctuating variation, or the sudden change of type, use and disuse, natural, artificial, sexual or organic selection—both continuity in the process of bionomic change and maintenance of the change once produced, demand the conception of a hereditary likeness. Without inheritance the establishment of a stock would be impossible, and without a stock, variations and mutations