Page:Popular Science Monthly Volume 37.djvu/373

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359
HUMAN HEREDITY.

HUMAN HEREDITY.
By JAMES H. STOLLER,

PROFESSOR OF NATURAL HISTORY IN UNION COLLEGE.

IN common speech we use the term heredity as signifying simply that principle by which the qualities of parents are transmitted to their children. We give the term a meaning broad enough to cover facts which come within our ordinary notice. We see that the features of children—the shape of the brow and nose, the color of the hair and eyes—bear a resemblance to those of the parents; as they grow older we notice not only physical but also psychical resemblances—the temperament, tastes, and aptitudes are more or less like those of the parents. We find an explanation of these likenesses in the principle of heredity; and, as no evidence of any deeper operation of such a principle comes within our ordinary observation, we limit it to these particulars. It is true that occasionally we are reminded that the principle may extend to a second generation; we see the traits of the grandparent reappearing in the child, this being most noticeably true in respect to certain bodily disorders, as scrofulous diseases and certain forms of insanity. But we seldom think that the principle of heredity operates through more than the two or three generations of our immediate ancestors, or that any other qualities than those which are specifically peculiar to us—that mark our individuality of body or mind—come to us by it.

A little reflection, however, must convince us that this principle works more deeply. Those qualities that distinguish us as members of a nationality—whence come they? As Americans we pride ourselves that there is something distinctive about us, that places us in a different category from Englishmen and Frenchmen. Whence come these national characteristics? They were possessed by our fathers and our grandfathers, and the immediate inference, therefore, is that they come to us by inheritance. Of course, we have to consider that the fathers who were the founders of the nation did not inherit the American characteristics, since we must regard them as the original possessors of them. The fact seems to be that national characteristics originate in external causes, but once established they are perpetuated by inheritance. It may be urged, of course, that external causes operate upon succeeding generations as well as the antecedent one, as evidenced in our nationality by its rapid absorption of foreign stock. No doubt the direct influence of our institutions is a constant force in the development of the national characteristics, and goes a great way toward Americanizing citizens of foreign birth even in a single generation. But to native-born Ameri-