studied biology, and is so much a part of the tradition of society, that the question must be here examined, before we can proceed confidently with our program of eugenics.
The problem is first to be defined.
It is evident that all characters which make up a man or woman, or any other organism, must be either germinal or acquired. It is impossible to conceive of any other category. But it is frequently hard to say in which class a given character falls. Worse still, many persons do not even distinguish the two categories accurately—a confusion made easier by the quibble that all characters must be acquired, since the organism starts from a single cell, which possesses practically none of the traits of the adult.
What we mean by an inborn character is one whose expression is due to something which is present in the germ-plasm; one which is inherent and due to heredity. An acquired character is simply a modification, due to some cause external to the germ-plasm acting on an inborn character. In looking at an individual, one can not always say with certainty which characters are which; but with a little trouble, one can usually reach a reliable decision. It is possible to measure the variation in a given character in a group of parents and their children, in a number of different environments; if the degree of resemblance between parent and offspring is about the same in each case, regardless of the different surroundings in which the children may have been brought up, the character may properly be called germinal. This is the biometric method of investigation. In practice, one can often reach a decision by much simpler means: if the character is one that appears at birth, e.g., skin color, it is usually safe to assume that it is a germinal character, unless there is some evident reason for deciding otherwise, as in the case of a child