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 born with some disease from which the mother had been suffering for the previous few months. In general, it is more difficult to decide whether a mental trait is germinal, than whether a physical one is; and great care should be used in classification. To make the distinction, one ought to be familiar with an individual from birth, and to have some knowledge of the conditions to which he was exposed, in the period between conception and birth,--for of course a modification which takes place during that time is as truly an acquired character as one that takes place after parturition. Blindness, for example, may be an inborn defect. The child from conception may have lacked the requisites for the development of sight. On the other hand, it may be an acquired character, due to an ill-advised display of patriotism on July 4, at some time during childhood; or even to infection at the moment of birth. Similarly small size may be an inborn character, due to a small-sized ancestry; but if the child comes of a normal ancestry and is stunted merely because of lack of proper care and food, the smallness is an acquired character. Deafness may be congenital and inborn, or it may be acquired as the result, say, of scarlet fever during childhood.