Natural Selection and Artificial Selection.—The selective method practised by Nature works by means of the procreation of millions of individuals, and by the subsequent elimination of those individuals which are imperfectly or not at all adapted to their environing conditions; that is to say, natural selection operates repressively or destructively. Artificial selection, on the other hand, aims at preventing the procreation of individuals inadequately adapted to their environment; it deliberately eliminates those elements which are useless to society, or which can be utilised by society only at excessive cost: thus artificial selection is a preventive method.