By Frederick Adams Woods, M.D., _Harvard Medical School._ The relative influence of heredity and environment has long been a subject for debate, but, for the most part, such debates have not been profitable. It is true that heredity cannot be separated from environment if only one individual be considered; but as soon as we inquire into the causes of the differences between man and man, it is perfectly possible to gain real light on this subject, so important to the advocates of eugenics. Everything must be made a problem of differences. The mathematical measurements of resemblances between relatives close of kin will sometimes serve. At other times, the correlation co-efficient is of no avail, and only an intensive study of detailed pedigrees will bring out such differences as cannot be due to the action of surroundings. History and genealogy both speak unmistakably for heredity. Men of genius have as many eminent relationships as the expectations of heredity demand. The same is true among the highest aristocratic classes, and is equally true under democratic government, as is proved by a study of the family history of those Americans whose names are in the Hall of Fame. History shows that about half of the early monarchs were not cruel or were not licentious. Alternative heredity can well account for that. Virtuous types have only slightly increased in numerical proportion. Environment cannot be very effective; but there are biological factors of a more hidden nature which are silently making for progress. Mental qualities are correlated with moral; and in the European dynasties the survivors have been generally the descendants of the morally superior. Physical differences can also be demonstrated, coming in the course of generations. A study of the portraits of royal, noble, and other historical personages shows that the bony framework of the face, especially about the nose and eyes, has changed rapidly since the beginning of the sixteenth century. In explaining the rise and fall of nations, gametic and personal causes can be measured and marked. All the evidence of history points to the power and importance of a very few great personalities--they themselves the product of inborn forces. These have been the chief causes of political and economic differences, but non-gametic (environmental) causation can be occasionally detected, and separated out; as, for instance, the modern scientific productivity in Germany and the proportionate intellectual activity among women in America. It is estimated that there are four hundred thousand books on history. These form an almost unworked mine of information, easily available to every student of eugenics. It is high time that the human record, so ancient in its beginnings, should be used to contribute to that most modern of sciences, the improvement of the human breed. DEMOGRAPHICAL CONTRIBUTIONS TO THE PROBLEMS OF EUGENICS. (Abstract.) By Dr. Corrado Gini,