Of the various laws limiting freedom of marriage three are of biological import. First, the limitation of relationship between the mates; second, the limitations in mental capacity of the mates; and third, limitations of race. For the first there is a biological justification in so far as cousin marriages are apt to bring in from both sides of the house the same defect. For the second the justification is partial; but there is equal reason for forbidding the marriage of normal persons both of whom have mentally defective parents or other close relatives. The denial of marriage between races has this justification, that most other races have not, through selection, attained the social status of the Caucasian. In such cases the socially inadequate should be sterilized or segregated in other races as well as in the Caucasian. EUGENIC SELECTION AND THE ORIGIN OF DEFECTS. (Abstract.) By Frédéric Houssay, _Professor of Science, University of Paris._ Eugenics, which is a social application of biological science, cannot yet be judged by its results; it must be judged by its tendencies. To determine these, we must adjust them to principles generally admitted. And inasmuch as it advocates practical rules and seeks to check the propagation of the unfit, by isolation or sterilization (voluntary or enforced), it is an artificial selection. Its justification lies in the fact that, without intervention, the descendants of defectives or degenerates would, in a few generations, eliminate themselves by early death of children or by natural sterility. This would produce a natural selection which Eugenics simply proposes to anticipate by social economy. It seems that, by applying Darwinian principles, the group of defectives, considered at a given moment, could be rapidly extinguished. But this group is continually reinforced by fresh degeneration of healthy stocks which become tainted. Hence the need to keep our eye on the re-formation of the group as well as its elimination, and to keep in touch with Lamarckian principles. The study of the origin and hereditary conservation of defects points already as essential factors, to alcoholism, syphilis, and more generally every chronic ailment and diathesis, among which gout must be put in a leading position. Everything which will tend to restrain the action of these factors is of capital importance from our present point of view, whether it occurs in the ranks of rich or poor. The questions, thus, which Eugenics seeks to answer would be on this view reduced to questions of hygiene and morals. So that the different biological principles, which sometimes seem in mutual opposition, would become convergent, and would find in Eugenics a ready reconciliation and a field of useful co-operation. PRELIMINARY REPORT TO THE FIRST INTERNATIONAL EUGENICS CONGRESS,