All poor +.01 Prosperous poor +.16 Middle classes +.24 Professional classes +.28 It can hardly be argued that infection between husband and wife would vary like this, even if infection, in general, could be proved. Moreover, the least resemblance is among the poor, where infection should be greatest. Professor Pearson thinks, as seems reasonable, that this series of figures indicates principally assortative mating, and shows that among the poor there is less choice, the selection of a husband or wife being more largely due to propinquity or some other more or less random factor. With a rise in the social scale, opportunity for choice of one from a number of possible mates becomes greater and greater; the tendency for an unconscious selection of likeness then has a chance to appear, as the coefficients graphically show. If such a class as the peerage of Great Britain be considered, it is evident that the range of choice in marriage is almost unlimited. There are few girls who can resist the glamor of a title. The hereditary peer can therefore marry almost anyone he likes and if he does not marry one of his own class he can select and (until recently) usually has selected the daughter of some man who by distinguished ability has risen from a lower social or financial position. Thus the hereditary nobilities of Europe have been able to maintain themselves; and a similar process is undoubtedly taking place among the idle rich who occupy an analogous position in the United States. But it is the desire of eugenics to raise the average ability of the whole population, as well as to encourage the production of leaders. To fulfill this desire, it is obvious that one of the necessary means is to extend to all desirable classes that range of choice which is now possessed only by those near the top of the social ladder. It is hardly necessary to urge young people to widen the range of their acquaintance, for they will do it without urging if the opportunity is presented to them. It is highly necessary for parents, and for organizations and municipalities, deliberately to seek to further every means which will bring unmarried young people together under proper supervision. Social workers have already perceived the need of institutional as well as municipal action on these lines, although they have not in every case recognized the eugenic aspect, and from their efforts it is probable that suitable institutions, such as social centers and recreation piers, and municipal dance halls, will be greatly multiplied.