He has found that individuals of the lower classes show a smaller development of stature, of cranial capacity, of sensibility, of resistance to mental fatigue, a delay in the period when puberty makes its appearance, a slackening in growth, a very large number of anomalies, etc. The causes of these differences ascertained in comparing the two groups are of the _mesological_ and _individual order_. Of the _mesological_ order because the conditions of life where men of the lower classes are forced to live constitute one of the causes of the deterioration of their physical and mental characters. Of the _individual_ order because, thanks to biological variation, every man is born different from all other men, and men who are born with superior physical and mental characters tend to rise in the superior classes, while men who are born with inferior physical and mental characters tend to fall in the most wretched classes. However, in studying the catalogues of measurements and observations, the author has found that in the mass of men belonging to the superior classes one finds a small number of men with inferior qualities, while in the mass of men forming the inferior classes one finds a certain number of men presenting superior characters. It is between these two _exceptional_ categories that social exchanges should be made, allowing the best and most capable of the lower stratum to ascend, and compelling the unadapted who are found above to fall to the lower stratum. THE FERTILITY OF MARRIAGES ACCORDING TO PROFESSION AND SOCIAL POSITION. (Abstract.) By M. Lucien March, _Directeur de la Statistique Générale de la France._ Statistics of families furnish, perhaps, the most appropriate data for the examination of the factors which govern the productiveness of marriages or their sterility. Statistics concerning the children born in the eleven and a half million French families, classed according to occupation, have been prepared in France for the first time as a result of the census of 1906. These statistics give information as to the number of children per family, either alive on the day of the census or previously deceased, in each occupation, for all the families in the whole country taken together, and for the different provinces. Further, a special investigation of the 200,000 families of employees and workmen in the public services has furnished more circumstantial details, which have enabled the number of children and number of deaths of children in a family to be brought into relation with the income of the head. The results obtained by the method described above are the subject of this report. The effects of occupation, social position and income are analysed by means of co-efficients expressing the productiveness of marriages, after eliminating the influence of such factors as duration of marriage, age, and habitat, all of which may obviously affect the productiveness of a marriage.