_Certain Contributory Causes._--The influence upon infant mortality of certain causes commonly regarded as important is in fact small. Statistical data prove beyond dispute that local and climatic factors exercise no direct influence at all upon the infantile death-rate; such influence as these factors do exercise is an indirect one, operating through the effect which climate and locality may have upon social conditions. The same qualification applies to the influence of race and of religion upon infant mortality. There are differences in the infantile death-rates as between Teutons and Slavs, and as between Christians and Jews; but these differences are in no way directly dependent upon the differences in race or in religion, and they must be ascribed to the differences in social conditions. Fertility is well known to exert a decisive influence upon infant mortality; but variations in fertility are not the direct effect of any differences in race or creed; they are a consequence of the varying social conditions in which those of the respective races or creeds actually live. Thus it is only in certain social conditions that Slavs are more fertile than Teutons, and Jews more fertile than Christians. The constitution of the parents exercises a considerable influence upon infant mortality; but the parental constitution must be regarded as largely dependent upon the social environment in which the parents themselves have grown to maturity. _The Chief Causes of Infant Mortality._--Among the commonly enumerated conditions affecting infant mortality the following are conspicuous: the proportion of infants reared by artificial feeding instead of being suckled; work for wages by the mothers of infants; the general intelligence of the lower classes of the population, and their knowledge of the care and management of infants; the general state of the public health, including such conditions as the degree to which the general population is enabled to avail itself of the medical knowledge of our time (in all the countries claiming to be “civilised,” bald official statistics prove beyond dispute that a large proportion of the children dying before attaining the age of one year die without having ever received any medical treatment whatever); the number of illegitimate births, &c. But all these conditions are in essence nothing more than social conditions. Thus we are practically justified in saying that the determining factors of infant mortality are social conditions and nothing else. With striking unanimity, those who have made a special study of this question formulate the conclusions summarised in the following paragraph.