_Causes of the Movement for the Protection of Proletarian Children._--To-day great stress is laid upon attention to the health not only of the general population, but in especial to the health of children. During the nineteenth century the view became general that in the interests of the health of the children, society ought to be prepared to make any sacrifices. In the domain of social hygiene--that is, of the science which occupies the borderland between the science of public health and the science of sociology--neither the men of theory nor the men of practice can venture to adopt a one-sided class outlook. During recent years, upon the groundwork of these sound conceptions, a number of new institutions have been founded, by means of which the general condition of public health and the hygiene of childhood (including that of proletarian childhood) have been considerably improved. In many directions the advances in medical science tend to counteract with success the disorders consequent upon the development of capitalism. The technique of artificial feeding has been greatly improved, and this has led to a reduction in infantile mortality; ophthalmia of the new-born can now be efficiently prevented, and this has led to a decrease in the number of blind persons. To the upper classes of society the health of the lower classes is of importance for two reasons--(_a_) the former have need of the working powers of the latter, and in bad hygienic conditions these working powers are impaired; (_b_) if the health of the lower classes is neglected, it is not these classes alone which suffer, but the rich suffer as well. For example, the well-to-do are endangered when nothing is done to check the spread of infectious diseases among the poor, and when poor persons attacked by these diseases are left without proper treatment. If the health of poor children be neglected, the results are extremely serious, not for these children alone, but for the children of the well-to-do and for adults.