(2) No doubt the pressure of economic conditions is not responsible for small families in some elements of the native white population in the United States, for oftentimes the smallest families are found among the wealthy, among whom there could be no danger of a large family lowering the standards of living or pressing upon other economic needs. We must accept as a second factor in the situation, therefore, the inherent selfishness in human nature which is not willing to be burdened with the care of children. In other countries, and apparently in all ages, the wealthy have been characterized by smaller families than the poor. The following table from Bertillon, [Footnote: Quoted by Newsholme, Vital Statistics, p. 75.] showing the number of births per thousand women between fifteen and fifty years of age in Paris, Berlin, and London among the various economic classes, shows conclusively that it is not altogether the pressure of economic wants which leads to the limiting of a population: BIRTHS PER THOUSAND WOMEN PER ANNUM Paris Berlin London. Very poor ....... 108 157 147 Poor ............ 95 129 140 Comfortable ..... 72 114 107 Rich ............ 53 63 87 Very rich ....... 34 47 63 (3) Besides economic conditions and individual selfishness we must unfortunately add another cause of decreasing birth rate in our population which has been definitely ascertained, and that is vice. Vice cuts the birth rate chiefly through the diseases which accompany it. About 20 per cent of American marriages are childless, and medical authorities state that in one half of these childless marriages the barrenness is due to venereal diseases. According to Dr. Prince A. Morrow, in his _Social Diseases and Marriage_, 75 per cent of the young men in the United States become impure before marriage. This serves to disseminate venereal diseases among the general population, especially among innocent women and children. The consequence is, on the one hand, a considerable number of sterile marriages and on the other hand a high infant mortality. It need not be assumed, as we have already said, that vice is more prevalent to-day than in previous generations, but on account of the conditions of our social life diseases which accompany vice are now more widely disseminated than they have been at any time in our previous history; therefore, even the physical results of vice are different to-day than they were a generation or more ago.