"A peculiar configuration is observed in these coefficients in that a quite pronounced positive correlation exists at the central age group, but disappears with some regularity towards both extremities of life. If the mortality has any influence upon the natality this cannot be in the form of replacement of lost infants and deceased old people, therefore, as has frequently been suggested. That a high death-rate at the child-bearing age should be conducive to increased fertility is absurd, neither does it seem likely that a large number of children should make the parents more liable to diseases which are prevalent at this period of life. The reasons must, then, be looked for in a common factor. "Now the only disease of importance representing the same age-curve as do the correlation coefficients is tuberculosis. This disease causes in France 2 per cent. of the deaths under one year, 24 per cent. of the deaths from 1 to 19 years of age, not less than 45 per cent. from 20 to 39, 18 per cent. at ages 40 to 59, and less than 2 per cent. at the ages over 60. Will a high tuberculosis mortality, then, be conducive to great fertility, or do we have to fear that a decrease of the natality will be the result of energetic measures against tuberculosis? Hardly. The death-rate may be reduced, then, without detrimental effects upon the birth-rate. "What can the factor be which influences both the tuberculosis incidence and the birth-rate? We know that the prevalence of tuberculosis is conditioned principally by poverty and ignorance of hygiene. The Parisian statistics, as compiled by Dr. Bertillon and recently by Professor L. Hersch, show a much higher birth-rate in the poor wards than in the richer districts, and the high birth-rates may be furnished largely by the poorer elements of the population. A comfortable degree of wealth does not imply a low birth-rate, as is abundantly shown elsewhere, and one of the important questions which suggest themselves to the French statistician and sociologist is evidently the following: How can the intellectual and economic standard of the masses be raised without detriment to the natality? "We believe that the time is opportune for solving this question. The past half-century has been lived under the shadow of defeat and with a sense of limitations, and of impotence against fate. This nightmare is now thrown off, and, the doors to the world being open and development free, the French people will learn that new initiative has its full recompense and that a living and a useful activity can be found for all the sons and daughters they may get. The habit of home-staying is broken by the war, and new and great undertakings are developing in the ruined north-east as well as in the sunny south." [34] [Footnote 25: _The Lancet_, 1879, vol. ii, p. 703.]