Statistics of births are now complete enough to afford a fairly reliable basis for some interesting conclusions. These are made the subject of an elaborate study by J. B. Nichols,1 who has obtained data aggregating 693,785,722 living births and 13,635,986 stillbirths, or 707,421,708 births in all. These data are chiefly supplied by the exhaustive compilation of birth statistics published in Statistique générale de la France2 supplemented by some data from original and other sources. The statistics regarding illegitimate births are of questionable value in consequence of the incomplete report and registration of these births, and, therefore, the estimate of total births is subject to some doubt. Some problems relating to the proportion of sexes have either received insufficient investigation or the data are imperfect so that a definite conclusion can not be given. This is true of the relations to war, climate, race, country and city, age, vigor,