+The habit of breast-feeding as running in families and infant mortality.+ With this goes the following explanation: "The two figures illustrate the proportion of mortality of the infants in 143 bottle-feeding families and 376 breast-feeding families of the first order. As the line could not be drawn very sharply, and as in the bottle-feeding families there had to be included those in which as an exception one or other child was suckled for a few days or perhaps for a week, one can see in these groups only the expression of the habit, but not the power of suckling. Both figures illustrate the largely avoidable sacrifice in young lives which still goes on through a want of knowledge and of feeling of responsibility towards the coming race. With the absence of breast-feeding the unfavourable influence of a very large number of children becomes much more apparent; whereas in breast-feeding families the difference in the mortality between medium-sized families (four to six children) and very large families (above ten children) amounts to only 1.39%, it reaches 12.90% with the non-suckling families. Here, if the number of children surpasses ten, nearly every second child dies in the suckling age, and amongst thirteen families there is not a single one which has not lost a child in that period, whereas in breast-feeding families of the first order, with the same large number of children, only every thirteenth child died in infancy, and of sixteen families seven (= 43.75%) lost no infant." The same material is treated in a different way by Dr. Marie Baum, of Dusseldorf, in Figures C 63-66. [Sidenote: C 63] +As the length of the period of suckling of the preceding child increases, there is a constant and rapid decrease in the number of children who are born at intervals of less than one year.+ If the preceding child was not breast-fed a new birth occurred before the expiration of one year in 9.6 cases out of 100. With a suckling period of one-half to three-quarters of a year of the preceding child, this figure is reduced to 1.8 per cent., and after a still longer suckling period to 1 per cent. Out of one hundred mothers who have only partly or not at all suckled the preceding child, seventy must count on a fresh birth within a period of 1-3/4 years. If the preceding child was suckled for at least 39 weeks, only thirty-eight, and with a suckling period of more than a year only twenty mothers have to reckon on a fresh birth within 1-3/4 years. Dependence of Infant Mortality on the Duration of Breast-Feeding and the Length of Time Intervening Between Successive Births. [Illustration: Figure C 63.] [Sidenote: C 64]