is shown by the fact that a high mortality of boys extends through the whole of the first year, and through five years, in a diminishing ratio, and also that the tenacity of woman on life, as will be shown immediately, is greater at every age than man's except during a period of about five years following puberty. "There must be," says Ploss, "some cause which operates more energetically in the removal of male than of female children just before and after birth;"[86] but, besides the more violent movement of boys and their greater size, no explanation of the cause has been advanced more acceptably than Haushofer's teleological one, quoted by Ploss, that Nature wished to make a more perfect being of man and therefore threw more obstacles in his way. A satisfactory explanation is found if we regard the young female as more anabolic, and more quiescent, with a stored surplus of nutriment by which in the helpless and critical period of change from intra- to extra-uterine conditions it is able to get its adjustment to life. The constructive phase of metabolism has prevailed in them even during fetal life. That there is need of a surplus of nutrition in the child at birth, or that a surplus will stand it in good stead, is indicated by the results of the weighing of children communicated by Winckel to the Gynaecological Society in Berlin in 1862. Winckel weighed 100 new-born children, 56 boys and 44 girls, showing that birth was uniformly followed by a loss of weight. The average diminution was about 108 grams the first day, and but little less the second day. At the end of five days the loss was 220 grams, six-sevenths of which occurred during the first two days.[87] The tendency to decreased vitality in girls after maturity and before marriage, just referred to, must be associated with the katabolic changes implied in menstruation and the newness to the system of this destructive phase of metabolism. We should expect the death-rate of men to run high during the period of manhood, in consequence of their greater exposure to peril, hardship, and the storm and stress of life. But two tendencies operate to reduce the comparative mortality of men between the twentieth and about the fortieth year: the fact of the severe male mortality in infancy, which has removed the constitutionally weak contingent, and the fact that during this period women are subject to death in connection with childbirth. So that in the prime of life the mortality of males does not markedly exceed that of females. But the statistics of longevity show that with the approach of old age the number of women of a given age surviving is in excess of the men, and that their relative tenacity of life increases with increasing years. Ornstein has shown, from the official statistics of Greece from 1878 to 1883, that in every period of five years between the ages of 85 and 110 years and upward a larger number of women survive than of men, and in the following proportion: