In a very small number of cases an unduly large loss of blood follows the expulsion of the placenta. Fortunately, by treatment which consists usually in spurring Nature to more vigorous action we are well equipped to deal with this emergency. A wonderful mechanism has been provided by Nature to control excessive bleeding after delivery. If the forces upon which this mechanism depends are sluggish, the physician stimulates them. As in the preceding stages, the muscle fibers of the uterus supply the power in question, and because of this role an observant obstetrician once called them, "living ligatures." Certain of these fibers encircle the mouths of the blood- vessels which have been left open through the detachment of the placenta. When they contract the vessels are squeezed, impeding the escape of blood. The necessity of this action explains the contractions which continue even after the placenta has been expelled, when they are vigorous enough to cause discomfort they are spoken of as "after-pains." After-pains seldom follow the birth of the first child, but they regularly follow later confinements. In any case, such contractions do not persist very long, for tiny clots form within the blood vessels and effectually close them. As soon as the lining of the womb has been restored the clots are absorbed, leaving the organ in much the same condition as before conception took place. THE EFFECT OF LABOR UPON THE CHILD.--Unless the experience of countless generations had taught us otherwise, we should fear the child would be injured by its passage through the birth-canal. Immediately after the birth evidence of the journey is seldom wanting, but it quickly disappears. The unusual size of the infant's brain requires the head to be large, and bestows upon it a contour which differs from that of the mother's pelvic cavity. Since the bones of the pelvis are rigid, while those of the fetal skull are malleable, the head is molded as it descends into the pelvic cavity, so that its passage may be made the easier. As the result of this process of accommodation the skull becomes relatively longer from crown to chin than in adults. Within a few weeks, however, the modification vanishes. If an infant is born with the buttocks first, the head does not linger in the birth-canal, a fact which in such cases explains the pleasing shape of the skull, which emerges with the contour determined by fetal growth.