Frequently, prospective mothers are told they must not "reach up" for fear the cord will become entangled. Such a precaution is quite unnecessary. No matter what the mother does, or does not, the cord will be found around the child's neck at the time of birth in one of every three cases. It is not difficult to understand how this happens. The cord is longer than the uterine cavity and must fall in coils toward the bottom of it. Now, since the fetus is free to move it enters and withdraws from these loops, many times, in the course of pregnancy. Finally, when it takes up a position head downward, as it nearly always does, the head is the part of the fetus which passes through the coil, should one happen to lie in its path. After the head is delivered the physician always feels about the neck to discover whether a loop of cord is there. If it is, he can release it easily. This condition, since it occurs so frequently and since it so rarely produces harmful consequences, should not be considered unnatural. After the child is born, the physician cuts the cord, and in due time the after-birth is expelled through the same passage as was the child. The expulsion of the after-birth frees the mother of all the tissue derived from the growth of the ovum, for the intricate mechanism that served to nourish and protect the embryo was almost entirely developed from the ovum itself. It is a remarkable provision of Nature that very little of the mother's tissue is cast off at the end of pregnancy; and even this small portion is promptly replaced. By about the sixth week after delivery, the wound which was made by the separation of the fetal sac has completely healed. Meanwhile the mucous membrane that underwent elaborate preparations to receive the ovum, the cavity that was adjusted to its growth, and the muscle fibers that were strengthened to insure its safe entry into the world have all regained their original state. Except for the activity of the breasts, the mother is left in the same physical condition as before she became pregnant. CHAPTER III THE EMBRYO The Development of Form--The Determination of Sex--Twins--The Rate of Growth--The Newborn Infant--Heredity--Maternal Impressions.