Whatever part of the womb the ovum attaches itself to is stimulated to intense activity, to growth. Numerous bloodvessels begin to grow and that part of the lining membrane with its numerous bloodvessels constitute the placenta, or as it is commonly called _afterbirth_, because it comes out _after_ the _birth_ of the child. From the placenta there is also reflected a membrane over the ovum, so as to give it additional protection. That membrane forms a complete bag over the fetus; this bag becomes filled with liquid, so that the fetus floats freely in a bag of waters; this bag bursts only during childbirth. The fetus is not attached close to the placenta, but is, so to say, suspended from it by a _cord_, which is called the _umbilical cord_. When the child is born, the umbilical cord is cut, and the scar or depression in the abdomen where the umbilical cord was attached constitutes the navel or umbilicus (in slang language--button or belly button). The umbilical cord consists of two arteries and one vein embedded in a gelatin like substance and enveloped by a membrane, and it is through the umbilical cord that the blood from the placenta is brought to and carried from the fetus. The blood of the fetus and the blood of the mother do not mix; the bloodvessels are separated by thin walls, and it is through these thin walls that the fetal blood receives the ingredients it needs from the mother's blood. In other words, it receives its nourishment from the mother by _absorption_ or _osmosis_. The blood from the placenta also furnishes the fetal blood with oxygen, so that the fetus breathes by the aid of the placenta, and not through its own lungs. It is well to remember that there is absolutely no nervous connection between mother and child. There are no nerves whatever in the umbilical cord, so that the nervous systems of the fetus and of the mother are entirely distinct and separate. And this will explain why certain nervous impressions and shocks received by the mother are not readily transmitted to the child. It is only through changes in the mother's blood that the fetus can be influenced. As will be seen in a later chapter we are skeptical about "maternal impressions." CHAPTER FIFTEEN LACTATION OR NURSING No Perfect Substitute for Mother's Milk--When Nursing is Injurious to Mother and Child--Modified Milk--Artificial Foods--Care Essential in Selecting Wet Nurse--Suckling Child Benefits Mother--Reciprocal Affection Strengthened by Nursing--Sexual Feelings While Nursing--Alcoholics are Injurious--Attention to Condition of Nipples During Pregnancy Essential--Treatment of Sunken Nipples--Treatment of Tender Nipples--Treatment of Cracked Nipples--How to Stop the Secretion of Milk When Necessary-- Menstruation While Nursing--Pregnancy in the Nursing Woman.