The vital importance of pre-natal life is beginning to receive recognition and we have begun to recognize that a woman is not necessarily physically and otherwise fit to be a mother, merely by reason of the fact that she is a woman.

In many important particulars the most important period of the physical life of an individual is the pre-natal period. It is during this period that all the foundations are laid, all the tissues and organs are formed and cellular activities are at their highest. The heart, lungs, liver, brain, nerves, eyes, ears, teeth, skin, bones, muscles, kidneys and other tissues and organs are formed and prepared for their functions during the nine months of intra-uterine life.

From a minute mass of "protoplasm" 1/125 of an inch in diameter, by the orderly processes of cell multiplication, cell specialization, combination, and organization there is built up, step by step, in orderly sequence, the complete and perfectly formed infant. Food is the material out of which the body of the infant is built and this material is supplied by the mother.

Nature has made a wonderful provision for nourishing the developing embryo. In women the maternal structures directly, without the intervention of a special apparatus, supply nourishment to the fertilized ovum, which is the potential child. Very early, however, in uterine life a peculiar mechanism is formed through which passes from the mother's blood stream, to the embryonic or fetal blood-stream, the nutrient materials needed by the developing child. This structure, known as the placenta (after birth), is developed partly by the mother and partly by the child.

The placenta acts in the double capacity of pulmonary and intestinal mucous membranes; taking up both oxygen and food carried in the mother's blood. The fetus then receives its nutritive materials from the placenta. The mother does not give even a drop of her own blood to the child. The latter forms its own blood, from the food material supplied through the placenta. The function of the placenta is chiefly absorptive but partly eliminative, for through it the fetus eliminates its waste.