Perhaps you will remember that I once told you that all life is from an egg, the life of the plant, the fish, the bird, the human being. In the book "What a Young Girl Ought to Know" we discussed how all life originates in an egg, and why there must needs be fathers as well as mothers. We found that some eggs were small, were laid by the mothers in various places, and then left to develop or to die. Others were larger, covered with a large shell, and kept warm by the mothers sitting over them until the little ones were hatched. Others were so small that they developed in the mother's body until, as living creatures, they were born into the world. This is the case with the human being. He is first an egg in the mother's ovary. When this egg has reached a certain stage of development it passes from the ovary through a tube into the uterus. If it meets there, or on its way there, the fertilizing principle of the male, it remains there and develops into the child. If it does not meet this principle, it passes out through the vagina and is lost. But the eggs, or ova--which is the Latin word meaning eggs--do not begin to ripen until the girl reaches the age of thirteen or fourteen, or, in other words, until she begins to become a woman. This passing away of the ovum (singular of ova) is called ovulation, and it occurs in the woman about every twenty-eight days. The uterus is lined by a mucous membrane similar to that which lines the mouth, and at this time of ovulation this membrane becomes swollen and soft, and little hemorrhages, or bleedings, occur for three or four days, the blood passing away through the vagina. This is called menstruation. Sometimes, when girls have not been told beforehand of the facts of menstruation, they become greatly frightened at seeing this blood and imagine that they have some dreadful disease. If they have no friend to whom they can speak freely they sometimes do very injudicious things in their efforts to remove that which to them seems so strange and inexplicable. I have known of girls who washed their clothes in cold water and put them on wet, and so took cold and perhaps checked the menstrual flow, and as a consequence were injured for life, or may even have died years after as a result of this unwise conduct. The girl who is wisely taught will recognize in this the outward sign of the fact that she has reached womanhood, that she has entered upon what is called the maternal period of a woman's life, the period when it is possible for her to become a mother.