It will thus be understood that during the first twenty-four hours after the Menstrual Flow has ceased, there is very little danger of impregnation, and in some females this time might be extended to two or three days with safety. The Zoospermes of the Semen will live for twenty-four hours within the Womb, and it is possible for the Egg to be impregnated by them the moment it leaves the Fallopian Tube. We therefore state the probable time that impregnation cannot take place to be twenty-four hours, allowing the second twenty-four hours for the possibility of there being living Semen in the Womb. After the Decidua and Egg have passed out of the Womb, which is from ten to sixteen days after the Menstrual Flow has ceased, impregnation, or conception, is then utterly impossible until after another monthly turn is over, and so on. French women are famous for a clear understanding of all the phenomena attending impregnation, and they generally avoid it at pleasure. They know exactly when the Decidua and Egg leaves them—they watch for it, and it is said many of them search for it and take it away violently. At all events, there are multitudes of the class called grisettes—females who are content to live and cohabit with any decent man who offers them a support—who never get into the family way at all. Their secret is supposed to be a physiological knowledge, or art, which enables them to destroy the Decidua, or membrane which keeps the Egg from passing out of the Womb. We confess we cannot understand how so delicate an operation can be performed by a woman upon her own person; but the thing is not impossible. Married people who desire to avoid having children might generally attain their object by refraining from sexual intercourse for a week or ten days after the cessation of the Menstrual Flow; or, they might follow the precaution recommended in our chapter on Prevention during that period. It is supposed that conception takes place within seven days after the monthly turn nineteen times out of twenty. But to be on the safe side, you should wait longer—even to sixteen days—unless you can discover when the Decidua and Egg pass off. There are certain symptoms connected with this expulsion of the Egg which may be detected. A thin, colorless, watery fluid comes from the Vagina, and is often so abundant as to wet the external parts. This will continue for some hours, and will be followed by a grayish-white clot about the size of a pea. The discharge of this clot is frequently accompanied by slight pains and bearing down of the Womb. This is the Decidua and Egg. When a woman can discover, with certainty, the passage of this clot, she is then safe from impregnation until after her next monthly turn.