The Hymen is a membranous fold, sometimes circular in shape, with an opening in the center, though in other cases it extends only across the lower part of the orifice. The opening in the center is for the purpose of allowing the menstrual blood and the other secretions of Uterus and Vagina to flow through. In a few cases this opening is absent, the Hymen being what is called "imperforate"; in which case the girl experiences difficulty when menstruation begins, and a physician is required to make a slit or opening in it. In some girls and women the Hymen is quite tough, while in others it is very thin and is easily broken. In the latter cases the young girl frequently breaks the membrane during vigorous exercise, such as jumping rope, etc. And, as has before been said, in some cases infant girls are born without even a trace of the Hymen. Under the circumstances, it is seen that the presence or absence of the Hymen is far from being an infallible proof of the presence or absence of virginity, and the belief in the same is now regarded as almost a superstition of the past. THE INTERNAL SEX ORGANS OF THE WOMAN. The internal sex organs of the woman are as follows: The Vagina; the Uterus and its appendages; the Fallopian Tubes; the Ovaries, and their ligaments, and the round ligaments. THE VAGINA is the canal or channel leading from the Vaginal Orifice to the Uterus or womb. It is situated in front of the rectum, and behind the bladder. In length, it averages from three to five inches; and it curves upward and backward, reaching to the lower part of the neck of the womb, or Uterus, which part of the neck is enclosed by it. It is a strong fibro-muscular structure, lined with mucous membrane; and is not smooth inside, but is arranged in inner folds or rings which are capable of great extension. On either side of the Vagina, near the outer orifice, are two small glands, about the size of a pea, which secrete a peculiar fluid, and which are known as the Glands of Bartholine. The office of the Vagina is that of a complementary to the male organ during the copulative process; to also sustain the weight of the Uterus; to also afford a passage for the infant at the time of its birth; and also to serve as a passage for the menstrual fluid. THE UTERUS, or Womb, is the internal sex organ of the woman which serves to hold the fertilized ovum, or egg, from the time of impregnation, during the period of pregnancy during which the ovum develops into the young child, and until the time of the delivery of the child.