In cases in which, in consequence of morbid conditions of the uterus, the ovaries, or the organism as a whole, the menstrual flow has at the time of the menarche either failed entirely to appear or been exceedingly scanty, hæmorrhages from other organs have since ancient times been witnessed, and these hæmorrhages have been regarded as vicarious menstruation. The congestion that occurs during menstruation is not limited to the genital organs, and when the flow of blood from the uterus fails to occur, the organism seeks another outlet, in order to restore the disturbed equilibrium of blood distribution, and vicarious hæmorrhages take place from the mouth, the nose, the intestines, the anus, the gums, the mammæ, the ears, and the lungs; or hæmorrhages occur in the brain, the nerves, or the eyes. Although it must be admitted that confusion has often occurred between vicarious menstruation and hæmorrhages dependent on pre-existing genuine organic disease, such as hæmoptysis due to pulmonary tuberculosis, or hæmatemesis due to gastric ulcer, still the existence of a true vicarious menstruation must be regarded as fully established. Thus, _Fricker_, _Fleischmann_, _Obermeier_, _Beigel_, _Withrow_, _Plyette_, and _Parsons_ observed vicarious epistaxis; _Watson_, _Decaisne_, _Edebohls_, _Fischel_, and _Seeligmann_, vicarious hæmatemesis; _Franchi_, _Hotte_, _Ratgen_, _Voigt_, and _Windmüller_, vicarious hæmoptysis; _Dunlap_, vicarious gingival hæmorrhage; _Law_ and _Petiteau_, vicarious otorrhagia; _Heusinger_ and _le Fort_, vicarious hæmorrhages, occurring variously from the anus, bladder, hand, ear, nipple, stomach, and nose; _Baumgarten_, vicarious hæmorrhage from the vocal cords and trachea; _Hahn_, from the bladder; _Kerley_, in the thyroid body; _Gallemairts_, in the eyes. _Puech_ found, in the cases he collected, that vicarious menstrual hæmorrhage occurred from the stomach thirty-eight times, from the mammary glands twenty-five times, from the lungs twenty-four times, and from the nasal mucous membrane eighteen times. In all the cases menstruation had long been in abeyance.