=An extra-uterine pregnancy= may be defined as a pregnancy which develops outside of the uterus, usually in a tube or ovary. Although in the normal course of events the fertilized ovum travels down the tube and becomes attached to the uterine lining, it is possible for it to stop, and more or less completely develop at any point along the way between the Graafian follicle, from which it has been projected, and the uterus toward which it is traveling. If the fetus develops in the ovary, it is termed an ovarian pregnancy, and a tubal pregnancy if it occurs in the tube, the latter being the most frequent variety of extra-uterine pregnancy. In the opinion of Dr. Mall, only about 1 per cent of all extrauterine pregnancies are capable of going to term. There may be an abortion, when the fetus and membranes are partly or completely extruded from the fimbriated end of the tube into the peritoneal cavity; or a rupture of the tube, when the fetus, with or without the membranes, may be expelled into the peritoneal cavity, or between the folds of the broad ligament. If the greater part of the placenta remains attached to the site of its development, in the case of a ruptured tube, it is possible for the fetus to live and grow and even go to term. But if the placenta is nearly, or completely separated, the fetus perishes and may be largely absorbed by the maternal organism, or mummified, or putrefactive changes may take place. It is usually customary to terminate an extra-uterine pregnancy as soon as it is diagnosed, for only a very small number can be expected to go to term, the majority aborting, or rupturing the tube, with serious hemorrhage from the mother as a frequent result. To sum up the normal pregnancy, we find that in the course of ten lunar months, following the fertilization of an ovum, the uterus grows from a small, flattened, pelvic organ, three inches in length, to a large, globular, muscular sac, constituting an abdominal tumor about fifteen inches long; it increases its weight thirty-two times, that is from two ounces to two pounds, while the capacity of the uterine cavity is multiplied five hundred times. Within the cavity is a child weighing about seven and a quarter pounds, surrounded by a quart or so of amniotic fluid. This fluid is contained in the sac composed of the fetal membranes, the amnion and chorion, which are excessively developed at one point into the placenta. The placenta, in turn, is attached to the child by means of the umbilical cord. The total weight of the uterus and its contents at term is usually about fifteen pounds. Quite as mysterious and inexplicable as the development of these complex structures from one tiny cell is the fact that when the new human being is ready to begin life as a separate entity, further changes occur within the mother’s body which produce uterine contractions of such a character as to entirely empty the uterus of its contents.