The surgical history of ectopic pregnancy is dotted with puzzling cases in which undoubted symptoms of the condition were present, and in which on operation a greater or less quantity of blood was discovered in the pelvis, and yet careful microscopic examination of the tissues removed failed to show any trace of the products of conception. In many of these cases careful examination has failed to disclose the source of hemorrhage.
Some recent studies in biology bearing on the implantation of the ovum in the uterine mucosa have revealed a process which when transplanted, as in tubal pregnancy, sheds a flood of light on many of these obscure cases. The established teaching has been that the impregnated ovum when it reaches the uterine mucosa nestles among its follicles, which at once take on a hypertrophic development, reach out on all sides and envelop it in their arms. Later developments bring