The primary vessels adhere pretty closely together at their roots, but are more loose or separated at their termination. They are at first only yielded by the fundus, and in a small degree by the surface, immediately above the cervix, whilst the cervix itself produces from the lacunæ, which are increased in magnitude, a jelly, which sometimes fills up the os uteri completely; at other times there is only a small quantity formed in the cervix, leaving the os uteri quite patent. The inferior part of the uterine surface, which yields the primary vessels, is not a quarter of an inch in breadth; and the cavity being there small and narrow, the vessels from the opposite sides soon come in contact, and intermix without forming any secondary vessels. This portion may be called the cervical efflorescence. The secondary vessels are very different from the primary; for, whilst the latter are short, straight, and parallel to each other, the former are more extended, intermix, and ramify together, so as to form an irregular tissue or sheet of vascular substance, the fibres or vessels of which assume a direction at right angles to the down or primary vessels which formed them. This direction seems to be very naturally produced by the weight of the secondary vessels, which makes them hang down or point to the os uteri. Very soon we can perceive ragged irregular processes, hanging into the cavity of the uterus, and extending toward the cervix, so that this layer of decidua presently appears to consist of a number of torn floating membranes, like portions of spiders’ webs, pendulous in the uterine cavity; but nearer examination shows that there has been no laceration, the margins being smooth and well defined. These I would call the processes of the decidua interna. Such is the structure of the decidua externa and interna, at three weeks or a month after impregnation; and at this period no fœtus is in the uterus. In one case I detected the vesicular ovum in the tube. It was about half way betwixt the two extremities, was rather smaller than a full-grown pea, and contained a little fluid. In another case I found it still in the ovarium, covered by the fimbriated extremity of the tube. By puncturing the peritoneal coat of the gland, the vesicle escaped. It has been the general opinion, since the time of Dr. Hunter, that the decidua extended a little way into the tube; and on his authority I stated this to be the case in an account which I formerly published. By careful examination, I am now convinced that this is not the case. My brother, in his dissections, even thought that the uterine extremity of the tube was less changed in point of vascularity, than any other part of it.