The organ increases slowly in size during the early. months of pregnancy, and more rapidly in the later. The walls are distended, however, not mechanically from the development of the ovum, but simultaneously with it, and from a physiological cause; in shape it becomes rounder, and towards the end of pregnancy it has an ovoid form. Simultaneously there is an alteration in its position; at first the neck subsides towards the floor of the pelvis; the presence of the rectum may incline the fundus to the right and the neck to the left; about the fourth month the uterus rises above the superior strait; at four months the fundus uteri is two or three fingers in breadth above the pubis; at five months it is within one finger’s breadth of the umbilicus; between the fifth and sixth month it passes the umbilicus; at seven months it is three fingers’ breadth above the naval; at eight months it is four or five above, but it does not rise higher during the last month. While it is rising it follows the direction of the axis of the superior strait; afterwards it inclines to the right oftener than to the left. At term, the superior part of the uterus is in contact with the abdominal walls usually, but sometimes there may be some of the intestines interposed between them. At full term the parietes of the womb are thicker than in the unimpregnated condition; at the point corresponding to the insertion of the placenta, thinner at the neck, and otherwise it retains about its original thickness. The uterus increases about forty times in weight during pregnancy; at term it weighs about twenty-four ounces, and its length is from twelve to fourteen inches, its breadth from nine to ten, and its depth, antero-posteriorly, eight to nine inches. The os uteri, after it is in the gravid state, becomes somewhat swollen, but soft and cushion-like. This softening is at first superficial. Towards the end of the third month, the lips of the os tincæ are softened throughout their whole thickness, and the softening increases from below upward. The _neck of the uterus_ seems somewhat elongated at the first, but at the commencement of the sixth month the length of the cervix seems to diminish; there is, however, no considerable shortening until the middle of the eighth month; during the last fortnight of pregnancy it diminishes very rapidly, and finally is totally effaced. In primapara the os tincæ is rounded at first, and is not dilated. In females that have had children the external orifice is widely open, and the cavity in the neck is funnel-shaped, continuing to increase until it reaches the internal orifice.