To carry this sketch of the progress of midwifery farther, or extend it to the diseases of women and chil dren, would exceed the limits proper to a work of this kind. To notice all the eminent writers and teachers of the present day would be impossible, and„ to make a selection where so many are to be found, would be both difficult and invidious.* Of the Gravid Uterus.
Tim first visible change produced on the uterus and ovaria by conception, is increased vascularity. Simul taneous with this is an augmentation of the bulk of the womb, or enlargement of its cavity, and a secre tion within that cavity. The cervix uteri is filled with inorganic jelly, whilst the lundus and body arc lined with a coating consisting partly of lymph, and partly of vessels. This has been called the memb•ana decidua, and is formed before the ovum can be de tected in the uterus. Whilst a receptacle is thus pre paring for the child, changes -are going on in the ova rium, where the ovum first appears. This becomes more vascular, and at one part a small vesicle becomes prominent. The exterior covering of the ovarium seems at this part to be absorbed, whilst the fitnbriat ed exti emity of the tube adheres firmly over it, and receives the vesicle or ovum, as it is extricated from the ovarium outface, conveying it down into the ute rus itself, whence it is to be developed. That part of the ovarium whence the embryo has issued, undergoes certain changes in appearance, forming a distinct sub stance, known under the name of corpus luteum, the presence of which is considered as an indication of conception having at one period or other taken place. At a very early stage, several vesicles may be dis covered under the covering of the ovarium, at least the writer has observed this in two or three instances, but whether these be ova which fade, is not determined. The ovum, from the earliest time when it can be ex amined, consists of two vesicles, one within the other. The innermost is much smaller than the outermost, but is connected with it at one spot. The internal contains a little transparent fluid, and the minute em bryo. The space between the two vesicles is filled with clear jelly, like the vitreous humour of the eye, and the outer surface of the external vesicle is covered with small vessels, which in a short time increase so much that they form a distinct vascular covering, known under the name of the spongy chorion, whilst the vesicle they cover is called the membranous elm rion the vesicle within both is called the amnion, and the fluid it contains, and which is in immediate con tact with the embryo, is named the liquor amnii. For
a considerable time after the ovum enters the uterus, the chorion and amnion, except at one point, are far distant from each other, but presently the amnion en larges more rapidly, so as to fill the space enclosed by the chorion, and the intervening jelly is absorbed in the same proportion. In common language, the em bryo is said to be within these membranes, but anato mists know well that it is exterior, as the bowels lie without the peritoneum For it is next to be noticed, that at one part, namely, where the embryo is situ ated, a small prolongation of both membranes is turn ed inward, so as to form a short tube, along which vessels run from the spongy chorion to the embryo, and from the embryo to the chorion. This prolonga tion is afterwards called the umbilical cord, and the passing vessels the umbilical vessels. 'When the ovum enters the uterus, it dues not pass down unconnected through the tube, nor fall loosely into the uterine ca vity, but, arrived at the end of the tube, and entering the womb, it meets with the decidua vera, as it has been called, and an intermixture of vessels takes place between the chorion and decidua, and in proportion as the ovum expands and fills the cavity, the decidua ex pands or grows with it ; affording a covering, until it grows so large as to fill the cavity. This expansion of the decidua has received the name of decidua reflexa, and it becomes thinner and more gelatinous as preg nancy advances. It has been already stated, that the embryo sends vessels which ramify over the chorion, and part of which there unite to the decidua reflexa ; but at that part where they pass out from the embryo, they are more numerous than elsewhere, and unite with the decidua vera, and form a thick vascular cake called placenta, which consists thus of two portions, one formed by the womb, and one by the foetus, and it serves as the intermedium between them, and the source whence nourishment is derived, and a substi tute for the lungs in the foetal circulation. To be more minute on this subject is not consistent with the plan of this work.