COOPER MEDIAL COLL.

SAN FRANCISCO, CAL

and is not to be removed from the yen by any person or xt whatever.

of which M. Coste speaks in the above quotation. The cavity is very minute-bean-shaped, and filled with an apparently slimy matter as in Fig. 52.

In an opossum examined last winter, there being present Drs. J. Wallace and E. Wallace, the aorta was injected with size colored with vermilion. Much of the injection was found to be effused into the small bean-shaped cavity of the wombs bb; but there was a great

Fig. 52.

multitude of tubuli standing vertically to the paries of the womb, that were filled with the red injection, presenting the appearance of waving, or straight red lines, that passed from the inner superficies of the substance of the womb down through the soft deciduous matter to the inner boundary of it. The Fig. 52,

gives a pretty correct view of the appearances presented upon cutting

one of the wombs open in its longitudinal diameter. The lenticularshaped cavity is seen in it as well as the converging tubuli. It gives also a good idea of the thickness of the membranous uterine walls, compared with the accidentally developed interior muco-tubular membrane. On the exterior of the womb is seen the ovary, with part of its Fallopian tube. I think no one who has examined M. Coste's engraving of the gravid womb, opened, can fail to be struck with the immense comparative development of these uterine tubuli during the rut in the opossum. It was, probably, among the slimes of this tubular texture that the Rev. Dr. Bachman, of Charleston, S. C., found the young embryons moving-as expressed in his paper to the Philad. Acad. of Natural Sciences, 1848. I in vain searched for such free embryos in the various specimens of Didelphis in rut that I examined with the Drs. Wallace.

There is one circumstance that ought not to be overlooked by the Student while making up his settled opinion as to the decidua. It is this. In the solidungula, the pachydermata, and the cetacea, the entire exterior surface of the chorion becomes placenta; for the placental tufts are processes from the exterior surface of the chorion. In all these animals, while it is impossible to conceive of a decidua reflexa, it is equally difficult to admit of a Hunterian vera to which the whole exterior surface of the chorion could affix itself. Ought not the Student, then, to pause and consider whether this great and very general fact in embryogeny does not afford one of the strongest sanctions of M. Coste's views of the original organic nature of the decidua? The means by which ends are produced, in nature, are always few; and as the uterine products in all the other mammals are formed without the intervention of a Hunterian decidua, it seems on that account probable it could not be indispensable in human embryogeny.

I leave it to the Student therefore to judge for himself, as to the nature of the deciduous coat of the womb; and to decide betwixt the Hunterian explanation of it already given, and the new doctrine, of which he has here the sufficient elements for the end of making up his opinion.

The ovum, after reaching the uterine cavity, grows rapidly. At first, it must be supposed to augment by endosmose, which conveys to its interior the cytoblastema found in mucous fluids amidst which it exists within the womb. Gradually developing its substance by means of changes by segmentation of the yelk, and also, probably, by means of the pabulum it finds in the mucus by which it is surrounded, it soon commences the acts of evolution of its parts. This process is effected by sending forth to all its parts, by means of the ventricles of

the heart, the sanguine materials which it first creates and then con

verts.

As the foundations of the tissues are being built up in these histological deposits, the nervous mass is everywhere deposited among them, and as in fact their most essential element. This nervous mass, in the form of nervous molecules, fibrils, and cords, is, like all the rest of the solids, derived from the blood; for nothing is truer than Oken's assertion, that "the blood is the fluid body, and the body the fixed and rigid blood"-so that the whole of the developments of the embryo and foetus come to be at last the results of organic deposits, derived from its blood alone.

The embryo requires an engine for the circulation of its own blood. Hence the features of the heart must be early disclosed-the path of the aorta is laid out by the blood itself; and the courses of the omphalo-mesenteric vessels are traced in order that the functions of the umbilical vesicle may not too soon fail.

The aorta, as it grows longer, divides into two branches, which are not two primitive iliacs, but two umbilical arteries, designed to send the blood of the embryo to circulate near the mother's blood, and to take from her the quantity of oxygen requisite for its aëration, and also a certain plasma which it brings back to the body of the embryo. These two umbilical arteries after some time give off branches which at length become sufficiently large to be easily demonstrated as external iliacs, femorals, popliteals, &c., the vessels of the limb, which are productions from the umbilicals, at last assuming their permanent character as iliacs, femorals, popliteals, &c. The blood of the embryo, by the extension of its umbilical vessels, comes at length to circulate among the cellular mass that is developed on the outer surface of the chorion, amidst which it receives its supplies of oxygen and also its alible elements. So that it is true to say, along with Professor Owen, that a placenta is a fleshy and vascular process from the exterior surface of the chorion.

When the embryo becomes at last developed within its amnion, chorion, decidua reflexa, and decidua uterina, it cannot be considered, of itself, to have any contact with the maternal surfaces-nor has it any other connection with the mother, save by its vessels and blood alone, which it sends forth far beyond the limits of its own body, into the distal tufts of the branches of its umbilical vessels, to spread it upon the living wall of its mother's tissues, there to receive its endow ment of oxygen.

The only part of the child that really touches the mother is the blood of the child.

The embryonal blood, having traversed the capillary system of the placental tufts, returns by the channels of the umbilical veins. All the umbilical venules and capillaries have, probably, the power of taking up, by endosmose or absorption, some species of plasma or cytoblastema, from the maternal surfaces. They convey this, together with the aërated blood of the umbilical capillaries, into the single tube of the umbilical vein, which delivers it over to the child, by pouring it partly into the hepatic porta, and partly into the inferior cava by way of the ductus venosus, which is the continued tube of the umbilical vein. Professor Liebig's Researches on the Motion of the Juices in the Animal Body may be one's sufficient warrant to believe that the placenta can take up from the maternal tissues an amount of organic material adequate to the development of the uterine embryo and foetus by endosmose.

While the embryo is growing, the amnios continues to fill with larger and still larger quantities of water, the placenta increases in size, and the womb, which affords a nidus for the tender young, aug. ments pari passû with the ovum and its contents.

The womb yields to the antagonistic force of the expanding ovum. It undergoes a compulsory hypertrophic development. The womb always resists this expanding power; it makes daily and perhaps. hourly efforts to cast forth the burden from its cavity. It is not stretched, but compelled to grow.

The ovum commences its career of development not in the neck, but in the cavity of the womb, which is composed of the wall of the fundus and corpus uteri.

The long cylindrical cervix is not at first interested in the struggle or contest between the expanding ovum and the resisting cavity. It stands as the guardian of the fruit of the conception. The cervix uteri is the seat of what the ancients called the facultas retentrix, and it continues superior in force to the facultas expultrix until the close of pregnancy, when, being finally exhausted, the facultas expultrix acquires sole dominion, and labor commences. If at any time, during the course of a pregnancy, the retentive power of the cervix should. fail, the expulsive power of the fundus and corpus uteri immediately begins to expel the ovum.

Many of the abortions that we meet with are caused by this weakness of the womb-that is to say, by weakness of the cervix uteri, which gradually yields to the antagonizing contraction of the body and fundus, and allows the ovum to come forth and be lost. The physician makes use of this principle in the treatment of cases in which the indication is plain to bring on premature labor. He dilates

the canal of the cervix with his finger or with a sponge tent or a colpeurynter, and he takes away the facultas retentrix, and the ovum comes off.

It is curious to observe the care and providence with which the retentive faculty is fortified in certain of the tribes of creatures. In the cetacea, for example, there is a double cervix, a double os uteri, one within the other, so that one of them being dilated may leave the other still undilated and capable of resisting the antagonism of the fundus until the last moment of uterine gestation is accomplished. (See a paper on the Reproductive Organs of Delphinus nesarnak, in the Transactions of the Acad. of Nat. Sciences of Philad., with engravings, by Ch. D. Meigs.)

While the uterus is thus the reluctant servant of the forces of the ovum, it gradually increases in weight and volume, as well as in the cubic content of its cavity. After labor, it weighs a pound and a half; in the non-gravid state, it weighs two ounces and a half. It follows, therefore, that, in the course of a gestation, a vast increment of its mass takes place, and that this whole sum consists in living organic molecules, whether fluid or solid, that are deposited within its limits and become constituents of them.

I shall not endeavor to give the rationale of the influence exercised upon the womb by the growing ovum. Perhaps John Hunter would ascribe it to the stimulus of distension. Suffice it for me to say, that at any time in the course of the whole career, that career may, by the physician, be instantly arrested and brought to a speedy close, by destroying or withdrawing the ovum, or by overcoming the retentive power of the cervix uteri. To discharge the waters of the amnios by puncture, to dilate the canal of the cervix with a sponge-tent, or to energize immoderately the facultas expultrix of the fundus and corpus uteri by means of ergot, is to arrest and bring to a close the whole operations of the reproductive processes.

As the womb grows larger, its arteries and veins become elongated, and their tubes become more considerable in size and weight. The nerves are enlarged, or, at least, they are extended or produced. The absorbents, in like manner, are augmented, and, more than all, the great masses of muscular tissue existing in the virgin womb in potentia rather than in reality, acquire a visible and palpable magnitude and a great force.

As the womb expands, forced outwards in every dimension from its centre, its walls do not diminish in thickness, although they become softer and more succulent. Torrents of blood circulate in the tortuous branches of the uterine arteries, and soak along in the immense