degenerate with astonishing rapidity after the death of the embyro. This appears to be true, especially with reference to the villi of young placenta. When the embryo has been dead a short time only, the epithelium of the villi shows marked degenerative changes, and two to three weeks after fetal death the villi are very frequently degenerated so completely that only the most intimate acquaintance with their configuration and distribution enables one to recognize what is left of them in a mass consisting mainly of fibrin, the remnants of blood corpuscles, and the derivatives of chemically changed hemoglobin. The clinical history of cases of tubal gestation frequently furnishes data from which the time of the death of the fetus can be pretty accurately estimated, the time intervening between this date and that of the operation gives the period during which the degeneration of the villi has been going on.

A careful microscopic examination of the small placenta brought out the following points to be emphasized:

Amnion: The amniotic epithelium is well preserved in most places. It is, however, not found in a single layer throughout only, but frequently in an irregularly double layer. This is not apparent only and due to the obliqueness of the cut, but real, and there has evidently taken place a proliferation of the amniotic epithelium, most probably due to nutritive disturbances dependent upon the death of the embryo and other causes. Amniotic epithelia are found desquamated, forming more or less irregular masses near the membrane. The epithelia show quite marked deviations from their normal type, they are smaller than usual, and their nuclei are not regularly round or oval vesicular, but more or less contorted in outlines, and very rich in chromatin. Some of the desquamated amniotic epithelia show signs of hydropic swelling. The amniotic mesoderm is poor in nuclei, and in a stage of hyaline degeneration. Amnion and chorion are adherent to each other.

Chorion: The chorionic mesoderm next to the amnion shows a small strip in an advanced stage of hyaline degeneration. The larger extent of the chorionic mesoderm, however, is well preserved, showing typical spindle cells, with well staining nuclei. The chorionic epithelium, as a rule, is very much degenerated. Its place is taken by a strip, or band, which has uniformly and deeply taken up the nuclear stain. In some places, however, the outlines of epithelial cells and their nuclei can be made out, including a differentiation into the syncytium and the cell layer of Langhaus. The

placental chorion, which is particularly well preserved at the margin of the placenta, does not show any decidual cells in its mesoderm. It is well known that decidual cells grow into the chorion at the margin of the placenta in the eighth month of pregnancy.

Villi: The villi, though in some places greatly degenerated, are everywhere perfectly plain as to their outlines and configuration. In other places the mesoderm as well as the ectodermal epithelium are so well preserved that all the details can be clearly recognized, including a perfect differentiation of the syncytium and the cell layer of Langhans.

a.

b.

No. 5.

Leitz obj. No. 3; eyepiece, No. 3.

Amnion: a, Ectodermal epithelium partly in a double layer.

b, Amniotic mesoderm (connective tissue) showing a number of nuclei.

c, Hyaline zone of amniotic mesoderm directly under epithelium.

d, Desquamated amniotic epithelia.

e, Epithelium of amnion, x450.

The villi are, without exception, of that type which is found in younger placentæ; those numerous crowded small slender villi as they are found in placentæ at or near full term are nowhere seen; about their absence a careful examination leaves no doubt. Numerous syncytial buds seem to be present, but they are so changed that no positive statement can be made as to their definite presence.

The intervillous space shows a fibrinous network of varying density, hæmatoidin granules, and in some places, though very pale, yet still well recognizable, red blood corpuscles. Erythrocytes of this type also densely fill the larger blood vessels of the placental chorion.

Apparent decidual islands, the so-called "Zellknoten" of Kastschenko, are also found in the intervillous space. A layer of Lang

hans canalized fibrin is well marked, and of considerable extent at the margin of the placenta; right at the center of the placenta the band of canalized fibrin is of small extent only.

Decidua: The split in the decidua serotina is partly found in the compact, partly in the spongy layer. In the vera it is entirely in the spongy layer. The decidual cells are very characteristic, with large oval or round nuclei, not very rich in chromatin, and large cell-bodies, mostly oval in general outlines, quite a number with processes. Polymorpho- and mononuclear leucocytes are quite numerous everywhere. Areas showing the evidences of coagulation necrosis are found in the decidua serotina to a moderate extent, but the outer layer of the decidua vera shows everywhere the evidences of degenerative changes.

The decidua reflexa disappears, as has been ascertained, in the fifth month of of gestation. In the small placenta under discussion a degenerated decidua is still present. It could easily be separated from the chorion near the margin of the placenta. It is about 0.2 by 0.4 m.m. in thickness, and shows remnants of decidual cells near both of its surfaces. These cells are found in a fibrinous matrix. Next to these remnants of decidual cells the tissue is entirely hyaline, while the middle of the membrane shows a fibrinous structure. There are scattered throughout the tissue of the decidua reflexa large pale nuclei of a doubtful nature. A few polymorphonuclear leucocytes are also seen. By far the most decidual cells in the serotina and vera are mononuclear, quite a number contain two nuclei, very few three. Polynuclear giant decidual cells, which are said to appear in the placenta during the fifth month, I have not been able to find.

Looking over the picture, as furnished by the microscopic examination, I should say that there is very little, if any, reasonable doubt left, that this placenta is younger than five full months, and considering its state of preservation, that its embyro at the time of parturition could not have been dead more than two or three weeks. Since the larger fetus beyond doubt is one near full term, the case, therefore, has to be looked upon as one of superfetation. It is an interesting feature of this case that the older ovum had, as it seems, become attached in an abnormal place, and developed a placenta. previa lateralis. This furnishes a condition which undoubtedly must make it easier for a second, younger ovum to be met by spermatozoa, and to find a place favorable for implantation.

Case II. occurred in the practice of Dr. Frank T. Andrews. The following is the history, as furnished to me by Dr. Robert H. Harvey, to whom the specimen had been first turned over by Dr. Andrews. On September 16th, 1897, Mrs. N. introduced into her cervix the tip of a syringe, and forced water into her uterus; as a result of this procedure she had severe abdominal pain lasting two days, and some pain for two weeks. On October 6th there was a slight hemorrhage, which gradually increased, and on the 9th of October I packed the vagina. October 10th, on removing the packing a considerable number of clots were in the vagina, and an ovum (the larger one). Membranes intact.

On examining the interior of the uterus, the second ovum was found. The woman stated that August 15th was the first day of her last period before the abortion.

No. 6. Leitz obj. No. 7; eyepiece, No. 3.

Villus cut transversely, still showing in part the inner Langhans, and the outer syncytial epithelial layer.

From the history, as given above, it may be assumed that when the woman mentioned therein missed the menses she expected before the middle of September, she instituted on September 16th attempts to bring about an abortion. In spite of the vigorous efforts she made in this direction, an abortion did not take place immediately, which is by no means so very astonishing, since we know that during the early months of pregnancy the uterus can occasionally stand the most violent insults without expelling the ovum it contains. During the first third of October the abortion took place, and two embryos, different in size, were expelled. It may now be assumed that the smaller embryo had been killed at or about the time when the attempt at abortion was made, and that the larger embryo was not killed at this time, but continued to

develop until about the period when it was expelled. If this were the case, the smaller ovum, which then would have been dead about four weeks, should show the signs of an advanced degeneration or decomposition, as the case might be.

Before describing the ova as I received them for examination, I must make mention of the fact that, as some of you may remember, they have previously been presented, and passed around before this society by Dr. Andrews.

It appears that some of our members are not sufficiently aware of the fact that human embryos a few weeks old cannot very well stand such a handling as would little inconvenience a piece of dry bone, or possibly a well hardened fibroid of the uterus. In consequence of this oversight, the two ova, when they came into my possession, through the kindness of Dr. Andrews, were a good deal the worse on account of the wear and tear they had been subjected to. The parts received consisted of:

The larger ovum, which had a largest diameter of 5.2 c.m. One pole of the ovum is bald, the larger part of its surface is covered by branched villi, several m.m. long. This larger chorionic vesicle, which was open' when received by me, contained an embryo minus its head. What is left of the embryo is 10 m.m. long, so that the embryo when intact measured from 16 to 17 m.m. The right anterior extremity is likewise missing. Umbilical cord: Length 10 to 12 m.m.; diameter about 2 m.m.; umbilical vesicle very thin but quite long, almost as long as the umbilical cord.

Small ovum: Diameter of chorionic vesicle, 3 c.m. The chorion is bald on one pole; villi on chorion frondosum, 2 to 3 m.m. long; branching less developed than on villi of larger ovum.

There were found in the smaller chorionic vesicle:

1st. A small mass 3 to 4 m.m. long, which cannot be identified macroscopically, but which the microscopic examination proves to be the head of a very young embryo.

2d. What apppears to be the yolk sac; its dimensions are 3 by 2 m.m.; its pedicle is thicker than the pedicle of the yolk sac of the larger ovum. In connection with this mass is found part of an umbilical cord, the microscopic examination confirms the correctness of the view that the above described mass contains the yolk

sac.

3d. A roundish mass, 3 by 4 m.m., which cannot be identified by naked eye inspection. Microscopic examination shows that this