The specimen is also valuable, as it affords positive evidence of the mode in which the placenta is formed, for here we actually see the process of absorption of part of the involucra, on which that process depends.
Some who have seen this specimen, confound it with a case of hydatous placenta; and a few similar preparations exist under that name in more than one collection. It is evidently by mistake that they are so styled, as we shall see in a succeeding Plate.
Professor CARUS of Dresden, (a name revered by anatomists and physiologists,) here comes to my assistance. That accurate and indefatigable observer, on submitting an entire Ovum, expelled towards the sixth week of gestation, to a powerful microscope, remarked that the greater number of the filiform vessels were diaphanous as well as their ramifications, and that their free extremities terminated into little roundish knobs, not unlike the terminal bulbs of the villosities of the intestines. These bulbous expansions of the filiform vessels of the Ovum adhered so firmly to a superincumbent dense membrane (which Carus calls decidua, but must be the _cortex_) that they could not be separated from it without tearing some of them[27]. These very expansions, or roundish knobs then, of the filiform vessels of the Ovum, are precisely those which, from plethora of the involucra lying over them, acquired what, in my specimen, I have called “a dropsical bead-like enlargement,” as represented in figure 17 of an “Uviform Ovum.” SOEMMERING has also noticed these terminal bulbs of the filiform vessels, which he calls _noduli vel vesiculæ_, somewhat _like_ hydatids.
In questions of natural history, it is impossible to desire and meet with a more satisfactory corroboration of the explanation of any given fact, than the above observation of Carus affords to my view of the conformation of the “Uviform Ovum.” Nor can a more convincing refutation be required after it, of the doctrine of hydatids in the placenta being the cause of that singular conformation.
There was but a trifling hemorrhage after the coming away of the present Ovum, and scarcely any suffering. During the three preceding weeks the patient had had some slight, colourless, and thin discharge from the vagina.