In animals in whom the “conception” adheres to the uterus, (and in very many it does not do so until the fœtus is fully formed), this takes place in various modes. In some it is adherent in one place by the intervention of a fleshy substance, which in the woman is called the “placenta,” from its resemblance to a round cake (placenta): in others it is attached at many points by certain fleshy bodies, or “carunculæ:” these are five in number in the hind and doe; more numerous, but of smaller size, in the cow; and in the sheep they are in great numbers and of various sizes. In dogs and cats these fleshy bodies entirely surround each ovum like a girdle. A similar substance, in the hare and mole, grows to the side of the uterus: like the human placenta, which embraces about half the “conception,” (just as the cup does the acorn at the commencement of its growth), it is attached by its convex aspect to the uterus, and by its concave surface to the chorion.
With these observations premised, I shall now state my opinions on the humours, membranes, fleshy substance of the uterus, and the distribution of the umbilical vessels, in the order described by Fabricius.
The words δεύτερα and ὔστερα are correctly understood by Fabricius[379] to answer to “secundæ” and “secundina” (the secundines): and by these are implied not only the membranes, but everything which comes away from the uterus at the last stage of parturition, or at least not long after it, viz. the humours, membranes, fleshy substance, and umbilical vessels.
Of the Humours.
The doctrines inculcated on the subject of the humours, and which, as being entertained by the ancients, Fabricius regards as certain truths requiring no farther proof, are altogether inconsistent and false; the doctrines, I mean, that the fluid within the amnion, wherein the fœtus swims, consists of sweat; and that within the chorion of urine. For both these humours are found in the “conception” before any trace of the fœtus is visible; added to which, the fluid they call urine can be seen before that which they regard as sweat. In truth, these humours, especially the outer one, may be observed in unfruitful conceptions where nothing like a fœtus is discoverable.
Women sometimes expel conceptions of this kind, analogous to the subventaneous or wind egg. Aristotle[380] says they are called “fluxes;” among ourselves they are termed “false conceptions,” or “slips.” An ovum of this kind was aborted in the case of Hippocrates’s pipe-player. “In all creatures,” we are informed on the authority of Aristotle,[381] “which breed another within themselves, immediately on conception an egg-like body is formed; that is to say, a body in which a fluid is contained within a delicate membrane just like an egg with the shell removed.” The humour in the chorion, which Fabricius and other physicians consider to be urine, Aristotle seems to have regarded as the seminal fluid (spermatis sive genituræ liquor). He says,[382] “when the semen is received into the uterus, after a certain time it becomes surrounded by a membrane, and if expulsion takes place before the fœtus is formed, it has the appearance of an egg with the shell removed and covered by its membrane: this membrane, moreover, is loaded with vessels.” It is, in fact, the chorion; so called from the conflux or multitude of veins. I have often observed ova of this kind escape in the second and third month; they are frequently decomposed internally, and come away gradually in the form of a leucorrhœal discharge, and thus the hopes of the parent are lost.
Another reason why these humours cannot be sweat and urine, is, that they exist in such abundance at the very beginning;—for the purpose, no doubt, of preventing the body of the fœtus from coming in contact with the adjacent parts when the mother runs, jumps, or uses violent exertion of any kind.
Added to which, many animals never sweat at all, (and we must remember what is said by Aristotle,[383] “that all creatures which swim, walk, or fly,” I will add serpents and insects, whether viviparous or oviparous, or generated spontaneously, “are produced after the same manner,”) as is the case with birds, serpents, and fishes, which neither sweat nor pass urine. The dog and cat also never sweat; neither in fact does any animal in which the urinary secretion is very abundant. Besides, it is impossible that urine can be passed before the kidneys and bladder are formed.
Moreover, and this is the strongest argument that can be brought forward, those humours can never be excrementitious into which so many branches of the umbilical vessels are distributed by means of the chorion; these vessels, in fact, in this manner taking up nourishment, (as it were from a large reservoir,) and then conducting it to the fœtus.
Besides what need is there of an allantois, if the fluid within the chorion is urine? And if that in the amnion is sweat, why does Nature, who contrives all things well, ordain that the fœtus should float about in its own excrement? And why, too, should the mother (as is the case with some animals) immediately after birth, so greedily devour the excretions of its own offspring, together with the containing membranes? Some have even observed that if the animal fails to eat up these matters it does not give its milk freely.