OF THE
UTERINE MEMBRANES AND HUMOURS.
“Four kinds of bodies” are enumerated by Hieronymus Fabricius[377] “as existing externally to the fœtus; these are the umbilical vessels, the membranes, the humours, and a fleshy substance.” On these subjects, guided by my observations, I shall briefly state wherein I differ from him; first, however, giving his statement in his own words.
“There are,” he says, “three membranes, two of which envelope the whole fœtus, but the third does not do so. Of those which envelope the whole fœtus, the innermost, immediately investing one, is called ἃμνιον, i. e. the mantle. That which follows next is entitled by the Greeks χόριον; the Latins, however, have not given it a name, although some interpreters have thought proper erroneously to call it “secundæ” or “secundina,” the secundines; this also envelopes the entire fœtus. The third is called ἀλλαντοειδὴς, i. e. gut-like, from its resemblance to a stuffed intestine; it does not entirely encompass the fœtus, but is applied upon the thorax and part of the abdomen, and extends to either horn of the uterus.” He allows that this last membrane is only found in the fœtus of the sheep and cow; he asserts also that it is continuous with the urachus, and by means of this receives the urine from the bladder. Hence, he goes on, “horned animals, in whom this allantois is found, have the urachus so wide and straight, that it resembles a small intestine; it gradually decreases in size until it reaches the fundus of the bladder; whence it would appear to owe its origin rather to the intestine than to the bladder itself. But in man and other animals furnished with incisors in both jaws, and in whom the allantois is wanting, the size of the urachus is so diminished, that although it rises from the fundus of the bladder as a single tube, it afterwards splits into innumerable fibres, which pass beyond the umbilicus together with the vessels, and carry the urine into the chorion, although the exact mode in which it does so cannot be demonstrated.” On this ground he accuses Arantius of a double error—first, his denial of the existence of the urachus in man; and, secondly, his assertion that the fœtus passes its urine through the genital organs.
For my own part, I must confess I am a willing party to the errors of Arantius, if errors they are to be called. For I am quite sure, if pressure be made on the bladder of a full-grown fœtus, whether of man or of any other animal, that urine will flow by the genitals. But I have never seen an urachus, nor observed that the urine is propelled into the membranes by making pressure on the bladder. I have indeed seen in the sheep and deer what appeared to be a process of bladder between the umbilical arteries, and which contained urine; but it in no way resembled the urachus as described by Fabricius. Not that I would obstinately deny the existence of an allantois; for the minor membranes are so delicate and transparent (those, for example, which we have described as existing between the two “whites” of the egg) that they may easily escape observation. Moreover, in the hen’s egg a white excrementitious matter, and even fæces are found between the colliquament and albumen, i. e. between the amnion and chorion; this I have mentioned before, and Coiterus has also observed it. Added to which, the membrane of the colliquament itself, in which the fœtus swims, although it is so exceedingly transparent and delicate that Fabricius himself allows nothing can be imagined more so, nevertheless (for according to him all membranes, however thin, are double) may nature sometimes find herself compelled to deposit urine or some other matter between its duplicatures. An allantois of this kind I am ready to allow Fabricius; but that other intestine-like body produced into either horn of the uterus, I do not discover among the membranes in cloven-footed animals, nor aught else, in fact, except the conception itself. I can only find, as I before said, a process of the bladder, situated between the umbilical arteries, which contains an excrementitious matter, and varies in length in different animals. Wherefore, in my opinion, the tunic which Fabricius calls the allantois is, in fact, the chorion; and the ancients applied the name of allantois to it on account of its resemblance to a double intestine. For that external membrane, constricted in the middle, and resembling a saddle-bag in form, which is stretched upwards to each horn of the uterus, and in its passage is pinched in by that part of the uterus which connects the horns, is in truth the chorion; and in the sheep, goat, roe, fallow-deer, and other cloven-footed animals, it can be raised by the hand in the middle of its course, and easily extracted whole; this is the same as what is called the “conception” or ovum. Like an egg, it contains within itself two fluids, and the fœtus with its appendages; it is possessed besides of those characters which Aristotle attributes to the egg; these are, that out of part of it the embryo is originally formed, and that the remainder constitutes the sustenance of the new animal, as has been frequently explained. I believe, then, the tunic which Fabricius called the allantois to be either the chorion or else some unnatural structure formed out of the reduplication of the membranes. It is accordingly only found to exist in some animals, and not always in these; it cannot be traced from the commencement of conception, and in some animals it is more apparent than in others: whilst in others nothing can be seen except a mere process of the bladder. Besides, Fabricius himself allows that its purpose is not to envelope the fœtus, but to contain its urine. In truth, I must think that he has described it rather to defend the doctrine of the ancients, than because he really believed he had discovered such a membrane, or that it served any good purpose. For he allows, with the ancients, and every medical school, that the chorion contains urine, when he says[378] that there are two humours encircling the fœtus, one, viz. in the amnion, consisting of sweat; the other in the chorion, consisting of urine. It is, therefore, clear that the ancients under the two names understood one and the same membrane; and that in the cloven-footed animals they called it “allantois,” on account of its form; but in others “chorion,” because they thought its object was to receive the urine. Wherefore they allow that this tunic is neither found in man nor any of the other animals. For what need can there be of another tunic to retain the urine, when they themselves admit that the office of doing so belongs especially to the chorion? There can be no probable reason assigned why this tunic should exist in the sheep, goat, and the other cloven-footed animals, and not also in the dog, cat, mouse, and others. For in truth, if the object of this membrane were to contain the urine, the fœtus of the sheep and cow must secrete a much larger quantity than those of animals furnished with incisors in both jaws; there must then either be three different humours, or at least two receptacles for the urine. For myself, I am sure that the chorion from the first is full of water. I will not, however, enter into controversies; I would rather record what I have found by my own observations.
To do as Fabricius has done, and give the structure of the full-grown and perfect embryo, is one thing, but it is another to enter fully on the subject of its generation and first formation: just as they are very different things to describe the ripe fruit of an apple or any other tree, and to explain the manner in which it is produced from the germ. I will, therefore, briefly go through the stages by which the “conception” is brought to maturity, in which way the true doctrines in the matter of the membranes and other fœtal appendages will be better ascertained.
In the production of all living creatures, as I have before said, this invariably holds, that they derive their origin from a certain primary something or primordium which contains within itself both the “matter” and the “efficient cause;” and so is, in fact, the matter out of which, and that by which, whatsoever is produced is made. Such a primary something in animals (whether they spring from parents, or arise spontaneously, or from putrefaction) is a moisture inclosed in some membrane or shell; a similar body, in fact, having life within itself either actually or potentially; and this, if it is generated within an animal and remain there, until it produce an “univocal” (not equivocal) animal, is commonly called a “conception;” but if it is exposed to the air by birth, or assumes its beginning under other circumstances, (than within an animal), it is then denominated an “egg,” or “worm.” I think, however, that in either case the word “primordium” should be used to express that from whence the animal is formed; just as plants owe their origin to seeds: all these “primordia” have one common property—that of vitality.
I find a “primordium” of this kind in the uterus of all viviparous animals before any trace of a fœtus appears: there is a clear, thick, white fluid (like the albumen of the egg) inclosed in a membrane, and this I call the ovum. In the roe, fallow-deer, sheep, and other cloven-footed animals, it fills the whole uterus and both its horns.
In process of time an extremely limpid and pure watery fluid (similar to that which in the hen’s egg I have called the colliquament) is secreted by this “primordium” or “ovum;” in clearness and brilliancy far exceeding the remaining fluid of the ovum in which it is contained. It is of a circular form, and inclosed in a very delicate and transparent membrane of its own called the “amnion.” The other fluid, of a denser and thicker character, is contained in the outer envelope, or chorion, which is in immediate contact with the concave surface of the uterus, and which also encompasses the entire ovum: the shape of this second membrane varies according to that of the uterus: in some animals it is oval, in others oblong, but in those with cloven feet it resembles a saddle-bag. After a short time a red pulsating point shows itself within the transparent substance, and from this point exceedingly fine twigs, or rather rays of vessels, start forth. By and by the first aggregated portion of the body makes its appearance, folded upon itself orbicularly, and somewhat resembling a grub: the remaining parts follow in the order described in our history. For I have ascertained that the production of the fœtus from their ova or “conceptions” in viviparous animals, takes place exactly in the same way as the growth of the chick within the egg.
As I before observed, “conceptions” in viviparous animals vary in form, number, and in their modes of attachment to the uterus. At first, especially in the cloven-footed animals, the “conception” does not adhere to the uterus, but is only in contact with, and fills and distends the organ, and can be easily extracted entire. In cloven-footed animals, which conceive within the horns of the uterus, and also in the solidungula, one ovum only of this kind is found, and that stretching up into either horn of the uterus: and although these animals sometimes produce one, sometimes two young at a birth, and so sometimes one, sometimes two colliquaments are found, one in the right, the other in the left horn of the uterus, yet the two are always contained in one and the same ovum.
In other animals, however, the number of ova answers to the number of fœtuses, and within them are as many colliquaments: this is the case in the dog, cat, mouse, and other animals of this kind with teeth in either jaw. In cloven-footed animals the ovum is shaped like a saddle-bag: the form, in fact, under which Fabricius represented the allantois. In the mare, the figure of the uterus internally resembles an oblong bag; in the woman it is of a globular form.