The experience and observations of most anatomists are contrary to this supposed discovery. They admit there is a kind of ligament which adheres by one end to the external surface of the bottom of the bladder, and extends to the navel; but it becomes so delicate, on entering into the cord, as to be nearly reduced to nothing: in common this ligament is not hollow, and we can see no orifice at the bottom of the bladder.
The fœtus has no communication with the open air, and the experiments made upon the lungs prove they have never respired; for they sink to the bottom when put in water: whereas those of infants who have breathed always float on the top; the fœtus then does not respire in the womb, consequently it cannot form any sound by its voice; and therefore what has been related of the groaning and crying of children before their birth may be considered as fables. After the flowing of the waters it may happen, that the air has found an entrance into the cavity of the matrix, and then the infant may begin to respire before it is brought forth. In this case it may be able to cry, as the chicken cries before the shell of the egg is broken, which it can do from there being air in the cavity which is between the external membrane and the shell. This air is found in all eggs, and is produced by the internal fermentation of matters contained in them[AF].
[AF] See La Statique des Vegetaux, Chap. vi.
The lungs of the fœtus being without any motion, have no more blood enter into them than is requisite to nourish and make them grow; and there is another road opened for the course of its circulation. The blood in the right auricle of the heart, instead of passing into the pulmonary artery, and returning, after having ran through the lungs into the left auricle by the pulmonary vein, passes immediately into the left by an opening, called the foramen ovale, which is in the partition of the heart between the two auricles. It enters afterwards into the aorta, which distributes it by its ramifications, at going out of which the venous branches receive it, and bring it back to the heart by uniting all in the vena cava, which terminates at the right auricle of the heart. The blood which this auricle contains, instead of passing entirely by the foramen ovale, may escape in part into the pulmonary and the aorta by an arterial canal, which goes immediately from the one to the other. It is by these roads that the blood of the fœtus circulates without entering into the lungs, as it enters into those of children, adults, and every animal which breathes.
It has been thought that the blood of the mother passes into the body of the fœtus, by means of the placenta and umbilical cord. It was supposed that the sanguinary vessels of the matrix opened into the vacuities, and those of the placenta into the nipples, and that they joined one to the other; but experience is quite contrary to this opinion; for if the arteries of the umbilical cord is injected the liquor returns by the veins, and not any part of it escapes externally. Besides, the nipples may be drawn from the vacuities where they are lodged, without any blood issuing either from the matrix or placenta: a milky liquor only issues from both, and which, we have already observed, serves the fœtus for nutriment. This liquor possibly enters into the veins of the placenta, as the chyle enters into the subclavian vein; and perhaps the placenta in a great measure performs the office of the lungs in bringing the blood to maturity. It is certain that the blood appears much sooner in the placenta than in the fœtus, and I have often observed in eggs that have been under the hen for a day or two, that the blood appeared at first in the membranes, and that their sanguinary vessels are very large and numerous, while the whole body of the chicken, excepting the point where these blood-vessels terminate, is only a white and almost transparent matter, in which there is not the smallest sign of a sanguinary vessel.
It has been imagined, that the liquor of the amnios is a nutriment the fœtus receives by its mouth. Some naturalists pretend to have observed this liquor in the stomach, and to have seen some fœtuses to which the umbilical cord was entirely wanting, and others who had but a very small portion, which did not at, all adhere to the placenta; but in this case might not the liquor have entered into the body of the fœtus by the small portion of the umbilical cord, or by the umbilical vessel itself? Besides, to these observations we may oppose others. Some fœtuses have been found whose lips were not separated, and others without any opening in the œsophagus. To conciliate these circumstances, some anatomists have thought that the aliments passed into the fœtus partly by the umbilical cord, and partly by the mouth: none of these opinions appear to have any foundation. It is not the question to examine the growth of the fœtus alone, and to seek from whence and by what it draws its nutriment, but how the growth of the whole is made; for the placenta, liquor, and membrane increase in size as well as in the fœtus; and consequently the instruments and canals employed to receive or carry this nutriment to the fœtus, have a kind of life themselves. The expansion of the placenta and membranes is as difficult to conceive as that of the fœtus; and we might say, with equal propriety, that the fœtus nourishes the placenta, as that the placenta nourishes the fœtus. The whole mass is floating in the matrix, and without any adherence at the commencement of this growth: therefore the nourishment can be only made by an absorption of the milky matter contained in the matrix. The placenta appears first to draw this nutriment, to convert this milk into blood, and to carry it to the fœtus by veins. The liquor of the amnios appears to be only this milky liquor depurated, the quantity of which increases by a like absorption, proportionate to the increase of the membranes, and the fœtus probably absorbs the liquor, which appears to be the necessary nutriment for its expansion. For we must observe, that for the first two or three months the fœtus contains very little blood; it is as white as ivory, and appears to be composed of lymph which has taken some solidity; and as the skin is transparent, and all the parts very soft, we may easily conceive that the liquor in which the fœtus swims may penetrate them, and thus furnish the necessary matter for its nutrition and expansion. It may be supposed that the fœtus in the latter stages takes its nutriment by the mouth, since in the stomach we find a liquor similar to that in the amnios, urine in the bladder, and excrements in the intestines; and as we find neither urine nor meconium in the amnios, there is reason to conclude that the fœtus does not void its excrements, especially as some are born without having the anus pierced, although they had a great quantity of meconium in the intestines.
Although the fœtus does not immediately adhere to the matrix, but is only attached to it by small external nipples, though it has no communication with the blood of its mother, but is as independant of her who bears it, in many respects, as the egg is of the hen that hatches it, yet it has been pretended, that all which affects the mother affects the fœtus; that the impressions of the one act on the brain of the other; and to this imaginary influence resemblances, monsters, and especially marks on the skin of some children, have been attributed. I have examined many of these marks, and they all appear to me to have been caused by a derangement in the texture of the skin. Every mark must have a figure which will resemble something or other; but I am certain the resemblances so formed depend rather on the imagination of those who see them than on that of the mother. On this subject the marvellous has been carried as far as it could go. It has not been only said that the fœtus carried real representations of the longings of its mother, but that, by a singular sympathy, the marks, which represent strawberries, cherries, &c. change their colour, and become deeper in the season of those fruits. With a little more consideration, and less prejudice, this colour may be seen to change much oftener, and that it must happen every time the motion of the blood is accelerated, whether by the heat of summer or from any other cause. These marks are either yellow, red, or black, because the blood gives these tints to the skin when it enters in too great quantities into the vessels. If these marks have the longings of the mother for their cause, why have they not the forms and colours as varied as the objects of her desires? What a curious assemblage of figures would be seen if all the whimsical desires of the mother were written on the skin of the child?
As our sensations have no resemblance to the objects which cause them, it is impossible that desire, fear, horror, or any passion, or internal emotion, can produce real representations of those objects; and the child being in this respect as independant of the mother as the egg is of the hen, I should as soon believe that a hen, which saw the neck of a cock twisted, would hatch chickens with wry necks, as that, by the power of imagination, a woman, who happened to see a man broke upon the wheel, would bring forth a child with its limbs broken in the same manner.
But even supposing this circumstance attested, I should still support the opinion, that the imagination of the mother had not been the cause, for what is the effect of horror? an internal motion, a convulsion in the body of the mother, which might shake, compress, and agitate the womb. What can result from this commotion? nothing similar to the cause, for if this commotion was very violent the fœtus might be killed, wounded, or deformed in some of its parts; but how is it to be conceived that this commotion can produce any thing resembling the fancy of the mother in the fœtus, unless we believe, with Harvey, that the matrix has the faculty of conceiving ideas, and realizing them on the fœtus?