The Works of William Harvey M.D. / Translated from the Latin with a life of the author

by William Harvey

Within a day or two this sac becomes filled with a clear, watery, sluggish albuminous matter, and now presents itself as a long-shaped pudding full of fluid. It adheres by its external glutinous matter to the containing walls of the uterus, but so that it is still easily separated from these; for if it be taken hold of cautiously in the strait of the uterus, where it is constricted in its course, it can be drawn entire out of either horn.

The conception arrived at this stage removed entire, presents itself with the figure of a wallet or double pudding; externally, it is covered with a purulent-looking matter; internally, it is smooth, and contains in its cavity a viscid fluid not unlike the thinner white of egg.

This is the conception of the hind and doe in its first stage. And since it has now the nature and state of an egg, and the definition given by Aristotle[338] of an egg is applicable to it, namely: “A body from one part of which an animal is produced, the remainder serving as nourishment to that which is engendered;” and farther, as it is the primordium of the future fœtus, it is therefore called the ovum, or egg of the animal, in conformity with that passage of the philosopher where he says:[339] “Those animals which engender internally, have a certain oviform body produced after the first conception. For a humour is included within a delicate membrane, such as that which you find under the shell in the egg of the hen; wherefore the blightings of conceptions that are apt to take place about this period are called fluxes.” This conception, therefore, as we have already said of the egg, is the true sperma or seed, comprising the virtue of both sexes in itself, and is analogous to the seed of the vegetable. So that Aristotle, describing the first conception of women, says,[340] that it is “covered with a membrane like an egg from which the shell has been removed;” such as Hippocrates describes as having been passed by the female pipe-player. And I have myself frequently seen such ova, of the size of pigeons’ eggs, and containing no fœtus, discharged by women about the second month after conception; when the ovum was of the size of a pheasant’s or hen’s egg, the embryo could be made out, the size of the little finger nail, floating within it. But the membrane surrounding the conception has not yet acquired any annexed placenta; neither is it connected with the uterus; there is only at its upper and blunter part a kind of delicate mossy or woolly covering which stands for the rudiments of the future placenta. The inner aspect is smooth and polished, and covered with numerous ramifications of the umbilical vessels. In the third month this ovum exceeds a goose’s egg in size, and includes a perfect embryo of the length of two fingers’ breadths. In the fourth month it is larger than an ostrich’s egg. All these things I have noted in the numerous careful dissections of aborted ova which I have made.

In the way above indicated do the hind and doe, affected by a kind of contagion, finally conceive and produce primordia, of the nature of eggs, or the seeds of plants, or the fruit of trees, although for a whole month and more they had exhibited nothing in the uterus, the conception being perfected about the 18th, at furthest, the 21st of November, and having its seat now in the right, now in the left horn, occasionally in both at once. The ovum at this time is full of a colliquate matter, transparent, crystalline, similar to that fluid which in the hen’s egg we have called the colliquament or eye, of far greater purity than that fluid in which the embryo by and by floats, and contained within a proper tunic of extreme tenuity, and orbicular in form. In the middle of the ovum, vascular ramifications and the punctum saliens—the first or rudimentary particle of the fœtus—and nothing else, are clearly to be perceived. This is the first genital part, which, once constituted, is not only already possessed by the vegetative, but also by the motive soul; and from this are all the other parts of the fœtus, each in its order, generated, fashioned, disposed, and endowed with life, almost in the same manner as we have described the chick to be produced from the colliquament of the egg.

Both of the humours mentioned are present in the conceptions of all viviparous animals, and are regarded by many as the excrements of the fœtus,—one the urine, the other the sweat, although neither of them has any unpleasant taste, and they are always and at all periods present in conceptions, even before a particle of the fœtus has been produced.

Of the membranes investing the two fluids, of which there are only two, the outer is called the chorion, the inner the amnion. The chorion includes the whole conception, and extends into either cornu; the amnion swimming in the midst of the liquid of the former, is found in one of the horns only, except in the cases where there is a twin conception, when there is an amnion present in each of them; just as in a twin-fraught egg there are two colliquaments. Where there are two fœtuses consequently, both are contained in one common conception, in one egg, as it were, with its two separate collections of crystalline fluid included. If you incise the external membrane at any point, the more turbid fluid which it contains immediately escapes from either horn of the uterus; but the crystalline liquid in the interior of the amnion does not escape at the same time unless the membrane have been simultaneously implicated.

The vein which is first discerned in the crystalline fluid within the amnion takes its rise from the punctum saliens, and assumes the nature and duty of an umbilical vessel; increasing by degrees it expands into various ramifications distributed through the colliquament, so that it seems certain that the nourishment is in the first instance derived from the colliquament alone in which the fœtus swims.

I have exhibited this point to his serene highness the king, still palpitating in the uterus laid open; it was extremely minute indeed, and without the advantage of the sun’s light falling upon it from the side, its tremulous motions were not to be perceived.

When the ovum with the colliquament entire was placed in a silver or pewter basin filled with tepid water, the punctum saliens became beautifully distinct to the spectators. In the course of the next ensuing days, a mucilage or jelly, like a tiny worm, and having the shape of a maggot, is found to be added; this is the rudiment of the future body. It is divided into two parts, one of which is the head, the other the trunk, precisely in the same way as we have already seen it in the generation of the chick in ovo. The spine, like a keel, is somewhat bent; the head is indifferently made up of three small vesicles or globules, and swimming in transparent water grows amain, and by degrees assumes its proper shape. There is only this to be observed, that the eye in embryos of oviparous animals is much larger and more conspicuous than that of viviparous animals.

After the 26th of November the fœtus is seen with its body nearly perfect, in one case in the right in another in the left horn of the uterus; in twin cases in both horns.