Admitting that the hypenemic egg is possessed of a certain vital principle, still it is not prolific; so that it must further be confessed that the hen of herself is not the efficient cause of a perfect egg, but that she is made so in virtue of an authority, if I may use the word, or power required of the cock. For the egg, unless prolific, can with no kind of propriety be accounted perfect; it only obtains perfection from the male, or rather from the female, as it were upon precept from the male; as if the hen received the art and reason, the form and laws of the future embryo from his address. And so in like manner the female fowl, like to a fruitful tree, is made fertile by coition; by this is she empowered not only to lay eggs, but these perfect and prolific eggs. For although the hen have as yet no rudiments of eggs prepared in her ovary, nevertheless, made fertile by the intercourse of the male, she by and by not only produces them there, but lays them, teeming with life, and apt to produce embryos. And here that practice of the poor folks finds its application: “Having hens at home, but no cock, they commit their females to a neighbour’s male for a day or two; and from this short sojourn the fecundity of the whole of the eggs that will be laid during the current season is secured.”[223] Not only are those eggs which are still nothing more than yelk and have no albumen, or which exist only as most minute specks in the ovary, but eggs not yet extant, that will be conceived long afterwards, rendered fertile by the same property.
EXERCISE THE THIRTIETH.
Of the uses of this disquisition on fecundity.
This disquisition on the inherent qualities of the egg and the cause of its fecundity, is alike in point of difficulty and subtlety, but of the highest importance. For it was imperative on us to inquire what there was in the conception, what in the semen masculinum, and what in the female fowl, which render these fertile; and what there is in the fruitful cock which makes him differ from a bird that is barren. Is the cause identical with that which we have called the vital principle (anima) in the embryo, or it is a certain portion of the vegetative principle? Because, in order to apprehend the entire cause of generation, it is of much moment that the first cause be understood; for science is based upon causes, especially first causes, known. Nor is this inquiry less important in enabling us to understand the nature of the vital principle (anima). These questions, indeed, rightly apprehended, not only are Aristotle’s opinions of the causes of generation refuted or corrected, but all that has been written against him is easily understood.
We ask, therefore, whether it is the same thing or something different, which in the rudimentary ovum, yelk, egg, cock and hen, or her uterus, confers fruitfulness? In like manner in what respect does this something agree or differ in each? Still farther, is it a substance whence the fecundating virtue flows?—it appears susceptible of powers, faculties, and accidents. Likewise, is it corporeal also? for that which engenders mixture appears to be mixed:—the progeny has a common resemblance to the mother and father, and exhibits a doubtful nature when animals of dissimilar species, such as the pheasant and common fowl, engender; that, too, appears to be corporeal which suffers from without, and to such an extent that not only are weakly embryos procreated, but even deformed and diseased ones, obnoxious to the vices as well as to the virtues of their progenitors.
With respect to these several particulars we may farther be permitted to doubt whether that which confers fecundity is engendered or accrues from without? Whether, to wit, it is transfused from the egg to the embryo and chick, from the hen to the egg, from the cock to the hen? For there appears to be something that is transferred or transfused, something, namely, which from the cock is transfused into the hen, and from her is given to the uterus, to the ovary, to the egg; something which passing from the seed to the plant, is rendered again by the plant to the seed, and imparts fecundity. Because there is this common to all things which are perpetuated by generation, that they derive their origin from seed. But the semen, the conception, and the egg, are all of the same essential kind, and that which confers fertility on these is one and the same, or of like nature; and this indeed is divine, the analogue of heaven, possessed of art, intelligence, foresight. This is plainly to be seen from its admirable operations, artifices, and wisdom, where nothing is vain, or inconsiderate, or accidental, but all conduces to some good end.
Of the general principles and science of this subject we shall treat more at length in the proper place; we have now said as much incidentally as seems necessary, the occasion having presented itself along with our consideration of the hen’s egg, namely, how many things inhere which induce fertility, and how this is induced, and whether it is an affection, a habit, a power, or a faculty; whether it is to be regarded as a form and substance, as a something contained generally, or only in some particular part—since it is quite certain that a hypenemic egg is a perfect egg in so far as each sensible particular is concerned, and yet is barren; the uterus in like manner, and the hen and the cock are all perfect; yet are they severally sterile, as being without that which confers fecundity. All of these matters we shall advert to after we have shown what and how two principles, male and female, concur in the production of the egg and the process of generation, and in what way both may be regarded as efficient causes and parents of the egg.
EXERCISE THE THIRTY-FIRST.
The egg is not produced by the cock and hen in the way Aristotle would have it.
It is certain, as we have said, that a fruitful egg is not produced without the concurrence of the cock and hen; but this is not done in the way that Aristotle thought, viz. by the cock as prime and sole ‘agent,’ the hen only furnishing the ‘matter.’ Neither do I agree with him when he says:[224] “When the semen masculinum enters the female uterus, it coagulates the purest portion of the catamenia;” and shortly afterwards: “but when the catamenia of the female has set in the uterus, it forms, with the semen masculinum, a coagulum like that of milk; for curd is milk containing vital heat, which attracts like particles around it, and combines and coagulates them; and the semen of the male (genitura) bears the same affinity to the nature of the catamenia. For milk and the menstrual discharge are of the same nature. When coagulation has taken place, then an earthy humour is excreted and is drawn around, and the earthy portion drying up, the membranes are produced both as matter of necessity, and also for a certain purpose. And these things take place in the same manner in all creatures, both oviparous and viviparous.”