EXERCISE THE FORTY-NINTH.
The inquiry into the efficient cause of the chick is one of great difficulty.
The discussion of the efficient cause of the chick is, as we have said, sufficiently difficult, and all the more in consequence of the various titles by which it has been designated. Aristotle, indeed, recites several efficient causes of animals, and numerous controversies have arisen on the subject among writers, (these having been particularly hot between medical authors and Aristotelians,) who have come into the arena with various explanations, both of the nature of the efficient cause and of the mode of its operation.
And indeed the Omnipotent Creator is nowhere more conspicuous in his works, nowhere is his divinity more loudly proclaimed, than in the structure of animals. And though all know and admit that the offspring derives its origin from male and female, that an egg is engendered by a cock and a hen, and that a pullet proceeds from an egg, still we are not informed either by the medical schools or the sagacious Aristotle, as to the manner in which the cock or his semen fashions the chick from the egg. For from what we have had occasion to say of the generation of oviparous and other animals, it is sufficiently obvious that neither is the opinion of the medical authorities admissible, who derive generation from the admixture of the seminal fluids of the two sexes, nor that of Aristotle, who holds the semen masculinum for the efficient, and the menstrual blood for the material cause of procreation. For neither in the act of intercourse nor shortly after it, is aught transferred to the cavity of the uterus, from which as matter any part of the fœtus is immediately constituted. Neither does the “geniture” proceeding from the male in the act of union (whether it be animated or an inanimate instrument) enter the uterus; neither is it attracted into this organ; neither is it stored up within the fowl; but it is either dissipated or escapes. Neither is there anything contained in the uterus immediately after intercourse, which, proceeding from the male, or from the female, or from both, can be regarded as the matter or rudiment of the future fœtus. Neither is the semen galli stored and retained in the bursa Fabricii of the hen or elsewhere, that from thence, as by the irradiation of some spiritual substance, or by contact, the egg may be fashioned or the chick constituted from the egg. Neither has the hen any other semen save papulæ, yelks, and eggs. These observations of ours, therefore, render the subject of generation one of greater difficulty than ever, inasmuch as all the presumptions upon which the two old opinions repose are totally overthrown. The fact is especial, as we shall afterwards demonstrate, that all animals are alike engendered from eggs; and in the act of intercourse, whether of man or the lower quadrupeds, there is no seminal fluid, proceeding from the male or the female, thrown into the uterus or attracted by this organ; there is nothing to be discovered within its cavity, either before intercourse, during the act, or immediately after it, which can be regarded as the matter of the future fœtus, or as its efficient cause, or as its commencement.
Daniel Sennert, a man of learning and a close observer of nature, having first passed the reasonings of a host of others under review, approaches the subject himself; and concludes that the vital principle inheres in the semen and is almost identical with that which resides in the future offspring. So that Sennert does not hesitate to aver that the rational soul of man is present in his seminal fluid, and by a parity of reasoning that the egg possesses the animating principle of the pullet; that the vital principle is transported to the uterus of the female with the semen of the male, and that from the seminal fluids of either conjoined, not mixed (for mixture, he says, is applied to things of different species), and endowed with soul or the vital principle a perfect animal emerges. And therefore, he says, the semen of either parent is required, whether to the constitution of the ovum or of the embryo. And having said so much, he seems to think that he has overcome all difficulties, and has delivered a certain and perspicuous truth.
But in order that we should concede a soul or vital principle (anima) to the egg, and that combined from the souls of the parents, these being occasionally of different species, the horse and the ass, the common fowl and the pheasant, for example, this vital principle not being a mixture but only an union; and allow the pullet to be produced in the manner of the seeds of plants, by the same efficient principle by which the perfect animal is afterwards preserved through the rest of its life, so that it would be absurd to say that the fœtus grew by one vital principle without the uterus or ovum, and by another within the uterus or ovum—did we grant all this, I say (although it is invalid and undeserving faith), our history of generation from the egg, nevertheless, upsets the foundations of the doctrine, and shows it to be entirely false; namely, that the egg is produced from the semen of the cock and hen, or that any seminal fluid from either one or other is carried to the uterus, or that the embryo or any particle of it is fashioned from any seminal fluid transported to the uterus, or that the semen galli, as efficient cause and plastic agent, is anywhere stored up or reserved within the body of the hen to serve when attracted into the uterus, as the matter and nourishment whence the fœtus which it has produced should continue to grow. The conditions are wanting which he himself admits, after Aristotle, to be necessary, viz., that the embryo be constituted by that which is actual and preexists, and the chick by that which is present and exists in the place where the chick is first formed and increases; further, that it be produced by that which is accomplished immediately and conjunctly, and is the same by which the chick is preserved and grows through the whole of its life. For the semen galli (and whether it is viewed as animate or inanimate is of no moment) is nowise present and conjunct either in the egg or in the uterus; neither in the matter from which the chick is fashioned, nor yet in the chick itself already begun, and as contributing either to its formation or perfection.
He dreams, too, when he seeks illustrations of his opinions on an animated semen from such instances as the seeds of plants and acorns; because he does not perceive the difference alleged by Aristotle[266] between the “geniture” admitted in intercourse and the first conception engendered by both parents; neither does he observe on the egg produced originally in the cluster of the vitellarium, and without any geniture, whether proceeding from the male or the female, translated to the uterus. Neither does he understand that the uterus is, even after intercourse, completely empty of matter of every kind, whether transmitted by the parents, or produced by the intercourse, or transmuted in any way whatever. Neither had he read, or at all events he does not refer to the experiment of Fabricius, namely, that a hen is rendered so prolific by a few treads of the cock, that she will continue to lay fruitful eggs for the rest of the year, although in the interval she receives no new accessions of semen for the fecundation of each egg as it is laid, neither does she retain any of the seminal fluid which she received so long ago.
So much is certain, and disputed by no one, that animals, all those at least that proceed from the intercourse of male and female, are the offspring of this intercourse, and that they are procreated as it seems by a kind of contagion, much in the same way as medical men observe contagious diseases, such as leprosy, lues venera, plague, phthisis, to creep through the ranks of mortal men, and by mere extrinsic contact to excite diseases similar to themselves in other bodies; nay, contact is not necessary; a mere halitus or miasm suffices, and that at a distance and by an inanimate medium, and with nothing sensibly altered: that is to say, where the contagion first touches, there it generates an “univocal” like itself, neither touching nor existing in fact, neither being present nor conjunct, but solely because it formerly touched. Such virtue and efficacy is found in contagions. And the same thing perchance occurs in the generation of animals. For the eggs of fishes, which come spontaneously to their full size extrinsically, and without any addition of male seminal fluid, and are therefore indubitably possessed of vitality without it, merely sprinkled and touched with the milt of the male, produce young fishes. The semen of the male, I say, is not intromitted in such wise as to perform the part of “agent” in each particular egg, or to fashion the body, or to introduce vitality (anima); the ova are only fecundated by a kind of contagion. Whence Aristotle calls the milt of the male fish, or the genital fluid diffused in water, at one time “the genital and fœtific fluid,” at another, “the vital virus.” For he says[267]: “The male fish sprinkles the ova with his genital semen, and from the ova that are touched by this vital virus young fishes are engendered.”
Let it then be admitted as matter of certainty that the embryo is produced by contagion. But a great difficulty immediately arises, when we ask: how, in what way is this contagion the author of so great a work? By what condition do parents through it engender offspring like themselves, or how does the semen masculinum produce an “univocal” like the male whence it flowed? When it disappears after the contact, and is naught in act ulteriorly, either by virtue of contact or presence, but is corrupt and has become a nonentity, how, I ask, does a nonentity act? How does a thing which is not in contact fashion another thing like itself? How does a thing which is dead itself impart life to something else, and that only because at a former period it was in contact?
For the reasoning of Aristotle[268] appears to be false, or at all events defective, where he contends “That generation cannot take place without an active and a passive principle; and that those things can neither act nor prove passive which do not touch; but that those things come into mutual contact which, whilst they are of different sizes, and are in different places, have their extremes together.”
But when it clearly appears that contagion from noncontingents, and things not having their extremities together, produce ill effects on animals, wherefore should not the same law avail in respect of their life and generation? There is an “efficient” in the egg which, by its plastic virtue (for the male has only touched though he no longer touches, nor are there any extremes together), produces and fashions the fœtus in its kind and likeness. And through so many media or instruments is this power, the agent of fecundity, transmitted or required that neither by any movement of instruments as in works of art, nor by the instance of the automaton quoted by Aristotle, nor of our clocks, nor of the kingdom in which the mandate of the sovereign is everywhere of avail, nor yet by the introduction of a vital principle or soul into the semen or “geniture,” can the aforementioned doctrine be defended.
And hence have arisen all the controversies and problems concerning the attraction of the magnet and of amber; on sympathy and antipathy; on poisons and the contagion of pestilential diseases; on alexipharmics and medicines which prove curative or injurious through some hidden or rather unknown property, all of which seem to come into play independently of contact. And above all on what it is in generation which, in virtue of a momentary contact—nay, not even of contact, save through several media—forms the parts of the chick from the egg by epigenesis in a certain order, and produces an “univocal” and like itself, and that entirely because it was in contact at a former period. How, I ask again, does that which is not present, and which only enjoyed extrinsic contact, come to constitute and order all the members of the chick in the egg exposed without the body of the parent, and often at a long interval after it is laid? how does it confer life or soul, and a species compounded of those of the concurring generants? Inasmuch as nothing, it seems, can reproduce itself in another’s likeness.