EXERCISE THE FORTY-EIGHTH.
The opinion of Fabricius on the efficient cause of the chick is refuted.
As I have chosen Aristotle, the most eminent among the ancient philosophers, and Fabricius of Aquapendente, one of the foremost anatomists of modern times, as my especial guides and sources of information on the subject of animal generation, when I find that I can make nothing of Aristotle upon a particular topic, I straightway turn to Fabricius; and now I desire to know what he thought of the efficient cause of generation.
I find that he endeavours to satisfy three doubts or difficulties involved in this subject: First, What is the ‘efficient’ of the chick? This he answers, by saying, the semen of the male. Secondly, How does this appear in the egg, and in what way does the semen of the cock fecundate the egg? Thirdly and lastly, In what order are the parts of the chick engendered?
As to the first query, it appears from our observations, that the cock and his seminal fluid are verily the ‘efficient,’ but not the ‘adequate’ cause of generation; that the hen comes in here as something. In this place, therefore, we are principally to inquire how the semen of the cock fecundates the egg otherwise unprolific, and secures the engenderment of a chick from it?
But let us hear Fabricius:[265] “Those things differ,” he observes, “that are produced from eggs, from those that originate from semen, in this, that oviparous animals have the matter from which the embryo is incorporated distinct and separate from the agent; whilst viviparous animals have the efficient cause and the matter associate and concorporate. For the ‘agent’ in the oviparous animal is the semen of the male, in the fowl the semen of the cock, which neither is nor can be in the egg; the ‘matter,’ again, is the chalazæ from which the fœtus is incorporated. These two differ widely from one another; for the chalazæ are added after the vitellus is formed, whilst it is passing through the second uterus, and are an accession to the internal egg; the semen galli, on the contrary, is stored near the fundament, is separated from the chalazæ by a great interval, and nevertheless by its irradiating faculty, fecundates both the whole egg and the uterus. Now in the viviparous animal, the semen is both ‘matter’ and ‘agent,’ the two consisting and being conjoined in the same body.”
Our author appears to have introduced this distinction between oviparous and viviparous animals, that he might spare, or at all events, that he might not directly shock or upset the notions of medical writers on the generation of man, they teaching that the seminal fluids of either sex, projected together in intercourse, are mingled; that as one or other preponderates, this becomes the ‘efficient,’ that stands in lieu of the ‘matter;’ and that the two together, tending to the same end, amalgamate into the ‘conception’ of the viviparous animal.
But when he finds that neither in the egg nor uterus of the fowl is there any semen or blood, and avows his belief that nothing is emitted by the male in intercourse, that can by possibility reach the uterus of the female, nor in the egg discovers a trace of aught supplied by the male, he is compelled to doubt how the semen, which is nowhere to be detected, which is neither mixed with the ‘geniture’ of the female, nor yet is added to it, nor touches it, can fecundate the egg, or constitute the chick. And this all the more urgently, when he has stated that a few connections in the beginning of the season suffice to secure the fecundity of all the eggs that will be laid in its course. For how should it seem otherwise than impossible that from the semen galli communicated in the spring, but now long vanished, lost or consumed, the eggs that continue to be laid through the summer and autumn, should still be rendered fruitful and fit to produce pullets?
It is that he may meet such a difficulty half way, that he coins the difference which has been noticed. By way of bolstering up his views, he farther adduces three additional considerations:—First, since the semen galli is neither extant in the egg, nor was ever present in the uterus, nor is added as ‘material cause’ as in viviparous animals, he has chosen to make it resident for a whole year in the body of the hen. And then that he may have a fit receptacle or storehouse for the fecundating fluid, he finds a blind sac near the inlet to the uterus, in which he says the cock deposits his semen, wherein, as in a treasury, it is stored, and from which all the eggs are fecundated. Lastly, although the semen in that bursa comes into contact neither with the uterus, nor the egg, nor the ovary, whereby it might fecundate the egg, or secure the generation of a chick, he says, nevertheless, that from thence, a certain spiritual substance or irradiation penetrates to the egg, fecundates its chalazæ, and from these produces a chick. By this affirmation, however, he appears to support the opinion of Aristotle, namely, that the female supplies the ‘matter’ in generation, the male the ‘efficient force;’ and to oppose the postulate of medical writers about the mixture of seminal fluids, for the sake of which, nevertheless, as I have said, he seems to have laid down his distinction between oviparous and viviparous animals. To give an air of greater likelihood to this notion of his, he goes on to enumerate the changes which the semen, not yet emitted, but laid up in the testes and vesiculæ seminales of animals, occasions.
But besides the fact that all this does not bear upon the question, for the principal element under discussion is, not how the semen galli renders the egg prolific, but rather, how does the semen galli fashion and construct the chick from the egg? Almost everything he adduces in support of his view appears either false or open to suspicion, as is obvious, from the facts stated in our history; for neither is the blind cavity situated at the root of the uropygium or coccyx of the fowl, which he entitles “bursa,” destined as a receptacle for the semen of the cock, nor can any semen be discovered there, as we have said; but the cavity is encountered in the male as well as in the female fowl.
Our authority nowhere explains what he understands by a “spiritual substance,” and an “irradiation;” nor what he means by “a substance through whose virtue the egg is vivified:” he does not say whether it is any “corporeal” or “formal” substance, which by “irradiation” proceeds from the semen laid up in the bursa, and, (what is especially required,) constructs a pullet from the egg.
In my opinion, Fabricius does no more here than say: “It produces the chick because it irradiates the egg; and forms because it vivifies;” he attempts to explain or illustrate the exceedingly obscure subject of the formation of a living being by means still more obscure. For the same doubt remains untouched, how, to wit, the semen of the cock without contact, an “external efficient” at best, separate in point of place, and existing in the bursa, can form the internal parts of the fœtus in ovo,—the heart, liver, lungs, intestines, &c., out of the chalazæ by “irradiation.” Unless, indeed, our author will have it that all takes place at the dictum as it were of a creator seated on his throne, and speaking the words: Let such things be! namely, bones for support, muscles for motion, special organs for sense, members for action, viscera for concoction and the like, and all ordered for an end and purpose with foresight, and understanding and art. But Fabricius nowhere demonstrates that the semen has any such virtue, nowhere explains the manner in which without so much as contact the semen can effect such things; particularly when we see that the egg incubated by a bird of another kind than that which laid it, or cherished in any other way, or in dung, or in an oven, far from the bursa of the parent hen, is still quickened and made to produce an embryo.
The same difficulty still remains, I say: how or in what way is the semen of the cock the “efficient” of the chick? It is in no wise removed by invoking the irradiation of a spiritual substance. For did we even admit that the semen was stored in the bursa, and that it incorporated the embryo from the chalazæ by metamorphosis and irradiation, we should not be the less deeply immersed in the difficulty of accounting for the formation of all the internal parts of the chick. But these notions have already been sufficiently refuted by us.
Wherefore, in investigating the efficient cause of the chick, we must look for it as inhering in the egg, not as concealed in the bursa; and it must be such, that although the egg have long been laid, be miles removed from the hen that produced it, and be set under another hen than its parent, even under a bird of a different kind, such as a turkey or guinea-fowl, or merely among hot sand or dung, or in an oven constructed for the purpose, as is done in Egypt, it will still cause the egg to produce a creature of the same species as its parents, like them, both male and female, and if the parents were of different kinds, of a hybrid species, and having a mixed resemblance.
The knot therefore remains untied, neither Aristotle nor Fabricius having succeeded even in loosening it, namely: how the semen of the male or of the cock forms a pullet from an egg, or is to be termed the “efficient” of the chick, especially when it is neither present in, nor in contact with, nor added to the egg. And although almost all assert that the male and his semen are the efficient cause of the chick, still it must be admitted, that no one has yet sufficiently explained how it is so, particularly in our common hen’s egg.