Hence are we farther made more certain as to the commencement of animal generation and the prime inherent principle of the egg. For it is assuredly known that the cicatricula or spot on the yelk is the chief point in the egg, that to which all the rest are subordinate, and to which, if to any one thing more than another, is to be referred the cause, whatever it be, of fecundity in the egg:—certain it is that the generation of the embryo is begun within its precincts. Wherefore, as we have said, the first effect of incubation is to cause dilatation of the cicatricula, and the formation of the colliquament, in which the blood first flushes and veins are distributed, and where the effects of the native heat and the influence of the plastic power first show themselves. And then, the more widely the ramifications of these veins extend, in the same proportion do indications of the presence of the vital power and vegetative force appear. For every effect is a clear evidence of its efficient cause.
In a word I say,—from the cicatricula (in which the first trace of the native heat appears) proceeds the entire process of generation; from the heart the whole chick, and from the umbilical vessels the whole of the membranes called secundines that surround it. We therefore conclude that the parts of the embryo are severally subordinate, and that life is first derived from the heart.
EXERCISE THE FIFTY-FOURTH.
Of the order of the parts in Generation from an egg, according to Fabricius.
Having already determined what part is to be esteemed the first, the blood, to wit, with its receptacles, the heart, veins, and arteries, the next thing we have to do is to speak of the rest of the parts of the body and of the order and manner of their generation.
Fabricius, in whose footsteps we have resolved to tread, in speaking of the generation of the chick in ovo, passes in review the actions which take place in the egg, and by the effect of which the parts are produced, discussing them seriatim, as if a clearer view were thence to be obtained of the order or sequence of generation. “There are three primary actions,” he says,[286] “which present themselves in the egg of the bird: 1st, the generation of the embryo; 2d, its growth; 3d, its nourishment. The first, or generation, is the proper action of the egg; the second and third, viz. growth and nutrition, go on for the major part without the egg, though they are begun and also perfectly performed within it. Now these actions, as they flow from three faculties, the generative, the nutritive, and auctive, so do three operations follow them. From generation all the parts of the chick result; from increase and nutrition, the growth and maintenance of its body. From studying the formation of the chick, we perceive that, under the influence of the generative faculty, the parts of the creature which formerly had no existence are produced: the matter of the egg is changed into the organized body of a chicken. But whilst any part or substance undergoes transmutation into another, it must needs be that its proper essence undergoes change, otherwise would it still remain as it was and unaltered; it must at the same time receive figure, position, and dimensions apt and convenient to its new nature; and indeed it is into these two states or circumstances that procreation of matter resolves itself, viz. transformation and conformation. The transformative and the formative faculties would therefore be the cause of these functions; and whilst one of them has produced every individual part of the chick, such as we see it, from the chalaza of the egg, the other has given it figure, articulations, and position, fitting it for its destined uses. The first, the transformative or alterative faculty, is entirely natural, and acts without all consciousness; and taking the hot, the cold, the moist, and the dry, it alters all through the substance of the chalaza, and in altering this substance changes it into the component parts of the chick, that is to say, into flesh, bones, cartilages, ligaments, veins, arteries, nerves, and all the other similar and simple parts of the animal, and these, through the proper and innate heat and spirit of the semen of the cock, out of the substance of the egg, that is to say, its chalaza; by altering and commuting, it engenders, creates, produces the proper substance of the chick, imparting at the same time to every substance its appropriate quality. The other, which is called the formative faculty, and which out of similar forms dissimilar parts,—namely, giving them elegance through figure, due dimensions, proper position, and congruous number—is much more noble than the former, is possessed of consummate sapience, and acts not naturally [or instinctively], but with election, and consciousness, and intelligence. For the formative faculty appears to have exact cognizance and foresight both of the future action and use of every part and organ. So much of the primary action of the egg, which is the generation of the chick, and to accomplish which both the semen of the cock as agent and fecundator, and the chalaza as matter are required. In the second place comes accretion or growth, which is accomplished by nutrition, whose faculties consist in attraction, retention, concoction, expulsion, and, finally, apposition, agglutination, and assimilation of food.”
But for my part I neither regard such a distribution of actions as correct, or useful, or convenient in this place. It is incorrect, because those actions which he would make distinct in kind and in time—for instance, that parts are first produced similar by the alterative or transformative faculty, to be afterwards fashioned and organized by the formative faculty, and finally made to grow by the auctive faculty—are never apparent in the generation of the chick; for the several parts are produced and distinguished and increased simultaneously. For although in the generation of those animals which are formed by metamorphosis, where from matter previously existing, and already adequate in quantity and duly prepared, all the parts are made distinct and conformed by transformation, as when a butterfly is formed from a caterpillar, a silkworm from a grub, still in generation by epigenesis the thing is very different, nor do the same processes go on as in ordinary nutrition, which is effected by the various actions of different parts working together to a common end, the food being here first assumed and retained, then digested, next distributed, and finally agglutinated. Nor is the similar constitution the result of the transformative faculty, void of all foresight, as Fabricius imagined; but the organic comes from the formative faculty which proceeds with both consciousness and foresight. For generation and growth do not proceed without nutrition, nor nutrition or increase without generation; to nourish being in other terms to substitute for a certain quantity of matter lost as much matter of the same quality, flesh or nerve, in lieu of the matter, flesh or nerve, that has become effete. But what is this but to make or engender flesh or nerve? In like manner, growth cannot go on without generation, for all natural bodies are increased by the accession of new particles similar to those of which they formerly consisted, and this, taking place according to all their dimensions, they are distinguished as regards their parts, and are organized at the same time that they grow.
But to engender the chick is in truth nothing else than to fashion or make its several members and organs, which, although they are produced in a certain order, and some are postgenate to others,—the less important to the more principal organs—still, whilst the organs themselves are all distinguished, they are not engendered in such wise and order that the similar parts are first formed, and the organic parts afterwards compounded from them; or so that certain composing parts existed before other compounded parts which must be fashioned from them. For although the head of the chick and the rest of the body exist in the shape of a mucus or soft jelly, whence each of the parts is afterwards formed in sequence, and all are of similar constitution in the first instance, still are they simultaneously produced and augmented in virtue of the same processes directed by the same agent; and in the same proportion as the matter resembling jelly increases, in like measure are the parts distinguished; for they are engendered, transmuted, and formed simultaneously; similar and dissimilar parts exist together, and from a small similar organ a larger one is produced. The thing, in short, is not otherwise than it is among vegetables, where from the straw proceeds the ear, the awns, and the grain—distinctly, severally, and yet together; or as trees put forth buds, from which are produced leaves, flowers, fruit, and finally seed.
All this we learn from an attentive study of the parts and processes of the incubated egg, inasmuch, as from things done, actions or operations are apprehended; from operations, faculties or forces, and from these we then infer the artificer, generator, or cause. In the generation of the pullet, consequently, the actions or faculties of the engendering cause enumerated by Fabricius, namely, the metamorphic and formative, do not differ in kind, or even in the relation of sequence, as that one is first and the other second, but, as Aristotle is wont to say, are one and the same in reason; not as happens with reference to the actions of the nutritive faculty,—attraction, concoction, distribution and apposition, to wit,—which all come into play in several places at several times. Were this not so, the engendering cause itself would be forced to make use of various instruments in order to accomplish its various operations.
Fabricius, therefore, asserts erroneously that the transmutative force works with the properties of the elements,—hot, cold, moist and dry—as its instruments; whilst the formative faculty acts independently of these and by a more divine power, performing its task with consciousness, as it seems, with foresight and election. But if he had looked more closely at the matter he would have seen that the formative as well as the metamorphic force made use of the hot and the cold, the moist and the dry, as instruments; nor would he have been less struck with indications of the Supreme Artificer’s interference in the processes of nutrition and transformation than in that of formation itself. For nature ordained each and all of these faculties to some definite end, and everywhere labours with forethought and intelligence. Whatever it is in the seeds of plants which renders them fertile and exercises a plastic force in their interior; whatever it is which in the egg performs the duty of a most skilful artificer, producing and fashioning the parts of the pullet, warming, cooling, moistening, drying, concocting, condensing, hardening, softening and liquefying at once, impressing distinctive characters on each of them by means of configuration, situation, constitution, temperament, number and order,—still is this something at work, disposing and ordering all with no less of foresight, intelligence, and choice in the business of transmuting, than in the processes of nutrition, growth, and formation.