ON ANIMAL GENERATION. (continued 3)

And now it is that the rudiments of the embryo first become conspicuous, as may be seen in the fifth and sixth figure of Fabricius; the egg being put into fair water it will be easy to perceive what parts of the body are formed, what are still wanting. The embryo now presents itself in the form of a small worm or maggot, such as we encounter on the leaves of trees, in spots of their bark, in fruit, flowers, and elsewhere; but especially in the apples of the oak, in the centre of which, surrounded with a case, a limpid fluid is contained, which, gradually inspissated and congealed, acquires a most delicate outline, and finally assumes the form of a maggot; for some time, however, it remains motionless; but by and by, endowed with motion and sensation it becomes an animal, and subsequently it breaks forth and takes its flight as a fly.

Aristotle ascribes a similar mode of production to those creatures that are spontaneously engendered.[187] “Some are engendered of the dew,” he says, “which falls upon the leaves.” And by and by he adds, “butterflies are engendered from caterpillars, but these, in their turn, spring from green leaves, particularly that species of raphanus which is called cabbage. They are smaller than millet seeds at first, and then they grow into little worms; next, in the course of three days into caterpillars; after which they cease from motion, change their shape, and pass into chrysalides, when they are inclosed in a hard shell; although, if touched, they will still move. The shell after a long time cracks and gives way, and the winged animal, which we call a butterfly, emerges.”

But our doctrine—and we shall prove it by and by—is, that all animal generation is effected in the same way; that all animals, even the most perfect, are produced from worms; a fact which Aristotle himself seems to have noted when he says: “In all, nevertheless, even those that lay perfect eggs, the first conception grows whilst it is yet invisible; and this, too, is the nature of the worm.”[188] For there is this difference between the generation of worms and of other animals, that the former acquire dimensions before they have any definite form or are distinguished into parts, in conformity with what the philosopher[189] says in the following sentence: “An animal is fashioned from an entire worm, not from any one particular part, as in the case of an egg, but the whole increases and becomes an articulated animal,” i. e. in its growth it separates into parts.

It is indeed matter worthy of admiration, that the rudiments of all animals, particularly those possessed of red blood, such as the dog, horse, deer, ox, common fowl, snake, and even man himself, should so signally resemble a maggot in figure and consistence, that with the eye you can perceive no difference between them.

Towards the end of the fifth day or the beginning of the sixth, the head is divided into three vesicles: the first of these, which is also the largest, is rounded and black; this is the eye, in the centre of which the pupil can be distinguished like a crystalline point. Under this there lies a smaller vesicle, concealed in part, which represents the brain; and over this lies the third vesicle, like an added crest or rounded summit crowning the whole, from which the cerebellum is at length produced. In the whole of these there is nothing to be discovered but a little perfectly limpid water.

And now the rudiment of the body, which we have called the carina, distinctly proclaims itself to be the spinal column, to which sides soon begin to be added, and the wings and the lower extremities present themselves, projecting slightly from the body of the maggot. The venous conduits are, further, now clearly referrible to the umbilical vessels.

EXERCISE THE NINETEENTH.

The fifth inspection of the egg.

On the sixth day the three cells of the head present themselves more distinctly, and the coats of the eyes are now apparent; the legs and the wings also bud forth, much in the way in which, towards the end of June, we see tadpoles getting their extremities, when they quit the water, and losing their tails assume the form of frogs.

In the chick, the rump has still no other form than is conspicuous in animals at large, even in serpents; it is a round and slender tail. The substance of the heart now grows upon the pulsating vesicle; and shortly afterwards the rudiments of the liver and lungs are distinguished; the bill, too, makes its appearance at the same time. Everything is of a pure white colour, especially the bill. About the same epoch all the viscera and the intestines are conspicuous. But the heart takes precedence of all the parts; and the lungs are visible before the liver or brain. The eyes, however, are seen first of all, by reason of their large size and black colour.

And now, too, the embryo has a power of motion, and raises its head and slightly twists itself, although there is still nothing of the brain to be seen, but only a little limpid fluid inclosed in a vesicle. It is at length a perfect maggot, only differing from a caterpillar in this, that when worms are set free from their cells they creep about hither and thither and seek their food, whilst the worm in the egg is stationary, and, surrounded with its proper food, is furnished with aliment through the umbilicus.

The viscera and intestines being now formed, and the fœtus able to execute motions, the anterior portion of the body, without either thorax or abdomen, is perceived to be completely open; so that the heart itself, the liver and the intestines, are seen to hang pendulous externally.

Towards the end of this day and the beginning of the seventh, the toes are distinguished, and the embryo already presents the outlines of the chick, and opens its beak, and kicks with its feet; in short, all the parts are sketched out, but the eyes, above all, are conspicuous. The viscera, on the contrary, are so indistinct, that Coiter affirms, that whilst he plainly saw the eyes and beak he could discover no viscus, even obscurely and confusedly shadowed forth.

The changes that take place from the beginning of the sixth to the end of the seventh day, occur for the major part in some eggs more quickly, in others a little more tardily. The coats of the eyes are now visible, but they only include a colourless and limpid fluid in their interior. The eyes themselves project somewhat beyond their orbits, and each of them does not less exceed the brain in size, than the head with which they are connected exceeds the whole of the rest of the body.

The vesicle, which like a ridge or crest expands beyond the confines of the brain, occupies the place of the cerebellum; and, like the other vesicles, is filled with a transparent fluid.

The brain is perceived to be obscurely bipartite, and refracts the light less than the cerebellum, though it is of a whiter colour. And as the heart is seen lying without the confines of the thorax, so likewise does the cerebellum protrude beyond the limits of the head.

If the head be removed, the vessels ascending to the brain may be observed as bloody points, with the use of a magnifying glass. And now, too, the rudiments of the spine begin to be first perceived distinct from the rest of the pulp, of a milky colour, but firmer consistence. So in the same way, and like flimsy threads of a spider’s web, the ribs and other bones make their appearance in the guise of milky lines, amidst the pulp of the body; and the same thing appears more clearly in the formation of the larger oviparous animals. The heart, lungs, liver, and by way of intestines certain most delicate filaments, all present themselves of a white colour. The parenchyma of the liver is developed upon delicate fibrous stamens over the umbilical vein at the part where it enters, almost in the same manner as we have said that the rudiments of the body grow to the vein descending from the heart, or the vesicula pulsans. For in the same way as grapes grow upon the stalk of the bunch, buds upon twigs, and the ear upon the straw, does the liver adhere to the umbilical vein, and arise from it, even as fungi do from trees and excessive granulations from ulcers, or as sarcoses or morbid growths spring around the minute branches of conterminous arteries by which they are nourished, and occasionally attain to an excessive size.

Looking back upon this office of the arteries, or the circulation of the blood, I have occasionally and against all expectation completely cured enormous sarcoceles, by the simple means of dividing or tying the little artery that supplied them, and so preventing all access of nourishment or spirit to the part affected; by which it came to pass that the tumour, on the verge of mortification, was afterwards easily extirpated with the knife, or the searing iron. One man in particular (and this case I can confirm by the testimony of many respectable persons) had an enormous hernia carnosa, or sarcocosis of the scrotum, larger than a human head, and hanging as low as the knee; from its upper part a fleshy mass, of the thickness of the wrist, or such a rope as is used on ship-board, extended into the abdomen; and the evil had attained to such a height, that no one durst attempt the cure, either with the knife or any other means. Nevertheless, by the procedure above indicated, I succeeded in completely removing this huge excrescence which distended the scrotum, and involved the testicle in its middle; this latter organ, with its vas præparans and vas deferens, and other parts which descend in the tunica vaginalis, being left all the while safe and uninjured. But this cure, as well as various others, accomplished in opposition to vulgar opinion and by unusual procedures, I shall relate at greater length in my Medical Observations, if God grant me longer life.

I mention such cases with a view of more clearly showing that the liver grows upon the vessels, and is only developed some time after the appearance of the blood; that its parenchyma is derived from the arteries whence the matter is effused, and that for a while it remains white and bloodless, like various other parts of the body. Now in the same manner and order precisely as the chick is developed from the egg, is the generation of man and other animals accomplished.

Whence it appears that the doctrine which makes the liver the author and fashioner of the blood, is altogether groundless, although both formerly and at the present time this view obtained universal assent; this was the reason wherefore the liver was reckoned as among the principal and first-formed organs of the body. This viscus indeed was so highly dignified that it was thought to be produced in the very beginning, and simultaneously with the heart, from the seminal fluid of the mother; and the medical fable of the three vesicles or three kids, as they were called, was eagerly defended. Among the number of modern abettors of such views, Parisanus has of late with confidence enough, but little skill, been singing to the old measure. These good people do not consider that the vesicles are in motion in the egg, that the heart is palpitating and the blood present and perfectly concocted, before any sign or vestige of the liver appears. The blood is much rather to be accounted the efficient cause of the liver, than this the author of the blood: for the liver is engendered after the blood, and from it, being adnate to the vessels that contain it.

But neither can I agree with the Aristotelians, who maintain that the heart is the author of the blood; for its parenchyma or proper substance arises some little time after the blood, and is superadded to the pulsating vesicles. I am, however, in much doubt as to whether the pulsating vesicle or point, or the blood itself be the older; whether it be the fluid contained, or the containing sacs. It is obvious, nevertheless, that that which contains is formed for the sake of that which is contained, and is, therefore, made later. And this much, upon the faithful testimony of our eyes, is certain, that the first particle and prime basis of the body are the veins, to which all the other parts are posthumous and superadded. But upon this point we shall say more by and by.

Meantime we may be permitted to smile at that factitious division of the parts into spermatic and sanguineous; as if any part were produced immediately from the seminal fluid, and all did not spring from the same source!

I return to our subject. The colliquament now extends over more than half the egg. The heart, hanging outwards, is at some short distance from the body. And if you look attentively you may perceive some of the umbilical vessels pulsating.

EXERCISE THE TWENTIETH.

The sixth inspection.

Everything is still more distinct upon the seventh day, and the rudiments of several of the particular parts are now conspicuous, viz., the wings, legs, genital organs, divisions for the toes, thighs, ilia, &c. The embryo now moves and kicks, and the form of the perfect chick is recognizable; from this time forward, indeed, nothing is superadded; the very delicate parts only increase in size. The more the parts grow the more is the albumen consumed, and the external membranes united come to be of the nature of the secundines, and ever more and more closely represent the umbilical cord. Wherefore I conceive that, from the seventh, we may at once pass on to the tenth day, nothing of any moment occurring in this interval which is not particularly noted by other writers, especially by Aristotle.

It happens, nevertheless, that when a number of eggs are examined together, some are found more precocious and forward, having everything more distinct; others, again, are more sluggish, and these have the parts less apparent. The season of the year, the place where the incubation is carried on, the sedulousness with which it is performed, and other accidents, have undoubtedly great influence on this diversity of result. I remember on one occasion, on the seventh day to have seen the cavity in the blunt end enlarged in a sluggish egg, the colliquament covered with veins, the vermicular embryo in its middle, the rudiments of the eyes, and all the rest as it is met with in the generality of eggs on the fifth day; but the pulsatory vesicles were not yet apparent, nor was the trunk or root of the veins from which we have said that they originate, yet to be discovered. I therefore regarded this egg as of a feeble nature and left behind, as possessed of an inadequate reproductive faculty, and near to its death; all the more when I observed its colliquament less pellucid and refractive than usual, and the vessels not of such a bright red colour as wont. When the vital spirit is about to escape, that part which is first influenced in generation and earliest attracts attention is also the first that fails and disappears.

EXERCISE THE TWENTY-FIRST.

The inspection after the tenth day.

All that presents itself on the tenth day is so accurately described by Aristotle that scarcely anything remains for us to add. Now his opinion, according to my interpretation of it, is this, viz., that “on the tenth day the entire chick is conspicuous,”[190] being pellucid and white in every part except the eyes and the venous ramifications. “The head at this time is larger than the whole of the rest of the body; and eyes larger than the head are connected with it,” (adhering, and being in some sort appended to the head,) “but having as yet no pupils,” (perfectly formed pupils must here be understood, for it is not difficult to make out the distinct tunics of the eye at this epoch;) “the eyes, if removed at this time, will be found as large as beans and black, and if they be incised, a clear humour flows out, cold, and refracting the light powerfully, but nothing else,” i. e., in the whole head there is nothing but the limpid water which has been mentioned. Such is the state of matters from the seventh to the tenth day, as we have said above. “At the same time,” he continues, “the viscera also appear, and all that appertains to the abdomen and intestines,” viz., the substance of the heart, the lungs, liver, &c., all of a white colour, mucilaginous, pulpy, without any kind of consistency. “The veins, too, that issue from the heart are already in connexion with the umbilicus, from which one vein extends to the membrane that includes the vitellus, which has now become more liquid and diffluent than it was originally; another to the membrane which surrounds everything,” (i. e., the tunica colliquamenti,) “and embraces the fœtus, the vitellus and the interjacent fluid. For the embryo increasing somewhat, one portion of the vitellus is superior, another inferior; but the albumen in the middle is liquid, and still extends under the inferior portion of the vitellus, as it did previously.” Thus far Aristotle.

And now the arteries are seen distinctly accompanying the veins, both those that proceed to the albumen and those that are distributed to the vitellus. The vitellus also at this time liquefies still more and becomes more diffluent, not entirely, indeed, but, as already said, that portion of it which is uppermost; neither do the branches of the veins proceed to every part of the vitellus alike, but only to that part which we have spoken of as resembling melted wax. The veins that are distributed to the albumen have, in like manner, arteries accompanying them. The larger portion of the albumen now dissolves into a clear fluid, the colliquament, which surrounds the embryo that swims in its middle, and comes between the two portions of the vitellus, viz., the superior and the inferior; underneath all (in the sharp end of the egg), the thicker and more viscid portion of the albumen is contained. The superior portion of the yelk already appears more liquid and diffluent than the inferior; and wherever the branches of the veins extend, there the matter seems suddenly to swell and become more diffluent.

“On the tenth day,” continues our author, “the albumen subsides, having now become a small tenacious, viscid, and yellowish mass”—so much of it, that is to say, as has not passed into the state of colliquament.

For already the larger portion of the white has become dissolved, and has even passed into the body of the embryo, viz., the whole of the thinner albumen, and the greater portion of the thicker. The yelk, on the contrary, rather looks larger than it did in the beginning. Whence it clearly appears that the yelk has not as yet served for the nutrition of the embryo, but is reserved to perform this office by and by. In so far as we can conjecture from the course and distribution of the veins, the embryo from the commencement is nourished by the colliquament; upon this blood-vessels are first distributed, and then they spread over the membrane of the thinner albumen, next over the thicker albumen, and finally over the vitellus. The thicker albumen serves for nutriment after the thinner; the vitellus is drawn upon last of all.

The delicate embryo, consequently, whilst it is yet in the vermicular state, is nourished with the thinnest and best concocted aliment, the colliquament and thinner albumen; but when it is older it has food supplied to it more in harmony with its age and strength.

Aristotle describes the relative situation of the several parts in the following words: “In the anterior and posterior part, the membrane of the egg lies under the shell,—I do not mean the membrane of the shell itself, but one under this, in which there is contained a clear fluid”—the colliquament; “then the chick and the membrane including it, which keeps it distinct from the fluid around it.” But here I suspect that there is an error in the text; for as the author himself indicates the thing, it ought rather to stand thus: “then the chick, enveloped in a membrane, continues or swims in the clear fluid;” which membrane is not exterior to the one that immediately lines the shell, but another lying under this; which, when the first or external albumen is consumed, and the remainder of the thicker albumen is depressed into the sharp end of the egg, of two membranes forms a single tunic that now begins to present itself like the secundine called the chorion. And Aristotle says well, “there is a clear fluid contained in it,” by which words he does not mean the albumen, but the colliquament derived from the albumen, and in which the embryo swims; for the albumen that remains subsides into the small end of the egg.

EXERCISE THE TWENTY-SECOND.

The inspection after the fourteenth day.

From the seventh to the fourteenth day everything has grown and become more conspicuous. The heart and all the other viscera have now become concealed within the abdomen of the embryo, and the parts that formerly were seen naked and projecting externally, can now only be perceived when the thorax and abdomen are laid open. The chick too now begins to be covered with feathers, the roots of which are first perceived as black points. The pupils of the eyes are distinguished; the eyelids appear, as does also the membrana nictitans in the greater canthus of the eye, a membrane which is proper to birds, and which they use for cleansing the eyeball. The convolutions of the brain farther make their appearance; the cerebellum is included within the skull; and the tail acquires the characteristic shape of the bird’s rump.

After the fourteenth day the viscera, which up to this time have been white, gradually begin to assume a flesh or reddish colour. The heart, having now entered the penetralia of the thorax and been covered with the sternum, inhabits the dwelling place which itself had formed. The cerebrum and cerebellum acquire solidity under the dome of the skull; the stomach and intestines, however, are not yet included within the abdomen, but, connected with the parts within, hang pendulous externally.

Of the two vessels that proceed from the abdomen to the umbilicus, near the anus, one is an artery, as its pulse proclaims, and arises from the arteria magna or aorta, the other is a vein, and extends from the vitellus by the side of the intestines to the vena portæ, situated in the concave part of the liver. The other trunk of the umbilical vessels, collecting its branches from the albumen, passes the convexity of the liver, and enters the vena cava near the base of the heart.

As all these things go on becoming clearer from day to day, so the greater portion of the albumen is also gradually consumed; this, however, is nowise the case with the vitellus, which remains almost entire up to this time, and indeed is seen of the same size as it was the first day.

In the course of the following days five umbilical vessels are conspicuous; one of these is the great vein, arising from the cava above the liver, and distributing its branches to the albumen; two other veins proceed from the porta, both having the same origin, and run to the two portions of the vitellus, which we have but just described; and these are accompanied by two arteries arising one on either side from the lumbars.

The chick now occupies a larger space in the egg than all the rest of the matter included in it, and begins to be covered with feathers; the larger the embryo grows, the smaller is the quantity of albumen that is present. It is also worthy of observation, that the membrane of the colliquament which we have said unites with the external investing membrane, and constitutes the secundine or chorion, now includes the whole of the vitellus in one, and becoming contracted, draws the vitellus along with the intestines towards the chick, conjoins them with its body, and incloses them as it were in a thick sac. Everything that was previously extremely delicate and transparent, becomes more opaque and fleshy as the sac contracts, which at length, like a hernial tumour of the scrotum, includes and supports both the intestines and the yelk; contracting every day in a greater and greater degree, it comes finally to constitute the abdomen of the chick. You will find the yelk, about the eighteenth day, lying [in its bag] among the intestines, the belly at large being lax; yet are the parts not so firmly fixed but that the intestines (as in the case of a scrotal hernia), along with the vitellus, can be pushed up into the belly, or forced out of it as it were into a pouch. I have occasionally seen the vitellus prolapsed in this way from the abdominal cavity of a pigeon, which had been prematurely excluded from the shell in the summer season.

The chick at this epoch looks big-bellied and as if it were affected with a hernia, as I have said. And now the colliquament, which was at first in large quantity, gradually grows turbid, suffers change, and is consumed, so that the chick comes to lie bent over the vitellus. At the same period, before the liver assumes its sanguineous colour, and performs the business of what is called the second concoction, the bile, which is commonly believed to be separated as an excretion by the power of the liver, is seen of a green colour between the lobes of that organ. In the cavity of the stomach there is a limpid fluid contained, obviously of the same appearance and taste as the colliquament in which the fœtus swims; this passing on by the intestines, gradually changes its colour, and is converted into chyle; and finally in the lower portion of the bowels an excrementitious matter is encountered, of the same character as that which is met with in the lower intestines of chicks already excluded from the egg. When the chick is further advanced you may even see this fluid concocted and coagulated; just as in those animals that feed on milk, a coagulum is formed, which afterwards separates into serum and firmer curd.

When the albumen is almost all removed, and only a very small quantity of the colliquament is left, for several days before the exclusion, the chick no longer swims, but, as I have said, bends over the vitellus; and rolled up into a round ball, with the head for the most part placed between the right thigh and wing, it is seen with its beak, nails, feathers, and all other parts complete. Sometimes it sleeps, and sometimes it wakes, and moving about it breathes and chirps. If you apply the egg to your ear, you will hear the chick within making a noise, kicking, and unquestionably chirping; according to Aristotle, he now also uses his eyes. If you cautiously drop the egg into warm water, it will swim, and the chick within, aroused by the warmth, will leap, and, as I have already said, cause the egg to tumble about. And it is by this means that our country folks distinguish prolific from unproductive eggs which sink when put into water.

When the albumen is entirely gone, just before the exclusion, the umbilical vessel, which we have described as distributed to the albumen, is obliterated; or as Aristotle says,[191] “that umbilicus which proceeds to the external secundines is detached from the animal and dies; but the one which leads to the vitellus becomes connected with the small intestine of the chick.”

The excrement that is first formed in the intestines is white and turbid, like softened egg-shell; and some of the same matter may be found contained in the secundines. The philosopher admits this when he says: “At the same time, too, the chick discharges a large quantity of excrement into the outer membrane; and there are white excrements within the abdomen, as well as those that have been evacuated.”

Time running on, very shortly before the exclusion, light green fæces are formed, similar to those which the chick discharges when excluded from the egg. In the crop, too, we can discover a portion of the colliquament which has been swallowed; and in the stomach some curd or coagulum.

Up to this time the liver has not yet acquired its purple or blood-red colour, but has a tint verging from white into yellow, such as the liver of fishes presents. The lungs, however, are of a florid red.

The yelk is now contained in the abdomen among the intestines: and this is the case not merely whilst the chick is in the egg, but even after its exclusion, and when it is running about following its mother in search of food. So that what Aristotle frequently asserts appears to be absolutely true, viz., that the yelk is destined for the food of the chick; and the chick does certainly use it for food, included in his interior as it is, during the few first days after his exclusion, and until such time as his bill gains the hardness requisite to break and prepare his food, and his stomach the strength necessary to digest it. And, indeed, the yelk of the egg is very analogous to milk. Aristotle gives us his support in this opinion in the place already so frequently referred to:[192] “The chick now lies over much of the yellow, which at last diminishes, and, in process of time, disappears entirely, being all taken into the body of the bird, where it is stored, so that on the tenth day after the exclusion of the chick, if the belly be laid open, you will still find a little of the yelk upon the intestines.” I have myself found certain remains of the yelk even upon the thirteenth day; and if the argument derivable from the duct of the umbilical veins which we have described as terminating in the porta of the liver by one or another trunk, be of any avail, the chick is already nourished almost in the same manner as it is subsequently, the sustenance being attracted from the yelk by the umbilical vessels, in the same way as chyle is by and by transmitted by the mesenteric veins from the intestines. For the vessels terminate in either case in the porta of the liver, to which the nourishment attracted in the same way is in like manner transmitted. It is not necessary, therefore, to have recourse to any lacteal vessels of the mesentery, which, in the feathered tribes, are nowhere to be distinguished.

Let me be permitted here to add what I have frequently found: With a view to discovering more distinctly the relative situations of the embryo and the fluids, I have boiled an egg hard, from the fourteenth day of the incubation up to the day when the exclusion would have taken place, the major part of the albumen being already consumed, and the vitellus divided. Breaking the shell, and regarding the position of the chick, I found both the remains of the albumen and the two portions of the vitellus (which we have said are divided by the colliquation induced by the gentle heat), possessing the consistency, colour, taste, and other qualities which distinguish the yelks of unincubated eggs similarly boiled. I have, therefore, frequently asked myself how it came to pass that unprolific eggs set under a hen are made to putrefy and become offensive by the same extraneous heat which produces no such effect upon prolific eggs, both of the fluids of which remain sweet and unchanged, although they have an embryo in the midst of them, (and this even containing some small quantity of excrementitious matter within it,) so that did any one eat the yelk of such an egg in the dark, he would not distinguish it from that of a fresh egg which had never been sat upon.

EXERCISE THE TWENTY-THIRD.

Of the exclusion of the chick, or the birth from the egg.

The egg is, as we have said, a kind of exposed uterus, and place in which the embryo is fashioned: for it performs the office of the uterus and enfolds the chick until the due time of its exclusion arrives, when the creature is born perfect. Oviparous animals consequently are not distinguished from viviparous by the circumstance of the one bringing forth their young alive, and the other not doing so; for the chick not only lives and moves within the egg, but even breathes and chirps whilst there; and, when it escapes from the shell, enjoys a more perfect existence than the fœtus of animals in general. Oviparous and viviparous animals rather differ in their modes of bringing forth; the uterus or place in which the embryo is formed being within the animal in viviparous tribes, where it is cherished and brought to maturity, whilst in oviparous tribes the uterus, or egg, is exposed or without the animal, which, nevertheless, by sitting on it does not cherish it less truly than if it were still contained within the body.

For though the mother occasionally quits her eggs on various errands, it is only for a short season; she still has such affection for them that she speedily returns, covers them over, cherishes them beneath her breast and carefully defends them; and this on to the twenty-first or twenty-second day, when the chicks, in search of freer air, break the shell and emerge into the light.

Now we must not overlook a mistake of Fabricius, and almost every one else in regard to this exclusion or birth of the chick. Let us hear Fabricius.[193]

“The chick wants air sooner than food, for it has still some store of nourishment within it; in which case the chick, by his chirping, gives a sign to his mother of the necessity of breaking the shell, which he himself cannot accomplish by reason of the hardness of the shell and the softness of his beak, to say nothing of the distance of the shell from the beak, and of the position of the head under the wing. The chick, nevertheless, is already so strong, and the cavity in the egg is so ample, and the air contained within it so abundant, that the breathing becomes free and the creature can emit the sounds that are proper to it; these can be readily heard by a bystander, and were recognized both by Pliny and Aristotle,[194] and perchance have something of the nature of a petition in their tone. For the hen hearing the chirping of the chick within, and knowing thereby the necessity of now breaking the shell in order that the chick may enjoy the air which has become needful to it, or if you will, you may say, that desiring to see her dear offspring, she breaks the shell with her beak, which is not hard to do, for the part over the hollow, long deprived of moisture, and exposed to the heat of incubation, has become dry and brittle. The chirping of the chick is consequently the first and principal indication of the creature desiring to make its escape, and of its requiring air. This the hen perceives so nicely, that if she hears the chirping to be low and internal, she straightway turns the egg over with her feet, that she may break the shell at the place whence the voice proceeds without detriment to the chick. Hippocrates adds,[195] “Another indication or reason of the chick’s desiring to escape from the shell, is that when it wants food it moves vigorously, in search of a larger supply, by which the membrane around it is torn, and the mother breaking the shell at the place where she hears the chick moving most lustily, permits it to escape.”

All this is stated pleasantly and well by Fabricius; but there is nothing of solid reason in the tale. For I have found by experience that it is the chick himself and not the hen that breaks open the shell, and this fact is every way in conformity with reason. For how else should the eggs that are hatched in dunghills and ovens, as in Egypt and other countries, be broken in due season, where there is no mother present to attend to the voice of the supplicating chick, and to bring assistance to the petitioner? And how again are the eggs of sea and land tortoises, of fishes, silkworms, serpents, and even ostriches to be chipped? The embryos in these have either no voice with which they can notify their desire for deliverance, or the eggs are buried in the sand or slime where no chirping or noise could be heard. The chick therefore is born spontaneously, and makes its escape from the eggshell through its own efforts. That this is the case appears from unquestionable arguments: when the shell is first chipped, the opening is much smaller than accords with the beak of the mother; but it corresponds exactly to the size of the bill of the chick, and you may always see the shell chipped at the same distance from the extremity of the egg, and the broken pieces, especially those that yield to the first blows, projecting regularly outwards in the form of a circlet. But as any one on looking at a broken pane of glass can readily determine whether the force came from without or from within, by the direction of the fragments that still adhere, so in the chipped egg it is easy to perceive, by the projection of the pieces around the entire circlet, that the breaking force comes from within. And I myself and many others with me besides, hearing the chick scraping against the shell with its feet, have actually seen it perforate this part with its beak, and extend the fracture in a circle like a coronet. I have further seen the chick raise up the top of the shell upon its head and remove it.

We have gone at length into some of these matters, as thinking that they were not without all speculative interest, as we shall show by and by. The arguments of Fabricius are easily answered. For I admit that the chick in ovo produces sounds, and these perchance may even have something of the implorative in their nature; but it does not therefore follow that the shell is broken by the mother. Neither is the bill of the chick so soft, nor yet so far from the shell, that it cannot pierce through its prison walls, particularly when we see that the shell, for the reasons assigned, is extremely brittle. Neither does the chick always keep its head under its wing, so as to be thereby prevented from breaking the shell, but only when it sleeps or has died. For the creature wakes at intervals and scrapes and kicks, and struggles, pressing against the shell, tearing the investing membranes, and chirps, (and that this is done whilst petitioning for assistance I willingly concede,) all of which things may readily be heard by any one who will use his ears. And the hen listening attentively when she hears the chirping deep within the egg does not break the shell, but she turns the egg with her feet and gives the chick within another and a more commodious position. But there is no occasion to suppose that the chick by his chirping informs his mother of the propriety of breaking the shell, or seeks deliverance from it. For very frequently for two days before the exclusion you may hear the chick chirping within the shell. Neither is the mother, when she turns the egg, looking for the proper place to break it; but as the child when uncomfortably laid in his cradle is restless and whimpers and cries, and his fond mother turns him this way and that, and rocks him till he is composed again, so does the hen when she hears the chick restless and chirping within the egg, and feels it, when hatched, moving uneasily about in the nest, immediately raise herself and observe that she is not pressing on it with her weight, or keeping it too warm, or the like, and then with her bill and her feet she moves and turns the egg until the chick within is again at its ease and quiet.

EXERCISE THE TWENTY-FOURTH.

Of twin-bearing eggs.

Twin-bearing eggs are such as produce twin chickens, and according to Aristotle,[196] “are possessed of two yelks, which, in some are separated by a layer of thin albumen, that they may less encroach on one another; in others, however, there is nothing of the sort, and then the two yelks are in contact.”

I have frequently seen twin eggs, each of the yelks in which was surrounded by an albumen, with common and proper membranes surrounding them. I have also met with eggs having two yelks connate, as it were, both of which were embraced by a single and common albumen.

“Some fowls” says Aristotle,[197] “always produce twins, in which the particulars relating to the yelk that have been stated are clearly perceived. A certain fowl laid within two of twenty eggs, all of which, except those that were unprolific, produced twins. Of the twins, however, one was always larger, the other smaller, and the smaller chick was frequently deformed in addition.”

With us twin eggs are occasionally produced, and twin chicks too, although very rarely, are engendered. I have never myself, however, seen both of these chicks live and thrive; one of them either died within the egg or at the time of the exclusion. And this the words of Aristotle prepare us to expect, when he says “one of the two is larger, the other smaller;” this is as much as to say that one of them is stronger and of greater age, the other weaker and less prepared for quitting the shell: my own opinion therefore is, that the two yelks are of different origins and maturity. It is therefore scarcely possible but that the stronger and more advanced chick, if the egg be broken and it emerge into the light, will cause the blight and abortion of the other. But if the stronger bird do not chip the shell, he himself is threatened with a present danger, viz. want of air. At the exclusion from the shell, consequently, certain death hangs over one or other, if not over both.

Fabricius either not observing the above words of Aristotle, or neglecting them, says: “If an egg have now and then two yelks, it engenders a chick having four legs or wings, and two heads—a monster, in short; never two chicks distinct from one another, and that can be spoken of as a pair; there is but one trunk, to which are appended two heads, &c.”

Whence we may infer that he himself had never seen nor heard from credible persons that such eggs produce two pullets, and therefore that he agrees with me in regarding such eggs as rare, and in holding that they never produce two chicks both alike capable of living.

I am surprised nevertheless that, with the authority of Aristotle before him, he should have said that “two chicks, distinct and separate, are never produced from such eggs,” but always a monster; the rather as he thinks that the embryo is engendered from the chalazæ as from the appropriate matter, and he could not but see that there are four chalazæ in every twin-egg.

I should rather imagine that when two vitelli are included by the same albumen in a twin-egg, and are so intimately associated that their cicatriculæ, when they are resolved together, constitute a single eye or colliquament, may engender a monstrous embryo with four feet, two heads, &c., because I see nothing to hinder this; and such a production do I conceive to have been engendered by the egg of which Fabricius speaks.

But where two yelks have existed separately, parted by their several membranes, and furnished with chalazæ, albumens, and all else requisite to the generation of the chick, I hold that we must conclude, with Aristotle, that such an egg, as it has all the parts of two eggs except the shell, so does it also possess the faculty or faculties of as many; and unless it be a wind or barren egg, that it will for the most part produce two embryos, and but rarely a single monstrous individual.

EXERCISE THE TWENTY-FIFTH.

Certain Deductions from the preceding History of the Egg.

Such is the history of the hen’s egg; in which we have spoken of its production, and of its action or faculty to engender a chick, at too great length, it may appear to those who do not see the end and object of such painstaking, of such careful observation. Wherefore I think it advisable here to state what fruits may follow our industry, and in the words of the learned Lord Verulam, to “enter upon our second vintage.” Certain theorems, therefore, will have to be gathered from the history given; some of which will be quite certain, some questionable and requiring further sifting, and some paradoxical and opposed to popular persuasion. Some of these, moreover, will have reference to the male, some to the female, several to the egg, and finally, a few to the formation of the chick. When these have been carefully discussed seriatim, we shall be in a condition to judge with greater certainty and facility of the generation of all other animals.

EXERCISE THE TWENTY-SIXTH.

Of the nature of the egg.

Of the theorems that refer to the egg, some teach us what it is, some show its mode of formation, and others tell of the parts which compose it.

It is certain, in the first place, that one egg produces one chick only. Although the egg be in a certain sense an external uterus, still it most rarely engenders several embryos, but by far the most frequently produces no more than a single pullet. And when an egg produces two chicks, which it does sometimes, still is this egg to be reputed not single but double, and as possessed of the nature and parts of two eggs.

For an egg is to be viewed as a conception proceeding from the male and the female, equally endued with the virtue of either, and constituting an unity from which a single animal is engendered.

Nor is it the beginning only, but the fruit and conclusion likewise. It is the beginning as regards the being to be engendered; the fruit in respect of the two parents: at once the end proposed in their engendering, and the origin of the chick that is to be. “But the seed and the fruit,” according to Aristotle,[198] “differ from one another in the relations of prior and posterior; for the fruit is that which comes of another, the seed is that from which this other comes: were it otherwise, both would be the same.”

The egg also seems to be a certain mean; not merely in so far as it is beginning and end, but as it is the common work of the two sexes and is compounded by both; containing within itself the matter and the plastic power, it has the virtue of both, by which it produces a fœtus that resembles the one as well as the other. It is farther a mean between the animate and the inanimate world; for neither is it wholly endowed with life, nor is it entirely without vitality. It is still farther the mid-passage or transition stage between parents and offspring, between those who are, or were, and those who are about to be; it is the hinge and pivot upon which the whole generation of the bird revolves. The egg is the terminus from which all fowls, male and female, have sprung, and to which all their lives tend,—it is the result which nature has proposed to herself in their being. And thus it comes that individuals in procreating their like for the sake of their species, endure for ever. The egg, I say, is a period or portion of this eternity; for it were hard to say whether an egg exists for the sake of the chick that it engenders, or the pullet exists for the sake of the egg which it is to engender. Which of these was the prior, whether with reference to time or nature,—the egg or the pullet? This question, when we come to speak of the generation of animals in general, we shall discuss at length.

The egg, moreover,—and this is especially to be noted,—corresponds in its proportions with the seeds of plants, and has all the same conditions as these, so that it is to be regarded, not without reason, as the seed or sperma of the common fowl, in the same way as the seeds of plants are justly entitled their eggs, not only as being the matter or that from which, but the efficient or that by which the pullet is engendered. In which finally no part of the future offspring exists de facto, but in which all parts inhere in potentia.

The seed, properly so called, differs however from the geniture, which by Aristotle is defined to be “that which, proceeding from the generator, is the cause, that which first obtains the principle of generation; in those, to wit, whom nature destined to copulate. But the seed is that which proceeds from these two in their connection: and such is the seed of all vegetables, and of some animals, in which the sexes are not distinct; like that which is first produced by male and female commingled, a kind of promiscuous conception, or animal; for this already possesses what is required of both.”

The egg consequently is a natural body endowed with animal virtues, viz. principles of motion and rest, of transmutation and conservation; it is, moreover, a body which, under favorable circumstances, has the capacity to pass into an animal form; heavy bodies indeed do not sink more naturally, nor light ones float, when they are unimpeded, than do seeds and eggs in virtue of their inherent capacity become changed into vegetables and animals. So that the seed and the egg are alike the fruit and final result of the things of which they are the beginning and efficient cause.

For a single pullet there is a single egg; and so Aristotle[199] says: “from one seed one body is engendered; for example, from a single grain of wheat one plant; from a single egg one animal; for a twin-egg is, in fact, two eggs.”

And Fabricius[200] with truth observes: “The egg is not only an exposed uterus, and place of generation, but that also on which the whole reproduction of the pullet depends, and which the egg achieves as agent, as matter, as instrument, as seat, and all else, if more there be, that is needful to generation.” He shows it to be an organ because it consists of several parts, and this, from the statement of Galen, who will have the very essence of an organ to be that “it consist of several parts, all of which conspire to one and the same action though diverse in faculty and use; for some are principal instruments in the action; some are indispensable to it,—without them it could not take place; some secure its better performance; and some, in fine, are extant for the safety and preservation of everything else.” He also shows it to be an agent, when from Aristotle and Galen he lays down the two actions of the egg, viz.: “the generation of the chick, and the growth and nutrition of the pullet.” At the conclusion he expresses himself clearly in these words: “In the works of nature we see conjunct and one, the artificer, the instrument, and the matter; the liver, for instance, is both the agent and the instrument for the production of the blood; and so every part of the body; Aristotle,[201] therefore, said well that the moving powers were not easily distinguished from the instruments. In artificial things, indeed, the artificer and the instrument are distinct, as much so as the workman and his hammer, the painter and his pencil. And the reason adduced by Galen[202] is this: that in things made by art the artificer is without the work; in natural things, again, the artificer is within it, conjunct with the instruments, and pervading the whole organization.”

To this I add these perspicuous words of Aristotle.[203] “Of extant things some are consistent with nature, others with other causes. Animals and their parts, and plants, and simple bodies, as earth, fire, air, and water, consist with nature, and are allowed universally to do so; but these bodies differ entirely from those that do not consist with nature. For whatsoever consists with nature is seen to have within itself a principle of motion and of rest, now according to place, now according to increment and decrement, and again according to change. A couch or litter, a garment, and other things of the same description, however designated, inasmuch as they are made by art, have no inherent faculty of change; but inasmuch as they are made of [wood, or] earth, or stone, [or of wool, silk, or linen,] or of mixtures of these, they have such a faculty. As if nature were a certain principle and cause wherefore that should move and be at rest in which she inheres originally, independently, and not by accident. I say, particularly, not by accident, because it might happen that one being a physician should himself be the cause of his own good health; but he is not familiar with medicine in the same respect as he has worked his own cure; it happens simply that the man who here recovers his health is a physician. It therefore occasionally happens, that these two things are distinct and separate. But it is not otherwise with everything besides that is of art: none of these has in itself a principle of performance or action, though some of them have such a principle in other things and beyond themselves, such as a house, and aught else that is made with hands; and some have even such a principle inherent, but not per se and independently: everything, for example, may by accident become a cause to itself. Nature is therefore, as stated [that which has an inherent principle of motion]; and those things have nature within them which possess this principle. Now all such are substances; for nature is always some subject, and inheres in the subject.”

These things I have spoken of at length, and even quoted the words of the writers appealed to, that it might thence appear first, that all I attribute to the egg is actually there, viz.: matter, organ, efficient cause, place, and everything else requisite to the generation of the chick; and next and more especially, that the truth in regard to the following very difficult questions might be made clearly to appear, viz.: Which and what principle is it whence motion and generation proceed? By what virtue does the semen act, according to Aristotle? What is it that renders the semen itself fruitful? (for the philosopher will have it that nature in all natural bodies is the innate principle of motion and of rest, and not any second accident.) Whether is that which in the egg is cause, artificer, and principle of generation and of all the vital and vegetative operations—conservation, nutrition, growth—innate or superadded? and whether does it inhere primarily, of itself, and as a kind of nature, or intervene by accident, as the physician in curing diseases? Whether is that which transforms the egg into a pullet inherent or acquired, or is it already conceived in the ovary, and does it nourish, augment, and perfect the egg there?

What is it besides that preserves the egg sweet after it is laid? What is it that renders an egg fruitful—is it to be called soul, or a portion of the soul, or something belonging to the soul, or something having a soul, or is it intelligence, or, finally, is it Divinity? seeing that it acts to a definite end, and orders all with inimitable providence and art, and yet in an incomprehensible manner, always obtaining what is best both for simple being and for well-being, for protection also and for ornament. And all this not only in the fruitful egg which it fecundates, but in the hypenemic egg which it nourishes, causes to increase, and preserves. Nay, it is not merely the vitellus in the vitellarium or egg-bed, but the smallest speck whence the yelk is produced, of no greater size than a millet or a mustard-seed, that it nourishes and makes to grow, and finally envelopes with albumen, and furnishes with chalazæ, and surrounds with membranes and a shell. For it is probable that even the barren egg, whilst it is included within the fowl and is connected with her, is nourished and preserved by its internal and inherent principle, and made to increase (not otherwise than the eggs of fishes and frogs, exposed externally, increase and are perfected), and to be transformed from a small speck into a yelk, and transferred from the ovary to the uterus (though it have no connexion with the uterus), there to be endued with albumen, and at length to be completed with its chalazæ, membranes, and shell.

But what that may be in the hypenemic egg as well as in the fruitful one, which in a similar manner and from the same causes or principles produces the same effects; whether it be the same soul, or the same part of the soul, or something else inherent in both, must be worthy of inquiry: it seems probable, however, that the same things should proceed from similar causes.

Although the egg whilst it is being produced is contained within the fowl, and is connected with the ovary of the mother by a pedicle, and is nourished by blood-vessels, it is not therefore to be spoken of as a part of the mother; nor is it to be held as living and vegetating through her vital principle, but by a virtue peculiar to itself and an internal principle; just as fungi, and mosses, and the misletoe, which although they adhere to vegetables and are nourished by the same sap as their leaves and germs, still form no part of these vegetables, nor are they ever so esteemed. Aristotle, with a view to meeting these difficulties, concedes a vegetative soul to the egg, even to the hypenemic one. He says:[204] “Females, too, and all things that live are endowed with the vegetative virtue of the soul, as has been often said; and therefore this [hypenemic] egg is perfect as the conception of a plant, but imperfect as that of an animal.” And he inculcates the same doctrine elsewhere,[205] when he asks: “In what manner or sense are hypenemic eggs said to live? For they cannot do so in the same sense as fruitful eggs, otherwise a living thing might be engendered by their agency. Nor do they comport themselves like wood or stone; because these perish by a kind of corruption, as having formerly had life in a certain manner. It is positive, therefore, that hypenemic eggs have a certain kind of soul potentially; but what? of necessity that ultimate soul, which is the appanage of vegetables; for this equally inheres in all things, in animals as well as vegetables.”

But it is not the same soul that is found in hypenemic as in fruitful eggs; otherwise would a pullet be indifferently produced from both; but how and in what respects the soul attached to each is different from the other, Aristotle does not sufficiently explain, when he inquires:[206] “Wherefore are all the parts of an egg present in the hypenemic egg, and it still incapable of producing a chick? because,” he replies, “it is requisite that it have a sensitive soul.” As if in fruitful eggs, besides the vegetative soul, there were a sensitive soul present. Unless you understand the vegetative soul as inhering actually in the fruitful egg, which contains the sensitive soul within it potentially; whence the animal, and the sensible parts of the animal are subsequently produced. But neither do writers satisfactorily untie this knot, nor set the mind of the inquirer free from the difficulties that entangle him. For he sees that the egg is a true animal seed, according to this sentence of the Stagyrite:[207] “In those things endowed with life, in which the male and female sexes are not distinct, the seed is already present as a conception. I entitle conception the first mixture from the male and female (the analogue of the vegetable seed therefore). Wherefore from one seed there is engendered one body, as from one egg one animal.”

It appears, consequently, that for one egg there is one soul or vital principle.[208] But whether is this that of the mother, or that of the father, or a mixture of the two? And here the greatest difficulties are occasioned by those eggs that are produced by the concurrence of animals of different species, as, for example, of the common fowl and pheasant. In such an egg, I ask, is it the vital principle of the father or that of the mother, which inheres? or is it a mixture of the two? But how can vital principles be mingled, if the vital principle (as form) be act and substance, which it is, according to Aristotle? For no one will deny, whatever it be ultimately which in the fruitful egg is the beginning and cause of the effects we witness, that it is a substance susceptible of divers powers, forces, or faculties, and even conditions,—virtues, vices, health and sickness. For some eggs are esteemed to be longer, others shorter lived; some engender chickens endowed with the qualities and health of body that distinguished their parents, others produce young that are predisposed to disease. Nor is it to be said that this is from any fault of the mother, seeing that the diseases of the father or male parent are transferred to the progeny, although he contributes nothing to the matter of the egg; the procreative or plastic force which renders the egg fruitful alone proceeding from the male; none of its parts being contributed by him. For the semen which is emitted by the male during intercourse does by no means enter the uterus of the female, in which the egg is perfected; nor can it, indeed, (as I first announced, and Fabricius agrees with me,) by any manner or way get into the inner recesses of that organ, much less ascend as high as the ovary, near the waist or middle of the body, so that besides its peculiar virtue it might impart a portion of matter to the numerous ova whose rudiments are there contained. For we know, and are assured by unquestionable experience, that several ova are fecundated by one and the same connexion,—not those only that are met with in the uterus and ovary, but those likewise that are in some sort not yet begun, as we shall state by and by, and indeed, as we have already had occasion to assert in our history.

If, therefore, an egg be rendered fruitful by its proper vital principle, or be endowed with its own inherent fecundating force, whence or whereby either a common fowl, or a hybrid betwixt the fowl and the pheasant is produced, and that either male or female, like the father or the mother, healthy or diseased; we must infallibly conclude that the egg, even when contained in the ovary, does not live by the vital principle of the mother, but is, like the youth who comes of age, made independent even from its first appearance; as the acorn taken from the oak, and the seeds of plants in general, are no longer to be considered parts of the tree or herb that has supported them, but things made in their own right, and which already enjoy life in virtue of a proper and inherent vegetative power.

But if we now admit that there is a living principle in a fertile egg, it may become matter of discussion whether it is the same living principle which already inheres in the egg that will inhere in the future chick, or whether it is a different one that actuates each? For it is matter of necessity that we admit the inherence of a certain principle which constitutes and causes the egg to grow, and which farther engenders and makes the chick to increase. We have to inquire, therefore, whether the animating principle of the egg and of the chick be one and the same, or several and different? And then, were several vital principles recognized, some appertaining to the egg, others to the chick, we should next have to inquire: whence and at what epoch the animating principle of the chick entered it? and what is it in the egg which causes the cicatricula to dilate before the advent of the living principle; which draws the eye of the vitellus upwards, as stated, and produces the colliquament, changes the constitution of the fluids of the egg, and preordains everything for the construction of the future chick before there is even a vestige of it to be seen? Or whence shall we say the aliment fit for the embryo is derived, and by which it is nourished and made to grow, before it is yet in being? For these acts are seen to be the work of the vegetative soul of the embryo, and have reference to the coming pullet, ensuring its nutrition and growth. And again, when the embryo is begun, or the chick is half formed, what is it which constitutes that embryo or that chick one and continuous and connex with the liquids of the egg? What nourishes and makes the chick to grow, and preserves the fluids that are fit for its nutrition from putrefaction, and prepares, and liquefies, and concocts them?

If the vital principle be the act of the organic body possessing life in potentia, it seems incredible that this principle can inhere in the chick before something in the shape of an organized body is extant. Nor is it more credible that the vital principle of the egg and chick can be identical, if the vital principle be conservative of that only to which it belongs; but the egg and the chick are different things, and manifest dissimilar and even opposite vital acts, in so much so that one appears to be produced by the destruction of the other. Or should we perchance maintain that the same principle and cause of life inheres in both, in the pullet half fashioned, to wit, and the egg half consumed, as if it were one and a simple act of the same body; or as if from parts producing one natural body, one soul or vital principle also arose, which was all in all, as is commonly said, and all in each particular part? Just as with leaves and fruit conspicuous on the stem of a tree, wherever a division is made we still say that the principle or first cause of the slip and of the whole tree is the same; the leaves and the fruit are, as it were, the form and end, the trunk of the tree the beginning. So too in a line, wherever a division is made, this will become the end or boundary of the part behind it, the commencement of the part before it. And the same thing is seen to obtain in respect of quality and motion, that is to say, in every kind of transmutation and generation.

So much at this time upon these topics, which will by and by engage us at greater length, when we come to speak of the nature of the living principle of the embryos of animals in general; of its being; of its accession in respect of the how and the when; and how it is all in all, and all in each particular part, the same and yet different. Points which we shall determine from numerous observations.

EXERCISE THE TWENTY-SEVENTH.

The egg is not the product of the uterus, but of the vital principle.

“As we have said,” says Fabricius,[209] “that the action of the stomach was to convert the food into chyle, and the action of the testicles to produce semen, because in the stomach we find chyle, in the testes semen, so do we definitely assert that the egg is the product of the uterus of birds, because it is found in this part. The organ and seat of the generation of eggs is, therefore, intimately known and obvious to us. And farther, inasmuch as there are two uteri in birds, one superior and the other inferior, and these are considerably different from one another, and consequently perform different offices, it is in like manner clear what particular action is to be ascribed to each. The superior is devoted to the production of the yelk, the inferior to that of the albumen and remaining parts, or of the perfect egg, as lies obvious to sense; for in the superior uterus we never find aught beyond a multitude of yelks, nor in the inferior uterus, other than entire and perfect eggs. But these are not all the functions of the uteri as it appears, but the following are farther to be noted and enumerated, viz.: the increase of the egg, which succeeds immediately upon its production, and proceeds until it is perfected and acquires its proper dimensions. For the fowl does not naturally lay an egg until it has become complete and has acquired its due dimensions. The actions of the uteri are consequently the increase as well as the engenderment of the egg; but increase supposes and includes nutrition, as is obvious. And since all generation is the effect of the concurrence of two, viz., the agent and the matter, the agent in the generation of an egg is nothing else than the instruments or organs aforesaid, to wit, the double uterus; and the matter is nothing but the blood.”

Now whilst I admit the action of the uterus to be in a manner the generation of the egg, I by no means allow that the egg is nourished and increased by this organ. And this, both for the reasons already alleged by us when we treated of the vital principle of the egg, which is that which nourishes it, and also because it appears little likely (according to Aristotle,[210] it is impossible,) that all the internal parts of the egg, in all their dimensions, should be fashioned and made to increase by an external agent, such as the uterus is with reference to the egg; for how, I beseech you, can that which is extrinsic arrange the natural matter in things that are internal, and supply fresh matter according to the several dimensions in the place of that which has been lost? How can anything be affected or moved by that which does not touch it? Wherefore, without question, the same things happen in the engenderment of eggs which take place in the beginning of all living things whatsoever, viz.: they are primarily constituted by external and preexisting beings; but so soon as they are endowed with life, they suffice for their own nourishment and increase, and this in virtue of peculiar inherent forces, innate, implanted from the beginning.

What has already been said of the vital principle appears clearly to proclaim that the egg is neither the work of the uterus, nor governed by that organ; for it is manifest that the vegetative principle inheres even in the hypenemic egg, inasmuch as we have seen that this egg is nourished and is preserved, increases and vegetates, all of which acts are indications of the presence of the principle mentioned. But neither from the mother nor the uterus can this principle proceed, seeing that the egg has no connexion or union with them, but is free and unconnected, like a son emancipated from pupillage, rolling round within the cavity of the uterus and perfecting itself, even as the seeds of plants are perfected in the bosom of the earth, viz., by an internal vegetative principle, which can be nothing else than the vegetative soul.

And it will appear all the more certain that it is possessed of a soul or vital principle, if we consider by what compact, what moving power, the round and ample yelk, detached from the cluster of the ovary, descends through the infundibulum—a most slender tube composed of a singularly delicate membrane, and possessed of no motory fibres—and opening a path for itself, approaches the uterus through such a number of straits, arrived in which it continues to be nourished, and grows and is surrounded with albumen. Now as there is no motory organ discoverable either in the ovary which expels the vitellus, or in the infundibulum which transmits, or in the uterus which attracts it, and as the egg is not connected with the uterus, nor yet with the ovary by means of vessels, nor hangs from either by an umbilical cord, as Fabricius truly states, and demonstrates most satisfactorily, what remains for us contemplating such great and important processes but that we exclaim with the poet:[211]

And although the rudiments of eggs, which we have said are mere specks, and have compared to millet seeds in size, are connected with the ovary by means of veins and arteries, in the same manner as seeds are attached to plants, and consequently seem to be part and parcel of the fowl, and to live and be nourished after the manner of her other parts, it is nevertheless manifest, that seeds once separated from the plants which have produced them, are no longer regarded as parts of these, but like children come of age and freed from leading-strings, they are maintained and governed by their own inherent capacities.

But of this matter we shall speak more fully, when we come to treat of the soul or living principle of the embryo in general, and of the excellence and divine nature of the vegetative soul from a survey of its operations, all of which are carried on with such foresight, art, and divine intelligence; which, indeed, surpass our powers of understanding not less than Deity surpasses man, and are allowed, by common consent, to be so wonderful that their ineffable lustre is in no way to be penetrated by the dull edge of our apprehension.

What shall we say of the animalcules which are engendered in our bodies, and which no one doubts are ruled and made to vegetate by a peculiar vital principle (anima)? of this kind are lumbrici, ascarides, lice, nits, syrones, acari, &c.; or what of the worms which are produced from plants and their fruits, as from gall-nuts, the dog-rose, and various others? “For in almost all dry things growing moist, or moist things becoming dry, an animal may be engendered.”[212] It certainly cannot be that the living principles of the animals which arise in gall-nuts existed in the oak, although these animals live attached to the oak, and derive their sustenance from its juices. In like manner it is credible that the rudiments of eggs exist in the ovarian cluster by their proper vital principle, not by that of the mother, although they are connected with her body by means of arteries and veins, and are nourished by the same food as herself. Because, as we have stated in our history, all the vitellary specks do not increase together, like the grapes of a bunch, or the corns of an ear of wheat, as if they were pervaded by one common actuating force or concocting and forming cause; they come on one after another, as if they grew by their own peculiar energy, each that is most in advance severing itself from the rest, changing its colour and consistence, and from a white speck becoming a yelk, in regular and determinate sequence. And what is more particularly astonishing is that which we witness among pigeons and certain other birds, where two yelks only come to maturity upon the ovarian cluster together, one of which, for the major part, produces a male, the other a female, an abundance of other vitellary specks remaining stationary in the ovary, until the term comes round for two more to increase and make ready for a new birth. It is as if each successive pair received fertility from the repeated addresses of the male; as if the two became possessed of the vital principle together; which, once infused, they forthwith increase spontaneously, and govern themselves, living of their own not through their mother’s right. And, in sooth, what else can you conceive working, disposing, selecting, and perfecting, as respects this pair of vitellary papulæ and none others, but a peculiar vital principle? And although they attract nourishment from the mother, they still do so no otherwise than as plants draw food from the ground, or as the embryo obtains it from the albumen and vitellus.

Lastly, since the papula existing in the ovary receives fecundity from the access of the male, and this of such a kind that it passes into the form and likeness of the concurring male, whether he were a common cock or a pheasant, and there is as great diversity in the papulæ as there are males of different kinds; what shall we hold as inherent in the papulæ themselves, by whose virtue they are distinguished from one another and from the mother? Undoubtedly it must be the vital principle by which they are distinguished both from each other and from the mother.

It is in a similar manner that fungi and parasitic plants live upon trees. And besides, we in our own bodies frequently suffer from cancers, sarcoses, melicerides, and other tumours of the same description, which are nourished and grow as it seems by their own inherent vegetative principle, the true or natural parts of the body meantime shrinking and perishing. And this apparently because these tumours attract all the nourishment to themselves, and defraud the other parts of the body of their nutritious juices or proper genius. Whence the familiar names of phagedæna and lupus; and Hippocrates, by the words το θεῑον, perhaps understood those diseases which arise from poison or contagion; as if in these there was a certain vitality and divine principle inherent, by which they increase and through contagion generate similar diseases even in other bodies. Aristotle[213] therefore says: “all things are full of soul;” and elsewhere he seems to think that “even the winds have a kind of life, and a birth and a death.”[214] But there is no doubt that the vitellus, when it is once cast loose and freed from all connexion with the fowl, during its passage through the infundibulum and its stay in the cavity of the uterus, attracts a sluggish moisture to itself, which it absorbs, and by which it is nourished; there too it surrounds itself with albumen, furnishes itself with membranes and a shell, and finally perfects itself. All of which things, rightly weighed, we must needs conclude that it is possessed by a proper vital principle (anima).

EXERCISE THE TWENTY-EIGHTH.

The egg is not produced without the hen.

Leaving points that are doubtful, and disquisitions bearing upon the general question, we now approach more definite and obvious matters.

And first, it is manifest that a fruitful egg cannot be produced without the concurrence of a cock and hen: without the hen no egg can be formed; without the cock it cannot become fruitful. But this view is opposed to the opinion of those who derive the origin of animals from the slime of the ground. And truly when we see that the numerous parts concurring in the act of generation,—the testes and vasa deferentia in the male, the ovarium and uterus and blood-vessels supplying them in the female—are all contrived with such signal art and forethought, and everything requisite to reproduction in a determinate direction—situation, form, temperature,—arranged so admirably, it seems certain, as nature does nothing in vain, nor works in any round-about way when a shorter path lies open to her, that an egg can be produced in no other manner than that in which we now see it engendered, viz., by the concurring act of the cock and hen. Neither, in like manner, in the present constitution of things, can a cock or hen ever be produced otherwise than from an egg. Thus the cock and the hen exist for the sake of the egg, and the egg, in the same way, is their antecedent cause; it were therefore reasonable to ask, with Plutarch, which of these was the prior, the egg or the fowl? Now the fowl is prior by nature, but the egg is prior in time; for that which is the more excellent is naturally first; but that from which a certain thing is produced must be reputed first in respect of time. Or we may say: this egg is older than that fowl (the fowl having been produced from it); and, on the contrary, this fowl existed before that egg (which she has laid). And this is the round that makes the race of the common fowl eternal; now pullet, now egg, the series is continued in perpetuity; from frail and perishing individuals an immortal species is engendered. By these, and means like to these, do we see many inferior or terrestrial things brought to emulate the perpetuity of superior or celestial things.

And whether we say, or do not say, that the vital principle (anima) inheres in the egg, it still plainly appears, from the circuit indicated, that there must be some principle influencing this revolution from the fowl to the egg and from the egg back to the fowl, which gives them perpetuity. Now this, according to Aristotle’s views,[215] is analogous to the element of the stars; and is that which makes parents engender, and gives fertility to their ova; and the same principle, Proteus like, is present under a different form, in the parents as in the eggs. For, as the same intelligence or spirit which incessantly actuates the mighty mass of the universe, and compels the same sun from the rising to the setting, in his passage over the various regions of the earth, so also is there a vis enthea, a divine principle inherent in our common poultry, showing itself now as the plastic, now as the nutritive, and now as the augmentative force, though it is always and at all times present as the conservative and vegetative force, and now assumes the form of the fowl, now that of the egg; but the same virtue continues to inhere in either to eternity. And although some animals arise spontaneously, or as is commonly said from putrefaction, and some are produced from the female alone, for Pliny[216] says: “in some genera, as in certain fishes, there are no males, every one taken being found full of roe;” still whatever is produced from a perfect egg is so in virtue of the indispensable concurrence of male and female. Aristotle[217] consequently says: “the grand principles of generation must be held to be the male and the female;” the first two principles of the egg are therefore the male and the female; and the common point or conception of these is the egg, which combines the virtues of both parents. We cannot, in fact, conceive an egg without the concurrence of a male and female fowl, any more than we can conceive fruit to be produced without a tree. We therefore see individuals, males as well as females, existing for the sake of preparing eggs, that the species may be perennial, though their authors pass away. And it is indeed obvious, that the parents are no longer youthful, or beautiful, or lusty, and fitted to enjoy life, than whilst they possess the power of producing and fecundating eggs, and, by the medium of these, of engendering their like. But when they have accomplished this grand purpose of nature, they have already attained to the height, the ακμὴ of their being,—the final end of their existence has been accomplished; after this, effete and useless, they begin to wither, and, as if cast off and forsaken of nature and the Deity, they grow old, and, a-weary of their lives, they hasten to their end. How different the males when they make themselves up for intercourse, and swelling with desire are excited by the venereal impulse! It is surprising to see with what passion they are inflamed; and then how trimly they are feathered, how vainglorious they show themselves, how proud of their strength, and how pugnacious they prove! But, the grand business of life accomplished, how suddenly, with failing strength and pristine fervour quenched, do they take in their swelling sails, and, from late pugnacity, grow timid and desponding! Even during the season of jocund masking in Venus’s domains, male animals in general are depressed by intercourse, and become submissive and pusillanimous, as if reminded that in imparting life to others, they were contributing to their own destruction. The cock alone, replete with spirit and fecundity, still shows himself alert and gay; clapping his wings, and crowing triumphantly, he sings the nuptial song at each of his new espousals! yet even he, after some length of time in Venus’s service, begins to fail; like the veteran soldier, he by and by craves discharge from active duty. And the hen, too, like the tree that is past bearing, becomes effete, and is finally exhausted.

EXERCISE THE TWENTY-NINTH.

Of the manner, according to Aristotle, in which a perfect and fruitful egg is produced by the male and female fowl.

Shortly before we said that a fruitful egg is not engendered spontaneously, that it is not produced save by a hen, and by her only through the concurrence of the cock. This agrees with the matter of the following sentence of Aristotle:[218] “The principles of generation have particular reference to male and female; the male as supplying the original of motion and reproduction; the female as furnishing the matter.”

In our view, however, an egg is a true generative seed, analogous to the seed of a plant; the original conception arising between the two parents, and being the mixed fruit or product of both. For as the egg is not formed without the hen, so is it not made fruitful without the concurrence of the cock.

We have therefore to inquire how the egg is produced by the hen and is fertilized by the cock; for we have seen that hypenemic eggs, and these animated too, are engendered by the hen, but that they are not prolific without the intercourse of the cock. The male and the female consequently, both set their mark upon a fruitful egg; but not, I believe, in the way in which Aristotle imagines, viz.: that the male concurs in the motion and commencement of generation only, the female supplying nothing but the matter, because the contrary of this is obvious in hypenemic eggs. And although it be true as he says: “That male and female differ in respect of reason, because the faculty of each is different, and, in respect of sense, because certain parts differ likewise. The difference according to reason boasts this distinction, that the male has the power of engendering in another; the female has only the power of engendering in herself; whereby it comes that that which is engendered is produced, this being contained in that which engenders. But as males and females are distinguished by certain faculties and functions, and as an instrument is indispensable to every office, and the parts of the body are adapted as instruments of the functions, it was necessary that certain parts should be set aside for purposes of procreation and coition, and these differing from one another, whereby the male differs from the female.”

It does not, however, follow from thence, that what he appears inclined to infer is correct, where he says: “The male is the efficient agent, and by the motion of his generative virtue (genitura), creates what is intended from the matter contained in the female; for the female always supplies the matter, the male the power of creation, and this it is which constitutes one male, another female. The body and the bulk, therefore, are necessarily supplied by the female; nothing of the kind is required from the male; for it is not even requisite that the instrument, nor the efficient agent itself, be present in the thing that is produced. The body, then, proceeds from the female, the vital principle (anima) from the male; for the essence of every body is its vital principle (anima).” But an egg, and that animated, is engendered by the pullet without the concurrence of the male; whence it appears that the hen too, or the female, may be the efficient agent, and that all creative force or vital power (anima) is not derived exclusively from the male. This view indeed appears to be supported by the instance quoted by Aristotle himself, for he says:[219] “Those animals not of the same species, which copulate, (which those animals do that correspond in their seasons of heat and times of uterogestation, and do not differ greatly in their size,) produce their first young like themselves, but partaking of the species of both parents; of this description is the progeny of the fox and dog, of the partridge and common fowl, &c.; but in the course of time from diversity results diversity, and the progeny of these different parents at length acquires the form of the female; in the same way as foreign seed is changed at last in conformity with the nature of the soil, which supplies matter and body to the seed.”

From this it appears, that in the generation of the partridge with the common fowl it is not the male alone that is efficient, but the female also; inasmuch as it is not the male form only, but one common or subordinate that appears in the hybrid, as like the female as it is like the male in vital endowment (anima), and bodily form. But the vital endowment (anima) is that which is the true form and species of an animal.

Farther, the female seems even to have a superior claim to be considered the efficient cause: “In the course of time,” says the philosopher, “the progeny of different species assumes the form of the female;” as if the semen or influence of the male were the less powerful; as if the species impressed by him disappeared with the lapse of time, and were expelled by a more powerful efficient cause. And the instance from the soil confirms this still farther: “for foreign seeds are changed at length according to the nature of the soil.” Whence it seems probable that the female is actually of more moment in generation than the male; for, “in the world at large it is admitted that the earth is to nature as the female or mother, whilst climate, the sun, and other things of the same description, are spoken of by the names of generator and father.”[220] The earth, too, spontaneously engenders many things without seed; and among animals, certain females, but females only, procreate of themselves and without the concurrence of the male: hens, for example, lay hypenemic eggs; but males, without the intervention of females, engender nothing.

By the same arguments, indeed, by which the male is maintained to be the principle and prime ‘efficient’ in generation, it would seem that the female might be confirmed in the prerogative of ὲνεργεία or efficiency. For is not that to be accounted efficient in which the reason of the embryo and the form of the work appear; whose obvious resemblance is perceived in the embryo, and which, as first existing, calls forth the other? Since, therefore, the form, cause, and similitude inhere in the female not less—and it might even be said that they inhere more—than in the male, and as she also exists previously as prime mover, let us conclude for certain that the female is equally efficient in the work of generation as the male.

And although Aristotle[221] says well and truly, “that the conception or egg receives no part of its body from the male, but only its form, species, and vital endowment (anima), and from the female its body solely, and its dimensions,” it is not yet made sufficiently to appear that the female, besides the matter, does not in some measure contribute form, species, and vital endowment (anima). This indeed is obvious in the hen which engenders eggs without the concurrence of a male; in the same way as trees and herbs, in which there is no distinction of sexes, produce their seeds. For Aristotle himself admits,[222] that even the hypenemic egg is endowed with a vital principle (anima). The female must therefore be esteemed the efficient cause of the egg.

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.