ON ANIMAL GENERATION. (continued 7)

He gives another reason, viz. because the parts are formed of different kinds of matter: “Every more excellent part, the sharer in the highest principle is, farther, engendered from the most highly concocted, the purest and first nutriment; the other needful parts, produced for the sake of the former, from the worse and excrementitious remainder. For nature, like the sage head of a family, is wont to throw away nothing that may be turned to any useful purpose. But he still regulates his household so that the best food shall be given to his children, the more indifferent to his menials, the worst to the animals. As then, man’s growth being complete and mind having been superadded, (in other words, and, as I interpret the passage, adult man having acquired sense and prudence,) things are ordered in this way, so does nature at the period of production even compose the flesh and the other more sensitive parts of the purest matter. Of the excrementitious remainder she makes the bones, sinews, hair, nails, and other parts of the same constitution. And this is the reason why this is done last of all, when nature has an abundant supply of recrementitious material.” Our author then goes on to speak of “a twofold order of aliment:” “one for nutrition, another for growth;” “the nutritive is the one which supplies existence to the whole and to the parts; the augmentative, that which causes increase to the bulk.”

This is in accordance with what we find in the egg, where the albumen supplies a kind of purer aliment adapted to the nutrition of the embryo in its earlier stages, and the yelk affords the material for the growth of the chick and pullet. The thinner albumen, moreover, as we have seen, is used in fashioning the first and more noble parts; the thicker albumen and the yelk, again, are employed in nourishing and making these to grow, and further in forming the less important parts of the body. “For,” he says, “the sinews, too, are produced in the same way as the bones, and from the same material, viz.: the seminal and nutritive excrementitious matter. But the nails, hair, horns, beak, and spurs of birds, and all other things of the same description, are engendered of the adventitious and nutritive aliment, which is obtained both from the mother and from without.” And then he gives a reason why man, whilst other animals are endowed by nature with defensive and offensive arms, is born naked and defenceless, which is this: that whilst in the lower animals these parts are formed of remainders or excrements, man is compounded of a purer material, “which contains too small a quantity of inconcoct and earthy matter.”

Thus far have we followed Aristotle on the subject of ‘The Order in Generation,’ the whole of which seems to be referrible to one principle, viz.: the perfection of nature, which in her works does nothing in vain and has no short-comings, but still does that in the best manner which was best to be done. Hence in generation no part would either precede or follow, did she prefer producing them altogether, viz.: in circumstances where she acts freely and by election; for sometimes she works under compulsion, as it were, and beside her purpose, as when through deficiency or superabundance of material, or through some defect in her instruments, or is hindered of her ends by external injuries. And thus it occasionally happens that the final parts are formed before the instrumental parts,—understanding by final parts, those that use others as instruments.

And as some of the parts are genital, nature making use of them in the generation of other parts, as the means of removing obstacles the presence of which would interfere with the due progress of the work of reproduction, and others exist for other special ends; it therefore happens that for the disposition of material, and other requisites, some parts are variously engendered before others, some of them being begun earlier but completed at a later period, some being both begun and perfected at an earlier period, and others being begun together but perfected at different times subsequently. And then the same order is not observed in the generation of all animals, but this is variously altered; and in some there is nothing like succession, but all the parts are begun and perfected simultaneously, by metamorphosis, to wit, as has been already stated. Hence it follows, in fine, that the primogenate part must be of such a nature as to contain both the beginning and the end, and be that for whose sake all the rest is made, namely, the living principle, or soul, and that which is the potential and genital cause of this, the heart, or in our view the blood, which we regard as the prime seat of the soul, as the source and perennial centre of life, as the generative heat, and indeed as the inherent heat; in a word, the heart is the first efficient of the whole of the instrumental parts that are produced for the ends of the soul, and used by it as instruments. The heart, according to Aristotle, I say, is that for which all the parts of animals are made, and it is at the same time that which is at once the origin and fashioner of them all.

EXERCISE THE FIFTY-SIXTH.

Of the order of the parts in generation as it appears from observation.

That we may now propose our own views of the order of the parts in generation as we have gathered it from our observations, it appears that the whole business of generation in all animals may be divided into two periods, or connected with two structures: the ovum, i. e. the conception and seed, or that, whatever it be, which in spontaneous productions corresponds to the seed, whether with Fernelius it be called “the native celestial heat in the primogenial moisture,” or with Aristotle, “the vital heat included in moisture.” For the conception in viviparous animals, as we have said, is analogous to the seed and fruit of plants; in the same way as it is to the egg of oviparous creatures; to worms in spontaneously engendered animals, or to certain vesicles fruitful by the vital warmth of their included moisture. In each and all of these the same things inhere which might with propriety lead to their being called seeds; they are all bodies, to wit, from which and by which, as previously existing matter, artificer and organ, the whole of an animal body is primarily engendered and produced.

The other structure is the embryo produced from the seed or conception. For both the matter and the moving and efficient cause, and the instruments needful to the operation, must necessarily precede operation of any and every kind.

We have already examined the structure of the egg. Now the embryo to which it gives birth, in so far as this can be made out by observation and dissection, particularly among the more perfect animals with [red] blood, appears to be perfected by four principal degrees or processes, which we reduce to as many orders, in harmony with the various epochs in generation; and we shall demonstrate that what transpires in the egg also takes place in every conception or seed.

The first process is that of the primogenial and genital part, viz. the blood with its receptacles, in other words, the heart and its vessels.

And this part is first engendered for two principal reasons: 1st, because it is the principal part which uses all the rest as instruments, and for whose sake the other parts are formed; and, 2d, because it is the prime genital part, the origin and author of the rest. The part, in a word, in which inhere both the principle whence motion is derived, and the end of that motion, is obviously father and sovereign.

In the generation of this first part, which in the egg is accomplished in the course of the fourth day, although I have not been able to observe any order or sequence, inasmuch as the whole of its elements,—the blood, the vessels, and the pulsating vesicles—appear simultaneously, I have nevertheless imagined, as I have said, that the blood exists before the pulse, because, according to nature’s laws, it must be antecedent to its receptacles. For the substance and structure of the heart, namely, the conical mass with its auricles and ventricles, as they are produced long subsequently along with the other viscera, so must they be referred to the same class of parts as these, namely, the third.

In the production of the circulating system the veins are sooner seen than the arteries; such at least is our conclusion.

The second process, which begins after the fourth day, is indicated by a certain concrescence, which I designate vermiculum—worm or maggot; for it has the life and obscure motions of a maggot; and as it concretes into a mucous matter, it divides into two parts, the larger and superior of which is seen to be conglobed, and divided, as it were, into thin vesicles,—the brain, the cerebellum, and the two eyes; the less, again, constituting the carina, arises over the vena cava and extends in the line of its direction.

In the genesis of the head, the eyes are first perceived; by and by a white point makes its appearance in the situation of the beak, and the slime drying around it, it becomes invested with a membrane.

The outline of the rest of the body follows about the same period. First, from the carina something like the sides of a ship are seen to arise; the parts having an uniform consistence in the beginning, but the ribs being afterwards prefigured by means of extremely fine white lines. The instruments of locomotion next arise—the legs and wings; and the carina and the extremities adnate to it are then distinguished into muscles, bones, and articulations.

These two rudiments of the head and trunk appear simultaneously, but as they grow and advance to perfection subsequently, the trunk increases and acquires its shape much more speedily than the head; so that this, which in the first instance exceeded the whole trunk in size, is now relatively much smaller. And the same thing occurs in regard to the human embryo.

The same disparity also takes place between the trunk and the extremities. In the human embryo, from the time when it is not longer than the nail of the little finger, till it is of the size of a frog or mouse, the arms are so short that the extremities of the fingers could not extend across the breast, and the legs are so short that were they reflected on the abdomen they would not reach the umbilicus.

The proportion of the body to the extremities in children after their birth continues excessive until they begin to stand and run. Infants, therefore, resemble dwarfs in the beginning, and they creep about like quadrupeds, attempting progressive motion with the assistance of all their extremities; but they cannot stand erect until the length of the leg and thigh together exceeds the length of the rest of the body. And so it happens, that when they first attempt to walk, they move with the body prone, like the quadruped, and can scarcely rise so erect as the common dunghill fowl.

And so it happens that among adult men the long-legged—they who have longer legs, and especially longer thighs—are better walkers, runners, and leapers than square-built, compact men.

In this second process many actions of the formative faculty are observed following each other in regular order, (in the same way as we see one wheel moving another in automata, and other pieces of mechanism,) and all arising from the same mucaginous and similar matter. Not indeed in the manner that some natural philosophers would have it when they say, “that like is carried to its like.” We are rather to maintain that parts are moved, not changing their places, but remaining and undergoing change in hardness, softness, colour, &c., whence the diversities between similar parts; those things appearing in act which were before in power.[297] The extremities, spine, and rest of the body, namely, are formed, grow, and acquire outline and complexion together; the extremities, comprising bones, muscles, tendons, and cartilages, all of which on their first appearance were similar and homogeneous, become distinguished in their progress, and, connected together, compose organs, by whose mutual continuity the whole body is constituted. In like manner, the membrane growing around the head, the brain is composed, and the lustrous eyes receive their polish out of a perfectly limpid fluid.

That is to say, nature sustains and augments the several parts by the same nourishment with which she fashioned them at first, and not, as many opine, with any diversity of aliment and particles similar to each particular structure. As she is increasing the mucaginous mass or maggot, like a potter she first divides her material, and then indicates the head and trunk and extremities; like a painter, she first sketches the parts in outline, and then fills them in with colours; or like the shipbuilder, who first lays down his keel by way of foundation, and upon this raises the ribs and roof or deck: even as he builds his vessel does nature fashion the trunk of the body and add the extremities. And in this work she orders all the variety of similar parts—the bones, cartilages, membranes, muscles, tendons, nerves, &c.—from the same primary jelly or mucus. For thick filaments are produced in the first instance, and these by and by are brought to resemble cords; then they are rendered cartilaginous and spinous; and, lastly, they are hardened and concocted into bones. In the same way the thicker membrane which invests the brain is first cartilaginous and then bony, whilst the thinner membrane merely consolidates into the pericranium and integument. In similar order flesh and nerve from soft mucus are confirmed into muscle, tendon, and ligament; the brain and cerebellum are condensed out of a perfectly limpid water into a firm coagulum; for the brain of infants, before the bones of the head have closed, is soft and diffluent, and has no greater consistence than the curd of milk.

The third process is that of the viscera, the formation of which in the chick takes place after the trunk is cast in outline, or about the sixth or seventh day,—the liver, lungs, kidneys, cone and ventricles of the heart, and intestines, all become visible nearly at the same moment; they appear to arise from the veins, and to be connected with them in the same way as fungi grow upon the bark of trees. They are, as I have already said, gelatinous, white, and bloodless, until they take on their proper functions. The stomach and intestines are first discovered as white and tortuous filaments extending lengthwise through the abdomen; along with these the mouth appears, from which a continuous canal extends to the anus, and connects the superior with the inferior parts. The organs of generation likewise appear about the same time.

Up to this period all the viscera, the intestines, and the heart itself inclusive, are excluded from the cavities of the body and hang pendulous without, attached as it were to the veins. The trunk of the body presents itself, in fact, like a boat undecked or a house without a roof, the anterior walls of the thorax and abdomen not being yet extant to close these cavities.

But as soon as the sternum is fashioned the heart enters into the chest as into a dwelling which it had built and arranged for itself; and there, like the tutelary genius, it enters on the government of the surrounding mansion, which it inhabits with its ministering servants the lungs. The liver and stomach are by and by included within the hypochondria, and the intestines are finally surrounded by the abdominal parietes. And this is the reason wherefore without dissection the heart can no longer be seen pulsating in the hen’s egg after the tenth day of incubation.

About this epoch the point of the beak and the nails appear of a fine white colour; a quantity of chylous matter presents itself in the stomach; a little excrement is also observed in the intestine, and the liver being now begun, some greenish bile is perceived; facts from which it clearly appears that there is another digestion and preparation of nutriment going on besides that which takes place by the branches of the umbilical veins; and it is reasonable matter of doubt how the bile, the excrementitious matter of the second digestion, can be separated by the instrumentality of the liver from the other humours, when we see it produced at the same time as this organ.

In the order now indicated are the internal organs generated universally; in all the animals which I have dissected, particularly the more perfect ones, and man himself, I have found them produced in the same manner: in these, in the course of the second, third, and fourth month, the heart, liver, lungs, kidneys, spleen, and intestines present themselves inchoate and increasing, and all alike of the same white colour which belongs to the body at large. Wherefore these early days are not improperly spoken of as the days when the embryo is in the milk; for with the exception of the veins, particularly those of the umbilicus, everything is as it were spermatic in appearance.

I am of opinion that the umbilical arteries arise after the veins of the same name, because the arteries are scarcely to be discovered in the course of the first month, and take their rise from the branches that descend to either lower extremity. I do not believe, therefore, that they exist until that part of the body whence they proceed is formed. The umbilical veins, on the contrary, are conspicuous long before any part of the body is begun.

What I have now said I have derived from numerous dissections of human embryos of almost every size; for I have had them for inspection from the time they were like tadpoles, till they were seven or eight fingers’ breadth in length, and from thence onwards to the full time. I have examined them more particularly, however, through the second, third, and fourth months, in the course of which the greatest number of changes take place, and the order of development is seen with greatest clearness.

In the human embryo, then, of the age of two months, what we have spoken of as taking place in the “second process,” is observed to occur. For I rather think that during the first month there is scarcely anything of the conception in the uterus—at all events, I have never been able to discover anything. But the first month past, I have repeatedly seen conceptions thrown off, and similar to the one which Hippocrates mentions as having been voided by the female pipe-player, of the size of a pheasant’s or pigeon’s egg. Such conceptions resemble an egg without its shell; they are, namely, of an oval figure; the thicker membrane or chorion with which they are surrounded, however, is seen to be covered with a white mucor externally, particularly towards the larger end; internally it is smooth and shining, and is filled with limpid and sluggish water—it contains nothing else.

In the course of the second month I have frequently seen an ovum of this description, or somewhat larger, thrown off with the symptoms of abortion, viz. ichorous lochia; the ovum being sometimes entire, at other times burst, and covered with bloody coagula. Within it was smooth and slippery; it was covered with adhering blood without. Its form was that which I have just described. In some of these aborted ova, I have discovered embryos, in others I could find none. The embryo, when present, was of the length of the little finger-nail, and in shape like a little frog, save that the head was exceedingly large and the extremities very short, like a tadpole in the month of June, when it gets its extremities, loses its tail, and assumes the form of a frog. The whole substance was white, and so soft and mucilaginous, that unless immersed in clear water, it was impossible to handle it. The face was the same as that of the embryo of one of the lower animals—the dog or cat, for instance, without lips, the mouth gaping, and extending from ear to ear.

Many women, whose conceptions, like the wind-eggs of fowls, are barren and without an embryo, miscarry in the third month.

I have occasionally examined aborted ova of this age, of the size of a goose’s egg, which contained embryos distinct in all their parts, but misshapen. The head, eyes, and extremities were distinct, but the muscles were indistinct; there were no bones, but certain white lines in their situations, and as it seemed, soft cartilages. The substance of the heart was extremely white, and consisted of two ventricles of like size and thickness of walls, forming a cone with a double apex, which might be compared to a small twin-kernel nut. The liver was very small and of the general white colour. Through the whole of this time, i. e. during the first three months, there is scarcely any appearance of a placenta or uterine cake.

In every conception of this description I have seen, I have always found a surrounding membrane containing a large quantity of watery fluid, between which and the body of the embryo, suspended by its middle by means of a long and twisted umbilical cord, there is such disproportion, that it is impossible to regard this liquid as either sweat or urine; it seems far more probable that like the colliquament in the hen’s egg, it is a fluid destined by nature for the nourishment of the fœtus. Nor was there any indication to be discovered of these conceptions or ova having been connected with the uterus; there was only on the external surface of their larger extremity a greater appearance of thickening and wrinkling, as if the rudiments of the future placenta had existed there.

These conceptions, therefore, appear to me in the light of ova, which are merely cherished within the uterus, and, like the egg in the uterus of the fowl, grow by their own inherent powers.

In the fourth month, however, it is wonderful to find what rapid strides the fœtus has made: from the length of the thumb it has now grown to be a span long. All the members, too, are distinct and are tinged with blood; the bones and muscles can be distinguished; there are vestiges of the nails, and the fœtus now begins to move lustily. The head, however, is excessively large; the face without lips, cheeks, and nose; the gape of the mouth is enormous, and the tongue lies in its middle; the eyes are small, without lids to cover them; the middle integument of the regions of the forehead and sinciput is not yet cartilaginous, far less bony; but the occiput is somewhat firm and in some sort cartilaginous, indicating that the skull already begins to acquire solidity.

The organs of generation have now made their appearance, but the testes are contained within the abdomen, in the situation of the female uterus, the scrotum still remaining empty. The female organs are yet imperfect, and the uterus with its tubes resembles the two-horned uterus of the lamb.

The placenta, of larger size, and now attached to the uterus, comprises nearly one half of the entire conception, and presented itself to my eye as a fleshy or fungous excrescence of the womb, so firmly was its gibbous portion connected all around with the uterine walls, which had now grown to greater thickness. The branches of the umbilical vessels struck into the placenta like the roots of a tree into the ground, and by their means was the conception now, for the first time, connected with the uterus.

The brain presented itself as a large and soft coagulum, full of ample vessels. The ventricles of the heart were of equal capacity, and their walls of the same thickness. In the thorax, and covered by the ribs, three cavities, nearly of the same dimensions, were perceived; of these the lowest was occupied by the lungs, which are full of blood, and of the same colour as the liver and kidneys; the middle cavity was filled by the heart and pericardium; the superior cavity, again, was possessed by the gland called the thymus, which is now of very ample size.

In the stomach there was some chyle discovered, not very different in character from the fluid in which the embryo swam. It also contained some white curdled matter, not unlike the mucous sordes which the nurse washes particularly from between the folds of the skin of new-born infants. In the upper part of the intestines there was a small quantity of excrementitious or chylous matter; the lower bowels contained meconium. In the urinary bladder there was urine, and in the gall bladder bile. The intestinum cœcum, that appendix of the colon, was empty as in the adult, and apparently superfluous, not as in the lower animals—the hog, horse, hare, constituting as it were another stomach. The omentum, or apron, floated over the intestines at large like a thin and transparent veil or cloud.

The kidneys at this epoch are not yet formed into a smooth and continuous rounded mass, as in the adult, but are compacted of numerous smaller masses, as we see them in the calf and sturgeon, as if there were a renal globule or nipple placed at the extremity of each division of the ureter, from the orifice of which the urine distilled. Over the kidneys two bodies, first observed by Eustachius, are discovered, very abundantly supplied with blood, so that their veins, which anatomists designate as venæ adiposæ, are not much smaller than the emulgents themselves. The liver and spleen, according to their several proportions, are equally full of blood.

I may here observe, by the way, that in every strong and healthy human fœtus we everywhere discover milk; it is particularly abundant in the thymus gland, though it is also found in the pancreas, through the whole of the mesentery, and in certain lacteal veins and glands, as it seems, situated between the divisions of the mesenteric vessels. Moreover, it can be pressed and indeed sometimes flows spontaneously from the breasts of newly-bom infants, and nurses imagine that this is beneficial to the infant.

And it clearly appears that this fluid, which abounds in the ovum, is no excrementitious matter thrown off by the embryo, nothing like urine or sweat, because its relative quantity is diminished as the period of parturition approaches, when the fœtus is of course larger, and, as it consumes a greater quantity of nutriment, accumulates excrementitious matter more abundantly than it did in the first months of pregnancy. Let it be added, that the bladder is at this time distended with urine. For my own part I have never been able to discover that conduit for the urine, from the bladder to the umbilicus, which anatomists describe under the name of urachus; I have, on the contrary, frequently seen urine escaping by the penis, but never by any urachus, when the bladder was pressed upon with the hand.

So much for what I have observed with reference to the order of the parts in the development of the human fœtus.

In the fourth and last process the parts of the lowest state and order are produced, those, namely, that do not exist as needful to the being or to the maintenance of the individual, but only as defences against external injury, as ornaments, or as weapons of offence.

The outermost part of all, the skin, with its several appendages,—cuticle, hair, wool, feathers, scales, shells, claws, hooves, and other items of the same description, may be regarded as the principal means of defence or protection. And it is well devised by nature, who, indeed, never does aught amiss, that these parts are the last to be engendered, inasmuch as they could never be of use or avail as defences until the animal was born. The common domestic pullet is therefore born covered with down only, not with feathers, like certain other birds which have to be speedily prepared for flight, because it has to seek its food on foot, not on the wing, and by active running about hither and thither. In like manner the young of ducks and geese, which feed swimming, have their feathers and wings perfected at a later period than their feet and legs. It is otherwise with swallows, however, which have to fly sooner than to walk, because they feed on the wing.

The down of the pullet begins to appear after the fourteenth day, the fœtus being already perfect in all its parts. When the feathers first show themselves, they are in the guise of points within the skin, but by and by the feathers project, like plants from the ground, increase in length, become unfolded, invest the whole body, and protect it against the inclemencies of the atmosphere.

Feathers differ from quills in form, use, place of growth, and order of production. The pullet is feathered before it has any quills, for the quill-feathers only grow in the wings and tail, and also spring more deeply, from the very lowest part of the integument, or even from the periosteum, and serve essentially as instruments of motion; the feathers again arise superficially from the skin, and are everywhere present as means of protection.

“Nails, hair, horn, and the like,” says Aristotle,[298] “are engendered from the skin; whence it happens that they change colour with the skin; for the white and black and particoloured are so in consequence of the colour of the skin whence they arise.” In the bird, however, this is not so; for whatever the colour of the feathers, the skin is still never otherwise than of one tint, viz., white. And then the same feather or quill is frequently seen of different and often brilliant colours in different parts for the ornament of the creature.

In the human fœtus the skin and all the parts connected with it are in like manner perfected the last of all. In the earlier periods, consequently, we find neither lips, cheeks, external ears, eyelids, nor nose; and the last part to grow together is the upper lip in the course of the middle line of the body.

Man comes into the world naked and unarmed, as if nature had destined him for a social creature, and ordained him to live under equitable laws and in peace; as if she had desired that he should be guided by reason rather than be driven by force; therefore did she endow him with understanding, and furnish him with hands, that he might himself contrive what was necessary to his clothing and protection. To those animals to which nature has given vast strength, she has also presented weapons in harmony with their powers; to those that are not thus vigorous, she has given ingenuity, cunning, and singular dexterity in avoiding injury.

Ornaments of all kinds, such as tufts, crests, combs, wattles, brilliant plumage, and the like, of which some vain creatures seem not a little proud, to say nothing of such offensive weapons as teeth, horns, spurs, and other implements employed in combat, are more frequently and remarkably conferred upon the male than the female. And it is not uninteresting to remark, that many of these ornaments or weapons are most conspicuous in the male at that epoch when the females come into season, and burn with desire of engendering. And whilst in the young they are still absent, in the aged they also fail as being no longer wanted.

Our common cock, whose pugnacious qualities are well known, so soon as he comes to his strength and is possessed of the faculty of engendering, is distinguished by his spurs, and ornamented with his comb and beautiful feathers, by which he charms his mates to the rites of Venus, and is furnished for the combat with other males, the subject of dispute being no empty or vainglorious matter, but the perpetuation of the stock in this line or in that; as if nature had intended that he who could best defend himself and his, should be preferred to others for the continuance of the kind. And indeed all animals which are better furnished with weapons of offence, and more warlike than others, fall out and fight, either in defence of their young, of their nests or dens, or of their prey; but more than all for the possession of their females. Once vanquished, they yield up possession of these, lay aside their strut and haughty demeanour, and, crest-fallen and submissive, they seem to consume with grief; the victor, on the contrary, who has gained possession of the females by his prowess, exults and boastfully proclaims the glory of his conquest.

Nor is this ornamenting anything adventitious and for a season only; it is a lasting and special gift of nature, who has not been studious to deck out animals, and especially birds only, but has also thrown an infinite variety of beautiful dyes over the lowly and insensate herbs and flowers.

EXERCISE THE FIFTY-SEVENTH.

Of certain paradoxes and problems to be considered in connexion with this subject.

Thus far have we spoken of the order of generation, whereby the differences between those creatures that are engendered by metamorphosis and those that are developed by epigenesis, as well as between those that are said to proceed from a worm and those that arise from an egg, have been made to appear. The latter are partly incorporated from a prepared matter, and are nourished and increased from a certain remaining matter; the former are incorporated from the whole of the matter present; the latter grow and are formed simultaneously, and after their birth continue to wax in size and finally attain maturity; the former increase at once, and from a grub or caterpillar grow into an aurelia, and are then produced, consummately formed, as butterflies, moths, and the like. Wherefore Aristotle, as Fabricius[299] observes: “As he assigns a sort of twofold nature to the egg, and a twofold egg in this kind, so does he assert a twofold action and a twofold animal engendered. For,” he proceeds, “from the first eggs, which are the primordia of generation, a worm is constantly produced; viz.: from the eggs of flies, ants, bees, silkworms, &c., in which some fluid is contained, and from the whole of which fluid the worm is engendered; but from the second eggs, formed by the worms themselves, butterflies are engendered and disclosed, viz.: flying animals contained in a shell, or follicle, or egg, which shell giving way the winged creature escapes; precisely as Aristotle[300] has it where he speaks of the egg of the locust.” Finally, whilst the higher animals produced from eggs are perfected by a succession of parts, the lower creatures that arise in this way, or that are formed by metamorphosis, are produced at one effort, as it were, and entire. And in the same way are engendered both those creatures that are said to arise spontaneously, by chance or accident, and derive their first matter or take their origin from putrefaction, filth, excrement, dew, or the parts of plants and animals, as well as those that arise congenerately from the semen of animals. Because this is common to all living creatures, viz.: that they derive their origin either from semen or eggs, whether this semen have proceeded from others of the same kind, or have come by chance or something else. For what sometimes happens in art occasionally occurs in nature also; those things, namely, take place by chance or accident which otherwise are brought about by art. Of this Aristotle[301] quotes health as an illustration. And the thing is not different as respects the generation, in so far as it is from seed, of certain animals: their semina are either present by accident, or they proceed from an univocal agent of the same kind. For even in fortuitous semina there is an inherent motive principle of generation, which procreates from itself and of itself; and this is the same as that which is found in the semina of congenerative animals,—a power, to wit, of forming a living creature. But of this matter we shall have more to say shortly.

From what has just been said, however, several paradoxes present themselves for consideration. For when we see the cicatricula enlarging in the egg, the colliquament concocted and prepared, and a variety of other particulars all tending, not without foresight, to the development of the embryo, before the first rudiment or the merest particle of this is conspicuous, what should hinder us from believing that the calidum innatum and the vegetative soul of the chick are in existence before the chick itself? For what is competent to produce the effects and acts of life, except their efficient cause and principle, heat, namely, and the faculty of the vegetative soul? Therefore it would seem that the soul was not the act of the organic body possessing life in potentia; for we regard the chick with its appropriate form as the consequence of such an act. But where can we suppose the form and vital principle of the chick to inhere save in the chick itself? unless indeed we admitted a separation of forms and conceded a certain metamorphosis.

Now this appears most obviously where the same animal lives, as Aristotle has it, by or under a succession of forms, for example, a caterpillar, a chrysalis, a butterfly. For it is of necessity the same efficient, nutrient, and conservative principle that possesses each of these, although under different forms; unless we allow that there is one vital principle in the youth, another in the man, a third in the aged individual, or maintain that the forms of the grub and caterpillar are the same as those of the silkworm and butterfly. Aristotle has entered very fully into this subject, and we shall ourselves have more to say on it immediately.

It appears further paradoxical to maintain that the blood is produced, and moves to and fro, and is imbued with vital spirits, before any sanguiferous or locomotive organs are in existence. Neither is it less new and unheard-of to assert, that sensation and motion belong to the fœtus before the brain is formed; for the fœtus moves, contracting and unfolding itself, when there is nothing more than a little limpid water in the place of the brain.

Moreover, the body is nourished and increases before the organs appropriated to digestion, viz. the stomach and abdominal viscera, are formed. Sanguification, too, which is entitled the second digestion, is perfect before the first, or chylification, which takes place in the stomach, is begun. The excrementitious products of the first and second digestions, namely, excrement in the intestines, urine and bile in the urinary and gall bladder, are contemporaneous with the existence of the concocting organs themselves. Lastly, not only is there a soul or vital principle present in the vegetative part, but even before this there is inherent mind, foresight, and understanding, which from the very commencement to the being and perfect formation of the chick, dispose and order and take up all things requisite, moulding them in the new being, with consummate art, into the form and likeness of its parents.

In reference to this subject of family likeness, we may be permitted to inquire as to the reason why the offspring should at one time bear a stronger resemblance to the father, at another to the mother, and, at a third, to progenitors, both maternal and paternal, further removed? particularly in cases where at one bout, and at the same moment, several ova are fecundated. And this too is a remarkable fact, that virtues and vices, marks and moles, and even particular dispositions to disease are transmitted by parents to their offspring; and that while some inherit in this way, all do not. Among our poultry some are courageous, and pugnaciously inclined, and will sooner die than yield and flee from an adversary; their descendants, once or twice removed, however, unless they have come of equally well-bred parents, gradually lose this quality; according to the adage, “the brave are begotten by the brave.” In various other species of animals, and particularly in the human family, a certain nobility of race is observed; numerous qualities, in fact, both of mind and body, are derived by hereditary descent.

I have frequently wondered how it should happen that the offspring, mixed in so many particulars of its structure or constitution, with the stamp of both parents so obviously upon it, in so many parts, should still escape all mixture in the organs of generation; that it should so uniformly prove either male or female, so very rarely an hermaphrodite.

Lastly, many things are present before they appear, and some are begun among the very first which are completed among the very last, such as the eyes, the organs of generation, and the beak.

Several doubts and difficulties have thence arisen as to the principality and relative dignity of the several members, in which they who are fond of such things have displayed their ingenuity. Among the number: whether the heart gives life and virtue to the blood; or, rather, the blood to the heart. Whether the blood be extant for the sake of the body as matter, nourishment, and instrument; or, on the contrary, the body and its parts are the cause of the blood, and constituted for the sake of the vital principle which especially inheres in it. In like manner, whether the auricles or the ventricles of the heart are the chief, the auricles being the first to live and pulsate, the last to die. Further, whether the left ventricle, which in man is of greater length, and is also surrounded with thicker and more fleshy walls, and is regarded as the source of the spirits, be hotter, more spirituous, excitable, and excellent, than the right, which contains a larger quantity of blood, and is the last to become unstrung by death; in which the blood of the dying accumulates, congeals, and is deprived of life and spirit; to which, moreover, as to a fountain head, the first umbilical veins bring their blood, and from which they themselves derive their origin.

So much appears from careful observation of the order observed in the production of the parts, and certain other points that follow as deductions from these, and do not a little militate against the commonly received physiological doctrines, viz.: since it is manifest that sensation and motion exist before the brain, all sensation and motion do not proceed from the brain; from our history it is clearly ascertained that sense and movement inhere in the very first drop of blood produced in the egg, before there is a vestige of the body. The first scaffolding or rudiment of the body, too, which we have said is merely mucilaginous, before any of the extremities are visible, and when the brain is nothing more than a limpid fluid, if lightly pricked, will move obscurely, will contract and twist itself like a worm or caterpillar, so that it is very evidently possessed of sensation.

There are yet other arguments deduced from sense and motion whence we should infer that the brain was not so much the first principle of the body, in the way the medical writers maintain, as the heart, agreeably to Aristotle’s view.

The motions and actions which physicians style natural, because they take place involuntarily, and we can neither prevent nor moderate, accelerate nor retard them by our will, and they therefore do not depend on the brain, still do not occur entirely without causing sensation, but proclaim themselves subject to sense, inasmuch as they are aroused, called forth, and changed thereby. When the heart, for example, is affected with palpitation, tremor, lipothymia, syncope, and with great variety in the extent, rapidity, and order or rhythm of its pulsations, we do not hesitate to ascribe these to morbific causes implicating, deranging its sensation. For whatever by its divers movements strives against irritations and troubles must necessarily be endowed with sensation.

The stomach and bowels, disturbed by the presence of vitiated humours, are affected with ructus, flatus, vomiting, and diarrhœa; and as it lies not in our power either to provoke or to restrain their motions, neither are we aware of any sensation dependent on the brain which should arouse the parts in question to motions of the kind.

It is truly wonderful to observe the effect of taking a solution of antimony, which we neither distinguish by the taste, nor find any inconvenience from, whether in the swallowing or the rejection. Nevertheless there is a certain discriminating sense in the stomach which distinguishes what is hurtful from what is useful, and by which vomiting is induced.

Nay, the flesh itself readily distinguishes a poisoned wound from one that is not poisoned, and on receipt of the former contracts and condenses itself, whereby phlegmonous tumours are produced, as we find in connexion with the stings of bees, gnats, and spiders.

I have myself, for experiment’s sake, occasionally pricked my hand with a clean needle, and then having rubbed the same needle on the teeth of a spider, I have pricked my hand in another place. I could not by my simple sensation perceive any difference between the two punctures; nevertheless there was a capacity in the skin to distinguish the one from the other; for the part pricked with the envenomed needle immediately contracted into a tubercle, and by and by became red, and hot, and inflamed, as if it collected and girded itself up for a contest with the poison for its overthrow.

The sensations which accompany affections of the uterus, such as twisting, decubitus, prolapse, ascent, suffocation, &c., and other inconveniences and irritations, do not depend on the brain or on common sensation; yet neither are these to be presumed as happening without all consciousness. For that which is wholly without sense is not seen to be irritated by any means, neither can it be stimulated to motion or action of any kind. Nor have we any other means of distinguishing between an animate and sentient thing and one that is dead and senseless than the motion excited by some other irritating cause or thing, which as it incessantly follows, so does it also argue sensation.

But we shall have an opportunity of speaking farther of this matter when we discuss the actions and uses of the brain. Respect for our predecessors and for antiquity at large inclines us to defend their conclusions to the extent that love of truth will allow. Nor do I think it becoming in us to neglect and make little of their labours and conclusions who bore the torch that has lighted us to the shrine of philosophy. I am, therefore, of opinion that we should conclude in this way: we have consciousness in ourselves of five principal senses, by which we judge of external objects; but we do not feel with the same sense by means of which we are conscious that we feel—seeing with our eyes, we still do not know by them that we see, but by another sense or sensitive organ, namely, the internal common sensation or common sensorium, by which we examine those things that reach us through each of the external sensoria, and distinguish that which is white from that which is sweet or hard. Now this sensorium commune to which the species or impressions of all the external instruments of sensation are referred, is obviously the brain, which along with its nerves and the external organs annexed, is held and esteemed to be the adequate instrument of sensation. And this brain is like a sensitive root to which a variety of fibres tend, one of which sees, another hears, a third touches, and a fourth and a fifth smell and taste.

But as there are some actions and motions the government or direction of which is not dependent on the brain, and which are therefore called natural, so also is it to be concluded that there is a certain sense or form of touch which is not referred to the common sensorium, nor in any way communicated to the brain, so that we do not perceive by this sense that we feel; but, as happens to those who are deranged in mind, or who are agitated to such a degree by violent passion that they feel no pain, and pay no regard to the impressions made on their senses, so must we believe it to be with this sense, which we therefore distinguish from the proper animal sense. Now such a sense do we observe in zoophytes or plant-animals, in sponges, the sensitive plant, &c.

Wherefore, as many animals are endowed with both sense and motion without having a common sensorium or brain, such as earthworms, caterpillars of various kinds, chrysalides, &c., so also do certain natural actions take place in the embryo and even in ourselves without the agency of the brain, and a certain sensation takes place without consciousness. And as medical writers teach that the natural differ from the animal actions, so by parity of reason does the natural sense of touch differ from the animal sense of touch,—it constitutes, in a word, another species of touch; and whilst the one is communicated to the common sensorium, the other is not so communicated.

Further, it is one thing for a muscle to be contracted and moved, and another for it by regulated contractions and relaxations to perform any movement, such as progression or prehension. The muscles or organs of motion, when affected with spasms or convulsions from an irritating cause, are assuredly moved no otherwise than the decapitated cock or hen, which is agitated with many convulsive movements of its legs and wings, but all confused and without a purpose, because the controlling power of the brain has been taken away:—common sensation has disappeared, under the controlling influence of which these motions were formerly coordinated to progression by walking or to flight.

We therefore conceive the fact to be that all the natural motions proceed from the power of the heart, and depend on it; the spontaneous motions, however, and those that complete any motion which physicians entitle an animal motion, cannot be performed without the controlling influence of the brain and common sensation. For inasmuch as by this common sensation we are conscious of our perceptions, so also are we conscious that we move, and this whether the motion be regular or otherwise.

We have an excellent example of both of these kinds of motion in respiration. For the lungs, like the heart, are continually carried upwards and downwards by a natural movement, and are excited by any irritation to coughing and more frequent action; but they cannot form and regulate the voice, nor can singing be executed, without the assistance, and in some sort the command, of the sensorium commune.

But these matters will be more fully handled when we come to speak of the actions and uses of the brain, and to consider the vital principle or soul. So much we have thought fit to say by the way, that we might show the respect in which we hold our illustrious teachers, and our anxiety to carry them along with us in our labours.

EXERCISE THE FIFTY-EIGHTH.

Of the nutrition of the chick in ovo.

That the authority of the ancients is not to be rashly thrown off appears in this: it was formerly current doctrine, though many at the present day, Fabricius[302] among the number, reject it as a delusion and a foolish idea, that the embryo sucked in its mother’s womb. This idea nevertheless had Democritus, Epicurus, and Hippocrates for its supporters; and the father of physic contends for it on two principal grounds: “Unless the fœtus sucked,” he says,[303] “how should excrements be formed? or how should it know how to suck immediately after it is born?”

Now, whilst in other instances it is customary to swear by the bare statement of this ancient and most distinguished writer, his ipse dixit (ἀυτὸς ἔφη) sufficing, because he here makes an assertion contrary to the commonly received opinion, Fabricius not only denies the statement, but spurns the arguments in support of his conclusion. We, however, leave it to the judgment of skilful anatomists and learned physicians to say whether our observations on the generation of animals do not proclaim this opinion of Hippocrates to be not merely probable, but even necessary.

All admit that the fœtus in utero swims in the midst of an abundance of a watery fluid, which in our history of the egg we have spoken of as the colliquament, this fluid modern authorities regard as the sweat and excrement of the fœtus, and ascribe as its principal use the protection of the uterus against injury from the fœtus during any violent motion of the mother in running or leaping; and, on the other hand, the defence of the fœtus from injury through contact with neighbouring bones, or an external cause, particularly during the period when its limbs are still delicate and weak.

Fabricius[304] ascribes additional uses to this fluid, viz. “that it may moisten and lubricate all the parts around, and dispose the neck of the uterus to facile and speedy dilatation to the utmost extent; and all this is not less assisted by that thick, white, excrementitious matter of the third digestion, neglected by the ancients, which is unctuous and oily, and farther prevents the sweat, which may occasionally be secreted sharp and salt in quality, from excoriating the tender body of the fœtus.”

I readily acknowledge all the uses indicated, viz. that the tender fœtus may be secure against all sudden and violent movements of the mother, that he may ride safe in the “bat’s wings,” as they are called, and, surrounded with an abundance of water, that he may escape coming into contact with his mother’s sides, being restrained by the retinacular fluid on either hand: this circumambient fluid must certainly protect the body which floats in its middle from all external injury. But, as in many other instances, my observations compel me here to be of a different opinion from Fabricius. In the first place, I am by no means satisfied that this fluid is the sweat of the fœtus. And then I do not believe that the fluid serves those important purposes in parturition which he indicates; and much less that it is ever so sharp and saline that an unctuous covering was requisite to protect the fœtus from its erosive effects, particularly in those cases where there is already a thick covering of wool, or hair, or feathers. The fluid, in fact, has a pleasant taste, like that of watery milk, so that almost all viviparous animals lap it up, and cleanse their new-born progeny by licking them with their tongues, greedily swallowing the fluid, though none of them was ever seen to touch any of the excrements of their young.

Fabricius spoke of this fluid as saline and acrimonious, because he believed it to be sweat. But what inconvenience, I beseech you, were sweat to the chick, already covered with its feathers?—if indeed any one ever saw a chicken sweat. Nor do I think he could have said that the use of this fluid in the egg was, by its moistening and lubrifying qualities, to facilitate the birth of the chick; for the drier and older the shell of the egg, the more friable and fragile it becomes. Finally, were it the sweat of the embryo, or fœtus, it ought to be most abundant nearest the period of parturition: the larger the fœtus and the more food it consumes, the more sweat must it necessarily secrete. But shortly before the exclusion of the chick from the egg, namely, about the nineteenth or twentieth day, there is none of the fluid to be seen, because as the chick grows it is gradually taken up; so that if the thing be rightly viewed, the fluid in question ought rather to be regarded as nutriment than as excrement, particularly as he has said that the chick in the egg breathes, and lets its chirping be heard, which it certainly would not do were it surrounded with water.

But all experienced obstetricians know that the watery fluid of the secundines is of no great use either in lubricating the parts or in facilitating the progress of parturition in the way Fabricius would have it. For the parts surrounding the vulva are relaxed of themselves, and by a kind of proper maturity at the full time, without any assistance from the uterine waters; and particularly those that offer the greatest obstacles to the advance of the fœtus, namely, the ossa pubis and the os coccygis, to which the attention of the midwife is especially directed in assisting the woman in labour. For midwives are much less studious to anoint the soft parts with any emollient salves, lest they tear, than careful to pull the os coccygis outwards, a business in which, if the fingers do not suffice, they have recourse to the uterine speculum, applied by the hand of the experienced surgeon, an instrument having three sides or branches, one of which bearing on the os coccygis, the other two on the ossa pubis, the business of distension is effected by force. For the head of the child that is about to be born, when it makes the turn, and is forced downwards, relaxes and opens the os uteri; but coming down he will stick fast, and scarcely be brought forth if he chance to abut upon the point of the os coccygis, and immediately the case is one not without danger both to the child and mother. But nature’s intention was obviously to relax and soften all the parts concerned; and the attendant knows that when the uterine orifice is discovered in a soft and lax condition, by the finger introduced, it is an infallible sign that the delivery is at hand even though the waters have not broken. Indeed—and I do not speak without experience—if anything remains in the uterus for expulsion, either after delivery or at any other time, and the uterus make efforts to get rid of it, the orifice both descends lower and is found soft and relaxed. If the uterine orifice recedes, and is found somewhat hard after delivery, it is a sign of the woman’s restoration to health.

Taught by like experience, I assert that the ossa pubis frequently become loosened during labour, their cartilaginous connexion being softened, and the whole hypogastric region enlarged in the most miraculous manner, not, however, by any pouring out of watery fluids, but spontaneously, as ripe fruit gapes that the included seed may find an exit. The degree in which the coccyx may impede delivery, however, is apparent among quadrupeds having tails, which can neither bring forth, nor even discharge the excrement from their bowels, unless the tail be raised; if you but depress the tail with your hand, you prevent the exit of the dung.

Moreover, the most natural labour of all is held to be that in which the fœtus and afterbirth, the waters inclusive, or the ovum, is expelled entire. Now if the membranes have not given way, and the waters have not escaped, it comes to pass that the surrounding parts are more than usually distended and dilated by the labour pains, in consequence, to wit, of the entire and tense state of the membranes, by which it happens that the fœtus is produced more speedily, and with a less amount of effort, although with more suffering to the mother. In cases of this kind we have known women who were suffering much in their travail in consequence of the too great distension, immensely relieved by the rupture of the membranes and the sudden escape of the waters, the laceration being effected either with the nails of the midwife or the use of a pair of forceps.

Experienced midwives are farther aware that if the waters come away before the orifice of the uterus is duly dilated, the woman is apt to have a lingering time and a more difficult delivery, contrary to Fabricius’s notion of the waters having such paramount influence in softening and lubricating the parts.

Moreover, that the fluid which we have called colliquament is not the sweat of the fœtus is made obvious, both from the history of the egg and of the uterogestation of other animals: it is present before the fœtus is formed in any way, before there is a trace of it to be seen; and whilst it is still extremely small and entirely gelatinous, the quantity of water present is very great, so that it seems plainly impossible that so small a body should produce such a mass of excrementitious fluid.

It happens besides that the ramifications of the umbilical veins are distributed over and terminate upon the membrane which incloses this fluid, precisely as on the membranes of the albumen and yelk of the egg, a circumstance from which, and the thing being viewed as it is in fact, it appears to be clearly proclaimed that this fluid is rather to be regarded as food than as excrement.

To me, therefore, the opinion of Hippocrates appears more probable than that of Fabricius and other anatomists, who look on this liquid as sweat, and believe that it must prove detrimental to the fœtus. I am disposed, I say, to believe that the fluid with which the fœtus is surrounded may serve it for nourishment; that the thinner and purer portions of it, taken up by the umbilical veins, may serve for the constitution and increase of the first formed parts of the embryo; and that from the remainder or the milk, taken into the mouth by suction, passed on to the stomach by the act of deglutition, and there digested or chylified, and finally absorbed by the mesenteric veins, the new being continues to grow and be nourished. I am the more disposed to take this view from certain not impertinent arguments, which I shall proceed to state.

As soon as the embryo acquires a certain degree of perfection it moves its extremities, and begins to prove the actions of the organs destined to locomotion. Now I have seen the chick in ovo, surrounded with liquid, opening its mouth, and any fluid that thus gained access to the fauces must needs have been swallowed; for it is certain that whatever passes the root of the tongue and gains the top of the œsophagus, cannot be rejected by any animal with a less effort than that of vomiting. This fact is acted upon every day by veterinary practitioners, who in administering medicated drinks and pills or boluses to cattle, seize the tongue, and having put the article upon its root beyond the protuberant part, the animal cannot do otherwise than swallow it. And if we make the experiment ourselves, we find that a pill carried between the finger and thumb as far as the root of the tongue and there dropped, immediately the action of deglutition is excited, and unless vomiting be produced the pill is taken down. If the embryo swimming in the fluid in question, then, do but open his mouth, it is absolutely necessary that the fluid must reach the fauces; and if the creature then move other muscles, wherefore should we not believe that he also uses his throat in its appropriate office and swallows the fluid?

It is further quite certain that in the crop of the chick,—and the same thing occurs in reference to the stomach of other embryos—there is a certain matter having a colour, taste, and consistence, very similar to that of the liquid mentioned, and some of it in the stomach digested to a certain extent, like coagulated milk; and further, whilst we discover a kind of chyle in the upper intestines, we find the lower bowels full of stercoraceous excrements. In like manner we perceive the large intestines of the fœtuses of viviparous animals to contain excrements of the same description as those that distend them when they feed on milk. In the sheep and other bisulcated animals we even find scybala.

Towards the seventeenth day we find dung very obviously near the anus of the chick; and shortly before the extrusion I have seen the same matter expelled and contained within the membranes. Volcher Coiter, a careful and experienced dissector, states that he has observed the same thing.

Wherefore should we doubt, then, that the fœtus in utero sucks, and that chylopoiesis goes on in its stomach, when we find present both the principles and the recrementitious products of digestion?

And then, when we find the bladder both of the bile and the urine full of those excrements of the second digestion, wherefore should we not conclude that the first digestion, or chylopoiesis, has preceded?

The embryo, therefore seeks for and sucks in nourishment by the mouth; and you will readily believe that he does so if you rip him from his mother’s womb and instantly put a finger in his mouth; which Hippocrates thinks he would not seize had he not previously sucked whilst in the womb. For we are accustomed to see young infants trying various motions, making experiments, as it were, approaching everything, moving their limbs, attempting to walk, and uttering sounds, acts all of which when taught by repeated experience, they afterwards come to execute with readiness and precision. But the fœtus so soon as it is born, aye, before it is born, will suck; doubtless as it had done in the uterus long before. For I have found by experience that the child delayed in the birth, and before it has cried or breathed, will seize and suck a finger put into its mouth. A new-born infant, indeed, is more expert at sucking than an adult, or than he is himself if he have but lost the habit for a few days. For the infant does not suck by squeezing the nipple with his lips as we should, and by suction in the common acceptation; he rather seems as if he would swallow the nipple, drawing it wholly into his throat, and with the aid of his tongue and palate, and chewing, as it were, he milks his mother with more art and dexterity than an adult could practise. He therefore appears to have learned that by long custom, and before he saw the light, which we know full well he unlearns by a very brief discontinuance.

These and other observations of the same kind make it extremely probable that the chick in ovo is nourished in a twofold manner, namely, by the umbilical and by the mesenteric veins. By the former he imbibes a nourishment that is well nigh perfectly prepared, whence the first-formed parts are engendered and augmented; by the latter he receives chyle for the structure and growth of the other remaining parts.

But the reason is perhaps obscure why the same agent should perform the work of nutrition by means of the same matter in a variety of ways, since nature does nothing in vain. We shall therefore endeavour to explain this.

What is taken up by the umbilical veins is the purer and more limpid part; and the rest of the colliquament in which the fœtus swims is like crude milk, or milk deprived of its purer portion. The purer part does not require any of that ulterior concoction of which the remainder stands in need; and to undergo which it is taken into the stomach, where it is transmuted into chyle. Similar to this is the crude and watery milk which is found in the breasts immediately after parturition. The liquefied albumen of the egg, and the crude or watery milk of the mammæ seem to have in all respects the same colour, taste, and consistence. For the first flow of milk is serous and watery, and women are wont to express water from their breasts before the milk comes white, concocted, and perfect.

Just as the colliquament found in the crop of the chick is a kind of crude milk, whilst the same fluid discovered in the stomach is concocted, white, and curdled; so in viviparous animals, before the milk is concocted in the mammæ, a kind of dew and colliquament makes its appearance there, and the colliquament only puts on the semblance of milk after it has undergone concoction in the stomach. And so it happens, in Aristotle’s opinion, that the first and most essential parts are formed out of the purer and thinner portion of the colliquament, and are increased by the remaining more indifferent portion after it has undergone elaboration by a new digestion in the stomach. In the same way are the other less important parts developed and maintained. Thus has nature, like a fond and indulgent mother, been sedulous rather to provide superfluity, than to suffer any scarcity of things necessary. Or it might be said to be in conformity with reason to suppose that the fœtus, now grown more perfect, should also be nourished in a more perfect manner, by the mouth, to wit, and by a more perfect kind of aliment, rendered purer by having undergone the two antecedent digestions and been thereby freed from the two kinds of excrementitious matter. In the beginning and early stages, nourished by the ramifications of the umbilical veins, it leads in some sort the life of a plant; the body is then crude, white, and imperfect; like plants, too, it is motionless and impassive. As soon, however, as it begins by the mouth to partake of the same aliment farther elaborated, as if feeling a diviner influence, boasting a higher grade of vegetative existence, the gelatinous mass of the body is changed into flesh, the organs of motion are distinguished, the spirits are perfected, and motion begins; nor is it any longer nourished like a vegetable, by the roots, but, living the life of an animal, it is supported by the mouth.

EXERCISE THE FIFTY-NINTH.

Of the uses of the entire egg.

Having now gone through the several changes and processes which must take place in the hen’s egg, in order that it may produce a chick, Fabricius proceeds to consider the uses of the egg at large, and of its various parts; nor does he restrict himself to the hen’s egg, but condescends upon eggs in general. Among other things he inquires: wherefore some eggs are heterogeneous and composed of different elements; and others are homogeneous and similar? such as the eggs of insects, and those creatures that are engendered from the whole egg, viz. by metamorphosis, and are not engendered from one part of the egg, and nourished by another part.

I have no purpose myself of entering on a general consideration of eggs of all kinds and descriptions; I have not yet given the history of all, but only of the hen’s egg; so that I shall here limit myself to a survey of the uses of the common hen’s egg, keeping in view the end of all its actions, which is nothing less than the production and completion of a new being, as Fabricius has well and truly said.[305]

Among the points having reference to the whole egg, Fabricius speaks of the form, dimensions, and number of eggs. “The figure of the egg is round,” he says,[306] “in order that the mass of the chick may be stowed in the smallest possible space; for the same cause that God made the world round, namely, that it might embrace all things; and it is from this, as Galen conceives, that this figure is always felt to be most agreeable and consonant to nature. Further, as it has no angles exposed to injury from without, it is, therefore, the safest figure, and the one best adapted to effect the exclusion of the chick.” It had been well after such a preface to have assigned satisfactory causes why hen’s eggs are not spherical, like the eggs of fishes, worms and frogs, but oblong and pointed; to have shown what there is in them which hinders the presumed perfection of figure. Now to me the form of the egg has never appeared to have aught to do with the engenderment of the chick, but to be a mere accident; and to this conclusion I come the rather when I see such diversities in the shape of the eggs of different hens. They vary, in short, in conformity with the variety that obtains among the uteri of different fowls, in which, as in moulds, they receive their form.

Aristotle,[307] indeed, says that the longer-shaped eggs produce females, the rounder males. I have not made any experiments upon this point myself. But Pliny[308] asserts, in opposition to Aristotle, that the rounder eggs produce females, the others males. Now were there any certainty in such statements, either in one way or the other, some hens would always produce males, others always females, inasmuch as the eggs of the same hen are in many instances always of one figure, namely, either much rounded or acutely pointed. Horace[309] thought that the oblong eggs, as being the more perfect and better concocted, and therefore the better flavoured, produced males.

I willingly pass by the reasons alleged by Fabricius for the form of eggs, as being all irrelevant.

The size of an egg appears to bear a proportion to the size of the fœtus produced from it; large hens, too, certainly lay large eggs. The crocodile, however, lays eggs the size of those of the goose; nor does any animal attain to larger dimensions from a smaller beginning. It would seem, too, that the size of the egg and the quantity of matter it contained had some connexion with its fecundity, inasmuch as the very small eggs called centenines are all barren.

The number of eggs serves the same end as abundance of conceptions among viviparous animals—they secure the perpetuity of the species. Nature appears to have been particularly careful in providing a numerous offspring to those animals which, by reason of their pusillanimity or bodily weakness, hardly defend themselves against the attacks of others; she has counterbalanced the shortness of their own lives by the number of their progeny. “Nature,” says Pliny,[310] “has made the timid tribes among birds more fruitful than the bold ones.” All generation as it is instituted by nature for the sake of perpetuating species, so does it occur more frequently among those that are shorter-lived and more obnoxious to external injury lest their race should fail. Birds that are of stronger make, that prey upon other creatures, and therefore live more securely and for longer terms scarcely lay more than two eggs once a year. Pigeons, turtle and ring-doves, that lay but a couple of eggs, make up for the smallness of the number by the frequency of laying, for they will produce young as often as ten times in the course of a year. They therefore engender greatly although they do not produce many at a time.

EXERCISE THE SIXTIETH.

Of the uses of the yelk and albumen.

“An egg,” says Fabricius,[311] “properly so called, is composed of many parts, because it is the organ of the engenderer, and Galen everywhere insists on the constitution of an organ as implying multiplicity of parts.” But this view leads us to ask whether every egg must not be heterogeneous, seeing that every egg is organic? And every egg, indeed, even that of the fish and insect, appears to be composed of several different parts,—membranes, coverings, defences; nor is the included matter by any means without diversity of constitution in different parts.

Fabricius agrees farther, and correctly, with Galen, when he says:[312] “Some parts of the egg are the chief instruments of the actions that take place in it, others may be styled necessary,—without them no actions could take place; others exist that the action which takes place may be better performed; others, in fine, are destined for the safety and preservation of all of these.” But he is mistaken when he says: “If we speak of the prime action, which is the generation of the chick, the chief cause of this is the semen and the chalazæ, these two being the prime cause of the generation of the chick, the semen being the efficient cause, the chalaza the matter only.” Now according to the opinion of Aristotle, it must be allowed that that which generates is included in the egg; but Fabricius denies that the semen of the cock is contained in the egg.

Nor does he wander less wide of the mark when he speaks of the chalazæ as the matter from which, by the influence of the semen galli, the chick is incorporated. For the chick is not produced either from one or the other, nor yet from both of the chalazæ, as we have shown in our history. Neither is the generation of the chick effected by metamorphosis, nor by any new form assumed and division effected in the chalazæ, but by epigenesis, in the manner already explained. Nor are the chalazæ especially fecundated by the semen of the male bird, but the cicatricula rather, or the part which we have called the eye of the egg, from which, when it enlarges, the colliquament is produced, in and from which, subsequently, the blood, the veins, and the pulsating vesicles proceed, after which the whole body is gradually formed. Moreover, on his own admission, the semen of the cock never enters the uterus of the hen, and yet it fecundates not only the eggs that are already formed, but others that are yet to be produced.

Fabricius refers the albumen and vitellus to the second action of the egg, which is the nutrition and growth of the chick. “The vitellus and albumen,” he says,[313] “are in quantity commensurate with the perfect performance of this action, and with the due development and growth of the chick. The shell and membranes are therefore the safety of the whole of the egg as well as the security of its action. But the veins and arteries which carry nourishment are organs without which the action of the egg, in other words, the growth and nutrition of the chick, would not take place.” It is uncertain, however, whether the umbilical vessels of the embryo or the veins and arteries of the mother, whence the egg is increased, are here to be understood. For a like reason the uterus and incubation ought to be referred to this last class of actions.

We have to do, then, with the two fluids of the egg, the albumen and the vitellus; for these, before all the other parts, are formed for the use of the embryo, and in them is the second action of the egg especially conspicuous.

The egg of the common hen is of two colours internally, and consists of two fluids, severally distinct, separated by membranes, and in all probability of different natures, and therefore having different ends to serve, inasmuch as they are distinguished by different extensions of the umbilical veins, one of them proceeding to the white, another to the yelk. “The yelk and white of the egg are of opposite natures,” says Aristotle,[314] “not only in colour, but also in power. For the yelk is congealed by cold; the white is not congealed, but is rather liquefied; on the contrary, the white is coagulated by heat, the yelk is not coagulated, but remains soft, unless it be over-done, and is more condensed and dried by boiling than by roasting.” The vitellus getting heated during incubation, is rendered more moist; for it becomes like melted wax or tallow, whereby it also takes up more room. For as the embryo grows, the albumen is gradually taken up and becomes inspissated; but the yelk, even when the fœtus has attained perfection, appears scarcely to have diminished in size; it is only more diffluent and moist, even when the fœtus begins to have its abdomen closed in.

Aristotle[315] gives the following reason for the diversity: “Since the bird cannot perfect her offspring within herself, she produces it along with the aliment needful to its growth in the egg. Viviparous animals again prepare the food (milk) in another part of their body, namely, the breasts. Now nature has done the same thing in the egg; but otherwise than as is generally presumed, and as Alcmæon Crotoniates states it, for it is not the albumen but the vitellus which is the milk of the egg.”

For as the fœtus of a viviparous animal draws its nourishment from the uterus whilst it is connected with its mother, like a plant by its roots from the earth; but after birth, and when it has escaped from the womb, sucks milk from the breast, and thereby continues to wax in size and strength, the chick finds the analogue of both kinds of food in the egg. So that whilst in viviparous animals the uterus exists within the parent, in oviparous the parent may rather be said to exist within the uterus (the egg). For the egg is a kind of exposed and detached uterus, and in it are included in some sort vicarious mammæ. The chick in the egg, I say, is first nourished by albumen, but afterwards, when this is consumed, by the yelk or by milk. The umbilical vascular connexion with the albumen, therefore, when this fluid is used up, withers and is interrupted when the abdomen comes to be closed, and before the period of exclusion arrives, so that it leaves no trace of its existence behind it: in viviparous animals, on the contrary, the umbilical cord is permanent in all its parts up to the moment of birth. The other canal that extends to the vitellus, however, is taken up along with this matter into the abdomen, where being stored, it serves for the support of the delicate fœtus until its beak has acquired firmness enough to seize and bruise its food, and its stomach strength sufficient to comminute and digest it; just as the young of the viviparous animal lives upon milk from the mammæ of its mother, until it is provided with teeth by which it can masticate harder food. For the vitellus is as milk to the chick, as has been already said; and the bird’s egg, as it stands in lieu both of uterus and mammæ, is furnished with two fluids of different colours, the white and the yelk.

All admit this distinction of fluids. But I, as I have already said, distinguish two albumens in the egg, kept separate by an interposed membrane, the more external of which embraces the other within it, in the same way as the yelk is surrounded by the albumen in general. I have also insisted on the diverse nature of these albumens; distinguished both by situation and their surrounding membranes, they seem in like manner calculated for different uses. Both, however, are there for ends of nutrition, the outermost, as that to which the branches of the umbilical veins are earliest distributed, being first consumed, and then the inner and thicker portion; last of all the vitellus is attacked, and by it is the chick nourished, not only till it escapes from the shell but for some time afterwards.

But upon this point we shall have more to say below, when we come to speak of the manner in which the fœtuses of viviparous animals are developed, and at the same time demonstrate that these all derive their origin from eggs, and live by a twofold albuminous food in the womb. One of these is thinner, and contained within the ovum or conception; the other is obtained by the umbilical vessels from the placenta and uterine cotyledons. The fluid of the ovum resembles a dilute albumen in colour and consistence; it is a sluggish, pellucid liquid, in all respects similar to that which we have called the colliquament of the egg, in which the embryo swims, and on which it feeds by the mouth. The fluid which the fœtus obtains from the uterine placenta by the aid of the umbilical vessels is more dense and mucaginous, like the inspissated albumen. Whence it clearly appears that the fœtus in utero is no more nourished by its parent’s blood than is the suckling afterwards, or the chick in ovo; but that it is nourished by an albuminous matter concocted in the placenta, and not unlike white of egg.

Nor is the contemplation of the Divine Providence less useful than delightful when we see nature, in her work of evolving the fœtus, furnishing it with sustenance adapted to its varying ages and powers, now more easy, by and by more difficult of digestion. For as the fœtus acquires greater powers of digesting, so is it supplied with food that is successively thicker and harder. And the same thing may be observed in the milk of animals generally: when the young creature first sees the light the milk is thinner and more easy of concoction; but in the course of time, and with increased strength in the suckling, it becomes thicker, and is more abundantly stored with caseous matter. Those flabby and delicate women, therefore, who do not nurse their own children, but give them up to the breast of another, consult their health indifferently; for mercenary nurses being for the major part of more robust and hardy frames, and their milk consequently thicker, more caseous, and difficult of digestion, it frequently happens that milk of this kind given to the infants of such parents, particularly during the time of teething, is not well borne, but gives rise to crudities and diarrhœas, to griping, vomiting, fever, epilepsy, and other formidable diseases of the like nature.

What Fabricius says,[316] and strives to bolster up by certain reasonings, of the chalazæ standing for the matter of the chick, we have already thrown out in our history, and at the same time have made it manifest that the substance of the chick and its first rudiments were produced whilst the chalazæ were still entire and unchanged, and in a totally different situation.

Neither is it true, as he states,[317] “that the chalazæ, rendered fruitful by the semen of the cock, stand in the place of seed, and that from them the chick is produced.” Nor are the chalazæ, as he will have it,[318] “in colour, substance, and bodily properties so like seed, or bear so strong a resemblance to the embryo in a boiled egg, that we may rightly conceive all the parts designated spermatic to be thence engendered.” I am rather of opinion that the fluid which we have called colliquament, or the thinner portion of the albumen liquefied and concocted, is to be regarded as of the nature of seed, and, if the testimony of our eyes is to be credited, as a substitute for it.

The observation of this venerable old man is therefore unnecessary when he says,[319] “As the whole animal body is made up of two substances very different from one another, and even of opposite natures, viz. hot and cold—among the hot parts being included all those that are full of blood and of a red colour; among the cold all those that are exsanguine and white—these two orders of parts doubtless require a different and yet a like nourishment, if it be true that we are nourished by the same things of which we are made. The spermatic, white, and cold parts, therefore, require white and cold nourishment; the sanguineous, red, and hot parts, again, demand nourishment that is red and hot. And so is the cold white of the egg properly held to nourish the cold and white parts of the chick, and the hot and sanguine yelk regarded as a substitute for the hot and purple blood. In this way do all the animal parts obtain nourishment suitable and convenient for them.” Now we by no means admit that the two fluids or matters of the egg are there as appropriate means of nourishment for different orders of parts. For we have already said that the heart, lungs, kidneys, liver, spleen, muscles, bones, ligaments, &c., &c., were all alike and indiscriminately white and bloodless on their first formation.

Further, on the preceding view of Fabricius it would follow that the heart, lungs, liver, spleen, &c., were not spermatic parts, did not originate from the seed (which he, however, will by no means allow), inasmuch as they too are by and by nourished by the blood and grow out of it; for every part is both formed and nourished by the same means, and nutrition is nothing more than the substitution of a like matter in the room of that which is lost.

Nor would he find less difficulty in answering the question how it happens that when the albumen in the egg is all consumed, the cold and white parts, such as the bones, ligaments, brain, spinal marrow, &c., continue to be nourished and to grow by means of the vitellus? which to these must be nourishment as inappropriate as albumen to the hot, red, and sanguine parts.

Adopting the views commented on, indeed, we should be compelled to admit that the hot and sanguineous parts were the last to be produced: the flesh after the bones; the liver, spleen, and lungs after the ligaments and intestinal canal; and further, that the cold parts of the chick must come together and attain maturity, the white being all the while consumed, and the hot parts be engendered subsequently, when the vitellus fails and ceases from nourishing them; and then it would be certain that all the parts could not take their rise in and be constituted out of the same clear liquid. All such conclusions, however, are refuted by simple ocular inspection.

I add another argument to those already supplied: the eggs of cartilaginous fishes—skates, the dog-fish, &c.,—are of two colours—their yelks are of a good deep colour; nevertheless all the parts of these fishes are white, bloodless, and cold, not even excepting the substance of their liver. On the contrary, I have seen a certain breed of fowls of large size, their feathers black, their flesh well supplied with blood, their liver red; yet were the yelks of the eggs of these fowls—fruitful eggs—of the palest shade of yellow, not deeper than the tint of ripe barley straw.

Fabricius, however, seems in these words[320] to retract all he has but just said: “There is one thing to be particularly wondered at both in the yelk and the white, viz. that neither of them being blood, they are still so near to the nature of blood that they in fact differ but very slightly from it—there is but little wanting to constitute either of them blood; so that little labour and a very slight concoction suffice to effect the change. The veins and arteries distributed to the membranes of both the white and yelk are consequently seen replete with blood at all times; the white and yelk nevertheless continuing possessed of their own proper nature, though either, so soon as it is imbibed by the vessels, is changed into blood, so closely do they approach in constitution to this fluid.”

But if it be matter of certainty that blood exists no less in the vessels distributed to the albumen than in those sent to the vitellus, and that both of these fluids are so closely allied to blood in their nature, and turn into blood so readily; who, I beseech you, will doubt that the blood, and all the parts which are styled sanguineous, are nourished and increased through the albumen as well as the vitellus?

Our author, however, soon contrives a subterfuge from this conclusion: “Although all this be true,” he says,[321] “still must we conceive that the matter which is imbibed by the veins from the yelk and white is only blood in the same sense as the chyle in the mesenteric veins, in which nothing but blood is ever seen; now chyle is but the shadow of blood, and is first perfected in the liver; and in like manner the matter taken up by the veins from the white and yellow is only the shadow of blood,” &c. Be it so; but hiding under this shadow, he does not answer the question, wherefore the blood and blood-like parts should not, for the reasons cited, be equally well nourished by the albumen as by the vitellus?

Had our author, in like manner, asserted that the hotter parts are rather nourished by that blood which is derived from the vitellus than by that attracted from the albumen, and the colder parts, on the other hand, by that which is derived from the albumen, I should not myself have been much disposed to gainsay him.

There is one consideration in the whole question, however, which is sorely against him; it is this—how is the blood formed in the egg? by what agent is either white or yelk turned into blood whilst the liver is not yet in existence? For in the egg, at all events, he could not say that the blood was transfused from the mother. He says, indeed, “This blood is produced and concocted in the veins rather than in the liver; but it becomes bone, cartilage, flesh, &c. in the parts themselves, where it undergoes exact concoction and assimilation.” In this he adds nothing; he neither tells us how or by what means perfect blood is concocted and elaborated in the minute veins both of the albumen and vitellus, the liver, as I have said, not having yet come into existence,—not a particle of any part of the body, in fact, having yet been produced by which either concoction or elaboration might be effected. And then, forgetful of what he has previously said, viz. that the hot and hæmatous parts are nourished by the vitellus and the cold and anæmic parts by the albumen, he is plainly in contradiction with himself when he admits that the same blood is turned into bone, cartilage, flesh, and all other parts.

More than this, Fabricius has slipped the greatest difficulty of all, the source of not a little doubt and debate to the medical mind, viz. how the liver should be the source and artificer of the blood, seeing that this fluid not only exists in the egg before any viscus is formed, but that all medical writers teach that the parenchymata of the viscera are but effusions of blood? Is the work the author of its workman? If the parenchyma of the liver come from the blood, how can it be the cause of the blood?

What follows is of the same likelihood: “There is another reason wherefore the albumen should be separated from the yelk, namely, that the fœtus may swim in it, and be thus supported, lest tending downwards by its own weight, it should incline to one particular part, and dragging, should break the vessels, in preventing which the viscidity and purity of the albumen contribute effectually. For did the fœtus grow amid the yelk, it might readily sink to the bottom, and so cause laceration of that body.” Sufficiently jejune! For what, I entreat, can the purity of the albumen contribute to the support of the embryo? Or how should the thinner albumen sustain it better than the thicker and more earthy yelk? Or where the danger, I ask, of its sinking down, when we see that the egg in incubation is always laid on its side, and there is nothing to fear either for the ascent or the descent of the embryo? It is indubitable, indeed, that not only does the embryo of the chick float in the egg, but that the embryo of every animal during its formation floats in the uterus; this however takes place amidst the fluid which we have called colliquament, and neither in the albumen nor vitellus, and we have elsewhere given the reason wherefore this is so.