EXERCISE THE THIRTEENTH.
Of the diversities of eggs.
“The word ovum, or egg, is taken in a twofold sense, proper and improper. An ovum, properly so designated, I call that body to which the definition given by Aristotle[155] applies: An egg, says he, is that from part of which an animal is engendered, and the remainder of which is food for the animal so produced. But I hold that body to be improperly styled an egg which is defined by Aristotle[156] in the same place, to be that from the whole of which an animal is engendered; such as the eggs of ants, flies, spiders, some butterflies, and others of the tribe of extremely small eggs; which Aristotle almost always fears to commit himself by calling eggs, but which he rather styles vermiculi.” What precedes is from Fabricius;[157] but we, whose purpose it is to treat especially of the generation of the hen’s egg, have no intention to speak of the differences of all kinds of eggs; we shall limit ourselves to the diversities among hen’s eggs.
The more recently laid are whiter than the staler, because by age, and especially by incubation, they become darker; the cavity in the blunt end of a stale egg is also larger than in a recent egg; eggs just laid are also somewhat rough to the feel from a quantity of white powder which covers the shell, but which is soon rubbed off, when the egg becomes smoother as well as darker. New-laid eggs, unbroken, if placed near a fire will sweat, and are much more palatable than those that have been kept for some time—they are, indeed, accounted a delicacy by some. [Fruitful] eggs, after two or three days’ incubation, are still better flavoured than stale eggs; revived by the gentle warmth of the hen, they seem to return to the quality and entireness of the egg just laid. Farther, I have boiled an egg to hardness, after the fourteenth day of incubation, when the chick had already begun to get its feathers, when it occupied the middle of the egg, and nearly the whole of the yelk remained, in order that I might better distinguish the position of the chick: I found it lying, as it were, within a mould of the albumen, and the yelk possessed the same agreeable flavour and sweetness as that of the new-laid egg, boiled to the same degree of hardness. The yelk taken from the ovarium of a live fowl, and eaten immediately, tastes much sweeter raw than boiled.
Eggs also differ from one another in shape; some are longer and more pointed, others rounder and blunter. According to Aristotle,[158] the long-shaped and pointed eggs produce females; the blunt, on the contrary, yield males. Pliny,[159] however, maintains the opposite. “The rounder eggs,” he says, “produce females, the others males;” and with him Columella[160] agrees: “He who desires to have the greater number of his brood cocks, let him select the longest and sharpest eggs for incubation; and on the contrary, when he would have the greater number females, let him choose the roundest eggs.” The ground of Aristotle’s opinion was this: because the rounder eggs are the hotter, and it is the property of heat to concentrate and determine, and that heat can do most which is most powerful. From the stronger and more perfect principle, therefore, proceeds the stronger and more perfect animal. Such is the male compared with the female, especially in the case of the common fowl. On the contrary, again, the smaller eggs are reckoned among the imperfect ones, and the smallest of all are regarded as entirely unproductive. It was on this account too that Aristotle, to secure the highest quality of eggs, recommends that the hens be frequently trodden. Barren and adventitious eggs, he asserts, are smaller and less savoury, because they are humid and imperfect. The differences indicated are to be understood as referring to the eggs of the same fowl; for when a certain hen goes on laying eggs of a certain character, they will all produce either males or females. If you understand this point otherwise, the guess as to males or females, from the indications given, would be extremely uncertain. Because different hens lay eggs that differ much in respect of size and figure: some habitually lay more oblong, others, rounder eggs, that do not differ greatly one from another; and although I sometimes found diversities in the eggs of the same fowl, these were still so trifling in amount that they would have escaped any other than the practised eye. For as all the eggs of the same fowl acquire nearly the same figure, in the same womb or mould in which the shell is deposited, (much as the excrements are moulded into scybala in the cells of the colon,) it necessarily falls out that they greatly resemble one another; so that I myself, without much experience, could readily tell which hen in a small flock had laid a given egg, and they who have given much attention to the point, of course succeed much better. But that which we note every day among huntsmen is far more remarkable; for the more careful keepers who have large herds of stags or fallow deer under their charge, will very certainly tell to which herd the horns which they find in the woods or thickets belonged. A stupid and uneducated shepherd, having the charge of a numerous flock of sheep, has been known to become so familiar with the physiognomy of each, that if any one had strayed from the flock, though he could not count them, he could still say which one it was, give the particulars as to where it had been bought, or whence it had come. The master of this man, for the sake of trying him, once selected a particular lamb from among forty others in the same pen, and desired him to carry it to the ewe which was its dam, which he did forthwith. We have known huntsmen who, having only once seen a particular stag, or his horns, or even his print in the mud, (as a lion is known by his claws,) have afterwards been able to distinguish him by the same marks from every other; some, too, from the foot-prints of deer, seen for the first time, will draw inferences as to the size, and grease, and power of the stag which has left them; saying whether he were full of strength, or weary from having been hunted; and farther, whether the prints are those of a buck or a doe. I shall say thus much more: there are some who, in hunting, when there are some forty hounds upon the trace of the game, and all are giving tongue together, will nevertheless, and from a distance, tell which dog is at the head of the pack, which at the tail, which chases on the hot scent, which is running off at fault; whether the game is still running, or is at bay; whether the stag have run far, or have but just been raised from his lair. And all this amid the din of dogs, and men, and horns, and surrounded by an unknown and gloomy wood. We should not, therefore, be greatly surprised when we see those who have experience telling by what hen each particular egg in a number has been laid. I wish there were some equally ready way from the child of knowing the true father.
The principal difference between eggs, however, is their fecundity or barrenness—the distinction of fruitful eggs from hypenemic, adventitious, or wind eggs. Those eggs are called hypenemic, (as if the progeny of the wind,) that are produced without the concourse of the male, and are unfit for setting; although Varro[161] declares that the mares, in Lusitania, conceive by the wind. For zephyrus was held a fertilizing wind, whence its name, as if it were ζωηφερὀς, or life bringing. So that Virgil says:
And Zephyrus, with warming breath resolves
The bosom of the ground, and melting rains
Are poured o’er all, and every field brings forth.
Hence the ancients, when with this wind blowing in the spring season, they saw their hens begin laying, without the concurrence of the cock, conceived that zephyrus, or the west wind, was the author of their fecundity. There are also what are called addle, and dog-day eggs, produced by interrupted incubation, and so called because eggs often rot in the dog-days, being deserted by the hens in consequence of the excessive heat; and also because at this season of the year thunder is frequent; and Aristotle[162] asserts that eggs die if it thunders whilst the hen is sitting.
Those eggs are regarded as prolific, which, no unfavorable circumstances intervening, under the influence of a gentle heat, produce chicks. And this they will do, not merely through the incubation of the mother, but of any other bird, if it be but of sufficient size to cherish and cover them, or by a gentle temperature obtained in any way whatever. “Eggs are hatched with the same celerity,” says Aristotle,[163] “spontaneously in the ground, as by incubation. Wherefore in Egypt, it is the custom to bury them in dung, covered with earth. And there was a tale in Syracuse, of a drunken fellow, who was accustomed to continue his potations until a number of eggs, placed under a mat bestrewed with earth, were hatched.” The empress Livia, is also said to have carried an egg in her bosom until a chick was produced from it. And in Egypt, and other countries, at the present time, chickens are reared from eggs placed in ovens. “The egg, therefore,” as Fabricius[164] truly says, “is not only the uterus, and place where the generation of the chick proceeds, but it is that upon which its whole formation depends; and this the egg accomplishes as agent, as matter, as instrument, as place, and as all else that concurs.”
For it is certain that the chick is formed by a principle inherent in the egg, and that nothing accrues to a perfect egg from incubation, beyond the warmth and protection; in the same way as to the chick when disclosed, the hen gives nothing more than her warmth and her care, by which she defends it from the cold and from injury, and directs it to its proper food. The grand desideratum, therefore, once the chickens are hatched, is that the hen lead them about, seek for and supply them with proper food, and cherish them under her wings. And this you will not easily supply by any kind of artifice.
Capons, and hybrids between the common fowl and the pheasant, produced in our aviaries, will incubate and hatch a set of eggs; but they never know how to take care of the brood—to lead them about properly, and to provide with adequate care for their nurture.
And here I would pause for a moment, (for I mean to treat of the matter more fully by and by,) to express my admiration of the perseverance and patience with which the females of almost every species of bird, sit upon the nest for so many days and nights incessantly, macerating their bodies, and almost destroying themselves from want of food; what dangers they will face in defence of their eggs, and when compelled to quit them for ever so short a time, through necessity, with what eagerness and haste they return to them again, and brood over them! Ducks and geese, when they quit the nest for a few minutes, cover and conceal it with straw. With what true magnanimity do these ill-furnished mothers defend their eggs! which, after all, perhaps, are mere wind or addle eggs, or not their own, or artificial eggs of chalk or ivory;—it is still the same, they defend all with equal courage. It is truly a remarkable love which birds display for inert and lifeless eggs; and their solicitude is repaid by no kind of advantage or enjoyment. Who does not wonder at the affection, or passion rather, of the clucking hen, which can only be extinguished by a drenching with cold water. In this state of her feeling she neglects everything,—her wings droop, her feathers are unpruned and ruffled, she wanders about restless and dissatisfied, disturbing other hens on their nests, seeking eggs everywhere, which she commences forthwith to incubate; nor will she be at peace until her desire has been gratified, until she has a brood to lead about with her, upon which she may expend her fervour, which she may cherish, feed, and defend. How pleasantly are we moved to laughter when we see the poor hen following to the water the supposititious brood of ducklings she has hatched, wandering restlessly round the pool, attempting to wade after them to her own imminent peril, and by her noises and various artifices striving to entice them back to the shore!
According to Aristotle,[165] barren eggs do not produce chicks because their fluids do not thicken under incubation, nor is the yelk or the white altered from its original constitution. But we shall revert to this subject in our general survey of generation.
Our housewives, that they may distinguish the eggs that are addled from those that will produce chicks, take them from the fourteenth to the sixteenth day of the incubation, and drop them softly into tepid water, when the spoilt ones sink, whilst the fruitful ones swim. If the included chick be well forward, and moves about with alacrity, the egg not only rolls over but even dances in the water. And if you apply the egg to your ear for several days before the hatching, you may hear the chick within kicking, scratching, and even chirping. When the hen that is sitting hears these noises, she turns the eggs and lays them otherwise than they were, until the chicks, getting into a comfortable position, become quiet; even as watchful mothers are wont to treat their infants when they are restless and cry in their cradles.
Hens lay eggs in variable numbers: “Some hens,” says the philosopher,[166] “except the two winter months, lay through the whole year; some of the better breeds will lay as many as sixty eggs before they show a disposition to sit; though these eggs are not so prolific as those of the commoner kinds. The Adrianic hens are small, and lay every day, but they are ill-tempered, and often kill their young ones; they are particoloured in their plumage. Some domestic fowls will even lay twice a day; and some, by reason of their great fecundity, die young.”
In England some of the hens lay every day; but the more prolific commonly lay two days continuously and then miss a day: the first day the egg is laid in the morning, next day in the afternoon, and the third day there is a pause. Some hens have a habit of breaking their eggs and deserting their nests; whether this be from disease or vice is not known.
Certain differences may also be observed in the incubation: some fowls only sit once, others twice, or thrice, or repeatedly. Florentius says, that in Alexandria, in Egypt, there are fowls called monosires, from which the fighting cocks are descended, which go on sitting for two or three periods, each successive brood being removed as it is hatched, and brought up apart. In this way the same hen will hatch forty, sixty, and even a greater number of chickens, at a single sitting.
Some eggs too, are larger, others smaller; a few extremely small; these, in Italy, are commonly called centenina; and our country folks still believe that such eggs are laid by the cock, and that were they set they would produce basilisks. “The vulgar,” says Fabricius,[167] “think that this small egg is the last that will be laid, and that it comes as the hundredth in number, whence the name; that it has no yelk, though all the other parts are present—the chalazæ, the albumen, the membranes, and the shell. And it seems probable that it is produced when all the other yelks have been fashioned into eggs, and no more remain in the vitellary; on the other hand, however, a modicum of albumen remains, and out of this, it may be inferred, is the small egg in question produced.” To me, nevertheless, this does not appear likely; because it is certain that the whole ovary being removed, the uterus secundus also diminishes in size in the same proportion, and shrinks into a mere membrane, which contains neither any fluid nor any albumen. Fabricius proceeds: “The ova centenina are met with of two kinds: one of them being without a yelk, and this is the true centenine egg, because it is the last which the hen will lay at that particular season—she will now cease from laying for a time. The other is also a small egg, but it has a yelk, and will not prove the last which the hen will then lay, but is intermediate between those of the usual size that have preceded, and others that will follow. It is of small size because there has been a failure of the vegetative function, as happens to the peach, and other fruit, of which we see many of adequate size, but a few that are very diminutive.” This may be in consequence of the inclemency of the weather, or the want of sun, or from defective nutriment in point either of quantity or quality. I should not readily allow, however, that the eggs last laid are always small.
Monstrous eggs are not wanting; “for the augurs,” says Aristotle,[168] “held it portentous when eggs were laid that were all yellow; or when, on a fowl being laid open, eggs were found under the septum transversum, where the rudimentary eggs of the female usually appear, of the magnitude of perfect eggs.”
To this head may be referred those eggs that produce twins, that have two yelks. Such an egg I lately found in the uterus of a fowl, perfect in all respects, and covered with a shell; the yelks, cicatriculæ, and thicker albuminous portions being all double, and the chalazæ present in two pairs: a single thinner albumen, however, surrounded all these, and this in its turn was included within the usual double common membrane, and single shell. For, indeed, although Aristotle says that fowls always lay some eggs of this kind, I shall hardly be induced to believe that this does not occur against the ordinary course of nature. And although twin chicks are produced from such eggs as I have ascertained in opposition to the opinion of Fabricius, who says that they produce chicks having four legs, or four wings and two heads, which, however, are not capable of living, but for the most part speedily die, either by reason of want of room or of air in the shell, or because the one proves a hinderance to the other and blights it; nor can it happen that both should be equally prepared for exclusion—that one should not prove an abortion.
Briefly and summarily the differences among eggs are principally of three kinds: some are prolific, some unprolific; some will produce males and some females; some are the produce of the two sexes of the same species, others of allied species and will produce hybrids, such as we see between the common hen and the pheasant, the progeny being referrible either to the first or to the last male that had connexion with the hen. Because, according to Aristotle,[169] “the egg, which receives its constitution by intercourse, passes from its own into another genus, if the hen be trodden when she carries either an adventitious egg or one that was conceived under the influence of another male, and this renewed intercourse take place before the yellow is changed into the white. So that hypenemic or wind eggs are made fruitful, and fruitful eggs receive the form of the male which has connexion last. But if the change has taken place into the white, it cannot happen either that the wind egg is turned into a fertile one, or that the egg which is contained in the uterus in virtue of a previous intercourse, shall be altered into the genus of the male which has the second communication.” For the seminal fluid of the cock, as Scaliger wittily remarks, is like a testament, the last will or disposition in which is that which stands in force.
To these particulars it might perhaps be added, that some eggs are more strong and lusty than others, more full of life, if the expression may be used; though as there is a vital principle in the egg, so must there inhere the corresponding virtue that flows from it. For, as in other kinds of animals, some of the females are so replete with desire, so full of Venus, that they conceive from any and every intercourse, even once submitted to, and from a weakly male, and produce several young from the same embrace; others, on the contrary, are so torpid and sluggish, that unless they are assailed by a vigorous male, under the influence of strong desire, and that not once, but repeatedly, and for a certain time, they continue barren. This is also the case with eggs, some of which, though they may have been conceived in consequence of intercourse, still remain unprolific unless perfected by repeated and continued connections. Whence it happens that some eggs are more speedily changed by incubation than others, exhibiting traces of the fœtus from the third day; others again, either become spoiled, or suffer transformation into the fœtus more slowly, exhibiting no indications of the future chick even up to the seventh day, as shall be made to appear by and by, in speaking of the generation of the chick from the egg.
Thus far have we discoursed of the uterus of the fowl, and its function; of the production of the hen’s egg, and of its differences and peculiarities, from immediate observation; and from the instances quoted, conclusions may be drawn with reference to other oviparous animals.
We have now to pursue the history of the generation and formation of the fœtus from the egg. For indeed, as I have said above, the entire contemplation of the family of birds is comprehended in these two propositions: how is an egg engendered of a male and female; and by what process do males and females proceed from eggs?—the circle by which, under favour of nature, their kinds are continued to eternity.