Anatomical exercitations concerning the generation of living creatures to which are added particular discourses of births and of conceptions, &c. / by William Harvey ...

Of the difference of Eggs. (Book 13)

EXERCIT. XIII. (Book 13)

THere is a two-fold acceptation of the word Egge; proper, or improper. An egge in its proper Ac∣ceptation is that thing, to which Aristotles definition * 1.1 of an egge doth square: An egge is that thing, one part of which doth constitute an Animal, and the rest doth nourish it, when it is constituted. In its improper acceptation, it is that to which Aristotles definition * 1.2 about the same place is proportioned. An Egge is that thing out of which the whole Animal is constitu∣ted. And of this kinde are the eggs of Ants, Flies, Spiders, some kinde of Butterflies, and many other very small egges of that kinde: which Aristotle doth almost every where scruple to call by the name of eggs, but stileth them little wormes. Thus far Fabricins; but we (whose designe is chiefly to treat of the * 1.3 generation of Hen-eggs) have no intention to de∣liver the several distinctions of all sorts of Eggs, but only to lay down the diversities of Hen-eggs. Of Hen-eggs therefore, some are new-laid, and some staler, the former are whiter then the later; for * 1.4 time doth clowd them, and especially incubation. The New-laid also have a very small hollowness or cavity in the obtuse angle; and if they be very new indeed, they are something rough with a dust or powder that sticketh to their sides; but those that are stale, as their complexion is darker, so their shell is smoother. New-layed eggs (if they be whole) being put near the fire will sweat, and are of much pleasanter taste, and more esteemed of, then o∣ther. And eggs after two or three dayes incubati∣on,

are even then sweeter relished then stale ones are: as if the cherishing warmness of the Hen, did refresh and restore them to their primitive excel∣lence and integrity. And after full fourteen days (when the Chicken now beginneth to be downey, and extendeth his dominion over half the egge, and the jolke is almost still entire) I have boyled an egge till it was hard, that so I might discerne the position of the chicken more distinctly, which was limned out in the white of the egge, as if the chicken had been cast in a Mould: and yet the yolke was as sweet and pleasant as that of a new-laid egge, when it is in like manner boyled to an in∣duration. The yolke of an egge taken out of a live Hen, and presently eaten, tasteth much sweeter raw, then dressed.

Eggs are likewise distinguishable from their fi∣gure; * 1.5 for some are longer, and sharper then others. Out of these oblong and acute eggs (according to A∣ristotle) are hennes begotten, and of the blunt, cocks. But Pliny saith the contrary; The rounder sort of eggs (saith he) breed Hennes, the other, Cocks. And Columella is of his minde too: If one would have good store of Cocks (quoth he) let him place the longest and sharpest eggs under his Hen; and if the contrary, let him provide the roundest he can get for money. Ari∣stotles * 1.6 opinion is grounded upon this reason; namely, because the Rounder are the hotter; for it is the custom and condition of heat, to congre∣gate, and fix; and that heat is most powerful, that •••• most operative. And therefore from the strong∣er, and perfecter principle, the stronger and per∣fecter Animal doth arise. Now such is the Male in respect of the Female (especially the Cock being compared to the Henne.) And now on the other side, the lesser sort of egges are reputed imperfect,

and the least sort of all, utterly improlifical. And therefore Aristotle, to procure a constant race of egges of a fair size, recommendeth the frequent co∣ition of cock and hen; for he concludeth the barren and subvontuneous egges to be all of the lesser sort, and more insipid; and that because they are moi∣ster and imperfecter then others. Now this distin∣ction of egges here spoken of, is to be understood of the egges of one and the same hen (for should a hen lay eggs alwaies of the same dimensions, she would alwaies hatch them all cocks, or all hennes) because if you take it otherwise, the conjecture of which will be a cocke or a henne, raised from the signes above mentioned, will be very dubions. For several henns, lay eggs of a several shape, and mag∣nitude: for some lay oblong, some rounder, and li∣tle differing the one from the other. For though I have sometimes found a difference in the eggs lay∣ed by the same henn, yet the distinction is so ex∣ceeding small, that unless a man be very well ver∣sed, he will not perceive it. For since all the eggs of the same henne, are cast and modelled in the same womb (as in a Mould) they are all impressed with, neer upon, the same figure: and therefore it cannot be avoided, but that they should much re∣semble one another (as those excrements that are figured in the same complications of the same Co∣lon) insomuch that I my selfe have with case in a litle basket of egges sorted every hennes egges by themselves. And who ever practiseth it, shall be nimble at it. Certainly it is worth our wonder which dayly experience declareth in Keepers. The more diligent sort of Keepers of Parks, that have the charge of several herds of Deer, will tell you punctually which and which are the Hornes of such and such Deere, as often as they ca••

their Heads. A silly, ignorant Shepherd, who had the care of a great flock of sheep, grew so well acquainted with every particular sheep, that if a∣ny one were missing (though he had not arithme∣tick enough to count them) he could punctually tell which it was, of whom it was bought, and whence it came. And once, to make tryal of him, his Master commanded him, out of forty lambes which he penned up in a Fould on purpose, to sin∣gle out the particular lamb of such an Ewe, which he did exactly, and carried to the Damme. I know some Huntsmen, that if they have once seen a Deer, or the hornes of a Deer, or footsteps only in soft ground, are able to know the same Deer again from all the Herd besides, even by those very horns, or tread: (just as the Lion is distinguished by his Pew) nay having meerly seen the print of the Deers hoofe, they will exactly resolve, how large the Deer is, how fat, and how swift: as whether he be well in breath, or over-hunted; and also, whether a Buck or a Doe. And more then this, there are some, who when forty Dogs are pursuing the Chase, and are in full Cry, will distinguish them all, (though a great way off) and will by their •••••• inform you, which Dog is first, and which behinde; which hunteth upon the sent, and which is at a loss; whether the Deer be still in flight, or •••• a Bay, & disputing the conquest with his horns; whether he have stood long, or be newly rowsed. And all this in the very midst of the dogs, hunters, and windings of the horns, even in a woody Park, and where they were never in their lives before. We are not therefore to wonder so much, if those ••••••t practise it, can discover which Egge belong∣eth to which Hen: I would we could as easily judge which Son belongeth to which Father.

But the chiefe difference of Eggs consisteth in this, that some are fruitfull, and some addle, which * 1.7 are called Ova improlifica, irrita, Hypenemia, or subventanea, and Zephyria. They are called Hy∣penemia, which being layed by the Hen without conference had with the Cock, are therefore of no use to the generation of Chickens, being stiled hy∣penemia, quasi a vento prognata forent, as if they were begotten by the winde: as Varro saith, that Mares in Spain conceive by the Winde. For the * 1.8 West wind is exceeding fruitfull, and thence the name Zephyrus, quasi 〈 in non-Latin alphabet 〉〈 in non-Latin alphabet 〉, enlivening; for so Virgil:

—Zephyrique tepentibus auris Laxant arva sinus, superat tener omnibus burner, Parturit omnis ager, &c.

—And when warm Zephyrus blows, The fields dissolve, soft moisture overflows, And every Pasture grows.

And therefore the people of old, seeing their Hens in the Spring-time lay, this wind then blow∣ing, did conceive Zephyrus to be the Author of the generation of those eggs. Eggs are likewise Urine, and Cynosura (when the Hen will sit no longer upon them) so called, because egges grow oft∣en addle in the Dog-dayes, for the henne deserteth them by reason of the extream Heat; or else be∣cause about that time of the year, it thundered often: for Aristotle saith, that Egges rot, if at the * 1.9 time of the Hennes incubation it chance to thunders Those egges are esteemed foecunda, fruitfull, which (if there be no outward impediment) by a quick∣ning heat will generate chickens; which may be effected not onely by the incubation of the Hen••

whose egges they are, but of any other Fowle of competent magnitude to cherish and cover them, or by any other cherishing warmth whatsoever.

For Aristotle saith, That chickens are as well hatched upon the ground of their own accord, as by the * 1.10 birds incubation: As in Egypt they cover the egges with dung. And the Story goeth, That a good fellow of Syracusa sate so long upon a mat under the which eggs were layed, that ere he had done tipling the chic∣kens were hatched. The Emperesse Livia is also reported to have cherished an egge so long in her bosom, till the chicken was bred. And to this day in Egypt, and other parts, chickens are hatched by stoves and ovens. An egge therefore (as Fabricius truly affirmeth) is not only the Uterus, and place * 1.11 of residence of the chicken, but the matter also on which the whole generation of the foetus doth de∣pend: which generation the egge doth performe and accomplish, both as Agent, Matter, Instrument, Place, and ever other Requisite whatsoever. For certain it is, that the chicken is constituted by an internal principle in the egge, and that there is no accession to a complete and perfect egge, by the Hennes incubation, but bare cherishing and prote∣ction: no more then the Hen contributeth to the chickens which are now hatched, which is onely a friendly heat, and care, by which she defendeth them from the cold, and forreign injuries, and help∣eth them to their meat. And therefore the Incu∣bation of the Henne is required, that she may upon that relation undertake the education of the chic∣ken, instruct and direct their walks, prepare and look for their feeding, and by the comfort of her wings cherish them. And all these things will not be so well performed by any but her. We have in∣deed Capons, and mungrel-fowle, such as are the is∣sue

of a Pheasant-cock and a Dunghill-henne, which will sit upon the egges, and hatch them too, but they have no dexterity to guide the chickens, or mannage the charge of their education.

I can here but admire (intending to treat lar∣ger hereafter of the same matter) with what con∣stancy and patience, almost all female Birds will out-sit whole nights and dayes, and impare their healths, and almost famish themselves; and to what hazards they expose themselves in defence of their egges, which, if upon necessary occasion they are at any time constrained to leave, oh! how earnestly, and with what dispatch doe they hasten their return! Ducks, and Geese, for the time of their absence, cover their eggs with straw. And with what undaunted resolution will these feeble parents many times combat in right of their egges, which perhaps are subventaneous or addle, nay sometimes artificial of-springs, the issues of chalk or ivory, whose injuries yet they will revenge with the same magnanimity, with those done to their legitimate productions? Indeed the Birds affe∣ction towards the dull, liveless egge, is exceeding wonderful, which is altogether incapable of ma∣king any return of friendship or respect. Who can forbeare to be amazed at the affection, or phrensie rather of a Henne that is glocking, or ready to sit•• which nothing can extinguish, but a deluge of cold water; for so long as this rage is upon her, 〈◊〉〈◊〉 groweth quite careless, and walkes like a bed him, with her wings trailed, and feathers rough, and ad∣vanced, and she her self mournful, and restless: •••• she meet with any Henne sitting, she will depose•• her, having all her thoughts bent upon egges and incubation; nor will she desist, till shee either 〈◊〉〈◊〉 egges to sit upon, or chickens to discipline: which

then she doth assemble, nurture, feed, and protect with admirable zeal. Who can refrain smiling, to see a Henne follow young Ducklins, and having hatched up that supposititious brood (apprehend∣ing them to be her own) pursue them when they are now swimming in the Pond, while she her self circuites about the brimmes, and many times at∣tempts to sail after to the hazard of drowning, still calling, and enticeing them back, as if they had mistaken themselves.

Aristotle giveth this reason why steril egges pro∣duce * 1.12 no chickens, namely, because the juices con∣tained in them receive no thickening by incubation, neither doth their yolk or white recede any thing from the nature they were of before. But of this wee shall discourse hereafter, in our general contemplation of Generation.

Our women, that they may distinguish between egges that have chickens in them, and egges that are barren and addle, after the fourteenth or sixteenth day from the Hennes first sitting, do gently drop the egges into warme water, and those that sinke to the bottom they account barren, but those that swim, fertile. And if the chicken in the egge be of any considerable growth, and bestirre himself lustily, the egge will not onely tumble up and down, but leap and caper. And if you listen close for some dayes before exclusion, you may perceive the chic∣kens, kick, make a noise, and cry after their manner. Which kinde of Commotions when the Sitting Henne discovereth in her nest, she removeth the egges, and rowleth them to and fro, (as care∣full mothers do their disquiet and peevish infants in the craedle) till the chickens being accommodated with convenient posture, lye hushed, and still.

Hen-eggs are likewise distinguished from their * 1.13

Number. For some Hens (saith the Philosopher) lay * 1.14 all the year long, bating onely the two Winter moneths. Some gallant Hens will bring sixty eggs before the Su∣ting time; yet these are not so fruitfull as the ordinary sort of Hens. The Adrian Hens are small, but lay e∣very day; yet they are very testy, and many times 〈◊〉〈◊〉 their chickens; and their feathers are of change 〈◊〉〈◊〉 colours. Some domestick Hens will lay twice a day and the fecundity of some, shorteneth their dayes.

Some Hens in England lay every day; but the ordinary fertile race, for the most part, lay for two dayes together; namely, the first egg in the morn∣ing, the second in the evening following, and the third is a day of vacancy. Some Hens have an un∣lucky custome to break their eggs, and leave their nests; but whether this be their disease, or vice, is yet unresolved.

There are differences also taken from Incubation; for some Hennes sit once, some twice, others thrice, * 1.15 and some oftner. Florentinus writeth, that certain Hennes, Natives of that Alexandria which is in E∣gypt, called Monosirae, of whom springeth a race of Game-cocks, doe sit two or three times, having the chickens which they have newly hatched taken from them, & brought up apart. By which mean it cometh to pass, that one Hen will hatch forty, sixty, and sometimes more chickens at one sitting.

Some Eggs also are of a large, some of a less, and * 1.16 some of the least size of all; and these last are com∣monly called in Italy, Centenina; and our Women, to this day, (as of old also) bely them to be Cocks-eggs, and that they produce Basilisks. The Common people (saith Fabricius) think this small egge to be the Hennes concluding production, after she hath layed at * 1.17 hundred eggs (from whence it is called Centeninum, the Hundredth egge) which hath no yolk at all; yet

hath all the other parts, as the Chalazae, the White, the Membranes, and the Shell. For it is likely that this is then layed, when all the yolkes are already com∣pleted into Eggs, and there is no more remaining, yolks the Vitellary, that may become eggs; but yet on the other side, there is still some litle White behinde, and •••• of that Modicum of White it is probable this litle Egge is framed. But this seemeth not probable to 〈◊〉〈◊〉; because it is an assured truth, that when the Ovary is exhausted, the Second Uterus also (as him∣selfe confesseth) is also spent, and wasted into a ••eer membrane, not containing any residue of the White, or Moisture at all. Fabricius goeth on: There i•• sound a two-fold Ovum Centeninum, one without a yolk, (and this is properly called Centeninum) which is the last the henne layeth, with which the henne, con∣cludeth her Laying for that season: the other also is a very small egge, but hath a yolke, and is not the con∣cluding, but some intervenient egge, after which the henne doth persist to lay egges of a just magnitude, as before; but it faileth in its dimensions, by reason of some impair in the vegetal faculty, as it happeneth to Peaches, and other Fruits, whereof some are of a full growth, and others exceeding small. He might have accused for this mischance, the inclemency of the Aire, and Soile, also the penury, and pravity of the nourishment. But, that the last Egges are alwaies very litle, I cannot willingly consent.

Nor are even Egges without their Monsters. For * 1.18 the Augurs (saith Aristotle) did account it Ominous, when Eggs were laid that were all yolke; or when such egges were found in the henne, she being cut up, under the Septum Transversum, and they of the magnitude of a Perfect Egge.

And hither may be referred Ova Gemellifica, Twinne-eggs, which are furnished with two yolkes;

such as I lately found in the Uterus of a henne, i•• being complete, and guarded with a Shell, having Yolks, Cicatrices, and the grosser Whites, all doubles it had also four Chalazae; but, as for the White of thinner consistence, there was onely One, which did encompass all the rest: it had also two onely com∣mon investing Membranes, and one single Shell. For though Aristotle affirme, that some hennes alwaies produce such Eggs; yet, that it so happeneth by the course of nature, I can hardly believe. And though two chickens may be hatched out of such Eggs, (which I have experimented, contrary to Fabricius his perswasion, who saith, that of such all eg, the chicken hatched will have four legs, two heads, & four wings; of which hereafter) yet they are not vital, but commonly dye soon, and that either for defect of Aire, or room in the Shell, or that one is an impediment to the other, and doth violence to it; for it cannot be, that both should be equally rea∣dy and ripe for Exclusion, and that one should not prove an Abortion.

To summe up all: The Differences of Eggs are chiefly of three kindes: For some are Fertile, and some Addle; some produce Cocks, and some Hens; some spring from Parents of the same species, and some from Parents of a diverse species, and so bring mungril-chickens; such as are conceived from a Dunghill-hen, and a Cock-Pheasant, and so resem∣ble either the Cock that obtained the first, or last Coition.

For, according to Aristotle, the egge which is con∣stituted by Coition, passeth from its own kinde into an∣other, * 1.19 in case the henne proceed to Coition, (having either a barren egge in her, or else an egge conceive by the semen of cocks of different kinde) before the yolk have procured its white. And thus are barren egg

fructified, and fruitfull eggs entertain the form of that ••ocke, who had the last courtesie in Coition. But if the White be already obtained, it cannot be, that either barren eggs should be altered into fruitfull; or that those egges which are already conceived by Coition, should pass into the kinde of that cock who was last en∣tertained. For the Cocks semen is (as Scaliger sharp∣ly observeth) like A Testament, where the last will * 1.20 is that which taketh place.

To these differences may be perhaps added, that, whereby some Eggs are strong, veget, and (if wee may so say) couragious; for as there is a soule in Eggs, so have they likewise a competent vertue. For as in other sorts of Animals, some Females are so libidinous and full of venery, that they take like Tinder, from one single act of Coition (be it never so feeble, and the male never so impotent) and conceive forthwith, and bring diverse foetuses by that one act: others again are so dull and sluggish, that unless they be provided with a more gene∣rous male, and him also highly inflamed (and the coition likewise repeated and continued) they will remain unsuccessfull. The same also befalleth in Eggs, whereof some, though conceived by coition, are improlifical, unless they be impowered by re∣peated, and continued coition.

Hence it cometh to pass, that some egges are quickly altered, and after three dayes of Incuba∣tion discover some rudiments of a foetus: but o∣thers are either easily corrupted, or are slow in their progress towards chickens, and yield no ex∣pectation of a chicken, even at the seventh day: As shall be hereafter proved, in the discourse of the Ge∣neration of the Pulbus, or Chicken out of the Egge.

And thus farre of the Womb of the Hen, and its Office: as also of the Generation of the Hen-egge, its

differences, and accidents: wherein we have deli∣vered what we have experimented our selves; by which you may give judgement of other Ovip∣rous creatures.

It now remaineth that we should prosecute 〈◊〉〈◊〉 history, of the Generation, and Formation of the Foe∣tus out of the Egge. For (as I informed you be∣fore) the whole Contemplation of the brood of H•••• and Cocks is comprehended in these two things namely, how the Egge is produced of the Henne and Cocke, and how the Cock and Henne are fra∣med out of an Egge: and by this circle the pro∣pagation of their Race may by the benefit and fa∣vour of Nature, be prolonged, and continued.

Notes

• * 1.1

  Hist. an. l. 1. c. 5.
• * 1.2

  de gen. an. l. 1. c. 2.
• * 1.3

  pag. 19.
• * 1.4

  The di∣stinction and diffe∣rence of Eggs from their Age.
• * 1.5

  From their Fi∣gure. Hist. an. l. 6. c. 2. l. 10. c. 52. lib. 9. de Rust. c. 5.
• * 1.6

  Scaliger upon the place.
• * 1.7

  From their Fe∣cundity.
• * 1.8

  de Re rust. c. 1.
• * 1.9

  Hist an. l. 6. c. 2. Pliny lib. 10. c. 54.
• * 1.10

  Ibid.
• * 1.11

  pag. 19.
• * 1.12

  Hist. an. l. 6. c. 2.
• * 1.13

  From Number.
• * 1.14

  Hist. an. l. 6. c. 1.
• * 1.15

  Incuba∣tion.
• * 1.16

  Magni∣tude.
• * 1.17

  pag. 10.
• * 1.18

  Aldro∣vand. Or∣nithol. l. 14. pag. 260
• * 1.19

  Hist. an. l. 6. c. 2.
• * 1.20

  In loc.