Page:Cyclopaedia, Chambers - Volume 1.djvu/647

 EGG

Of the various Kinds of Eggs, thofc of Hens, or Pullets, being the moft ufual, and which have been the moil; ob- served ; we fhall fay fomewhat of the Structure thereof, and the Generation of the Chick therein.

The Exterior Part, then, of a Hen's Egg is the Shell} a white, thin* friable Cortex, including all the other Parts, and defending them from Injuries. Immediately under the Shell lies the Membrana. communis^ which lines the whole Cavity of the Shell, adhering pretty clofely to it, except at the bigger End, where a little Cavity is left between them, which with Age grows bigger. Under this Membrane are contain'd two Jllbumina, or Whites, each ■

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EGG

•H'P

d up

its own Membrane. In the middle of the inner White, is the Vitellus, or Yelk inclofed likewife, in its feparate In- volllcrurn, or Cover. The outer Albumen is oblong or oval, accommodated to the Figure of the Shell : The inner is fpherical, and of a more crafs, and vifcid Subftance ; and the Yelk is of the fame Figure. See Albumen and Yelk.

At each End is a Chalazza, or Treddle, which are, as it were, the Poles of this Microcofm : Theft: are white, denfe Bodies, confifting each of three little Globules like Hail connected together : In thefe not only the feveral Membranes are connected, or knit together ; by which Means the feveral Liquors are kept in their proper Place and Pufition to each other ; but they ferve alfo to keep one and the fame Part of the Yolk uppermoft 3 let the Egg be turn'd which Way it will. SeeCHALAzzA.

About the Middle, between the Chalazza, on the Side of the Yelk, and in the Membrane thereof, is a little Vefica or bladder, not unlike a Vetch, or Lentil, called the Cica- tricula, and by fome the Eye of the Fgg. In this Velicle is contain'd a Humour, in, a'.jj of which the Chick is ge- nerated. See Cicatricula.

All thefe Parts of a Pullet's Egg-, are found in all other 2-8£ s t0 which the Definition of an Egg properly and briefly agrees : Such Egg being that, of a Part whereof the Animal is form'd, the reft ferving for its Food. Accord- ingly, the firft Seed, or Stamen of the Chick, is in the Cicatricula.

The Albumen is the Nutritious Juice, whereof it is di- ftended and nourished till it become big ; and the Yolk ferves it for Food after it is well grown, and partly alfo after it is hatch'd. For, a good Part of the Yolk remains after Exclufion ; being receiv'd into the Chicken's Belly, as a Store-houfe, and convey'd thence by the Appendicula, or Dlltlus Inteflinalis, as by a Funnel, into the Guts, ferv- ing inftead of Milk. See Incubation, and Punctum Saliens.

An Egg, improperly fo call'd, is that of the whole whereof the Animal is form'd j fuch are the Eggs of Flies, Butterflies, &c. which Arifotle calls Vermiculi.

The Two have this further Difference, that whereas the former, after they are excluded from the Female, need no External Nutriment, nor any Thing but Warmth and in- cubation, to bring the Fcetus to Perfection : The latter, after they are fallen out ot the Ovary into the Uterus, require the Nutritious Juices of the Uterus to diftend and enlarge them 3 whence they remain much longer in the Uterus than the other.

The principal Differences among Eggs, properly fo call'd, are, that fome are perfetl, i. e. have all the Parts above defcribed, while in the Ovary, or Uterus : And others, Imperfecl, as not having all thofe Parts till after they are excreted or laid ; fuch are the Eggs of Fifties, which after they are brought forth, affume an Albumen to themfelves from the Water.

Another Difference is, that fome are fecundated, and others not : The firft are thofe which contain a Sperm, injected by Coition of the Male, to difpofe them for Con- ception : The reft, not impregnated with this Sperm, never breed young by any Incubation, but always putrify. An Egg fcecundified, contains the Rudiments of the Chick, e're ever the Hen have fate upon it. By the Microfcope we fee, in the middle of the Cicatricula, the plain Carina of the Chick, fwimming in the Liquamen or Humour 5 it confifts of fine white Zones, or Threads, which the Warmth of future Incubation enlarges, by rarifying and liquifying the Matter firft of the Albumen, and then of the Vitellus, and preffing them into the Veflels of the Cicatricula, for a further Preparation, Digeftion, Affimulation, and Accretion ; till the Chick, too big for its Covercle, breaks the Shell, and is deliver'd.

'Twas antiently thought that none but Birds and Fifties, with fome other Animals, were produced, ab Ovo, from Eggs ; but the Generality of the Moderns incline to think, that all Animals, even Man himfelf, are generated the fame Way. Harvey, Graafi Kerchringius, and feveral other great Anatomifts, have fo ftrenuoufly afferted this Opinion, that it now generally obtains.

In the Zeftes of Women, are found little Vefides, about the Size of green Peas, which are accounted as Errs ■ for which Reafon, thefe Parts, which the Antients call'd Teli'icles the Moderns call Ovaries. Thefe Eggs, fcecund.fied by the mod volatile and fpirituous Part of the Seed of the Male are detach'd from the Ovary, and fall down the Fallopian Tubes into the Uterus, where they grow and increafe. ' See Conception and Generation.

This Syftem is countenanced and confirm'd by Abun- dance of Obfervations and Experiments. Monf. de S. Maurice, upon opening a Woman at 'Paris, in 1S82, found a Fcetus perfectly form'd in the Tefticle.

M. Olivier, a Phyfician at Srefc, attefts, that in the Year 1684, a Woman, pregnant feven Months, was brought to Bed of a whole Plate full of Eggs, faften'd together like a Bunch of Grapes, and of various Sizes, from that of a Lentil, to that of a Pigeon's Egg. Wormms affures us, that he had himfelf feen a Woman who had lain an Egg. And Bartholin confirms him, Cent. I. Hifl. Auatom. IV. p. 11. The fame Author tells us, he knew a Woman at Copenhagen, who, after twelve Weeks Conception, was de- liver'd of an Egg wrapp'd up in a thin Shell. Lauzonus, Dec.ll. An.ix. Obf. 38. f. 73. of the Curiofl Nature, relates the fame Thing of another Woman feven Weeks gone : The Egg fire brought forth was of a Size between that of a Flen and a Pigeon ; and was cover'd with Mem- branes inftead of a Shell. The outer Membrane, or Chorion, was thick and bloody ; and the inner, or Amnios, thin and tranfparent, including a whitifti Humour, wherein the Embryo fwam faften'd by Umbilical Veffels, like Threads of Silk.

Sonetns, in a Letter to Zuingerus, publifhed in the Ephemcrides of the Curioji Nature, Dec. II. An. 2. Obf. i8«. /. 417. relates, that a young Maid had caft forth a great Number of little Eggs. Con. Virdungius obferves, that in differing a Woman who had a Rupture, or Defcent, he found Eggs of divers Sizes in the Cornu of the Womb. Laftly, we meet with divers Inftances of the fame Tning in Rbodins, Cent. III. Obf. 57. and in feveral Places of the Memoirs of the Curiofi Natltr<e. Infomuch that Server, in his TreatiCe de Natura humana, L. II. C. I. p. 41S1. makes no Scfuple to fettle it as his Opinion, that the only Difference between Animals, called Oviparous, and rhofe denominated Viviporous, confifts in this 3 that the former calls their Eggs out of the Body, and lay them in Nells ; and that their Eggs contain all the Nourilhment requisite for the Fruit, or Fcetus: Whereas in the latter, the Eggs are only lay'd from the Ovary into the Uterus ; that they have but little Juice 3 and that the Mother furnishes the reft.

There is not fo much as a Plant, whofe Generation, ac- cording to the Sentiment of Enipedocles, and fmce him of Malpighi, Rallius, Fabric, ab Aquapendente, Gretn, and others, is not eftccfed by the Way of Eggs. See Plant, iSc. On the other Hand, we have numerous Inftances of Ovi- parous Animals, producing their young abfolutely alive, and without Eggs. Such Inftances we have of a Crow, a Hen, Serpents, Fifties, Eels, (3c. See Ifibord. ab Ame- lanxen, Breviar. Memorabil. N. 28. in Append. M. Curios, Nat. Dec. II. An. 4. p. 20 r. Lyferus, Ob/. VI. Aldrovand. Hift. Serp. (3 Dracon.p. 309. Seb. Nuremberg, DeMirac. Natur. in Europ. C. 41. Franc. Paullin de Anguilla, S. I. C. 2. iSc.

But this is not all : Natural Hiftory abounds with In- ftances of Males, and even Men catting out Eggs by the Fun- dament. 1'he Thing will look fo odd to an Englip Reader, that we might be cenfured, were we to relate the various Accounts of this Kind in Form. We fhall, therefore, con- tent our felves to refer the Reader, who has Curiofity enough that Way, to the Authors and Places wher; he may meet with them 5 viz. Chrift. Paulin. Cynograj h. Curiof. Sed. I. E. 3. (j 5 g. M. Curiof. Nat. Dec. 11. A. 8. Obf. 117. p. x6i. and 'Dec. I. An. 2. Obf. 250. and Dec. II. An. 4. Append, p. 19c,. Scheuch. Hifl. Monfl. p. 129, £5V. M. Stolterforth is of Opinion, that at Jeatt, in fome of thefe Cafes, what was taken for Eggs might be no more than certain Aliments ill digefted, and coagulated; an In- ftance of which he himfelf had feen. As to thofe of Women, Wormms and Formanus, L. III. de Fafanat, P. VI. C. 20. § 9- P- 882. take it for the Effcft of the Devil : But Bartholin and Solterforth treat the Notion, as it deferves, with Derifion.

Goujfet, de Caufis LingUre Hebraiae, explodes the mo- dern Syftem of Generation ab Ovo, as contrary to Scripture : And others imagine they have feen the Animal alive, and form'd in the Seed of the Male. See Animalculi and Seed, Malpighi, has made very curious Obfervations with the Mifcrofcope, of all the Changes that happen in the Egg, every halt Hour of Incubation. Vofflus, and divers other Authors, are very follicitous about fettling the Queftion, which was form'd firft, the Egg or the Pullet, de Idolol. L. III. 67. 78. Hh* fa