Page:Cyclopaedia, Chambers - Supplement, Volume 1.djvu/646

 EGG

doubt but that we might, by this better way, breed many of the hardier birds, as the China and Egyptian hens, the par- tridges of other nations, as well as their pheafants, and per- haps many other delicate fowls, of which we have not yet fo much as the names with us. Thefe would eafily be hatched with us by their eggs thus preferved, and placed under fetting hens, and when thus hatched in any conflderable number, there is no doubt but that the males and females among them would propagate their fpecies, and perpetuate themfelvcs among us, as the turkeys, and many other birds, originally of foreign extract, have at times done. Hard fat is, of all the prefcrvatives of eggs, that which may be had more eafily every where, which is very cheap, and which eafily comes off from the egg ; but it is very certain, that any matter which can prevent the tranfpiration of the egg, will equally well preferve it ; it is only neceffary, that the fubftance ufed mould be naturally hard ; oil, for inftance, if rubbed over eggs, would, unqueftionably, in a great mea- fure, flop their pores, and prevent tranfpiration ; but oil, be- ing a fluid, would never remain upon every particular part as it ought to do, to preferve it, and even the act of tranfpi- ration of the juices would be fufficient to diflodge the thin coat of oil, and make their way through it. Wax, or a mixture of wax and pitch, orrefin, are able to preferve the egg as well as fat, but they are dearer, lefs ready at hand, and do not come fo eafily off from the egg in the drefling. All the aqueous gums, as gum arabic, and ifinglafs, will preferve eggs frefli much longer than they would naturally remain fo, but not fo long as the before mentioned fubftances. Memoirs Acad. Scienc. Par. 1735.

This method of preferving is not ty'd down to eggs alone, but may be of great ufe in keeping all forts of fubftances where an internal fermentation is feared. Mr. Reaumur try'd on bodies of many different kinds, and found it fucceed in all.

Artificial Method of batching Ecgs. See Hatching.

Ant-EoGs. See the article Ant.

Eggs of Flies. After the congrefs with the male, the female fly is feldom fo much as twenty-four hours before fhe begins to depofit her eggs on fome fubftance proper to give nouriih- ment to the worms that are to be produced from them. Thefe eggs in general are white and oblong, but there are tone of them which are fingular, and vary from this form. The defcription of one fpecies of thefe may give an idea of the reft, and it may not be improper to take, for this purpofe, thofe of the eggs of the fly found on hog-dung, and on other fuch matters. This fly is of the clafs of the great blue flelh fly, but differs from it in many particulars. Its body is more round, and a little hollowed on the belly fide, efpecially that of the male. The hinder end of the male is bent alio into a fort of hook. The wings crofs one another on the body, and exceed it in length. The male is yellow, often of a very beautiful, and fomewhat reddifh yellow. This colour is principally owing to a multitude of hairs with which the body is covered. The corcelet is of a paler yellow than the body, and has fome flight tinge of brown with it. It has only a number of black hairs on it, fewer, and placed more diftant than thofe of the body. The female has much fewer hairs, and is browner than the male. Reaumur, Hift. Inf. v. 4. p. 376.

Two pairs of thefe flies having been taken in the month of October, and (hut up in a box, with a quantity of hog' s dung, on which they were found, the females foon began to depofit their eggsi

The eggs of this fpecies are white and oblong, like thofe of the great blue flefh fly, but their figure has notwithftanding fomething very fingular in it. At one end of each of thofe eggs there are two little wings, which are feparated from one another in the manner of two horns, thefe do not reach be-

. yond that end of the egg, and have their infertion between that end, and the middle of the egg. Ibid. p. 377. Thofe wings feem formed of the fame membrane, which makes the outer covering of the egg, but they feem to have no bufinefs to contain any part of the fubftance of the egg, or any thing neceflary to the life of the embryo worm. The ufe of thefe wings, however, will be eafily difcovered, when we confider that the fly, as foon as fhe has laid them, always thrufts them into the dung : This is neceflary to the future hatching, as the coat of the egg muft necefTarily be kept foft, otherwife the embryo could never force its way out of it. It is eafy to conceive alfo, that if the whole egg were thus bu- ried, the creature would be fuffocated in the fubftance it was buried in, as foon as hatched. Nature has therefore fo pro- vided for its fafety, that a part of the egg only fhall be im- mers'd in the matter, and kept moift, and part remain out. This great provifion is made by thefe wings, for the fly makes the egg enter the dung as fhe lays it. It enters eafily at its fmaller end, which is the part firft protruded from her body ; but when it comes to be immerfed as far as thefe wings, the refinance encreafes, and the upper part of the egg remains open to the air. Ibid. p. 378.

The eggs are but a little time in hatching, and the growth, and all the changes of the animal, take up but a little time. The creature is found to make its way out of the upper part of the egg, and it is not more than three weeks from the lay-

EGG

ing the egg that is taken up, before the creature is feeri is form of a perfect fly ; if a female j and ready to depofit hers. Ibid. p. 379.

Among the butterfly clafs, the female has but one congrefs with the male, and immediately after it begins to depofit her eggs, and continues fo doing, without interruption, till (he. has finifhed ; but it is much otherwife with the two winged flies, for they, after having laid one fet of eggs, have repeated congrefles with the male for feveral days, and, after every one of thefe, lay a new fet. Ibid. p. 380. The eggs of the different fpecies of the two winged flies, are of very different figures, and doubtlefsthe great author of na- ture has had reafons for allotting the peculiar form of each, tho' we cannot always determine what thofe reafons were. Some fpecies there are which faften their eggs to the fides of veflels of water, thefe all lay oblong eggs, fome of them, however, are perfectly fmooth in all parts, and thofe of other fpecies fmooth only on their inner furface, and ridged longitu- dinally on the other. What is alfo the more remarkable in thefe, is, that they all have a fine thin flake running down all along the two fides, diametrically oppofite, and thefe two bands unrounding the whole egg in this manner, have much the appearance of a cafe, and give the egg the appearance of being cnclofed in a paper frame. 'Tis probable, that the ufe of this frame is to hold the body of the egg the better, fattened againft the veffel ; and probably thofe eggs which have it not, are depofitcd from the body of the female fly with a vifcoui matter about them, in fufficient quantity to faften them on without this afliftance. Ibid. p. 381.

Some eggs of the fly kingdom there are, which muft necefTarily be held fail to fome other body, in order for the worm to be able to make his efforts toward the opening of them, without carrying them away ; and fome of the fpecies require much more ftrong attachments of this kind than others. There is a fly a little fmaller than the common great blue flefh fly, but of the fame genus, whofe body is of a greyifh brown, and the whole a mixture of grey fpots upon a black ground. This fpecies depofits its eggs alfo on meat, but their figure is dif- ferent from that of the eggs of the great blue fly. They are fliorter than thofe, and are larger in the middle than at either of the ends ; they are alfo fomewhat flatted, and one may diftinguifh on them two fides; the one, which is more Bounded and convex, is covered with very fine furrows, and the other, which is flatter, has only five high ridges, and con- fequently only five furrows. Notwithftanding thefe differences in the eggs of this fpecies from thofe of the common blue fly, the worms, hatched from them, feem much the fame, and to undergo the fame changes. Ibid. p. 382. On the ftalks of the common meadow graftes there are alfo frequently found the eggs of flies depofited in great numbers. Thefe, examined by the microfcope, have all the form of fmall fnow-white boats, or rather of fmall mips, with the deck (landing up above their fides. The places where they are lodged, Slew evidently the care of the creature which laid them j the fly is not known, but they always produce a fmall white worm, with a variable head, and two hooks. Ibid. On other ftalks of grafs, one may often fee alfo yellow fpots and blotches, which may naturally enough pafs with an incu- rious obferver for maladies of the plants, but, when examined with the microfcope, all thefe appear to be, in reality, clufters of eggs of the fame boat-fafhion'd form, and amaffed in dif- ferent numbers ; fometimes alfo they are formed perfect and whole, and at others with their ends eaten. Thefe laft are fuch eggs from which the worms have made their way. Thefe worms are white, and have a variable head, armed with two hooks, but their changes are not known. Reaumur, Hift. Infeft. Vol. 4. p. 383. Eggs 0/ Gnats. There are few creatures in the winged king- dom more prolific than the gnat. Its whole feries of changes, from the egg to the perfect animal, is ufually accomplilned in three weeks, or a month, and there are commonly feven generations of them in a year, in each of which every female is the parent of two or three hundred young ones, if all the eggs come to good. Thefe eggs are arranged by the animal in the form of a fmall boat, and each feparate egg is of the fliape of a ninepin ; the thicker ends of thefe are placed down- wards, they are all firmly joined to one another by their middles, and their narrower, or pointed parts, ftand upward, and make the upper furface of the boat of eggs, as it were rough or prickly. Reaumur, Hift. Inf. T. 4. p. 615. When thefe eggs are examined fingly by the microfcope, they appear not exactly of the ninepin fhape ; the larger end is rounded, and terminated by a fhort neck, the end of which is border'd with a ridge which makes a kind of mouth. The neck of each of thefe is funk within the water on which the boat fwims, for it is neceffary that it fhould keep on the fur- face, fince, if wholly fubmerged, the worms could never be hatched.

The arrangement of thefe eggs in fuch nice and exact order, is a thing very worthy our admiration, and which cannot have been effected, but by the utmoft care and caution in the creature, while in the act of laying them. It is only in the morning hours that the gnats are to be found laying their eggs, and then they will frequently be found about the furfaces of

fuch