Page:Cyclopaedia, Chambers - Supplement, Volume 1.djvu/645

 EGG

EGG

among writers, and found no efFefl: in any of therri. Thefe Eft-flones never produced any viable effe& in his trials, in ne- phritic complaints, nor the eagle-ftone in womens labour, nor the ftones fwallowed by Caymans in quartans, tho' Me- nardes looks on thefe laft as infallible in this cafe.

EGESTION, in medicine, the fame with dejeaion.

EGG (Cycl.) — We have an account from no lefs art author than Wormius, of a woman's laying two eggs : They were brought into the world, he fays, with a live child, by the com- mon labour pains, and were of the fize of a common hen's egg. The women, who attended the lying-in woman, broke the firff, and found it to have a white and a yolk, like a hen's egg ; but the other was preferv'd whole, and given to Wor- mius, to enrich his collection of curiofities, where it remained fome time, and was afterwards given to the king of Denmark, and preferved in his mufsum at Copenhagen. There is at this time fhewn there a feeming egg ; but whether this was the real egg voided by the woman, or whether the ftory of the other, which was broken, having a regular white and yolk, was true, it is not eafy, at this time, to determine : Probably there has been either fome miftake, or fome fallacy, in the affair.

The learned Mr. Monro has given us a fummary of feveral obfervations made by the curious about eggs, and of the changes made in them by incubation, in order to determine the queftion about the nutrition of the foetus in oviparous animals. See Med. Eff. Edinb. vol. 2. art. 10. Some part of the humours of the egg efcapes thro' the (hell, and is not fupplied by any thing from without, as evidently appears from an egg's becoming fo much fpecifically lighter, as to fwim in water after incubation, tho' it funk in it when recent.

The eggs of the fmaller animals are not lefs taken care of by the female that lays them, than thofe of larger ones. In the butterfly clafs, the eggs have no increafe of bulk to arrive at, in the body of the female, all they have there to wait for, is to be fecundated by the male, and as foon as this is done, they are always ready to be laid. The female takes a pro- per time to lay them, and not only their number, but the nicety with which (he arranges them, and prepares for the family that is to be produced from them, makes this no fmall fpace. This is indeed the whole bufinefs of her life, and when they are all laid, file dies.

The female does not depofit them on any plant at random, on which (he happened to be placed when the male coupled with her, but fearches out fuch a fpecies of plant for the leaving them on, as is what the loved when in the caterpillar ftate, and what the young caterpillars to be hatched from them, will be able to feed on, that they may find food ready for them at the moment of their birth. She does not fcatter them about irregularly, and without order, but file difpofes them with perfect fymmetry, and fallens them one to an- other, not by their own glutinous nature, but by a vifcid li- quor, which (he feparates from her own entrails for that pur- pofe. In many fpecies alfo where the hinder part of the body of the female is covered with long hairs, (he, by degrees, throws off all thofe hairs, and with them makes a neft for the eggs (he is laying, where they are kept very foft, and fafely, till the time of their hatching. Memoirs Acad. Scienc. Par.

'73 -

The eggs of butterflies are of very different fizes, according to the fpecies ; they are alfo of many different figures, fome are fpheric, others fegments of fpheres, others conic, in different forms and degrees ; nor is this all, their furfaces are very different alfo in the different kinds. Some are elegantly wrought, as it were, fome dented, and others more deeply notched at the fides, and others channeled or furrow'd all over ; in fhort, the molt ingenious artift could fcarce contrive fo many various ornaments as there are on thefe eggs, all which alfo are invifible to the naked eye, being dilcoverable no way but by the microfcope. Prefervation of Eggs. Mr. de Reaumur, of the Paris aca- demy, thinking nothing, that could be a public benefit, be- neath the cognizance of a philofopher, beftowed confiderable pains on the finding a method of preferving eggs for a long lime, and fuceeded at length fo far in it, as to be able to pro- duce eggs of months, nay years old, which tailed as frefh and well as if they had been laid but the day before. The egg always is quite full, when it is firft laid by the hen, but from that time it gradually becomes lefs and lefs fo, to its decay ; and however compact and clofe its fhell may appear, it is neverthelefs perforated with a multitude of fmall holes, tho' too minute for the difcernment of our eyes. The effecf. of thefe, however, is evident by the daily decreafe of matter within the egg, from the time of its being laid ; a fluid mat- ter is continually perfpiring thro' thefe perforations of the fhell, which occafions the decay, and this is carried on in a much quicker manner in hot weather than in cold. To pre- ferve the egg frefh, there needs no more to be done, than to preferve it full, and flop its tranfpiration, and the plain and rational method of doing this, is by flopping up thefe pores, thro' which the matter tranfpires, with a matter which is not foluble in watery fluids, and therefore cannot be wafhed away by the matter perfpired by the egg ; and on this prin- Suppl. Voi. I.

ciple, ali kinds of vernifh, prepared with fpirit of wine, wiii preferve eggs frefh for a long time, if they are carefully rub- bed all over the (hell. This might feem to mod people a Very common and cheap fubftance, for this purpofe, but the misfortune is, that in country places, where it fhould be put. in practice, no fuch thing is to be had, and the poorer fort of country people are not eaiily brought into the ufe of any thing they are not ufed to.

To obviate the difficulty arifihg from this, Mr. Reaumur thought of fubftituting in the place of vernifh fome other fub- ftance, more common among thefe fort of people, and foon found that another fuhftance, which is very cheap, and every where to be had, would very welt fupply the office of vernifh ; for experiments proved, that any hard fat would have the fame effecf. Mutton fat may every where be had, and eggs carefully rubbed over wich this, will keep as long as thofe coated with vernifh. Common tallow, of which candles are made, ferves equally well to the fame purpofe ; but this might breed a diftafte in nice people s and the beft of all fat for this purpofe is found to be a mixture of that of mutton and of beef, thefe fhould be melted together over the fire, and drained thro' a linen cloth into an earthen pan ; and a pot of five or fix pounds of this may eafily be kept in a farm- houfe, and will ferve for a vad quantity of eggs. When it is to be ufed, the pan is to be fet over a gentle fire till the whole is melted, which is done in a few minutes, and when tho- roughly melted, an egg is to be dipped into it, and imme- diately taken out ag«in, and it is then in a date to keep perfectly frefh more than a twelve-month. The fat conti- nues fluid a long time, and a great number of eggs may be fuccefllvely dipped into it, and it will ferve again at other times for great numbers of others. Memoirs Acad. Scienc.

~ 1r - '735-

The only difficulty attending this method is, that the eggs cannot eafily be fo plunged into the fat, as that all their furfaces (hall be covered by it ; for if they are held in a pair of pincers, the parts of the egg where the pincers touch will be bare ; but this may be remedied by ufmg fuch pincers as touch only in fmall points, and thefe bare fpaces may eafily have a little of the melted fat rubbed over them with a feather, or a pencil ; or the eggs may be fufpended by a loop at the end of a thread, and, by that means, plunged in, and the thread being then coated over with the fat as well as the furface of the egg, will preferve that part which it covers, as well as the coat of fat will the red. The great care is to ufe this means while the eggs are perfectly frefh ; it ought indeed to be done on the very day when they are laid, for if the evaporation is begun, and the empty fpace once made, there is room for a fermentation, which never terminates but in the dedruction of the egg. There is one advantage in this ufe of fat, rather than vernifh, which is, that the eggs rubbed over with it boil as quick as if nothing had been done to them, the fat melting off as foon as they touch the hot water ; whereas the vernifh, not being foluble even in hot water, only becomes moidened by it, and dill hanging about the egg, prevents the tranfpiration of juices, necerfary to bring the egg to that date in which it is to be eat. When the egg, which has been preferved by fat, is taken out of the water, there remains very little fattynefs upon it, and what there does is eafily wiped off with a nap- kin, the egg is as nicely frefh as if laid but the day before, and no palate can didinguilh the lead tafte of fattynefs in it. The method of preferving them by means of fat, is greatly preferable alfo to that by vernifh, when they are intended for putting under a hen to be hatched. So long as the egg re- mains in the date of a frefh one, the embryo lives, either of the methods of preferving them will therefore fucceed fo far as to keep the embryo dill living ; but, when the hen fits upon them, the warmth of her body caufes a tranlpiration of their juices, which is effential to their hatching, and this can- not be done through the adventitious coat of fat or vernifh ; but the fat eafily melts off by the heat, while the vernifh re- mains on, and much impedes the progrefs of the chicken. If the heat of the body of the hen fhould not be thought diffi- dent to melt off the coat of greafe, it may eafily be taken away by dipping the egg in water, made jud fo warm as to, melt the fat, without at all affeaing the infide of the egg, which cannot be done in regard to the vernifhed ones. Me- moirs Acad. Scienc. Par. 1735.

There is one great advantage in this manner of preferving eggs, which is, that we may thus have the eggs of foreign fowls preferved upon the (pot, and fent over to us, which will be readily hatched by fetting them under a hen, and will af- ford us a great variety of the birds of value from other countries, in the eafied and mod natural way, and, thus hatch'd with us, they will be much more likely to live, than if brought over alive. Eggs are infinitely more eafily brought over in (hips, than birds, as requiring, when thus managed, no care hut a fafe package; whereas the birds muft be carefully watched, and fed, and very frequently they die, in fpite of all the care that can be taken of them. Many very beautiful and valuable birds might thus be naturalized among us ; and as we have already been able, without this ready means, to make paroquettes and Canary birds breed, with us, there is no io D d° ubt