Page:Cyclopaedia, Chambers - Supplement, Volume 1.djvu/711

 F E V

For inftance, the old barons of Arran and Lorn were obliged to furnifli their lord with a fhip in time of war ; and thence, it is that their arms carry ftiips orlymphods to this time.

EEVE, in natural hiftory, a name firft. given to the chryfalis of the iilk-worrrij and from thence to all chryfalifes of the but- terfly kind ; in which ferife it is now received and ufed with the moft accurate writers, and made a fynonymous term with the word chryfalis and aurelia. See the article WEB-cafe. The caterpillar putting off its own form to appear in this, and the expanding of this into the butterfly, have been fuppofed fudden changes of one animal into another; but this is a very incorre£t way of thinking, for each of thefe is the fame animal in its different ftages of growth. We call the crea- ture hatched from the egg of a butterfly, a caterpillar ; and it goes under this name till the chryfalis ftate, but it is eafy to fee that this creature is a butterfly all the time under the mask of a caterpillar. We know that the caterpillar changes its skin four or five times during its living in that ftate, and that all thefe skins are at firft produced with it from the egg, lying clofely over one another. It parts with or throws off all thefe one by one, as the butterfly, which is the real animal all this time within, grows more and more per feci: in the fe- veral firft changes. When it throws off one, it appears in an- other skin of exactly the fame form ; but at its final change from this appearance, that is, when it throws oft" the laft skin, as the creature within is now arrived at fuch a degree of perfection as to need no farther taking of nourishment, there is no farther need of teeth, or any other of the parts of a caterpillar. The mature in this laft change, proceeds in the very fame manner as in all the former, the skin opening

. at the back, and the animal making its way out in this fbape. if a caterpillar when about to throw off this laft skin, be thrown into fpirit of wine, and left there for a few days, the membranes within will harden, and the creature may be afterwards carefully opened, and the chryfalis taken out, in which the form of the tender butterfly may be traced in all its lineaments, and its eyes, legs, &c. evidently feen. It is not neceflary however to fcize upon this exact time for the proving the cxiftence of the chryfalis or butterfly in the cater- pillar, for if one of thefe animals be thrown into fpirit of wine, or into vinegar, fome days before that time, and left there for the flefh to harden, it may afterwards be differed, and all the lineaments of the butterfly traced out in it; the wings, legs, antennas, &c. being as evident here, and as large as in the chryfalis. Reaumur's Hift. Infect! v. i. p. 2, 28. It is very plain from this, that the change of the caterpillar into a chryfalis is not the work of a moment, but is carrying on of a long time before, even from the very hatching of the creature from the egg. The parts of the butterfly are not how- ever difpofed in exactly the fame manner while in the bo- dy of the caterpillar, as when left naked in the form of the chryfalis ; for the wings are proportionably longer and nar- rower, being wound up into the form of a cord, and the an- tennas are rolled up on the head ; the trunk alio is twilled up, and laid upon the head ; but this in a very different manner from what it is in the per feci: animal, and very different from that which it lies in within the chryfalis ; fo that the firft for- mation of the butterfly in the caterpillar by time arrives at a proper change of the difpoiition of its parts, in order to its be- ing a chryfalis.

It is plain, that the butterfly is, in all its parts, in the caterpillar, in all its ftates ; but that this becomes more eafily traced, as it grows nearer to the time of the chryfalis. The very eggs hereafter to be depofited by the butterfly are alio to be found not only in the chryfalis, but in the caterpillar itlelf, arranged in their natural, regular order. They are indeed in this ftate very fmall and pellucid; but after the change into the chryfalis, they have their proper colour. As foon as the feveral parts of the butterfly therefore arc arri- ved at a ftate proper for being expofed to the more open air, they are thrown out from the body of the caterpillar, fur round- ed only with thin membranes ; and as foon as they are arrived after this at a proper degree of ftrength and folidity, they la- bour to break through thefe thinner coverings, and to appear in their proper and natural form, The time of their duration in this ftate of chryfalis is very uncertain, fume remaining in it only a few days, others feveral months, and fome almoft a year in appearance. But there is a fallacy in this, that many arc not aware of. It is natural to think, that as foon as the creature has inclofed itfelf in its fhell, be that of what matter it will, it undergoes the change into the chryfalis ftate. And this is the cafe with the generality ; yet there are fome which are eight or nine months in the fhell before they become chry- falifes, fo that their duration in the real chryfalis ftate is much ftiorter than it naturally appears to be. When they arrive at the time of their quitting this ftate, or throwing off this laft envelopement, the operation is much lefs different than that of the leaving the caterpillar ftate to appear in this. The change of the chryfalis into the butterfly is always made within th< ftiell that covers it. In many fpecies therefore, in order to fee in what manner it is performed, one of thefe muft be care- fully taken out of its fhell ;■ or elfc one of the angular ones

fEV

chofen, which have no fhell at all, but hang tlremfelve; fcV the tail naked to a beam, or other thing; or, finally, one of thofe which are only covered with a few loofe hairs 'inftead of a fhell : in this cafe, a little attention will fhew the whole pro- grefs of the change. Mr. Reaumur carefully watched the au- riculated caterpillar of the oak into its feveral changes, and particularly from its chryfalis, which is of this laft kind, into the fly; and has given an account of the method of this, as an inftance of the general courfe of nature in thefe opera- tions.

The membranes which envelope the creature in this chryfalis ftate are at firft tough and firm, and immediately touch the feveral parts of the inclofed animal ; but by degrees, as thefe parts harden, they become covered, fome with hairs, and others with fcales. Thefe, as they continue to grow, by de- grees fall off the feveral particular membranes which cover the parts on which they are placed, to a greater diftance, and by degrees wholly looien them from the limbs. This is one rca- fon of thofe membranes drying and becoming brittle. There is alio another, which is, that the infide of this whole cafe was at firft full of a vifcous liquor, which kept it moiir. and fupple; hut in the progrefs of the growth of this animal, the liquor is all received into its vefTels, and the skins are left quite dry. When by thefe means the parts of the butterfly have grown to their due ftrength, and the membranes have at the fame time grown extremely weak and thin, it is no difficult matter for the creature, at a proper time, to make its way through them. Every time that it moves, though ever fo little, any of its limbs, or fuells out any other part of its body, it occafions the membranes to burft and crack at once in feveral different places ; and the fame motions continued or repeated, occafion the aperture to enlarge by degrees, till at length it is big enough for the whole limb ; and,~finally, for the whole animal to come out at. But it is remarkable', that the places in which the fhell breaks are always the lame in the lame fpecies j and that they are always formed by a number of cracks begun in the fame place, and propagated in the fame direction.

On the back of the chryfalis there is always a part called the corcelet, which is not divided into rings in the manner of the reft of the body, but is formed of one limple flat crufh This part is larger in fome fpecies, and fmaller in others: hut in all it arifes from the upper rings of the back, and termi- nates at a part of the fummit of the chryfalis, which maybe called its front. The firft of thefe parts is placed over the corcelet of the butterfly, the latter or front over its eyes and antennae. The corcelet joins itfelf on each fide to the mem- brane that covers the wings. It leems indeed to be prolong'd to the belly, and folded over it. The belly of the chryfalis is that part of it which is contained between the wings and the forehead, reaching down to the part where the bottoms of the wings crofs over one another, or at leaft where they meet. This part contains the legs, antennae, and trunk of the in- fed, all extended at full length. See Aureiia. The French call that part of the membrane which covers the belly, the breaft piece. In order to delcribe the manner in which the chryfalis is open'd to let out the butterfly, it is neceflary to know thefe feveral parts of it under diftimft names. The middle of the upper pai t of the corcelet is ufually mark- ed with a line, which runs in a longitudinal direction ; and this part is always more elevated than the reft, even in the conic kinds, which are no otherwife angular. This line is in fome very bold and plain, in others it is fu faint as not to be diftinguifhable without glaffes; but it is always in the midft of that line that the fhell begins to open. The motion of the head of the butterfly backwards firft occafions this crack, and a few repetitions of the fame motions open it the whole length of the line.

A very gentle motion ferves to this purpofe ; and when the corcelet is by this means divided into two pieces, the crack be- comes much wider, and fjiews a thin down that covers the body of the butterfly. After this the piece, which makes the front of the chryfalis, fplits into two pieces in the fame man- ner j and after this the corcelet is feparated at its edges, and the front at its anterior part from the breaft piece, and this hangs only by its point. Thus is an opening found for the creature's getting out: this had not been worthy fo parti- cular a defenption, but that it is always regularly the lame in all refpe&s.

As thefe cracks between the feveral pieces enlarge with thofe in their midft, they fhew more and more of the body of the animal ; and as the leaft force imaginable is fumcient to fepa- rate entirely parts which hang together fo very flightly as thefe feveral pieces now do, the creature in moving itlelf ever fo gently upwards makes its way out.

The clearing itfelf however entirely is a work of more time in this cafe, than is the pafling of the chryfalis out of the bo- dy of the caterpillar. In that cafe there is a crack fufficiently large in the skin of the back, and the whole chryfalis being loofe comes out at once. But in this cafe every particular limb, and part of the body, has its feparate cafe; and though thefe are almoft inconceivably thin and tender, yet it is ne-

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