CHR
C H R
chryfalifes which have two angular bodies on their heads, but fliorter than thofe of the preceding, and whole back fhews but a faint Hatch of the human face, and which have fewer fpines, and thofe lels {harp, always turn into that fort of but- terfly, the upper-wings of which are divided into fegments, one of which is io long as to reprefent a rail, and whole under - wings are folded over the upper part of the back. A careful
obfervation will eftablifh mam
- rules of this kind, which
is not fo perfect as to be free from all exceptions, yet are of great life, as they teach us in general what fort of fly we are to expect from the chryfolts, of which we know not the cater- pillar, and therefore can only judge from appearances. Thefe are the principal differences of the angular chryfalifes ; the round ones alio have their different marks not lefs regular than thofe.
The greater number of the round chryfalifes have the hinder part of their body of the figure of a cone j but the upper end, which ought to be its circular plane bafe, is ufually bent and founded into a fort of knee: this is ufually called the head of the chryfalis; but there are alfo fomeofthis kind, the head of which Is terminated by a nearly plane furface : fome of the creeping ten-legged caterpillars give chryjalifes of this kind, which have each of them two eminences that feem to bring them towards the angular kind. Some of thefe are of along and flender conic figure, terminating in a fharp point ; others arc more thick and fliort, and blunter at the ends ; and fome are very fhort, and have no part conic except the point : in fome of the kinds alfo the rounded end or head is flatted on two fides, and this flatnefs is continued a little way along the belly ; and of the conic ones, fome have a fort of hollow on the back, fefembling engraved work. Some of this kind alfo are not conic, but arc flatted on the belly, and only rounded on the back; and fome of them have, as it were, a fort of nofe that bends over the belly.
Among the angular chryfalifes there are fome wbofe colours feem as worthy our obiervation as the fhapes of the others. Many of them appear fuperbly clothed in gold : and this in the feveral ("pedes is of feveral colours ; in fome it is a pure yellow, in others a very pale whitifh yellow, and in others a greenilh ; but in all, the gold is very bright, and appears like --the burnifhed parts of gilding. It is thefe elegant fpecies which have obtained the names of chryfalis and aurelia, which are derived from Greek and Latin words, fignifying gold j and from thefe all other bodies of the fame kind have been called by the fame names, though lefs or not at all entitled to them. As fome kinds are thus gilded all over, fo others are ornament- ed with this gay appearance in a more fparing manner, hav- ing only a few fpots of it in different places on their back and belly. Some fpecies alfo have filver in the place of gold, ei- ther extending itfelf all over them, or forming fome particu- lar fpots upon their back and belly. Thefe obvious marks, however, are not to be depended upon as certain characters of diftinction, for accidents in the formation of the chry- falh may alter them ; and thole which naturally would have been gilded all over, may be fometimes only fo in part, and either thefe or the others may by accidents be fo formed as to flhew nothing of this kind at all, but be only of a duiky brown. Thofe, however, which have neither filver nor gold to re- commend them to our eyes, do not want other colours, and thofe beautifully variegated. Some of them are all over of an elegant green, as is the chryfalis of the fennel caterpillar ; others are of an elegant yellow, and fome of a bright greenilh tinge, variegated with fpots of a fhining black ; we have a Very beautiful inftance of this laft kind in the chryfalis of the elegant cabbage-caterpillar. The general colour of the chry- falis of the common butterflies, however, is brown ; they are of a very elegant chefnut colour, and vary from this into all the fhades of brown, from the moll deep and duiky to fuch as are almoft white. Some alfo are of a line deep black, and of thefe many are fo fmooth and gloffy, that they are equal to the fineft Indian japan. The common caterpillar of the fig-tree gives an inflance of one of thefe beautifully glofly ■ones i the caterpillar of the vine affords another of thefe fine black cbryfalifes.
The rounded chryfalifes do not afford any thing of that va- riety of colouring ib remarkably beautiful in the augularones; they are ufually of a dufky yellow, in different fhades, and are often varioufly fpotted with black : but thefe, as well as all other chryfalifes, before they arrive at their fixed colour, pais through feveral other temporary ones, fome being of a differ- ent colour when firft produced from the caterpillar, from what ihey are a few days afterwards j and fome varying fo great- Jy, though only in degree, as not to be diftinguilhable by the moil converfant eye for what they were when firft produced. The green rough caterpillar of the cabbage has a chryfalis which is green at firft, and from that gradually goes through all the fhades of green to a faint yellow, which is its latting colour ; .and one of the oak caterpillars yields a chryfalis beautifully spotted with red at its firft appearance, but thefe fpots change to brown for their fixed colour : the third day from their for- mation ufually fixes their lailing colours ; and if they are ob- "ferved ,to turn black in any part after this time, it is a fign that they are dead or dying. The feveral fpecies of infects, as a fly, a fpider, and an ant,
do not differ more evidently from one another, in regard td appearance, than do a caterpillar, its chryfalis, and a butterfly produced from it ; yet it is certain that thefe are all the pro- duct of the fame individual egg ; and nothing is more certain than that the creature which was for a while a caterpillar, is, after a certain time, zckryfalis, and then a butterfly; Thefe great changes produced in fo Hidden a manner, feem like the metamorphofes recorded in the fables of the antients, and in- deed it Is very probable that thofe fables firft, took their origin from thefe changes. It appears in thefe cafes, that an infect is immediately transformed into another perfectly different in- fect, and this was for a longtime fuppofed to be really the cafe; better obfervationj however, and the more improved modern philofophy informs us, that nature does not ufe any fuch vio- lent and fudden changes in any of her operations. Malpighi and Swammerdam were the firft whotraced the animal throuoh. all its feveral forms, and they focn found that there was in. reality no fuch change as was here talked of, but that the crea- ture remained the fame in all : they diffected the creature a little before the times of their feveral changes, and found that the whole fuppofed metamorphofis was due to the firft Sale's being a fort of cafe,' under cover of which it was necef- fary that certain parts, hereafter to become neceifary to the animal, fliould arrive at their proper Sate; and that thefe parts were very diftindt in the body of the animal at the time that it threw off its outer coat, in order to appear in another form, in which they had a better opportunity of becoming as dry and hard as they ought to be, and to be prepared for their final appearance in the open ftate of the flying infect. They evidently faw and proved, that the butterfly was all the time alive and growing within the body of die caterpillar, and that this growth was effected by a developemeut of parts, as we fee to be the cafe in all forts of organized bodies, in the veget- able as well as animal world : and while they threw off all the falfe marvels of the transformations and changes which the world had before believed, in regard to thefe animals, they gave matter enough of real admiration in the difcevcry of the ' truth itfelf.
The words transformation and metamorphofis then are found to be falfe terms in thefe fubjects ; but as we have already explained the true fyftem of the whole, we may be allowed to ufe thefe ftill, as the moft received terms, for thefe fudden changes.
Every animal of this kind, we find, undergoes two of thefe transformations, the one out of the caterpillar into the chry- falis, the other out of the chryfalis into the butterfly. The laft of thefe, when properly coniidered, has nothing very won- derful in it, as we find, on an accurate inflection, that the. chryfalis itfelf is a butterfly, only folded over with a thin flan. We find in it, while yet in this ftate, every part of a butter- fly j the wings, the legs, the antennae, and die trunk may be all traced out ; but they are folded and laid together in fuch a manner, that the creature cannot in this ftate make any ufe of them, nor is it fit that it fliould, as they are all of them yet too foft and tender for ufe, and are placed in this ftate with no other intent, than that they may be by degrees hardened. The back of a chryfalis, when nicely obferved, fhews us the origin of the wings - t and we may count in it the number of rings of the body. It is cafy to find that there are nine of thefe rings ; there are therefore three wanting of the num- ber that the caterpillar had : thefe are the three at the ante- rior end, and of thefe the third, or that moft diftant from the head, is in part Ccen and in part hid by a cruft, which is not divided in an annular manner, but which takes up the place of the two firft rings; this is ufually called the corcelet, in the chryfalis, becaufe it is found to lie over the corcelet of the body of the enclofed butterfly: but it is on examining the other fide, or belly of the chryfalis, that we find the feveral parts moft peculiar to the butterfly. This part of the chryfalis is always carved as it were in relief, and every figure of this work 'is fome part of the animal. Two plates, larger than all the reft, which have their origin at the corcelet, and either touch or nearly meet one another on the belly, are the elevations form- ed by the four wings ; thefe are placed two on each fide, and have a much fmaller extent allowed them than they have after- wards, when the animal is at liberty to fly about. There re- mains a triangular fpace between the origin of the wings and the place where they meet in a point, and this is the recep- tacle of the parts, of the utmoft confequence to the animal. In this part one may eafily trace nine ftreaks, running longitudi- nally from the top, or head part, toward the tail ; thefe are the legs, antennas, and trunk, of the butterfly, which are ail extended ftrait along the belly, in this ftate; thefe are all much fhorter than when die animal is in its perfect ftate ; and the trunk, when the chryfalis belongs to a fpecies that has one, is not rolled up into a fpiral form, but lies at length in the middle between the antenna and pairs of Je?s. The parts being thus diftinguiihable in the chryfalis, we eah> Iy find the difference of the fpecies or clafs oi the fly that is to proceed from it. The naked eye fhews whether it be one of thofe that have, or of thole that have not a trnnk, and the afliftance of a microfcope fhews the antenna: fo diftinctly, that we are able to difcern whether it belongs to the day or ni«ht clafs i and often to what genus, if not the very fpecies : nay.
