Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/778

 W I N

W I N

Among the two-winged flies, the great blue flefh-fly, and 'the common fly about houfes, give us mffances of this. The Wings of others crofs one another on the body of the creature, and the degrees in which they cover one another, give occafion to feveral other fub-di (Unctions ; for fome of them over-hang on each fide the body of the animal, while others crofs one another, in fuch a manner as not to cover the body of the fly entirely, but leave a rim of it vifible and unco- vered on each fide of them. Some of the flies bred of water- worms have their Wings in this manner. Others have their Wings thus difpofed, but crofflng one ano- ther only in a part of their furface, and that at their extremi- ties ; fo that though they there cover the body of the fly, they leave a portion of the anterior part of the body naked. The Wings of other flies not only crofs one another on the body of the animal, but they round themfelves there; thefe are not exactly parallel in their fituation, but the upper Wing is more elevated on the middle of the body than on the fides.

Some flies have their Wings placed upon their backs, and ap- plied againft one another. Thefe are in a perpendicular poii- tion; and feveral of the fmaller fpecies of libellze, and winged pucerons, are of this fort ; as are alfo the ephemerous, or day-flies.

The Wings of other flies are applied obliquely againft their fides, and meet above the body by their inner edges ; thefe form, by their junction above, a kind of hollow roof, under which the body is placed. The flies produced from the puce-

. ron-eater, and the formica-lco, are of this kind. Reaumur's Hift. Inf. Tom. 4. p. 136.

Other flies have their Wings thus applied to their fides, and, inftead of riiing erect, bending themfelves at their meeting upon the creature's back, and forming a flat depreffed roof over the body. Of this kind are the Wings of many of the flies produced from water-worms. Ibid. p. 137. And finally, there are fome of the flies which carry their Wings in an oblique direction, but have them meeting under their bellies. Thefe are placed exactly contrary to thofe which form a kind of high roof over the creature's back ; and of this kind arc the Wings of that elegant fly which is produced from the cherry-worm.

The ftru&ure of the Wings of different flies might alfo furnifh matter of farther diftinctions. The greater part of them are of a fine ftructure, and repreient the fined: gaufe, and are equally tranfparent, or nearly fo in all parts. Some flies, however, have Wings of a lefs degree of tranfparence, and fome even opake ones a. _ Others of the four-winged flies have obfeure fpots alfo diffributed near their very tranfparent texture ; fuch are the wings of the fcorpion- fly ; and fome of the two- winged flies have Wings partly opake, partly pellucid, the opake fpots being feparated by tranfparent lines b .— f Ibid. p. mi. -Ibid. p. ,38.]

wings of Butterflies. The beautiful Wings of this genus of infects, are dtftinguifhed from thole of the fly-kind, by their not being thin and tranfparent, like them, but thicker and opake. This opacity in them is owing only to the duft which comes off" of them, and flicks to the fingers in handling them, and it is alfo to this duft that they owe all their beautiful va- riety of colours. The earlier naturalifts, for this reafon, di- itmguifhcd thefe infects by the appellation of fuch as had fari- naceous things. Reaumur's Hift. Inf. vol. 1. P. 1. p. 282. The uie of the microfcopc has taught us, that this duff is not the refult of fome other fubifance broken into fragments ; but every particle of it is a regularly figured body, made for the place and order it has in the covering of the Wing. The fevefal fpecies of butterflies, and even the different parts of the fame Wing, aftbrd'thefe bodies of different fhapes and figures. Moil of the authors who have written ofmicrofco- pic objects, have given the figures of the principal varieties of thefe, j but no one has given fo many as fioriani in his Micro- graphia, in which work the figures of the various kinds take up four quarto plates.

It has been the general cuftom of authors to call thefe feathers ; .but they arc by Mr. Reaumur, with much greater juftice, cal- led icales. Their ftruaure has no refemblance to that of fea- thers, for they are little flat and thin bodies, of more or lefs length, and always having a fhort pedicle which enters into the fubffance of the Wing. That part of the fcale from which this pedicle is propagated, is rounded in molt cafes, and very frequently the other end is rounded alfo. The whole fcale therefore in thefe becomes of an oval figure. Others have a little dent in the middle of the end, oppofite to the pe- dicle, by which they are made to refemble the fhape of a heart at cards, and many of them are not abfolutely flat, but are more or lefs hollowed on the under fide ; And the ends, which are in fome plain and ftrait at the edges, are in others indented or jagged, and in fome cut into fmall and elegant fegments. The indentings of fome are but few in number, and thefe re- femble the fingers of a hand fpread open, the body of the fcale reprefeming the palm ; in fome, thefe fingers terminate in fharp

. points, in others they are more obtufe, and in fome there are only three of thefe to each fcale ; in others there are as far as eight ; feme are regular triangular blades, and have their bafe very fhort, m comparifon to the length of the fides ; but this

is varioufly cut and indented in all the manners before fpoken of. In fome thefe jags at the end feem propagated all along the fcale, and form in it fo many ridges, elevated above the reft of the furface on the upper fide, and hollowed on the un- der. Thofe which have thefe elongated ridges, have ufually alfo a lib running down the middle through their whole length, as the leaves of plants have, and the pedicle is in thefe fcales as in the leaves of vegetables, only an elongation of this middle fib.

Befide thefe, which are the more ufual figures of the feathers or fcales of the Wings of butterflies, there are fome others ex- tremely different, and which neither Bonani, nor any other author has given the figures of till Reaumur. Thefe have lefs title to the appellation of Icales than any of the others, and at firft fight might feem indeed to have none at all. Their pe- dicle is fo long and flender, that they might be miftaken for hairs ; but that each of them is terminated by a fmall flat plate, which is fplit a little way down the middle, and in all refpects refemblcs the fcales before defcribed, which adhere to their fhort pedicles. There are, however, fome of this laft kind, which can by no means be called fcales. What, in thofe de- fcribed above, is a flat plate placed at the end of a very long and flender pedicle, is, in thefe, only a divifion of the extre- mity of the long capillary pedicle, into four or five parts, which have not breadth enough to entitle them to the name of fcales. Reaumur's Hift. Inf. vol. 1. P. r. p, 255. The diftinction in names in thefe matters, is abfolutely necef- fary, and the calling thefe bodies, ufually termed feathers, fcales, cannot well be avoided by an accurate obferver, be- caufe there are, in fome of the butterflies, fome parts which are covered with real feathers, fome other parts have only hairs, and fome others fcales ; all thefe have been called fea- thers by fome ; but they are fo different in themfelves, that they well deferve different denominations. Befide all thefe, fome parts of fome of thefe creatures are befet with real prickles, and fometimes even the fame part, in the fame ani- mal, is jointly covered with all thefe feveral forts of inveffures. When the Wing of a butterfly is viewed by a microfcope, the arrangement of thefe feveral bodies in it is feen to be extremely beautiful and regular. The fcales lie as regularly and evenly one over another, as the tiles on a houfe, or the Icales on the fifh-kind, every feries of them covering a fmall part of that feries which runs below it. The upper and under part of the Wing are equally furnifhed with thefe, and there is no fpecies of this creature, in every Wing of which there are not feveral figures of thefe fcales in feveral parts : But the greater part of the furface, a little diftant from the edges, has only one fort in moft fpecies. But this kind is different in the feveral fpe- cies ; in fome we only find the plain oval ones, in others the cordated, and in others thofe which are divided at the end, in the manner of the fingers of a hand. In other fpecies the Wings make a lefs elegant appearance, though more loaded with thefe fcales ; for the feveral feries of the beautiful forts of fcales which have been before defcribed, are in thefe buried under other very thick feries of thofe which have long capillary ffems, and appear only like fo many hairs. The extremities of the Wings of thefe infects appear to the naked eye as if bordered with a fort of fringe ; but, when examined by the microfcope, this fringe appears to be compofed of a number of oblong fcales, of the nature of thofe triangular ones before-defcribed, which have very narrow ends, in proportion to the length of the fides, and thefe ends are varioufly fingered. The ftru&ure of the Wing itfelf, which fupports thefe feveral fcales, hairs, &c. is very worthy our attention. In order to examine this,, it is neceflary to rub off all the duft or fcales. We then find that the Wing itfelf is framed of feveral large and ffrongribs, which all take their origin at that part where the Wing is fixed to the body, and thence extend themfelves along the feveral fides of the Wing. The largeft and thickeft of thefe furrounds the outer edge of the Wing, the largeft next to this extends itfelf round the interior edge, and the others direct their courfc along the middleof the Wing, and then divaricate and become ramified in the manner of the ribs in the leaves of plants. The fubffance which connects and fills up the fpaces between thefe ribs, is of fo peculiar a nature, that it is not ■ eafy to find any name to defign it by, at leaft there is no fub- ftance that enters the compofition of the bodies of the larger animals, that is at all analogous to it : It is a white fubffance, tranfparent and friable, and feems indeed to differ in nothing from that of the large and thick ribs, but in that it is extended into thin plates ;. but this is faying but little toward the determining what it really is, fince we are as much at a lofs to know by what name to call the fubffance they are compofed of. Mal- pighi indeed calls them bones ; but though they do ferve in the place of bones, rendering the Wing firm and ftrong, without making it heavy, and are, when cut tranfverfely, found to be hollow ; yet, when ffrictly examined, they do not appear to have any thing of the ftructure of bones, but appear rather of the fubftance of fcales, or of that fort of imperfect fcales, of which the covering of thofe infects which we call cruftaceous is compofed. Reaumur's Hift. Inf. vol. 1. P. 1. p. 259. Be this fubffance however what it will, it admirably ferves'the office nature feems to have intended it for, making the PPings at once very light and very firm ; and the millions of, final!

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