Page:Cyclopaedia, Chambers - Supplement, Volume 1.djvu/690

 EYE

EYE

bleed plentifully ; this {hould be promoted by fomenting the Eye with a fpunge dipped in warm water. Heifter's Surgery, p. 379.

When the operation is over, great care is to be taken, that the wounded parts do not cohere together ; the patient muft move the eyelids about at times to prevent this, and the eye, ■when bound up at night, muft have a piece of gold-beater's fkin applied between the eyelids and the Eye. ■Many different inftruments have been ufed for the making the fcarification. Hippocrates ufed a prickle of a thiftle, and Celfus and iEgineta, a fteel rafp. Others have chofen the ftalks of the naked horfetail, called fhave-grafs, which do very well ; but the beft of all inftruments is a beard of barley or rye ; thefe beards are furniflied with rows of (harp teeth or hooks, and ten, twelve, or fifteen of thefe, are to be cut, and tied together by a firing, fo as to referable a brufli, the teeth of each beard being turned outward all round. Their flender ends, in this cafe, form a fort of handle, by which the body of the brufh may be moved about.

ContuJiens'oftbeEYE. When the Eye is, by any accident, con- tufed, it will be entirely deprived of fight, unlcfs the contufion be flight, or the proper remedies inftantly applied. If the Eye fmve received a very flight contufion, it will be proper to walh it frequently, for die firft day, with cold fpring water, laying on it linnen rags, wet with the fame : On the next day it muft be rubbed externally with camphorated fpirit of wine, and ■covered up with ftuphs wrung out of decoctions, made in wine of eye-bright, fpeedwell, hyfibp, fage, chamomile flowers, and fennel feeds ; but if thefe things are not to be had, bolfters dipped in warm wine muft be applied, and renewed very often, and, if the patient be of a plethoric habit, bleed- ing is alfo ncceflary. If the contufion of the Eye is fo violent, that you can plainly fee the extravafated blood thro' the cornea, and all objects appear red to the patient, a vein muft be opened either in the foot or neck, the Eye muft be kept con- tinually fomented with warm ftuphs, wrung out of the fame decoctions as are before mentioned) and the feet muft be bathed in warm water two or three times a day, and a few drops of pigeons blood muft be, two or three times a day, put into the Eye; and if all thefe attempts prove fruitlefs, you may very probably fucceed, by making an opening in the cornea with a lancet. Heifer's Surgery, p. 97.

Wounds of the Eye. If the Eye is wounded, but not fo as to let out the vitreous or cryftalline humour, the wound muft be anointed two or three times a day, with a feather, or fine rag, well dipped in the white of an egg, or elfe in a mucilage made of quince feeds, or of fleawort feeds, in rofe water; and, after each drcfling, a comprefs is to be laid on, well faturated with a collyrium, made of the whites of eggs. N°. 2. Two ounces and a half of rofe water, half a dram of oil of rofes, and three grains of camphor, well mixed together, and tho- roughly fliook up every time it is to be ufed. If the accident is attended with any great degree of inflammation, as is very frequently the cafe, it will be proper to cover the final] com- prefs, firft laid over the Eye, with a larger, dipped in warm fpirit of wine, with camphor. The bowels muft, in this cafe, be kept open, and the patient blooded, if of a plethoric habit. And if it happen, that the cryftalline humour, or any part of it, fticks in the orifice of the wound, it muft, in this •cafe, be pulled out, that it may not bring on a deformity, or worfe mifchief, to the .Ey*. iaW/?*r*s Surgery, p. 80.

Falling out of the Rye. See Prolapsus Oculi.

Eyes of Fish. Thefe differ fo much in the feveral kinds, that they make a very eflential part in their defcription, and often are cha- racters fufficient for the diftinguifliing the (pedes. Their dif- ferences are in regard to their figure, fituation, proportion, and integuments. In regard to their figure, fome are flat and deprefled, as is the cafe in the greater number of fifties. 2. Some are convex, as is the cafe in the plcuronedti of many kinds; the Eyes of thefe much refemble thofe of quadrupeds, the others are very different. 3. Some are rounder than ordi- nary, as in the Cyprini, conger and petromyzon ; and laftly, ■fome are oblong, as the Eyes of the eibces. Jrtedi, Ich- thyolog.

Thefe are the differences of (haEyes of fiih, as to figure : In re- 'gard to their fituation they alfo differ as much : 1. In moft fiih they are placed hi thefides of the head; inftances of this pofition are fufficiently common. 2. In fome they areplaced both in the upper part of the head, as in the uranofcope, or ftar- gazer. 3. They are, in fome, placed very clofe to one another, as in the pleuronecti, and, in others, they arefet at very remarka- ble diftances, as in the clarise. They differ alfo greatly in proportion, in icfpedt to the body of the fiih. Thus they are very fmall in the whales, and other cetaceous fifties ; and they are as remarkably large in the apua, boops, and gafterofteus. The Eyes, in fifh, differ alfo greatly in regard to their integu- ments. In fome fifh they are free, and are only covered with their proper membranes, as in the falmon, cyprini, cifV. a. They are, in fome, covered in part with the fkin of the head, as in the clupea, mackrel, &c. 3. In fome they are wholly covered with the fkin of the head, as with a fort of veil. Examples of this kind there are in the fyngrathi, pleu- ronecti, petromyza, and others. The pupil of the Eye is, in mod kinds of fifh, either round

or oblong ; but in fome, as in the falmons and coregones they run out into an acute angle in the anterior part. The colour of the iris, in feveral fifh, is fo very diftinct that it makes a very obvious and diftinctive character. The Eyes of almoft all fifti are without eyelids, properly fo called ; but feveral kinds have, befide the membranes, and common tunics, 1 a fort of tranfparent membrane, with which the Eye is in part, at times, covered. _ The cetaceous fifties, in particular, feem to have real eyelids: Tyfon has demonftrated them in his accurate and excellent anatomy of the phoexna. Eyes of Flics. Every natural'ift has obferved, that the Eyes of flics are of a reticulated texture ; and each reticulated Eye, of this kind, is truly an aflemblage of multitudes, often of many thoufands of fmall but perfect Eyes. The reticulated Eyes of flies are large, not only in proportion to the fizc of the crea- ture, but abfolutely and in themfelves. But the feveral fmall Eyes, of which they are compofed, are remarkably minute, in comparifon with thofe of the butterfly clafs. Many of the butterfly clafs have, in each of their reticulated Eyes, many thoufand fmall Eyes ; but the fly clafs greatly exceed them in number of thefe, as many of the tyes of thefe are three times as large as thofe of the butterflies, and befits, that each fmaller Eye is vaitly more minute than the fmall Eyes oi the butterflies.

That part of each lide of the head of a fly which is cut, as it were, into a multitude of fmall facets, is one of the reticulated Eyes of the creature, and is ufually fomewhat elevated above the furface of the reft of the head, but differently, and of a different form and extent in the feveral different flies. Reau- mur's Hift. Inf. vol. 4. p. 239.

It is the cuftom of nature to allot two of thefe reticulated Eyes to each fly, and, as they each contain fuch a vaft multitude of fmaller but perfect Eye s y one would imagine this to be very fufficient for all the occafions of the animal. There are, however, notwithftanding, certain flies of the ephemeron, or day-fly kind, which have four of thefe reticulated Eyes, two of which are placed as is ufual in the fly kind, and are but of fmall extent ; the other two have each the appearance of a fort of turban, and are placed one befide the other, upon the upper part of the head.

Thefe have each much of the figure of a mufiiroom, the head of it extended a little beyond the ftalk, and the upper convex furface, cut into almoft an innumerable quantity of facets. Id. Ibid. p. 240.

The firft pair of the reticular Eyes of this fly, which are placed as thofe of the other flies, are, in colour brown; thofe of the mufiiroom form are of a very beautiful citron colour, and as tranfparent as the moft pellucid reticular Eyes of the other flies ; for, among the various fpecies of flies, fome have thefe Eyes much more tranfparent than others. The fly, thus remarkably furniflied with Eyes, is produced from a worm of the fame kind with the common fpecies of ephemerons ; its body is of a pale yellow, and its wings white; the two inferior ones of thefe are fo fmall, that they are not eaftly diftinguiftied.

Among the fly clafs, thefe reticular Eyes are, in different fpe- cies, of different colours ; there arc fome which have themi brown, others yellow, others green, and others red, and this in all the different fliades of thofe colours. Some of them have alfo the glofs of metals highly polifhed, others afford us a view of changeable colours, and others have arrangements of different colours, but thole fixed and inva- riable. Id. Ibid. p. 241.

The Eyes of one ipecies of the gad fly, fo troublefome to oxen, have ftreaks of red, green and brown, placed alter- nately.

One would imagine, that, as every fly has two of thefe reti- cular Eyes, each compofed of fuch a multitude of real Eyes y they could have no occafion for any Eyes befide thefe ; but fo it has not appeared to the great hand that formed them, for they have, many fpecies of them at leaft, other Eyes befide thefe.

The Eyes, already defcribed, are properly called reticular ones, and, to avoid confufion, it will be neceflary to know the other Eyes, which are extremely different from thofe, by fome determinate name. Thefe other Eyes, when examined by the beft microfcopes, appear of a perfectly fmooth, glofly, and poliflied furface, but plain and fimple, without the leaft appearance of a reticulated texture. Thefe are alfo much fmaller than the reticulated Eyes, and may therefore be called, by way of diftinction, the fmaller Eyes, or the fmooth Eyes. Reaumur's Hift. Inf. v. 4. p. 241. Mr. De La Hire feemstohave been the firft perfon who difco- vered thefe little fmooth Eyes, in the fly race. He obferved three of them difpofed in a triangular form, on the back part of the heads of thefe little creatures. When he found that three fmall convex fhining bodies were ufually fituated in this part, he foon difcovered that they were tranfparent, and thence naturally judged them be of the fame nature with the cornea: of our Eyes, and really to ferve the fame office to the creature poffefied of them. Id. Ibid. p. 242.

We find three of thefe fmooth Eyes placed triangularly on the back part of the head of vaft numbers of the genera of

flies,