Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/789

 W O R

W O R

fcaly ; their body long, and fomewhat flatted, and is com- poied of eleven rings ; the laft of which is lefs flatted, and longer than any of the reft, and in one fpecies of thefe Warms is as long as five or fix of the other rings, though ■ it is not fo in others. Reaumur's Hill. Inf. Vol. 4. pag. 310.

The firfi: ring in thefe Worms is of a fomewhat fmaller dia- meter than the fecond ; this is of a fmaller than the fuc- ceedingone; and the three ] aft, or next the tail, are of a fmaller diameter, but more length than the others. The fkin of this Worm is confiderably tough and ftrong, though not cruftaceous but pliable and flexile like a piece of parch- ment ; and at the commifTure of the rings, the anterior has a fort of appendix which falls over that it joins to. They ibmething differ from one another in colour, fome are of a greeniih brown, others of a clearer brown, and o- thers of the greener kind are veined with brown, and of the browner with yellow ; they have no legs, but have fome cruftaceous hooks in their places under their belly, and thefe fo fmall as not to be diftinguifliable unlefs carefully looked for, and then only at the junctions of the three lair rings. Ibid. p. 311.

As one finds thefe Worms in the fame ftate and fame readi- nefs to undergo their metamorphoiis, fome only of feven or eight lines long, and others of three incites, there can be no doubt but thefe are of different fpecies. Thefe are fel- dom extended to their full length in the water, nor have they much power of contracting themfelves, or making one ring enter into another 3 but they can bend their bodies up- ward and downward at the junctions of all the rings. This is of the kind of Worms which have no teeth, proper- ly fo called, but many of its fpecies have a coniiderable number of fiefhy hooks. Others have but a few, and be- fide thefe they have a fcrt of beards. The end of this beard is larger than any other part ;, and the inject throws them out from the under part of i is head, and draws them in again at pleafure, with great fwiitneis ; and when they are out, it moves them backward and forward- with great fwiftnefs : The ends of thefe examined by the microfcope, fhew themfelves to be covered with duffers of hairs. Ibid. p. 112.

There are in this fpecies two fpots, a little browner and more poliihed than the reft of die fkin, placed one on each fide the head, which have fomewhat the appearance of eyes, at leaft the creature does not appear to have any if thefe are not fo. Ibid. p. 313.

At the extremity of the head there is a little flefhy protu- berance, which is probably either a mouth, or tucker, by which it takes in its nouriihment.

Notwithstanding that this is naturally an aquatic animal, it is however necefiary to its life, that it ihould breathe. For this purpofe, the laft ring of the body of thefe Worms is open at the end, and ferves them in the place of the poste- rior ftigmata, in others of the Fly-worms, The extremity of this ring is frequently to be feen on the furface of the water ; and about it there is always feen a fort of funnel made of a vaft number of hairs that grow there, and di- verge on this occaiion into this form.

Each of the hairs that forms this fort of funnel, is itfelf a fort of beard, furnifhed with numbers of fhort hairs on each fide ; and the ufe of the whole is to prevent the water from getting in at the aperture made to admit the air. If any doubt couid be had of the creature's refpiring by this means, it would be extremely eafily cleared by a iirnple and eafy difleition of the creature, feparating its belly from its back; for one then diicovers two large veilels running the whole length of the body, and filling up a great part of its fpace ; theie arc the two great tracheae ; they arc inlerted near the head, where probably the anterior ftigmata, are placed, and running through the body join and are inlerted again at the tail. Ibid. p. 314.

It is ftrange, that a creature like this, an inhabitant of the water, ihould be deftined in its fucceeding ftate to be an inhabitant of the air ; but it is evidently fo, this Worm tranf j forming itfelf into a two-winged fly. When one knew however that this was to be the cafe, one would naturally imagine that fome long-bodied fly of the libella kind, or fome other fuch fhould be the laft change of our long Worm ; but, on the contrary, the production is a very fhort- bodied fly; nor is this at all more wonderful than the cafe of thofe libellas, fome of the longeft bodied of which are im- mediately before their egrefs into that ftate in the form of very fhort Worms. Ibid. p. 317.

What is farther a great Angularity in this creature, is that when it changes into the fly, and at any time before that ftate, it undergoes no change in its exterior form, nor can the time of the change be at all forefeen ; and what is yet more Angular, the creature when it has undergone its change, and is no more living but in the ftate of a fhell to the en- clofed fly, is no way diftinguiihable by the eye from the livin? Worms, nor can be diicovered but by the touch. The difference then indeed is eafily perceived, as the living Worms are foft and flexile, thefe ftiff and rigid, and incapable of moving themfelves. It is no uncommon thing for the laft Suppl. Vol.. H.

ring of the body to be turned up, and make an angle with the reft, even in this ftate ; and often the. ninth ring in the fame ftate makes an angle with the eighth, but in a con- trary direction to the other. The Worm while living fre- quently makes alfo thefe angles, but then it changes them as it pleafes ; whereas, in this ftate, they are become im- moveable. Ibid. p. 318.

When therefore we find, among a number of thefe Worms, fome that are ftifF and rigid, we may determine that thefe have loft their original form, and that their fkin now only ferves them as a fhell for their transformation. When. this is the cafe, there is no infect, which fo .foon accomplifhes its changes. Thefe Worms frequently within five or fix days from the time of their fiift becoming ftifF and rigid, are transformed into flies.

The nymphs of this fly takes up -only a fmall part of the fhell made by the flsin of ti^e Pffarm, all the laft, rings, and part of the firft remaining empty, the middle ones only being occupied by the nymph. It is not impoffible, how- ever, but that thefe vacant fpaces may have their ufe, and may be neceifary to give paifage to the air, without which the embryo dy would perifh. Ibid. p. 319

Worms, called AJcarides. The name ijcarides is given by Mr. Reaumur, to a fort of fmall Worms or maggots, bred from the eggs of winged animals ; which bury themfelves between the membranes of the leaves of plants, and there eat away the parenchymatous fubftance. Thefe are a xtry minute fpecies of animals, and the fmall fpace of the infide of a leaf allotted for the place of their residence, is to them a vaft extent of country; and they .eat it away at various times, and in dint rent manners ; fpme eat very flowly, and only burrow themfelves a way in con- torted holes or cells ; thefe he calls 'jfajj&es ftarvu „■ Others eat more varioufly, devouring all that lies before and round about them, and not burrowing in different directions ; thefe laft are called fojjbies magni.

Thefe differ greatly one from another, and indeed are .the Worms of different animals ; fome afterwards changing into fmall butterflies, others into fmall flies of the common kind j but the manner of life- is the fame in all. The butterflies whofe eggs produce thefe, are extremely beautiful, glitter- ing with a multitude of gaudy colours, and with filver and gold among the reft ; but they are too minute to fhew their beauties to the naked eye. Thofe of the AJcarides, which do not in fine become butterflies, are two-winged flies,- or fmall beetles, in their ultimate ftate. As fmall as thefe AJ- carides in general are, they do not fail to fhew the proper characters, by which they may be reduced to regular claifes : Thofe which have had their origin from the eggs of butter- flies, are truly and properly caterpillars in miniature ; the o- thers are maggots, from flies ; and if from beetles, they are hexapode Worms. Of the little caterpillars, fome have fix- teen feet, fome only fourteen ; and fome of them are per- fectly fmooth and equal all over the body ; others have a number of rings or annular divifions, like the larger cater- pillars, their feveral changes for the arriving at the fry-ft'ate are the fame with thofe of the common filk Worm, and o- ther fpecies of large caterpillars.

The ovula of the parent butterfly are depofited fingly,. only one being placed on a leaf; for the little caterpillar is- of the nature of the folitary, not the gregarious animals. Thefe eggs are fo fmall, as to be fcarce vilible, except to an ob- ferver fo accurate as Mr.. Reaumur ; but he not only dif- covered them lying upon the leaves of plants, but traced them to the time of their hatching ; and obferved this cu- rious particular, that the caterpillar never enjoys the light or free air, but as foon as ever it is hatched eats its .way through the integument of the leaf; 'and^ under th ; cover of its fhell, buries itfelf among the parenchymatous matter, whence it. never comes out again till it arrives at the -fly ftate.

The Worms which are hatched of the eggs of flies, make their way as fpeedily into the fubftance of the leaf; but with this difference in the manner of doing it, that as the caterpillar eats its way. through with its teeth, the Worm ftrikes its head forcibly againft it feveral times, and by re- p ated blows at length breaks a hole in it, large enough to admit its little body ; and then feeds on the parenchyma of the leaf, in the fame manner with the caterpillar. Thefe finally change into their chryfalis ftate, within the covert of the membrane of the leaf.

The laft. kind of AJcarides which are to become beetles, make their way into the fubftance of the leaf in the fame manner ; and when they have fed their deftined time upon its parenchyma and juices, they fometimes change in the covering of the membrane, and fometimes come out of their holes and choofe the furface of the leaf for the fcene of this great cataftrophe. Reaumur's Hift. Inf. Tom. 1..

Bee-WoKM, the name given by naturalifts to the fmall white Worm, found in the cells of the honey-comb, and afterwards changing into a bee, in the manner of the white maggots, found in meat, tic. which, after a certain change, into a ftate of reft, become transformed into flies, like thofe t* which their eggs owe their origin.

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