Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/795

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ferent in different fpecies of the felfe caterpillars, will very properly furnifti matter for the fubordinate diftinctions of the genera.

A firft genus may be very properly eftabliftied of thofe which have no more than eighteen legs in all ; that is, fix crufta- ceous, and twelve membranaceous.

A fecond may be of thofe which have in all twenty legs ; and a third thofe which have twenty-two legs. The fpecies may be fufficiently diftinguifhed by their colours, and by their attitudes, which are very different in the different fpecies, and very conftant in the fame : Some of them always carry the hinder part of their body elevated, others are conti- nually rolled together ; and finally, others always extended;. The greater part of the falfe caterpillars are fmooth ; but there are, however, fome which have a very fingular fort of thorns, arranged with great fymmetry.

It might perhaps not be improper to arrange the thorny ones into a diftinct clafs, which, according to the figure and order of the thorns might be again fubdivided into feveral genera. Ibid. p. 1 86.

GW/y-WoRM. "J fGALLY-^orW.

GIozu-Worm. Glow- Worm.

Gnat-WoRM. Gnat.

Goofcbeny-W orm. Gooseberry.

//izy-WoRMs. Hay.

Horfe-WoRMs. Horse.

Lyfmacbla-W orms. )*See the article^ Lysimachia.

Muforoom-W orm. Mushroom.

Oj//i?r-WoRM. Oyster.

Pile- Worms. Pile.

Sbeep-Nofe- Worms. Sheep.

M-Worm. Silk.

Truffle-WoRMS. -J LTruffle.

Meal-WoRM. There are two very different infects found in our meal or flour ; the one is- fo fmall, that it is only to be feen by the microfcope ; all that the naked eye can difcover of jt is, that fomething is alive in the place, from the whole fub- ftance of theflour being in motion. See the article Flour. The other mcal-Worm is larger, and more frequently offers itfelf to our obfervation ; it confifts of eleven rings, and has three pairs of legs. The mouth of this Worm is made into a kind of forceps, and from this arife, on each fide, a great number of fmall fpinula? ; thefe ferve inftead of teeth, and the animal feeds by means of them. They are found fometimes very foft and tender, fometimes hard and firm, and at other feafons they are very brifk and lively ; at others they have fcarce any life in them.

The molt remarkable thing in regard to thefe Worms, is, that they are always exactly of the colour of the flour which they live among. Ray has obferved, that the white flour breeds white ones ; the coarfer flour breeds larger and greyer ones ; and that flour which has the bran among it, breeds brown ones, of the fame colour with itfelf. This is a pro- vifion of nature for the fafety of the animal, fince were it of a colour different from that of the flour, it muff be eafily difcovered among it, and would be picked out and thrown away. The caterpillar tribe are thus preferved, by being of the colour of the leaves they feed on ; their green, ufually fuking itfelf exactly to that of the tree or plant. Dcflandes, Trait. Phyf.

Worms of the Sea. The fca-Worms are of the number of thofe animals, which with the oyfter, and feveral other ftiell-fifh, fumifh us aninftance of animals which remain all their lives fixed In the manner of plants to one fpot, whence there is no pro- bability of their moving themfelves.

Thefe Worms are included in a fort of cafes or pipes, and may be divided into two clafles, according to the nature of thofe cafes. In the one fpecies thefe are only made of grains of fand, fragments of fliells, and the like, fattened together by a vifcous humour ; and in the other they are compofed of a true fhelly matter.

Thofe Worms which have fhelly cafes, are fixed fometimes to the fand at the bottom of the fea, fometimes to ftones, or fea plants, and fometimes to the fhells of other fifties; their fhells are rounded, and, in fome degree, conic, as they always gra- dually grow wider from their point or apex to the mouth ; as to the reft their fhape is different in almoft every individual, forming divers irregular curves, and often refembling the fhapes into which a common earth-Z^rm curls and twiffs it- felf in its various motions.

In order to know how thefe fhells become fo exactly faftened to the bodies on which we find them, it will be neceflary to confider the manner in which they are formed. The creature, when juft produced, is covered with a fhell but this fhel! no longer covers its whole body ; as it grows, new fhell is formed over this, from the condenfation of its own juices, and this fixes it down as it grows to the body, be that what it will, on which it is formed ; and as the Worm, in its growth, twifts itfelf varioufly about, it will be fixed down in that pofture by the new-formed fhell which covers it, and which adheres as well to the body on which the Worm lies, as to the old fhell.

The marine- Worms of the other kind, which are not regular fhells, but whofe cafes are made up of fragments of different bodies, and of grains of fand, live in the fame manner with

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the others, their whole lives in the fame hole. Thefe crea- tures bury themfelves in the fand of the fea, as the common earth-#^r?/w do in the earth ; and the glutinous matter which efcapes continually from their pores, not being either fufficient in quantity, or of a nature to harden into a perfect fhell ofit- felf, yet ferves to faften together the feveral fmall bodies that come into contact with it all about the body of the creature ; and fervc as a fort of mortar to cement together a multitude of little ftones, i$c. and of this connected mafs to form a coarfe fort of covering for the animal, which defends it from the common injuries.

7 he force of this vifcous or glutinous humour flowing from the bodies of thefe Worms, is very evidently feen in places in- habited by them, when left dry by the ebbing of the tide ; the furface of the fands, in thefe places, appears rough and ragged in a very fingular manner. The pipes in which thefe Worms are lodged, are ufuaily placed in great numbers near one ano- ther, and their ends all ftand out about an eighth of an inch above the furface of the fand ; and the reafon of this is, that the whole fand-bank was, when covered with the water> of a level with the mouths of thefe pipes ; the fea, in its recefs, has carried off about an eighth of an inch of the furface of the fand with it; but though it has done this every where, where the fand was loofe and free, it has not been able to do it where it was glued together by the vifcous juices of this animal, but has left fuch part of it handing out in form of pipes or cafes to the animal.

1 he ftrength of this glue is alfo feen in the common accident of thefeas wafhing off a piece of a fand-bank, in which they dwell ; in this cafe the fragment is found at fome diffance, with the interfficia! fand every where wafhe-d deep away from the . furface, but with the cafes of the Worms remaining prominent, and being perfect and unhurt at full length, with all their con- volutions.

Sometimes alfo thefe pipes or cafes are found perfectly detached from all fandy matter, and lying luofe on the bottom of the fea; in this cafe the glutinous juice, cementing the outer fur- face, being much weaker than that which keeps together the more internal part, much of the fuperficial coat is often worn away; nay, fometimes the cafes arc not thicker than apiece of writing-paper, yet ftill preferving their whole figure, The internal furface of thefe pipes is always perfectly fmooth, even, and polifhcd, which is wonderful, as they are compofed of fuch rugged particles as, one would think, could not eafily furnifti a fmooth furface ; but doubtlefs the mucous or vifcous humour of the animal fills up the mterftices between the par- ticles, and, by degrees, hardens fo far as to make one even furface with their prominent ends.

The Worm which inhabits thefe cafes is of a very fingular fi- gure; it is about an inch long, and of the thicknefs of a large wheat ftraw ; its head is of a very odd ftmcture ; it is rounded and flat, and is much broader than any other part of the body. At certain times the extremity of the head is of this round figure, and is divided into three parts ; that in the mid- dle is of an oval figure, and hollow ; the next to this is a circu- lar zone or band which furrounds this oval part ; and the third part is another circular zone, extended behind this laft ; on both thefe zones there arc a great number of lines marked, which feem a fort of rays, running from the center to the circumference.

Though this is at fome times the figure of the head ; yet at others it is of a very different form, relembling a crefcent or a horfe-fhoe; for there is a certain part in the middle of the head, which the creature can open when it pleafes. A little below the head, it has three oblong flender bodies, which ferve as oars on each fide ; its body approaches to a conic figure, and is terminated by a long tail ; all along the body there are placed, at different diffances, little flefhy pro- tuberances fhaped like hooks, which bend toward the tail. Thefe are placed in three ranges, and feem intended to ferve the creature in the place of legs or arms, when it has a mind to move upward or downward in the fhell. When we confider the effects of this glutinous juice iffuing from the body of this animal, in fattening together any toofe fubftances it meets with, fo as to form a cafe for it, it may be eafily fuppofed that the adhefion of the batam-marim, and other the like fhells, which remain all their lives fixed to fome one fpot, is performed in the fame manner. Mem. Acad. Par. 1711. flfater- Worms. There is a fingular fpecies of thefe creatures, which is found to be capable of reproduction or multiplication from cuttings, in the manner of the polype. Thedifcovery Mr. Trembley made of this ftrange property in the polype, gave occafion to the trying the experiment in re- gard to fome other infects. Worms were the moft natural ob- ject of thefe experiments; and though they failed in many fpe- cies, they yet iucceeded in feme, and proved, that nature has not given that amazing property of re-prod uction of its moft efiential parts, to one only fpecies of animals. Mr. Bonet tried the experiment on a very nimble kind of water-Worm, by cutting it in two in the middle, and the fuccefs perfectly anfwered the expectation ; for tbe-two pieces continued alive and vigorous, and in a little time became two complete Worms. The ftructure 'of thefe Worms, though it appear fimple to the naked eye, is very worthy the examina- tion