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power of contraction and extenfion. The arms are not able to contract like thofe of the common polype; but, when the animal retires into its cafe, they are brought together in a ciofe and curious order, fo as to be cafily drawn in. Though their general appearance when expanded is that, of a cup whole bafe and top are of an horfe fhoe form, they fometimes feparate into four parts, and range themselves as in fig. 36. fo as to resem-. ble four feparate plumes of feathers. Though their cyes cannot be difcovered, yet Mr Baker thinks they have fome perception of the light: for when kept in the dark, they always remain contracted; but on being expofed to the light of the fun or of a candle, they constantly extend their arms, and how evident figns of being pleased. Fig. 29. reprefents one complete colony or bell ftanding erect, with all the animals out of their kingdom, and their arms extended, exhibiting all together a very pretty appearance. a reprefents two oval bodies, fuppofed by Mr Baker to be eggs. Fig. 30. shows all the creatures withdrawn into their cells, and the end of the bell hanging downwards. Fig. 33. fhows the bell erect, with only one of the animals coming out, in order to how its connection with the bell. Fig. 34. fhows the head and arms of a fingle polype clofing together, and difpofing themfelves in order to be drawn into the bell. Fig. 5. fhows one complete animal greatly magnified, to fhow its feveral parts more diftinctly; viz. a, the head, refembling a horfe fhoe; bb, the arms feen from one fide; c, the narrow neck; d, the afophagus, e, the ftomach; f, the gut or laft inteftine through which the food paffes after being digefted in the ftomach; g, the anus, where the feces are difcharged in the little pellets: bi, that part of the bell which furrounds the body of the animal, and clofes upon it when it retires down. Fig. 37. the head and arms feen in front.

water, with duckweed in it, ftand quietly for 3 or 4 hours in glafs veffels in a windows or other place whence a trong light comes: for then, if any are about the duckweed, they will be found, on careful inspection, extending themfelves out of their cafes, and making an elegant appearance. The bell, or cafe, which thefe animals inhabit, being very transparent, all the motions of its inhabitants may be discerned through it diftinctly. It feems divided internally into feveral apartmeats, or rather to contain feveral fmaller facculi, each of which inclofes one of these animals. The openings at the tops of these facculi, are but just fuficient to admit the creature's head and a fmall part of its body to be thruft out beyond them, the reft remaining always in the cafe. It can, however, cccafionally retire in its cafe altogether: and never fails to do fo when alarmed by any fudden motion of the water, or of the vetiel which contains it. Besides the particular and feparate motion which each of thefe creatures is able to exert within its own case, and independent of the reft ; the whole colony together has a power of altering the pofition of the bell, or even of removing it from one place to another; and hence this bell is fometimes found tanding perfectly upright, as in i'l. XI. fig. 29, 33. and fometimes bending the upper part downwards, as in fig. 30. As thefe animalcales feem not to choose to stay together in focieties whofe number exceeds 15, when the colony happens to increase in number, the bell ay be obferved to split gradually, beginning from about the middle of the upper or ante nor extremity, and proceeding downwards towards the bottom, as in fig. 32. till they at last fparate entirely, and become two complete coJonies independent of each other, one of which fometimes removes to another part of the veffel, The arms of each individual of this colony are fet round the-head, to the number of 40, having cach the figure of an Italic, one of whose hooked ends is faftened to the head; and all together, when expanded, compofe a figure fhaped fomewhat like a horfe's fhoe, convex on one fide next the body, but gradually opening and turning outwards, fo as to leave a confiderable area within the outer extremities of the arms. When the arms are thus extended, the creature, by giving them a vibrating motion, can produce a current the water, which brings the animalcules, or whatever other minute bodies are within the iphere of its action, with great velocity to its mouth, fituated between the arms; where they are taken in if liked, or driven away by a contra ry motion. The food is conveyed immediately from the mouth or opening between the arms, through a narrow neck, into a paffage feemingly correfpondent to the fophagus in land animals; down which it paffes into the ftomach, where it remains for fome time, and then is voided upwards, in fmall round pellets, through a gut whofe exit is near the neck. The body confifts of three divifions; in the uppermost of which are contained all the above-mentioned intestines, which are only to be difcerned when the creature is full, at which time they become opaque. The other two divifions, which are probably fixed to the bell, feem to be of no other ufe than to give the creature a

(9.) ANIMALCULE, THE BEROE. Mr Ellis, in defcribing this Animalcule, complains, that "the excellent Linnæus has joined the berce with the polvox, one of the animalcula infuforia. The beroe is a marine animal, found on our coafts; of a gelatinous transparent nature, and of an oval or spherical form, about half an inch to an inch diameter; divided like a melon into longitudinal ribs, each of which is furnished with rows of minute fins; by means of which, this animal, like the animalcula infuforia, can fwim in all directions with great swiftness. In the fame manner I have feen moft of thofe minute animals move fo swift that we could not account for it, without fuppofing fuch a provifion in nature, which is really true, but cannot be feen till the animals grow faint, for want of water; then, if we attend, we may with good glaffes plainly difcover them. I have lately found out, by mere accident, a method to make their fins appear very diftinctly, ef pecially in the larger kind of animalcula, which are common to maft vegetable infufions; fuch as the terebella. This has a longifh body, with a cavity or groove at one end, like a gimlet: by applying, then, a small stalk of the horfe fhoe geranium (or geranium zonale of Linnæus), freth broken, to a drop of water in which thefe animalcula are fwimming, we fhall find that they will be

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come torpid inftantly; contracting themselves in- cend flowly to the top, where, after they have to an oblong oval fhape, with their fins extended remained for fome time expold to the air, their like fo many briftles all round their bodies. The green colour changes to a beautiful sky blue. fins are in length about half the diameter of the When they are weary of this fituation, they form middle of their bodies. Before I difcovered this themfeives into a kind of rope, which flowly deexpedient, I tried to kill them by different kinds fcends as low as they intend; but if they happen of falts and fpirits; but though they were deftroy- to be close to the fide of the jar, they will defcend ed by this means, their fins were fo contracted, upon it. They are fo nearly of the specific grathat I could not diftinguish them in the leaft. vity of water itself, that they will either remain After lying in this ftate of torpidity for two or at the bottom, float on the furface, or be fufthree minutes, if a drop of clean water is applied pended in the middle, according as they are ori to them, they will recover their fhape, and fwim ginally placed, or as they themfeives have a mind, about immediately, rendering their fins again in- A fmail quantity of the matter containing these vifible." animalcules having been put into a jar of water, it fo happened, that one part went down imme diately to the bottom, whilft the other continued floating on the top. When things had remained for fome time in this condition, each of thefe fwarms began to grow weary of its fituation, and had a mind to change its quarters. Both armies fet out at the fame time, the one proceeding up. wards, and the other downwards; fo that, after fome hours journey, they met in the middle. A defire of krowing how they would behave on this occafion, raged the olferver to watch them carefully; and to his furprise he saw the army that was marching upwards, open to the right and left, to make room for thofe that were de fcending. Thus, without confusion or intermix. ture, each held on its way; the army that was going up, marching in two columns to the top, and the other proceeding in one column to the bottom, as if each had been under the direction of wife leaders. The hair-like infect was firft dif covered in a ditch at Norwich, one end of which communicates with the river there, and the other end with a fecond ditch into which feveral ken nels empty themselves. The length of this ditch, when Mr Baker wrote his account of this anima cule, was at least 100 yards, and its breadth mire. The bottom, for more than a foot thick, was covered with a blackish green fubftance, in appear ance like mud, made up for the most part of these infects; but, fuppofing only an half or a quarter part of it to be compofed of them, according to the dimenfions we have given, their numbers c ceed all imagination.

(10.) ANIMALCULE, THE GLOBE. This animalcule, reprefented Pl. XI. fig. 38. is exactly glo, bular, having no appearance of either head, tail, or fins. It moves in all directions, forwards or backwards, up or down, either rolling over and over like a bowl, fpinning horizontally like a top, or gliding along fmoothly without turning itself at all. Sometimes its motions are flow, at other times very fwift; and when it pleases, it can turn round, as it were upon an axis, very nimbly, without removing out of its place. The whole body is tranfparent, except where the circular black spots are shown in the figure. Some of the animals have no fpcts, and others from one to Seven. The furface of the whole body appears, in fore, as if all over dotted with points; in others, as if granulated like fhagreen: but their more general appearance is, as if befet thinly round with short moveable hairs or briftles, which probably are the inftruments by which their motions are performed. Thefe animalcules, feen by the naked eye, appear only like moving points.

(11.) ANIMALCULE, THE HAIR-LIKE, or the hair-like infect, is fo called by Mr Baker on account of its fhape, being extremely lender, and frequently an hundred and fifty times as long as Froad. The body or middle part, which is rearby ftraight, appeals, in fome, compofed of fuch rings as the windpipe of land animals is made up of; but in others, feems rather fealed, or made up of rings that obliquely crofs one another. Its two ends are hooked or bent, pretty nearly in the fame degree, but in a direction oppofite to one another; and as no eyes can be difcerned, it is difficult to judge which is the head or tail. Its progreffive motion is very fingular, being perirmed by turning upon one end as a centre, and defcribing almoft a quarter of a circle with the other, as reprefented in Pl. XI. fig. 1. Its motions are very flow, and require much patience and attention in the obferver. Thefe creatures are fo fmall, that millions of millions of them might be contained in an inch fquare. When viewed fingly, they are exceedingly transparent, and of a beautiful green colour; but when numbers of them are brought together, they become opaque, lfe their green colour, and grow entirely black, Notwithfanding the extreme minuteness of thefe animalcules, they feem to be fond of fociety; for, after viewing for feme time a parcel of them taken up at random, they will be feen difpofing themfelves in a kind of regular order. If a multitude of them are put into a jar of water, they will form kes into a regular body, and af

(12.) ANIMALCULE, THE NET-LIKE-ARMED. The propertics and fhape of this little animal are very extraordinary. It is found only in cafcades, where the water runs very fwift. There thefe in feets are found in clufters, ftanding erect on their tails; and refembling when all together, the combs of bees at the time they are filled with their aurelia. On being taken out of the water, they fpin threads, by which they hang exactly in the fame manner as the garden fpider. Fig. 42 shows one of these infects magnified. Its hoy appears curioufly turned as upon a lathe; and at the tail are three fharp fpines, on which it rais itfelt, and fands upright in the water: lat the mcft curious apparatus is about its head, where it is furnified with two inftruments like fans or pets, which ferve to provide its ford. Thefe it frequently fpreads out and draws in 2 gain; and when drawn up they are folded ter ther with the utmoft nicety and exactness, fo 23 to be difcernible when brought clofe to the body.

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