Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/134

 NYM

Out of the two forts ef fhclls of thefe infects, the One in form of an egg, and the other of the worm itfelf, there are two Ways for the fly's egrefs.

For the flrft of thefe, it is always from the fame end of the (hell, in form of an egg, that the embryo fly is feen to make its way out. This is always that end which is near the head of the fly, and which was, originally, the head of the worm. . The head of the fly, however, is provided with no in ft rumen t to make this great opening. The point of the trunk is yet very foft, and, even when at its utmoft hardnefs, it could only make a very fmall, and, in a manner, imperceptible hole. Na ture has funiifiied the creature with another means of freeing itfelf from this fhell. The cap at the top of this is made, as it were, of two halves, and they fo loofely attached both to one another, and to the other part of the fhell, that they very rea- dily feparate with a fmall force, and fall off" from it. But this is not all ; for in every one of thefe fhells, toward the joining on of the cap to the head part, there are two ribs, or pro- minent lines, diametrically oppofite to one another, and reach- ing to fome diftauce in the fhell. 7"hcfe feem formed to ftrengthen the fhell, but they are, in reality, intended to Weaken it, and are the" places at which it not only eafieft breaks, but even fplits, and opens, with a fmall force. This, with the falling off" of the cap gives fufficicnt room of egrefs to the fly, and may be eafily difcovered to be intended (o to feparate by nature itfelf; fmce in breaking any other part of the fhell, it cracks irregularly, and indeterminately/' but here it feparates only at thefe lines.

It is eafy, indeed, for us by a flight force to feparate the two pieces of the cap of the fhell in thefe cafes, and a fmall force does it; but this, though fmall to us, is great in proportion to the ftrength and circumftances of the nymph t enclofed as it is on all fides.

The fkull of the fly, it is to be confidcred, however, is folid and cruftaceous, and of a conftant and regular figure, as in other larger animals ; yet the fly, in this ftate, is able to inflate and contract its head alternately, and, by that means effects much of the great bufmefs of its liberty. This extending the bulk of the head, is affifted by a fort of bladder which the creature., at each of thefe inflations, putties out to fome di- ftance from its head, and which, fometimes, even equals the head itfelf in fize. The air is the only means by which the fly can, in this manner, inflate and fwcll its head ; and, when ncceflary, it fwells its whole body in the fame manner. The inflation of the head, and the throwing out this fort of blad- der, which is an operation the fly is never able to do after- wards through its whole life, are evidently meant to diflodge and throw off the cap, and open the fide lines of the fhell. /c£<w«iz(r, Hift. Infect. Vol. 4. p. 332, feq.

NYMPH-oHwaz/, in natural hiftory, one of the terms ufed by Swammerdam, in his clafling the infects according to their ftates and productions. It exprefles thofe creatures which are produced in their perfect form from the egg, and are fubject to no changes of any kind afterwards. See Tkansforma- tion tffinjefts.

NltMPH-cbryfalisi or Nv"MPH-<?«rf/w, a name given by Swam- merdam in his hiftory of infects, to one of the four general clafles into which he has reduced all thofe animals in regard to their changes.

The creatures of this clafs are not hatched from the egg in their proper form, but in that of a worm, or caterpillar, and, after hatching, they obtain their perfection by flow degrees, not as the nymph vermicles of the grafliopper do, in a man- ner obvious to the eye, but under the covert of their fkin, and muft appear chryfalis's before they are perfect flies. The common day and night butterflies, and many other infects are of this clafs. Swammerd. Hift. Infect.

Nympha vermicith/s, in natural hiftory, a term ufed by Swam- merdam to exprefs one of the four general clafles of the tranfmutations of infects, or, as he more properly ftiles them, their manner of growth.

The animals of this clafs are not produced from the egg in their perfect figure, nor yet in the worm fhape, as the cater- pillar of the butterfly, and maggot of the fly, but the parts of the infect are imperfectly fhaped in the egg, and, after hatching, it does not appear properly itfelf, but acquires its perfection vifibly by means of outward food. The locuft, grafhopper, &c. are of this clafs. Swammerd. Hift. Infect.

Nympha vermifonnis, in natural hiftory, a word devifed by Swammerdam, and by him ufed to exprefs one of his four great clafles on infects, according to their production.

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Thofe of this clafs are not hatched from t'ie egg in their own form, but in the fhape of worms, and differ from the cater- pillar kind in this, that they always remain fhut up in the fkin of the worm, till they throw off both fkins at once, and ap- pear in their winged ftate. The common flies, &c. are of this clafs. Swamv.erd. Hift. Infect

NYMPH^A, the water lilly, in botany, the name of a genus of plants, the characters of which are thefe : The flower is of the rofaceous kind, confifting of fevera) petals arranged in a circular form ; the feed veffel arifes from the cup of the flower, and is, when ripe, of a giobofe or conic figure, multicapfular, and filled with oblong feeds. See Tab. i. of Botanv Clafs 6. ''

The fpecies of nympbaa enumerated by authors are thefe : i. The great white nympbaa, or water lilly. 2. The great Ame- rican water tidy, with very large rounded leaves, beautifully crenated, and purple underneath, and with large white flowers* 3. The American nympbeca, with fmaller rounded leaves, ob- tufely crenated, green underneath, and with white flowers. 4. The fame fpecies of water lilly are known when not in flow- er, by their large leaves, which float upon the furface of the water. Tourn. Inff. p. 260.

NYMPHARENA, in natural hiftory, the name of a ftone found in the beds of fome rivers, and having the appearance of i fea horfe's tooth. Doubtlefs it was a petrified tooth of that or fome other fuch animal, fuch things being often found now, though in thefe early ages they were little known or regarded.

NYMPH ARIUM, in botany, a name given by the Greek writers of the later ages to the water lilly. The word is formed of nympbaa, and is of the fame kind with many other names of plants devifed about the fame time, which feem a fort of diminutives formed on the before re- ceived names of the fame plants. Thus fcillarium is a name given by Ae'tius to the fquill, when the roots were fmall. Moft of thefe words were formed of the Arabian names of the things thofe new ones expreffed.

NYMPHARUM oculi, in natural hiftory, a name given bv fome of the antient writers to the ftone we call cculus Be'li, and fometimes to the operculum of a fhell-fifh, common on the fea fhores in many places, and called umbilicus veneris. We are told of Caligula that he carried his foldiers armed to the fea fide, to pick up the nympbarum oculi, and fhells. It is cer- tain in this place, the word only means the umbilicus veneris, for the other oculi nympbarum are found only on the fhores, and in the beds of fome particular rivers, not on the fea fhores among fhells.

NYMPHOIDES, in botany, the name of a genus of plants, ap- proaching to the nature of the water lilly, or nympham, in ex- ternal appearance, and thence ufually efteemed fpecies of that genus, but improperly.

The characters of this genus of plants are thefe : the flower confifts of one leaf, ufually of a rotated form, and divided in- to feveral fegments at the edge. The piftil arifes from the cup, and perforates the bottom of the flower, and finally ripens into a foft fruit, or capfule, of an oblong, compreffed figure, having only one cell, and containing many feeds wrapt up in a calyptra. See Tab. 1 . of Botany, Clafs 2. The fpecies of mmpboides enumerated by Mr. Tournefort are thefe : r. The common nymphides, which fwims on waters : this is called by moft other authors the yellow water lilly, with fimbriated flowers. 2. The mmpboides with leaves beautiful- ly ftained with purple fpots. 3. The Indian nymphoides, with white fimbriated flowers, called by authors nadil ambel. Tourn Inft. p. 153.

NYSSA, in botany, the name of a plant defcribed by Gro- novius, and made by Linnasus a diftinfl genus of plants, un- der the fame name. The charaBers are thefe : it produces male and female flowers ; in the male flower the cup is a five- leaved, expanded perianthium. The flower is monopetalous, but divided into five fegments, of the fhape and fize of thofe of the cup. The ftamina are ten pointed filaments, longer than the flower. The anthera: are double. In the female flower the cup is of the fame figure as in the male, but it remains upon the fruit. The flower is the fame as in the male ; the piftil has an oval germen under the cup ; the ftyle is fingle, and (lender, and is longer than the flower. The ftigma is oblong, compreffed, and bent. The fruit is a drupa of an oval figure, containing one cell, in which is contained an oval nut, (harp pointed at the ends, and rib'd with longi- tudinal lines. Linnai Gen. PI, p. 482. Grcnov. Virgin. p. 121.

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