PER
PERIOSTEUM (Gycl.)— The bones of the human body in their natural flate, are for the moft part covered exteriorly by a membrane, called by the general name ptriofleum. 1 his is extended over the cartilages and ligaments alfo, as well as the bones; but when it covers the cartilages, it is called perichon- drium, when the ligaments, periekftnium. The periofteum in general is a fine ftrong membrane, or mem branous expahfion, not equally thick in all its parts, more or lefs tranfparent, of a very clofe texture, not eafily y. elding. extremely fenfible, and compofed of feveral planes of fibres differently difpofed, and mixed with a great number of fine vefiels and nervous filaments. This membrane does not immediately furround thofe portions of bones which are.covered by cartilages, nor thofe in which ligaments or tendons are inferted ; neither does it cover thofe portions of cartilages which are expofed to friction, as in thi moveable articulations, channels, &c. and laftly, it does not cover thofe portions of the teeth which lie out of the focket; and gums. The innermoft plane of the fibrous texture of the Periojleum, or that which immediately adheres to the furface of the bones, is fixed thereto by an infinite number of fmall fibrous extremities, brought from all the planes, and which enter the pores of the bones. Thefe extremities are accom- panied by capillary vefiels and nervous filaments, which hav- ing run for fome fpace between the different planes of the pe- riofteum, perforate the innermoft at the orifices of the pores of the bones. The periofteum is of different thickneffes, but this difference of thicknefs does not appear near fo much on the outer furface, as on the inner ; which is marked in many places with impreflions, owing to the fulci, depreffions, lines, and inequalities on the furface of the bones. Some anatomifts have been of an opinion, that this membrane was not only united to, but clofely braced round the bones; and that therefore it might fet bounds to their growth. It is probable they had only examined a few bones on this occafion, for had they confidered thofe which have concave furfaces, depreffions, and inequalities, they would there have found only a fimple adbefion of the periojleum, without any tenfion. In places where it is only fixed to the bone by the filaments of its innermoft plane, it is eafily pulled off from the bones; but where the fibres of the other planes likewife penetrate the bones, efpecially when thefe planes are very numerous, and where the infertions of tendons and ligaments mingle with thefe fibres, the feparation is much more difficult. The periojleum in general ferves to fupport that admirable tex- ture of an infinity of capillary vefiels, by which the bones and all the parts belonging to them are nourished ; it likewife fup- ports a vaft number of nervous filaments, by which fenfation is communicated not only to this and to the internal membrane of the bones, but even, in fome degree, to fome portions of the bones themfelves. WinftovSs Anat. p. 1 16.
PERfPHALLlA, nsp#«AXia, in antiquity, the fame with phala- gogia. See Phallagogia and Dionysia.
PERIPLOCA, in botany, the name of a genus of plants, the
. characters of which are thefe : the flower confifts of only one leaf, and is very open at the mouth, fo as to refemble a wheel ; from the cup there arifes a piftil, which is fixed like a nail into the back part of the flower, and ripens into a fruit {o like that of the apacymim or dog's bane, that authors in general have confounded the two genufes. The pod is long, and is com- pofed of two vaginae, and fplits open lengthwife from the bafe to the apex. Toum. Inft. p. 93.
The fpecies otperiploca, enumerated by Tournefort, are thefe : 1. The long-leaved periploca, with purple flowers. 2. The long and narrow-leaved one, called by the ^Egyptians fee among. 3. The periploea of Monpelier, with roundifh leaves, called by many authors fcammonia Monfpdiaca. 4. The Montpelier periploea, with fharp pointed leaves. 5. The American peri- ploea, with a fomewhat echinated fruit. 6. The broad Ame- rican periploea, with a hard, oblong, fmooth and tumid pod. 7. The white flowered climbing peiiploca of America, with very narrow willow-like leaves. 8. The low fpreading Ame- rican periploea, with leaves like thofe of toad flax. g. Citron- leaved umbelliferous creeping periplo:a of America, with red flowers. io. Creeping white- flowered American periploea, with leaves like thofe of money-wort. n. Citron-leaved climbing American peripkea, with a very large fruit. And, 12. The climbing bindweed-leaved American perip!oca,w\th an alated fruit.
PERIPLYSIS, a name given by fome authors to a diarrhoea, in which the ftools are extremely thin and watry, and very fre- quent and large in quantity.
PERIPNEUMONY (Cycl).— This difeafe is very frequently confounded with the pleurify, and then one is m'iftaken for the other, fometimes even by phy-ficians. As this, however, is a diforder oi' the lungs, and the other of the pleura, there are fymptoms attending them by which they may be certainly diftinguifhed. See Plkurisy.
PERIPYEMA, a word ufed by chirurgical writers to exprefs a collection of matter, wholly furrounding any part.
PERIRRHANTERION, npepfef?* in antiquity, a veffel,
ufualty of ftone or brafs, filled with holy water, with which
all thofe that were admitted to the facrifices were fprinkled ;
' and beyond which it was unlawful for any one that was Bift&os,
PER
or profane, to pafs. Some fay it was placed in the A&rw, or inrrioft recefs^of the temple, into which none entered but the prieft i butCafaubon will have it to be placed at the door of the temple, which opinion fe ms moft probable, becaufe all perfons who were Aftfttot, or unpolluted, were permitted to pals be- yond it. Potter, Archaol. Gracl 2. c. 2. T. , D 180 PERISCYLAC1SMUS, n*****^ a method of purification in frequent ufe among the Greeks. It was done by drawing a whelp round the perfon to be purified. Patter, Archxol.
oft*' T" p : 22 3' The word comeb from «•*•& a whelp.
PERISSON, in botany, a name given by the antient Greeks, and afterwards by the Romans, in the time of Pliny, to a kind of night-ihade, which made thofe people who took it inter- nally run mad. It was called alfo pentad ;■;>* and anhydr on, and by fome manicum ftrychnum, or fimply tr.anicon. See the article Strychnum.
PERISSOSIS, a word ufed by Hippocrates to exprefs a redun- dance of humours.
PERlSSOLOGY, nsptiwc-oAoyt*, in rhetoric, a quality of ftile di- rectly oppofite to braibylogy, and is otherwife called macrol-gy. See Macrology, Brachylogy, and Diction.
PERISTERION, in botany, a £ name given by ibme authors to tiatfeabioja minor, or fmall fcabious. Ger. Emac. Ind. 2.
PERIS FERHES, the pigeon-Jtone, in natural hiftory, a name given by fome whimfical people to an odd conformation of a pebble, which they fuppofe to reprefent very exactly a pio-eon without its wings. It feems to have been a mere lufus nature, in the formation of a common pebble. The variations of fi- gure in the common pebbles are fo infinite, that a perfon of a fertile imagination might find refemblanccs to all the parts of the creation in the ftones of a fingle gravel-pit. The giving names to fuch accidental things is not only uniiecejlary, but mifchievous, as it caufes great confulion in natural hiftory.
PERISTERNA, the thorax'.
. anatomy, is ufed for the lateral parts of
PERIS 1 IARCHUS, nsptriap^oj, in antiquity, a name given to the perfon that officiated in a luftration. Potter, Archjeol. Gnec. T. 1. p. 35. The word comes from Utfuta, another name for RaO*^*.
PERISTOMA, in anatomy, a word ufed by authors to exprefs the villous coat of the inteftines.
PERIS TYLION, EtyinAiw, among the Athenians, alargefquare place, tho' fometimes oblong, in the mid die of the gymnajium, defigned for walking, and the performance of thofe exercifes which were not to be performed in the palajira. Pott.Axchxol. Grac. 1. 1. c. 8. T. 1. p. 39. j PERITERE, in architecture, a place encompaffed round with columns, and with a kind of wings about it. Here the pillars ftand without, whereas in the periftyle they ftand within.
PERIT'EXIS, a word ufed by the old medical writers to exprefs a colliquation.
PERI THE, a name by which fome of the writers of the middle ages have called the pyrites; they fay it has great virtues againft the gout : fome of them alfo have called it the lapis perldonius.
PERITONEUMfCvr/.;— In the fifli kind, the peritoneum, or membrane furrounding the abdomen, is very varioufly coloured. In fome it is of a mining filvery whitenefs, as in the cyprini, perch, efoces, c?V. In others it is of a fine pale flelh colour, as in the falmon ; and in fome it is wholly black, or elfe va- riegated with very numerous black fpots, as in the clupea?, gadi, cotri and fpari. Jrtedi's Ichthyolog.
PERIWINKLE, in natural hiftory, the Englifh name of a fpecies of fhells, called by authors buccina, fee Bcjccinum.
Periwinkle, pervinca, in botany. See Pervinca.
PERIZOMA, a word ufed by fome authors for a trufs.
PERMISSION, fermijjio, in rhetoric, a figure which differs in nothing from concejjtan, except that the latter relates only to argument and pleading, but the former to action : E. G. §h*omam, omnibus rebus creptis, f.lum m'thi fuperejl animus et corpus : hac ipfa, quce de multis relicla funt, vobis et veftra con- dono p-.teflati. Vos me quo paclo vobis videtur, utamtni, atque abuiamini ; licebit imputCe. In me, quicqv.id libet, jiatuite, &c.
PERNIONES, childblains. When thefe tumours tend to fupnu- ration, it is proper to treat them like other recent abfeefles ; the beft method is firft to cleanfe the wound with fome digef- tive ointment, then to drefs it with balfam of Peru, or other the like application ; and laftly, to apply fome of the lead or litharge plaifters. Oil of myrrh per diliquium is alfo found of vaft fervice in thefe cafes, as is alfo the applying a comprefs dipped in a mixture of equal parts of lime-water and campho- rated fpirit of wine, over the other remedies. In people who have been ufed to be afflicted with chilblains at the return of a certain feafon, it will be found a great pre- fervative againft thofe troublefome tumours, to anoint the parts where they are expected to appear, both before and during the accefs of the fevere cold, with oil of turpentine or petroleum ; and when the diforder firft begins to (hew itfelf, it is a very good method to wrap round the affected part a piece of a hog's bladder, well wetted with one or other of thofe oils, and care taken to keep off the cold. Heifer's Surg. p. 211.
PERODACVYL/EUS, in anatomy, a name given by Riolan and others to one of the mufcles of the foot, called by Albinus
the
