Page:Cyclopaedia, Chambers - Supplement, Volume 1.djvu/688

 EXT

a pariflj, it is faid to be Extra-parochial. Stat. 24. & 23. Car. 2.

EXTRA VASATED Blood. In the contufions, fiflures, depref- fions, fraflures, and other accidents of the cranium, one or more of the blood veflels diftributed on the dura mater are frequently divided. The blood that is difcharged from thefe veflels greatly opprefles the brain and difturbs its offices, frequently brings on pains and other mifchiefs, and often death itfelf, unlefs the patient be timely relieved. If the quantity of extravafated blood be ever fo fmall, it will certainly cor- rupt, and affeft the meninges, and the brain itfelf with the fame diforder; and from hence will proceed violent inflam- mations, deliriums, and ulcers, and finally death; and this will frequently be the cafe, after a violent blow upon the cra- nium, though the bone mould efcape without injury. In thefe injuries of the head, the blood is Ipilt either between the cra- nium and the dura mater, or between the dura and pia ma- ter, or between the pia mater and the brain, or laftly into the finufes of the brain. Either of thefe cafes is attended with very great danger, but the deeper the extravafation happens, fo much greater muft the danger be. Blood extravafated in the cavity of the cranium, will be difcovered from the violence of the fymptoms that fucceed a blow on the head; as if the patient lies fbill without fenfe or motion, if blood flows from the mouth, ears, or nofe; if the eyes are much inflamed and fwelled; if vomitings fucceed; when upon the remiffion of thefe fymptoms the patient complains of a re- markable heavinefs of head, fleepinefs, vertigo, blindnefs, fpafms, and diforders of this kind. When the quantity of extravafated blood on thefe accidents is very confiderable, arid oppreffes the cerebellum, the patient dies upon the fpot; but when it is hot in a very large quantity, or does not affect the cerebellum, life fbill remains, but the fymptoms juft men- tioned' come on. In this cafe, if no fifliire or contrafiflure is to be found, nor any external injury on the integuments of the head after a violent blow, it proves very difficult to find in what part of the head the extravafation is feated. It will be' proper in this cafe firft to (have the head all over, and then thoroughly to examine it, for if any part is fofter than ordi- nary; or is enlarged, or red from ffagnating blood, it is plain that this is the part that has received the injury. But if nei- ther this way, nor by enquiry among the perfons prefent at the accident, you can get light into the affair, it will be proper to cover the whole head with an emollient plaifter, laying' over it medicated bags of herbs, Isfe. well heated. This application will in a fewhours time produce a tumour and foft- riefs upon the injured part. Sometimes the patient alfo, tho' he lies fpeechlefs, and fcemingly fenfelefs, will be continually put- ing bis hand to the injured part; and if either fide of the pa- tient has loft fenfe or motion, and is become paralytic, it is an apparent fign, whatever fome might think to the contrary, that the injury has been received on the contrary or found fide. If after accidents of this kind you can difcover any wound in «Ke fkih, that muft be enlarged with the knife till the injury on the cranium, of whatever kind it be, is come at. When the feat of the injury is difcovered, the firft intention is to difcharge the extravafated blood, and then to clean the wound, and remove all fplinters, or extraneous bodies. Some Have recourfe on thefe occafions to the inftant ufe of the tre- pan; but patients have been often very fuccefsfully recovered without it. It is, therefore beft firft to open a vein, and take away as much blood as the ftrength of the patient will per- mit; this will take off the impetus of the veflels, and prevent the extravafation of more blood. Prefcribe after this a brifk purge to leffen the quantity of the fluids; foment the head with medicated bags,, and apply a melilot plaifter to it; en- deavour to roule the patient by volatile applications to the noffrik, fiich as fa! volatile, fpirit of fal armoniac, or fpirit of hartfhom; and give frequently attenuating fluids, fuch as the decoflions of betony, (age, rofemary, lavender-flowers, faffafras, and the like. This method does not immediately produce the defired effect, but is to be continued for fome time, and the prescriptions frequently repeated, particularly when the bad fymptoms feem by degrees to abate; and if the patient finds relief from the firft bleeding, it will be proper to repeat it a ftcond or third time, efpecially if he be of an afbleletic conftitufipn. When notwithftanding this method, the fymptoms are found however rather to encreafe than abate, it will be neceffary to make a perforation in the cranium with the trepan, to give a paffage for the difcharge of the confined grumous blood, and when there is no finding out the part affefled, the fkull muft be perforated in feveral parts till the right i s found., Heijter's Surg. p. qo.

EXTRA VERSlO, in chemiftry, a term ufed to cxprefs the ren- dering manifeft any thing faline, alcaline, or acid, concealed in mixed bodies; and is juft the revcrfe to one of the fpecies 6f concentration, which hides thefe qualities.

EXTREME (Cj;r/J— Extremes,, in right angled fpherical trigonometry. When one of the five circular parts of a right ang ed fpherical triangle, viz. (the three fides and two oblique angles, for the right angle' k rieglecTred) is pitched upon for the middle term, then the two circular parts lying immediately next to it are called Extremes ciujunB; and the two parts re- mote from the aflumed middle part, or not immediately next

E X U

it, Extremes disjuxtl. See Spheric Ai andTmANGiE Cycl. '

EXTREMITIES of Figures, in painting, is ufed for the head, hands, and feet. Thefe fhould be drawn with more nicety and exafinefs, or more terminated than ©ther p art6. and thus help to render the action more expreflive.

EXTTJBERANCES, in medicine, are fwellings forth, or rif- ings up in the flefh, or other parts of the body.

EXUCONTIANI, a branch of Arian heretics. See Exou-

CONTII.

EXVERR^, in antiquity, a kind of brufh ufed in cleaufin? houfes, out of which a dead perfon had been carried. Pitijc. Lex. Ant. in voc.

EXUPORA, in botany, a name, by which fome authors have called the verbena or common vervain. Ger. Emac. Ind 2.

EXUvI/E (Cycl.) — The outer integument of the body, which in man and other larger animals is fo durably fixed on the body, is in many of the animals of the reptile kind much more loofely fixed, and is changeable feveral times during the period of their lives. The ferpent kind all fhift their fkins feveral times in their lives, and the water-newt has been lately obiirved to do the fame; but no creature in the world does it fo often as the caterpillar, almoft every fpecies of thefe infects throw- ing oft their old fkin once in ten or twelve days, or lets; and this in fuch a manner as is extremely worthy an attentive ob- fervation. Malpighi obferved that the common filkworm changed its fkin four times during its continuance in that ftate; the firft of thefe changes happening at eleven or twelve days from its appearance from the egg, and the others at the diftance of five or fix days each; and probably the reft of the caterpillar kind obferve nearly the fame periods. Neither is this change of the fkin confined to the few creatures we have mentioned; but among the whole infect clafs, the moft numerous of that of all animated beings we know, there is fcarce one fpecies every individual of which does not throw off its fkin, once at leaft, before it arrives at its full growth. The term changing the fkin is fcarce expreflive enough for this operation in the caterpillar kinds; for the crea- ture throws off the external covering of every the mintiteit part and organ of its body, and the fkins they thus depofit have fo much the appearance of a compleat infect, that they are very often miftaken for fuch, prefenting us with every thing that we fee in the external appearance ©f the living ani- mal. If the caterpillar has been one of the hairy kinds, the fkin which it throws off is hairy, containing the integument as it were of every hair and of each of the legs; and even the claws and other parts which are not vifible without the affiftance of a microfcope, are as plain in this as in the living animal. But what is moft of all amazing, is to find that the very folid parts which form the head are alfo found in tho Exuviae, the fkull and teeth being plainly diftinguifhable in them; it is eafy to conceive that this muft be a ftrange ope- ration, for an animal in this manner to withdraw the feve- ral parts of its body out of their fheaths and cafes which they have plainly been fitted into in fo nice a manner, and parti- cularly the throwing off an old fkull and teeth to make way for new ones, feems an aft beyond all comprehenfion. The operation however appears as tedious and painful to the animal aswe can expect; if we examine it ftri&Iy, a dayor two before this change happens, the creature always refufes to eat, and lofes its former activity, either never walking at all, or at the utmoft but very (lowly; tho' they do not move out of their places, however, they are very full of fome particular motions in their body, they turn themfelves about from fide to fide, and often elevate their back and then gently deprefs it again; they frequently raife up their heads and ftrike them down rudely againft the thing they (land upon, and frequently the anterior half of the body is raifed from the place, and thruft very brifkly backwards and forwards from fide to fide, for three or four times together. Thefe are the more obvious motions, but befide thefe there are other lefs fenlible ones within every ring, thefe are feparately inflated and contracted again alternately, and by this means the fkin is greatly loofened from them, and by thefe motions and the remaining without food, it is that the body by degrees difengages itfelf from the fkin. Reaumur, Hift. Inf. V. I. p. 1. p. 225. Thofe caterpillars which live in communities retire into their web which ferves them for a habitation, at the time that they are to get off their fkins; and thofe who live folitary and have no fuch web always fpin themfelves a filky net-work over the ftalk or leaf of a plant, at the time that their change of fkin is approaching; the ufe of this is to entangle their legs in, that they may give a refiftance to the motions afterwards to be made by the body in order to throwing off this covering. When the time of the change approaches, all the colours of the fkin grow faint and lofe their beauty, being deprived of the power of receiving juices for its nourifhment, and becoming as it were dry. The fkin is then in the condition of the leaf of a tree, which receives no more nourifhment and is drying and ready to fall off; and when the creature continues its fwelling and fhrinking in again of its feveral .rings, at this time the fkin being no longer fupple or extenfible as before, cracks along the middle of the rings on the back of the ani- mal. The fecoud or third ring from the head are always the

part