First lines of physiology /

Abstract

CfiAP.L be earthy, by combuftion or long-continued pu- trefaction.iv. Thefe earthy particles derive connection and the power of cohefion, not from themfelves, but from interpofed gluten.We know this from the preceding obfervations fin.) ; and the eafy experiment, in which a burnt hair, whofe parts hang ft ill together, recovers a certain degree of firmneis by- being dipped in water or oil.Ivory and bones alfo become friable, by the extraction of their gelly.Long expofure to weather effects a limilar change, rendering bones a true earth, abforbent and bibu- lous.But even bone, become friable from having its gelly extracted, reacquires its cffeous hardnefs, when that gelly is reilored.The more fimple ani- mals conlift entirely of this gluten.v. Laftly, the chemical analy fis of bone, and hair, the gelly of bone, ivory, and horn, the nature of our aliments, &c.prove, that this gluten is compofed of water incorporated with oil by animal life.Nor does any other kind of gluten unite the parts of animals more ftrongly, as we fee in fize and com- mon glue.vi.The primary fimple fibre, fuch as we rather comprehend from reafon than fenfe, is compofed of earthy particles adhering longitudinally, and connected hy intervening and coheiive gluten.vii.But the fibres which appear primary to the fight are of two kinds.The firft is linear, whofe length is considerable in proportion to its breadth, and whofe elementary particles lie in a ftraight line, and thus generally parallel to thofe contiguous.We fee examples of this kind of fibre in bone, moft e^y in thofe of the foetus, and alfo in ten- dons, ligaments and mufcles, always recollecting that the eye fees not the moil minute fibres, but only the larger ones compofed of thefe, and fimi- lar to them in ftraightnefs and flendernefs.That the Chap.I.CELLULAR SUBSTANCE.3 the ultimate fibres are perfectly fimilar, we are convinced by the microfcopes of Muys and Leeuwenhoeck, in which the mufcular fibres, even the moft minute, appear exactly like the larger ones, and perfectly linear.vni.The fecond kind confifts of laminae, in which a breadth often greater is conjoined with a ihorter length.A loofe web of thefe has got the name of Cellular Tunic, though the term Tunic is on many accounts improper.ix.This cellular lubftance is compofed of an in- finite number of fmall laminae, which, by their various directions, inclofe fmall fpaces and cavities, Chap.L CELLULAR SUBSTANCE.7 ing, the filaments cohere, and the contiguous membranes are united, with lofs of motion.xvii.The cellular texture is more lax, and form- ed of laminae rather than fibres, where it divides the mufcular fibres, even the moil minute 5 where it ioofely accompanies and fuflains the verle.ls; and within the cavities of the bones, where it is corn- poled of bony as well as membranous laminae.That is likewife very lax, which, under the fur- face of the body, is every where inter poled betwixt the mufcles and the fkin : but the laxeft of all is that which furrounds with very wide cells the genital parts of the male.xvm.Into the empty mefhes of this cellular texture (xvii.)there is poured almoil every where, in the foetus, nrft a gelly, then a grumous, and laft- ly, under the whole fkin, and in its pits, a clotted fat.This fub fiance is lighter than water, infipid, inflammable, becomes folid in the cold, is found in greater quantity about the kidneys and in gra- minivorous animals ; in fifties, while alive, and probably alfo in man, nearly fluid, though apt to coagulate.In it an acid fait, aimoft in the pro- portion of one-fixth, is united with oil.xix.Through this cellular texture the blood- veflels run and are divided ; from the arterial ex- tremities of which, the fat is depofited and abforbed by the venous.The parTage, from the ar- teries into the adipofe cells, is -fo immediate and free, that they mult open by very large mouths, iince they admit injected mercury, air, water, fize, and oil, which is always very fluggiih, even in li- ving animals.It is not fecreted by any long duds of particular fabric, but tranfudes on all iides through the whole extent of the artery ; infomuch that, when an artery is filled with water, there is no part of the furrounding cellular fubitance which is not moiftened.The warm fat, during the pulfation of the arteries, eafily finds out the fame paffages.B 4 How 8 FIBRE.Chap.I.How quickly it is collected, appears from the fpeedy renovation of fatnefs after acute difeafes.xx.But that this fat is abforbed by the veins, we are taught from the fudden effects which muf- cular exercife has in confuming the fat, more e- fpecially of animals in which it abounds ; alfo from its confumption in fevers ; from the cure of dropiies, where the water eifufed into the cel- lular fubftance is in a manner abforbed and thrown out by the inteftinal tube ; and, laftly, from the venous tranfudation of water and oil, when injected by the fyringe, obferved in every part of the body.Are nerves diitributed upon the adipofe cells ?It is certain they run through this fub- ftance, and every where divide in it, into the mi- nutefl filaments, fo that they can no longer be traced by the knife.That they terminate in it, is not probable ; for the fat is both infenfible and unirritable.xxi.The mefhes betwixt the laminae of the cellular membrane, are every where open, and unite in forming one continuous cavity through- out the whole body.This appears from the infla- tion of the fkin over all the body, which butchers, and likewife the furgeons of Ethiopia, effect by a iingle wound ; from emphyfema, in which the air received by a wound of the fkin, being retained, caufes a fwelling throughout the whole body ; from the paifage of bodies, put under the fkin, to a place remote from that at which they entered ; from the paffage of pus, from an inflamed place to remote ulcers ; and, finally, from difeafes, in which water depofited in ail the cellular fub- ftance of the body, is completely evacuated by a fingle incifion.That none of the cellular tex- ture is excepted, appears from a cafe of emphyfema in which the vitreous body of the eye itfelf was inflated : and from a difeafe, in which the gelatinous Chap.I. CELLULAR SUBSTANCE.9 gelatinous ferum of a dropfy was transfufed even into the cavernous bodies of the penis.xxii.The great importance of this cellular fubftance will be evident to all who confider, that from it alone proceeds the due firmnefs and liability of all the arteries, nerves, and mufcular fibres, and confequently of all the rlelh and vifcera formed of thefe : but even the figures of the parts, their juft length, cavities, curvatures, flexures, depend entirely on the cellular membrane, being in fome places of a laxer, and in others of a denfer fabric : for when divided, every part is lengthened and collapfes.Of this fubftance, with vefTels, nerves, mufcular and tendinous fibres, (a great part of which are however formed of it), all the vifcera, all the mufcles, glands, ligaments and cap- fules, are compofed ; on it alone, and its different length, tenfion, quantity or proportion, the diveriity of our glands and vifcera depends ; and, laftly, it certainly conftitutes by far the greateft part of the body itfelf, if indeed the whole be not formed of cellular filaments of this kind.xxiii.It pofTeffes a contractile power, different from irritability, which, though not demonftrable by experiments, difpofes the cellular fibre to fhort- en itfelf, though for the moil part ilowlv, after having been ftretched.This power, excited by cold, renders the fkin rigid ; raifes the hairs ; draws up the fcrotum ; and, after geftation, re- ftores the fkin of the abdomen, and the uterus, to their former fize.The fame force, by a gentle but continual contraction, promotes the fecretion of fat of the liquors of the fabcutaneous and o- ther glands, and of pus : in the veins and receptacles, it refills dilatation ; and, when that is taken off, it regains its former mortnefs.Jn the foetus, this gentle force is among the principal caufes of the changes that happen to the body.XXIV.

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