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 Intestines in general, Inteftinum Duodenum • ormer, and they join in forming large rugae on the conin particular. ave furface of the ftomach, the greatefl part of which re tranfverfe, though irregular and waving. Between the pylorus and the veryloweft part of the In the interftices of thefe rugae, there is often found a abdomen, lies a long canal, bent in a great many diffort of flimy mucus, with which the whole cavity of by numerous convolutions or turnings, the ftomach feems likewife to be moiftened. This mu- ferent directions, theinteftin s. cus is much more fluid in living bodies, and is fupplied called This canal, thus and turned, forms a confidert>y the glands of the ftomach. It is termed fuccus gaftri- able bulk, yhich fillsfolded the greateft part of the cavity of the cus or ftomachicus. and it is connected, through its whole extent, On the inner furface of the fmall extremity of the fto- toabdomen; membranous productions or continuations of the perimach, at the place where it ends in the inteftinal canal, tonaeum, principally to thofe called the mefentery and we obferve a broad, thin, circular border, with a roundifh mefocolon. hole in the middle. This hole is the inferiour orifice of The incurvations of the inteftinal canal form two the ftomach, called by the Greeks pylorus, which figni- arches, a fmall one by which it is connected to the mefenfies a porter. and mefoc^lon, and a great one on the oppofite fide, This border is a fold or duplicature of the two inner tery which lies loofe. The whole canal is generally about coats of the ftomach, the nervofa and villofa ;. and it is feven eight times as long as the body. formed in part by a fafciculus of fie Pay fibres fixed in Theor inteftines general are compofed of feveral the duplicature of the tunica nervofa, and diftinguifhed coats, much in thein fame manner with the ftomach. not only from the other flefhy fibresof the extremity of the The and outermoft is a continuation of the mefenftomach, but alfo fromthofe of the inteftines, by a thin, tery, firft or of fome "other elongation or duplicature of the whitilh circle, which apppears even through the exter- peritonaeum. nal or common coat, round the union of the ftomach and This is commonly termed the common coat; and it inteftines. a cellular fubftance on its inner furface, like that of The figure of the pylorus is that of a ring, tranfverfe- has ftomach. ly flatted, the inner edge of which, or that next the theThe coat of the inteftines is flefhy or mufcular, center, is turned obliquely toward the inteftines, like a and madefecond up of two planes, one external, the other in broad portion of a funnel. This inner edge runs na- ternal. The external plane is very thin, and its fibres turally more or lefs into little plaits or gathers, like the longitudinal; the internal plane is thicker, and its fimouth of a purfe almoft fhut. It is therefore a kind of run tranfverfely round the circumVerence of the infphincter, which can contract the inferior orifice of the bres cylinder. ftomach, but feerris not capable of (hutting it quite clofe. teftinal coat is called nervofa, and is fomething The ftomach receives in general whatever the mouth Thethatthird of the ftomach. It has a particular plane, fends thither, through the canal of the cefophagus; but like which ferves as a bafis to fuftain it, made up of very its partciujar ufe is to receive the aliments, to contain fine, ftrong, oblique fibres, which feem to be of the lithem for a longer or fhorter time, in proportion as they or tendinous kind. ire more folid or fluid, and to digeft them, that is, to gamentary This coat fuftains two reticular fubftances which are put- them in a condition to be turned into that nutritious both vafcular, one arterial, the other venal, accompanied fluid called chyle. a great number of nervous filaments. Thefe veffels This operation, which goes by the general name of by and nerves are productions of the mefenteric veflels and digeflion, and by which chylification begins, is perform- nerves fome anatomifts have formed them into a diftinCt from the tunica villofa, and partly by the continual teftines, coat, by the name of tunica vafculofa. contraction and relaxation of the mufcular coat. The nervous coat fends off from its inner furface a The pylorus, or flefliy circle of the inferiour orifice great number of portions of fepta, more or lefs circuof the ftomach, ferves to retain the aliments in it, till lar, v/hich contribute to the formation of what are calthey have acquired a fufficient degree of fluidity to led valvuke conniventes. . pafs eafily through that-opening. fourth or innermoft coat is very foft, and is naThe gentle and alternate motions of the orbicular fi- medThetunica villofa. It has the fame extent with the bres of the mufcular coat, may affift in fending through third coat, which fupports it, and it lines all the fepta of the pylorus, in the natural way, the aliment that is fuffieientiy digefted. This was called the penftaltic or vermi- thatThethirdfmallcoat.inteftines form ope continued uniform canal; cular motion, by thofe who believed that it is fucceflively and though three portions of it have three different reiterated, like that of earth-worms when they creep. names, yet we have no fufficient marks whereby to diThe fituation of the ftomach, which is nearly tranfverfe, is likewife of ufe in making the aliment remain ftinguifh them, to fix the precife extent or length of long enough in that cavity, and may ferve to make the each portion, to fettle its juft limits. length of this ftay in fome mealure arbitary,: by means The firft and fhorteft portion of the whole canal-, of the different poftures of the body; for when we he on is called duodenum; the fecond, which is much longer, the left fide, the aliment muft remain longer, than when jejunum; and the third, which is ftill longer than the fecond, ileum. we lie on the right, d f.
 * and as they furround the whole canal of the ined partly by the fuccus gaftricus, which flows continually