INTESTINES. 



rSry in fize : fame are rojind^d, others comprcffed ; the 

 Idrper are Erenerally placed fiti^j'.y, the fmaller are placed 

 clofe together in cftUeftions of different extent. The open- 

 ings of the excretory dufts of the larjer ones on the mu- 

 cous ftirface of the inteftinc are fiifSciently confnictio'.is. 

 They fccm to poffefs a very fimple itmftiire ; we can ob- 

 L'rve in them merely a net-work of minute vafcularramifica- 

 tiotis, whicli depolit fheir fecreted mucus in a timple excre- 

 tory tube. 



According as thefe bodies are found fingle, or in collec- 

 tions, they have been called glaviduhe filitarix or agm-nat.z. 

 Again, they have been named in different parts, after per- 

 fons who firft dcfcribed them, glandulae Peyeri and Brun- 

 neri. 



The arteries of the jejunum and ileum are derived from tl»e 



trtink of the fuperior mefentcric : the veins all end in the 



mefenteric root of the vena portarum. The blood in thefe 



veins has been obferved to have white ftreaks in it ; but this 



: not peculiar to the mefenteric veflels. Fluids injefted into 



traflility, which refides in their mufcular coat ; thefe may-' 

 be witneded in living animals by expofing the abdomen, or 

 in thofe recently dead, and fometimes in the inteilines ex- 

 pofed by accident or furp^ical operations. The whole ca ul 

 is obferved to be in motion, and this is called pcnfalti:, wh ch 

 term fignifics merely contradtin?. One part of the tube is '.een 

 to be contraf^ed, wlii!e another is dilated ; one afcends, 

 vvhile another defcends ; one is extended, another rendered 

 fhorter : thus a general twilling and creeping is produced, 

 compared to the motion of wormsi and hence ca led vermi- 

 cular. Touch a part of the gut with a (harp inftrument, 

 or with any chemical ftimiilus, and it will be io contraifred . 

 as to c'ofe the canal. A (imilnr effeft follows the applica- 

 tion of ftimuli, fuch as air, or other fluids, to the internal.- 

 fiirface. This is not confined to the mere fpot irritated, but ■ 

 tl'.e neighbouring parts partake of the affi-ftion. This fen- ' 

 fibility continues fome time after death, and is manifefted 

 even in the intelline when removed from the body. 



The ordinary and natural iHmuli, by which the orwr.nic 

 the chvme or 



the mefesteric veins eaiily tranfude on the mucous furface contraftility of the inteitine is excited, are, 

 of the inteiline. aliment as it comes from the itomach, the air mix- d with 



The fuperficinl abforbing veflels have their origin in the and accompanying this, and the bile. The artificial and 



unufual ones are purgative medicines, worms, cold applied - 

 to the abdomen. Cold to the feet, and terror fometimes aft- 

 fympathetically. 



ferous m.embranc, aTaitpmofe very frequently with each 

 other, and with the deepfeated ones, pafs through the me- 

 fentery in a fuperior and inferior fet, and enter the mefen- 

 teric glands. The deeper-feated abforbents, arifing from 

 the villi of the mucous furface, are called the ladeal or 

 chyliferous veflels ; they arc often diflended in a varicofe 

 manner to a confiderable fize • their trunks accomp.iny thofe 

 of the bloo(t-veflels in the cirlliilar fubftance on the furface 

 of the mucous membrane, anaftomcfe very frequently with 



Phylioiogilh iiave diftinguiflied three kinds of motion in 

 the inteiline ; the defcending or regular one, proceeding from 

 the ftomach to the large inteftine ; the afcending or inverted, 

 the reverfe of the former ; and the mixed, which partakes 

 of both thefe. 



The following phenomena may be obferved in the motion 



each other, and with the fup-^rficial ones, both here and in of the inteftine. Paris of the canal are alternately diftendcd- 



the mefentery, fo as to form a complete net-work, and then 

 proceed to the glands. They are very numerous in the 

 duodenum and jejunum ; but are fewer in the reft of the 

 canal ; they foi-m a plexus in the mefentery, proceed from 

 gland to gland, becoming larger and larger, and (lill com- 

 municating together. Collefted into large trunks, they 

 arrive at the under and back furface of the pancreas, and 

 are united with the abforbing veflels of the ilorr.ach, fpleen, 

 and liver in the glands and plexufes fituated about this part. 

 They then bend downwards, forming new plexufcs, and 

 arrive at the glands placed about the aorta, uniting with all 

 the trunks fro.m the other abdominal vifcera, from the pelvis 

 and lower extremities : they then afcend again to term.inate 

 in the thoracic duft. . 



The mefenteric glands, am.ountingin number to one hun- 

 dred or more, even to one hundred and fifty, are chi-jfly 

 placed on the fuperior mefenteric artery, either fcattered 

 and feparated, or in a more clofe arrangement. They are 

 fewer and fmaller towards the lower part and right portion 

 of the mefentery and inteftine, than on the upper and left 

 part. They are moftly flattened, with a rou^id or oval cir- 

 cumference : and the larger are placed irregularly amon^ the 

 fmall ones. They have a brownifli red colour, but are paler 

 and fmaller in adults than in infants. When full of chyle they 

 are whiter. 



The nerves of the fmail inteftine are derived from the 

 cxliac ganglia; they form uct-works adhering very clofely 

 to the arteries. The animal fenfibihty of the inlefl;ines is 

 probably ver)' flight under ordinary circumftances ; the 

 funcUons of thefe parts are perforn-ed wilho-Jt our con- 

 fcioufnefs. Dif^iafe, however, develip-i a moft acute animal 

 fenlibility. Anin al contraftility is entirely deficient : no exer- 

 tion of the will can either accrlerate or retard the action of 

 the inte!line. But the moft I'riking phenomena of the iii- 

 teftinal funftions are derived from their orgar.ic fenlible con- 



and contracted ; moVed in various diredlions ; rendered tenfe 

 and loofe to the touch ; diftended with air or chyme ; incur-- 

 vated or extended ; appear longer or fhorter according as 

 the longitudinal or circular fibres act ; are filled or emptied ; • 

 in ftiort, they are alternately at reft: and in motion. 



The longitudinal fibres fliorten the canal lengthwife : the 

 circular ones produce an oppofite efieft. The latter admit 

 of diflention, until the gut exceeds an inch in diameter; 

 they contract it again to half a hne, or evt-n clofe the canal 

 entirely. 



The antiperiftaltic aftion feems juft fnfficient in degree,, 

 in a healthy animal, to retain the chyle for the action of the '. 

 abforbing veflels. In difeafes, or wheji an infuperable obfta- 

 cle exi'ls to the natural pa-fiage of the ahmcnt, this inverted 

 motion is carried to a great degree, to that the contents of 

 the f'nall and even large inteftine are conveyed- into the 

 ftomach, and expelled by vomiting. 



The large- inU^ine is that portion of the alimentary canal, 

 which extends from the end of the fmall inteftine to the' 

 anus, and is fo named becaufe its diameter confiderably ex-- 

 ceeds that of the fmall. It is diftinguilhed from the latter, not. 

 merely by its Jituation, connections, extern -.1 form and. 

 funftions, but alfo in its minute ilruclnre, fo that a very, 

 fmall portion of it might be difl^inguiThed from a fi-milar; 

 piece of the ftomach or fmall inteftine. 



Its fituation is more defined and conftant than that of the 

 fmall intedine. Beginning in the right iliac region, it rifes 

 in front of fhe right kidney, goes backwards under the hver,i 

 and then turns forwards and towards the lefi (".he firft or. 

 hepatic flexure of the colon). It contimiesin a ti-anfwer.'c. 

 direction, from right to left, under the gall-blaudcr, the 

 ftomach, and the notch of the f-^jleen bflow and b- hind 

 which it turns again, and forms a large :ingle (the !t cond ofi 

 fplenic flexure) It defi-ends on tlv; left fide of tiie ibdo-. 

 men, in front of the left kidney, forms in the left iliac r.gioai 



a large 



