INTESTINES. 



tJon between the two intedir.es, witJi a fnraolh furface, 

 making no fold, and coiifiiiiiig tlie parts ia tlieir relative 

 filiation to each other. The mufciilar and mucous coats, 

 and the cellular fubftance of the two mtellines, are conti- 

 nuous, and this continuity retains the folds of the valve in 

 their fttuation. Wiicn the pcritoueuin a»d mufcular parts 

 are cut througl), the mucous lining which for:ns the valve 

 is no longer retained ; the ileum may be withdrawn from the 

 colon, the two folds being dellroyed, the communication has 

 a circular appearance, and its dimenfious are equal to tliofe 

 of the fmuU inteftino. 



The ftniclure of this part is mod advantageoufly obferved 

 ty directing it under water. When theintelUne is inflated 

 and dried, the general figure and dircftion of the two folds, 

 and of the aperture between them, can be clearly feen : but 

 they are rendered rigid, fmooth, and (horter than is natu- 

 ral, and their margins are too far feparated. 



As the two folds, which compofe the valvula coli, rcpre- 

 fent two oblique planes, converging in fuch a manner as to 

 form a convexity towards the large, and a concavity towards 

 the fmall inteftine, whatever preffes againft them in the con- 

 cave furface will feparate them, and open more widely the 

 interval between them: whatever comes againd them on 

 their convex afpeA will approximate theni, and tend to de- 

 ftroy the opening. The contents of the ileum, palling in 

 their natural courfe, are in the former cafe ; and thofe of 

 the colon in the latter. Hence they prevent the admiffion 

 of feces into the fmall inteftine ; as we can generally prove 

 by diftending the large inteftine with air or water : thofe 

 fluids do not efcape by the ileum. Yet this experiment does 

 not always fucceed perfectly : and probably under particu- 

 lar circumftances in the living body, a retrograde paflfage 

 takes place : hence vomiting of feces and of matters thrown 

 up in clyfters. We muft recollecl, in arguing from the refult 

 of trials with air or water, tliat the feces, of which the 

 return is prevented, poftefs ufually confiderable confiftcnce. 

 The large inteftine is compofed of three coats or layers of 

 the fame nature, and diltinguiilied by the fame names as 

 thofe of the fmall. 



The external, or ferous covering, according to what we 

 liave faid concerning the connections of the organs, is a par- 

 tial one ia fome diviljons of the tube. This is elevated at 

 iiitervals into fmall procefles, contaimng fat, and completely 

 rcfembling portions of omentum. For an account of thefe 

 parts, which are ciiUed appendices cpiploicje, and are pe- 

 culiar to the large inteftine, fee Epiploon'. 



The mufcular covering of the inteftine is made up of two 

 orders of fibres : tliofe of the interior ftratuin are circular, 

 and uniformly extended over the mucous membrane, as in the 

 fmall inteftine : they are connetled to that coat by a limilar 

 copious cellular fubftance, defcribed often as a nervous coat. 

 The longitudinal fibres are collected into tlirce bands having 

 the appearance of ligaments, and placed at equal diilances 

 from each other on the furface of the tube. Thefe bands 

 are much Ihorter than the other coverings, which are there- 

 fore puckered up and form cells between them. The three 

 commence at one point about the appendix vermifonr.is, 

 diverge and grow broader as they afccnd over the caecum : 

 are continued through the whole length of the colon ; grow 

 broader and ftronger on the redlum, and are united into a 

 continuous mufcular (heath, including about the fix laft 

 niches of the gut. One band is on the unattached part of 

 the inteftine ; another is covered on the arch by the omen- 

 tum ; and the third is found at the attachment of ihe 

 mefocolon. The furface is level, tcnfe, and rather de- 

 prelfed in the fituations occupied by thefe bands ; in their 

 intervals th- furface confifts of a fcrics of elevations, fepa- 

 Voi,. XIX. 



rated by tranfverfe fold,';, the cells being fo placed as to cut 

 the long axis of the gut at right angles : externally, there- 

 fore, the tube feems made up of a triple feiies of hcnii- 

 fpl'.crical elevations, internally of the fame number of rows 

 of cells. This appearance is peculiar to the large inteftine : 

 it exlrts no longer in the reftum, where the bands are united 

 into an uniform ftratnm. 



The ferous and mucous coats with the circular f.bres are 

 fo plaitable in confequencc of the arrangement juft defcribed, 

 as to form on the infide very confiderable tranfverfe folds : 

 thefe are largeft at the beginning of the tube, become fmaller, 

 and are entirely loll in the rettum. The folds are of dif- 

 ferent fi/.es, and varioufly intermixed : between two of them 

 a cell is formed of an elliptical figure, narrower at its ob- 

 long oiilice, and larger about the middle. If the inteftine 

 be inflated, and the longitudinal bands cut through in feveral 

 parts, the whole inteftine may be extended into a much 

 greater length, the folds and cells diiappeai", and the tube 

 becomes nearly cylindrical. 



The mucous coat forms various folds in the cells of the 

 inteftines when. in its contradled ftate, fimilar to the folds 

 occurring in the ftomach : they difappear on diftention. 

 Its foft and pulpy furfixc is covered with a tenacious mu- 

 cus. It differs from that of the fmall inteftine in poi'- 

 feffing no villi. Numerous fingle mucous glands are found 

 over the whole large inteftine : they lie on the outer furface 

 of the mucous coat, which is penetrated by their dufts. 



The arteries of the large inteftine come from the fuperior 

 and interior niefenteric trui.ks ; the veins join the inferior 

 mefenteric branch of the vena portarum. The abforbents, 

 both fuperficial and deepfeated, pafs through glands which 

 lie clofe to the inteftine : thefe are fmaller than the mefen- 

 teric glands, and fewer in number, being reckoned from 2 J 

 to 50, and are nearer to tlie gut. After paffing through 

 feveral of tliem, the abforbents terminate, near the kidneys, 

 inferior mefenteric artery and pancreas, in the fame glands 

 at which the lacleal veftels of the fmall inteftine arrive. 

 They are, on the whole, m.uch fewer and fmaller than thofe 

 of the fmall inteftine. 



The nerves come from the plexufes of the great fym- 

 pathctics, and from the feveral branches, and are connefted 

 to the arteries. The end of the large inteftine is a point 

 at which the organic and animal lives are united ; here we 

 have ver)' obvious animal fenfibihty, and tlie mufcular ac- ^| 



tions are confiderably influenced by the will. Where the 

 fmall inteftine joins the large, the latter is produced, below 

 the opening of communication, into an obtufely conical pro- 

 cefs, two or three inches in length, having the fame unequal 

 furface as the reft of the tube, and terminating in a blind 

 extremity ; this is the part called the caecum. Ufually this 

 is larger in fize than the continuation of the tube, and has 

 been therefore called caput coli. It is covered almoft 

 entirely by peritoneum, but is connefted on its right fide, 

 for a fmall extent, to the ihacus internus, by ceUular fub- 

 Itance. It varies much in fize, form, and pofition ; fome- 

 times it is fcarcely one inch, fometimes nearly four in length. 

 It may be larger or fmaller, more or lefs irregular on the 

 furface, &c. 



From ^fs pofterior part of the caecum, a fmall inteftine, 

 about the fize of a quill, cylindrical in its figure, and termi- 

 nating after one or two turns in a rounded and blind extremity, 

 is continued obliquely towards the left. This is the njipendi.-c 

 yermiformis. It is rather larger at its commencement than 

 ia its progrefs, and is held by a fmall fold of peritoneum, 

 like a mefentery. Its coats contain numerous mucous ' 

 giands, and its cavity, which communicates freely with that 

 of the cxcum, is generally filled with a thickifli mucous 

 Q q fluid. 



