LIVER. 



nal, mucous, or villous coat, as It is fipqviently called, is 

 eoniieaed below and at the fides to the peritoneal covering ; 

 above to the proper membrane of the liver. The inner fur- 

 face prefents the rugx already noticed. It is of confiderable 

 thicknefs, and has a kind of fporgy texture. During life 

 it is white ; the tint of the bile never bemg communicated 

 until after death. Several anatomiils have defcribed mucous 

 elands and follicles in this membrane ; but tlicy cannot be 

 fitisfadorily afcertained. Soemmtrring, however, dcfcnbes 

 glands near the neck as large as millet feeds. On account of 

 the folds and rugsc of the internal fiirfacc, its extent is much 

 increafed when the cellulir fubdance is removed from the 

 cutfide. Afterafuccefsfulinjeftion of thehlood-vefl'els, this 

 coat appears to confift entirely of a vafcular net-work. 



The artery of the gall-bladder is a branch of the hepatic ; 

 the veins join the vena portarum. The lymphatics, v,fliich 

 are numerous and large, join tliofe of the inferior furface 

 of the hver. The nerves come from the hepatic plexus. 



Anatomiils formerly admitted the exillence of velTels 

 palling direftly from the liver into the gall-bladder, under 

 the name of hepatico-cyllic di.Cts. Such vcffels exill in 

 birds, but they certainly do not belong to the human fub- 

 jecl ; the only conneftion between the liver and gall-bladder 

 being through the medium of the hepatic and cyllic 

 dudts. 



The organifation of the hepatic and cyflic duels is elTen- 

 tially the fame. They have two coats, an external fibrous 

 one, and a mucous or internal lining. The former is thick, 

 denfe, and llrong, and compofed apparently of whitifh lon- 

 gitudinal fibres, vvhich have nothing mufcular in their ap- 

 pearance, and the nature of which is not well underilood. 

 The mucous coat is thin and foft, and prefents in fome parts 

 the fame areolated texture as on the internal furface of the 

 gall-bladder : the whole of the cyllic duCl has this peculiar 

 arrangement, and its internal membrane forms the tranfverfe 

 folds already mentioned. The hepatic duel, from the liver 

 to near the point at which it enters the intelline, is frnooth : 

 it has fome longitudinal folds about its middle, and is reti- 

 culated near the duodenum. 



Thefe dufts poffefs very great extenfibility : they are fomc- 

 times dilated, by the pafTage of calculi, to the fize of a 

 thumb. They, as well as the gall-bladder, acl on their 

 contents by the infenfible organic contraclility, or tonic 

 power. They are never feen to contrail fenfibly in any ob- 

 fervations of living animals, nor do the ftimuli, which excite 

 contraflions in the mufcles, produce the fame effect on 

 them. Probably the paffage of the food over the orifice of 

 the dud in the duodenum is the exciting caufe of their aftioils. 

 Although they are not fenfible in the natural ftate, difeafe 

 developes this property in them to a remarkable degree. 

 No pain is more acute than that produced by calculi in thefe 

 dufts. 



Divelsprmcnt of the Fiver. — This organ is difcerned in the 

 embryo before any of the other vifcera ; and it is propor- 

 tionaUy larger in the early months of conception, than at any 

 fjture time. Wrifberg faw it in a foetus of ten weeks fo 

 lari-e, that it occupied nearly the whole abdomen. Walter 

 fays that it can be feen at twenty-two days. At thefe periods 

 it appears to be net much lefs than half the weight of the 

 body. This great bu!k of the organ does not lad tlirough the 

 whole of gelliition ; after the fourth month, it does not 

 proceed fo rapidly in its growth, although it maintains a 

 remarkable predominance over the other viicera till the time 

 ef birth. As a general obfervation we may affert, that it is 

 larger in proportion as the animal is nearer to the time ef its 

 6rit formation. 



During fetal fxidenee, the blood of the umbilical vein 

 circulates through the liver, on Us way to the heart : but 

 the whole of this blood is fent to the left lobe. (See the 

 defcription of the umbilical veiFels in the article Embryo, 

 and the article CiKCUl.A riox.) Hence that lobe is quite as 

 large, if not larger, than the right. From this great bulk 

 of the organ, as well as from the breadth of the bafis of the 

 chell, and the fmall concavity of the diaphragm, the rel.itiona 

 of the liver to the furrountling parts are very didi-rcnt from 

 what we obferve in the adult. It not only fills both hypo- 

 chondria and the epigallric region, but deiccnds below thet 

 ribs, as far as the umbilicus, and fills halt the abdomen; 

 It is placed at this time more perpendicularly in the body, fo 

 that the convex and concave furlaccs, which are fupcriorand 

 inferior in the adult, are nearly anterior and pofterior in the 

 fcEtus. The anterior furface is extenfively in contiift wit!« 

 the abdominal parietes : the pofterior covers the llomach, 

 fpleen, and even omentum. Its tidue at this time is foft and 

 fpongy, and contains a large quantity of blood : the latter 

 circumltanee gives to the organ a darker colour than it has 

 in the adult. 



We are entirely ignorant of the funfiions performed by 

 the liver during fetal exillence, of the relation between its fize 

 and any of the procefics of the animal economy, and whether 

 any changes are produced in the blood as it paiies through 

 the organ. 



The excretory part of the hepatic fyftcm is not propor- 

 tioned in its developement to the fize of the liver in the 

 fostus : for the latter circumllance is conneftcd with the 

 circulation, and not with the biHary fccretion. The inter- 

 nal furface of the gall-bladder is at fird Imooth, and dees 

 not exhibit the areolated (IruClure until the latter months of 

 gellation. According to ilifierent authors this bag contains 

 no bile, but merely a reddifh mucus, until the 4th, j'h, or 

 6th month : its fundus is coir;pletely concealed beluid the 

 edge of the liver. At the time of birth it is always i'M of 

 bile ; but the fluid is ftill reddifh and mucou-s and peffefles 

 but little tafte. 



The fudden revolution that oceurs in the circulating fyf- 

 tem at birth, produces a remarkable change in the liver. The 

 interception of the blood, which was conveyed to the organ 

 by the umbilical vein, is followed by a very marked reduftion 

 in its fize affefting particularly the left lobe. The tiifue of 

 the organ is rendered more denfe, and its colour acquires a 

 brighter red tint, or becomes pale. After a certain time 

 the organ participates in the progrefs of the other parts of the 

 body. Tlie excretory apparatus undergoes no remarkable 

 change : it is not fo readily tinged with bile, as at a more ad- 

 vanced age, probably from fome change in ihe nature and pro- 

 perties of that fluid. In the old fubjtft the organ fometimes 

 is reduced in fize, and frequently becomes more ioft. On the 

 whole, however, after the changes confequent on birth have 

 been completely efieiled, and the liver has acquired its per- 

 manent relation to the other organs, very little change takes 

 place in it. 



Thefecret'ionandcourfeofthebile. — That this fluid is fe- 

 parated in the liver, and conveyed from that organ by the 

 hepatic du<El, are points fo clear, that they do not require aiiy 

 exprefs proof. From which order of veflels in the liver this 

 fecretion takes place, is a queftion not fo cafily anfwered. 

 Phyfiologilts have generally afcribed this office to the vena 

 portarum, and have confidered the hepatic artery to be the nu- 

 trient vefiel cf the organ, as the bronchial arteries are of the 

 lungs. They give the following reafons for this opinion. 

 J. The excretory duft is larger than tlie artery, a circum- 

 ltanee wliich does net occur in any other gland : its fize how* 



ever 



