The bile contained within the gall-bladder dillers from that which comes immediately from the liver, in being viscid, of a darker colour, and mixed a ith the mu cus secreted by that organ. It is chiefly on the bile of the gall-bladder, however, that experiments on the na ture and propertie. of this fluid have been made, as a sufficient quantity of bile from the hepatic duct can scarcely be procured.
Various parts of the liver and its appendages are of ten found affected with different degrees and modifica tions of inflammation. Sometimes the inflammation is confined to the peripheral membrane, and adhesions are observed to have taken place between this membrane and the adjacent peritoneal coat of the diaphragm, or of the neighbouring organs. The substance of the liver is not unfrequently seen in a state of inflammation, when it is of a deep purple colour, and generally enlarged. Sometimes abscesses of various extent are observed, and now and then the liver has been seen in a state of mortification. Very frequently there are found within the liver, masses called tub roles, which assume very different appearances, being sometimes hard and white. at others soft and brown, and of a reddish colour, and sometimes very nearly resembling those found within the lungs. The substance of the liver is sometimes unusually hard, at others preternaturally soft or flaccid, and in a few instances a part of its surface has been seen cartilaginous or bony. Lastly, the liver has been found ruptured or torn across.
The gall-bladder frequently partakes of the inflam mation that affects the peritoneal coat of the liver, though it is sometimes seen primarily affected with in flammation, ulceration, or scirrhous. Its coats have been found thickened, containing tubercles or even bony mat ter. The most common morbid appearances, however, of the gall-bladder, are those which affect its excretory duct, or the state of the bile contained within its cavity. The biliary ducts are frequently dilated, and are found obstructed by concretions formed from the solid matters of the bile. Instances have occurred, in which the cavity of the duct is completely obliterated. The gall bladder is often found distended with bile, and the ap pearance of biliary concretions in it is by no means un frequent. The physical nature and chemical proper ties of these concretions, as of some others that are found within the urinary bladder, will be considered under fu ture articles.
3. Of the Spleen.
The spleen is an organ of considerable size, though greatly inferior to the liver. It is of an oblong oval figure, a little depressed, and, like the liver, it is ex tremely vascular. It is of a soft consistence, and of a purple colour. It is situated in the left hypochondriac
region, nearly in a vertical position, just below the diaphragm, and between the large extremity of the stomach and the false ribs, with its sacral extremity lying behind the colon. On its lateral surface, it is con vex, smooth, and equal ; at its mesial side it is irregu larly concave, and is divided by a longitudinal fissure into a sternal and dorsal part, of which the former is the more concave. On its edges it is frequently deeply cleft, and sometimes it is furnished with appendages, or lesser spleens. Like the liver, it is enveloped in a peritoneal coat, b• doublings from which it is attached to the neighbouring organs. liesides this general Licit it has in CA amnion with most of the abdominal eiht (Tit, it i5 With a peculiar• inivest 111•lilbralll:, of a it bulsb gray colour, of con siderable thidmess, consistence, and elasticity, and resembling thy, fibrous membranes ol Ptichat. Produc tions front this mi•mbrane penetrate the substance ol the spleen, and C111 dope the trunks of its principal ves sels.
If Ave except the liter and the lungs, no organ of the human body is so sasrular as the spleen. Indeed, nearly its %%hole substance: is comp ,sed of ramifica tions of arterious and Nenous vessels. It is supplied with artcrieslrum the ceeliac arteries, and from what arc called the rasa breviu, that go to the stomach, and its veins are peculiarly large. Mr •verard Home states, that when both the trunk of the spienic vein, and that of the corresponding artery are injected with wax, the size of the former is live times that of the latter ; a proportion which does nut occur in any other part of the human bodv.—Phd. Trans. 1807. The substance of the spleen is much softer than that of the liver, the coats of its vessels being remarkably tender. The in timate structure ol this organ has not, till lately, been well understood. 'Malpighi, long ago, described a cel lular structure of the spleen, the cells of which con tain red blood, thus placed beta een the arteries and the veins. Culler mentions small corpuscles, of a white colour, which arc made to disappear by minute in jection, and the use of which is D'.1natonne Compuree, tom. iv. p. 58.) Mr Home, (inat tentively examining the spleen, has discovered, that these corpuscles are distinct cells, containing a fluid, which renders their membranous coat visible, and es capes when this is punctured. From these cells the venous branches appear to arise, forming plexuses round the cells, and passing of front them in a radiated direction, at right angles, to the circumference of the cells.