THE LIVER SECRETION OF BILE. 469 



channel through which the biliary matter is eliminated; 1 the urine becomes 

 tinged with the coloring principle of bile, being sometimes of a yellowish or 

 orange hue, and sometimes of a brown color with a considerable sediment; 

 and the presence of the most characteristic constituents of the bile has been 

 determined in the urine. The same result presents itself, when the biliary 

 duct has been artificially obstructed by ligature. Other secretions have been 

 found tinged with the coloring matter of bile: thus the pancreatic fluid has 

 been seen of a yellow color in jaundice ; and the milk has presented not merely 

 the hue, but the characteristic bitterness, of the biliary secretion. The cutane- 

 ous transpiration is not unfrequently so much impregnated with biliary matter, 

 as to communicate its tinge to the linen covering the skin ; and even the 

 sputa of patients affected with bilious fevers have been observed to be similarly 

 colored, and have been found to contain biliary matter. The secretions of 

 serous membranes, also, have been frequently seen to present the characteristic 

 hue of bile ; and biliary matter has been detected, by analysis, in the fluid of 

 the pleural and peritoneal cavities. Biliary matter, however, when unduly 

 present in the circulating current, is not removed from it by the secreting 

 organs alone ; for it seems to be withdrawn also in the ordinary operations of 

 nutrition, entering into combination with the solid tissues. Thus, in persons 

 affected with jaundice, we find the skin, the mucous and serous membranes, 

 the lymphatic glands, the brain, the fibrous tissues, the cartilages, the bones 

 and teeth, and even the hair, penetrated with the coloring matter of the bile, 

 which they must have withdrawn from the blood, and which seems to have 

 a particular affinity for the gelatinous tissues. It is impossible at present to 

 say, however, to what extent the more characteristic ingredients of the bile 

 are thus withdrawn from the blood ; for the presence of its coloring matter can- 

 not by any means be taken as an indication that its peculiar resinoid acids 

 are also incorporated with the normal components of the tissues. 



2. The Liver. Secretion of Bile. 



386. The Liver is probably more constantly present, under some form or 

 other, throughout the entire Animal series, than any other gland. Its form 

 and condition vary so greatly, however, in different tribes, that, without a 

 knowledge of its essential structure, we should be disposed to question whether 

 any identity of character exists among the several organs which are regarded 

 as Hepatic. It is, in fact, the presence of bile-secreting cells, that must be 

 held to constitute a Liver ; and these may be scattered over the general lining 

 membrane of the alimentary canal, or may be restricted within follicles which 

 are formed by depressions of it ; these follicles, again, may be multiplied in 

 some particular spot, so as to be aggregated into a mass, or may be extended 

 into long tubes. In all the Invertebrata, however, the Liver is obviously 

 conformable to the general type of glandular structures ; the hepatic cells 

 being in immediate relation with a basement-membrane, and being dis- 

 charged upon a free surface. This will be readily understood from an ex- 

 amination of any one of the higher forms of it, such as that presented in 

 the liver of the Crab, which, like the liver of the Mollusca generally, is a 

 lobulated glandular mass, formed by the aggregation of a multitude of 

 follicles with distinct csecal terminations ; these follicles discharging their 

 secreted products into cavities which occupy the centre of the lobules, 

 whence they are collected by the ducts which convey them into the alimen- 

 tary canal. On a careful examination of these follicles (Fig. 165, p. 470), 

 and a comparison of the size and contents of the cells at the bottom and to- 



1 See J. W. Legg in St. Barthol. Hospital Reports, vol. ix, p. 161. 



