80 BILE. 



following facts will, however, probably indicate the path by which 

 we may arrive at a knowledge of the mode of origin of the bile. 

 The first point in this investigation is, to decide the question where 

 the formation of the biliary constituents actually takes place, that 

 is to say, whether they exist ready formed in the blood, or whether 

 they are first formed in the secreting organ. The larger number 

 of well-confirmed facts tend to show that the principal con- 

 stituents of the bile are primarily formed in the liver itself from 

 certain constituents of the blood conveyed to this organ by the 

 portal vein. On comparing the histological formation of the liver 

 with that of the kidneys, we perceive that in the liver there cannot 

 be a pure transudation a mere process of filtration of certain con- 

 stituents of the blood such as occurs in the kidneys. We know 

 that in the liver the most minute blood-vessels are separated from 

 the smallest canals which convey the bile by a thick layer of 

 tolerably large cells, and that consequently in every case the 

 substances given off from the blood must pass through cells 

 endowed with vital force, before they can enter into the biliary 

 canals. No comparison can be instituted between these cells and 

 the epithelial cells which occupy the ducts of Bellini ; for these 

 hepatic cells close the extremities of the biliary canals (whether 

 these form blind and distended sacs or very minute loops); if the 

 smallest biliary canals possess a membrana propria, these cells, 

 united in rows and having a ccecal arrangement, lie external to it, 

 and consequently in this respect differ essentially from the epithe- 

 lial cells of the canaliculi contorti of the kidney, which take no 

 part whatever in the urinary secretion. But the microscope which 

 reveals to us the contents of these cells, indicates that they are 

 elaborated from materials resorbed from the blood; for in addition 

 to the round nucleus occurring in these cells, they contain a 

 greater or less quantity of small molecules and vesicles, which very 

 often become developed into distinct fat-globules; in numerous 

 cases, however, these hepatic cells are filled with a yellowish 

 matter, which sometimes appears in the form of distinct and 

 separate molecular granules, and sometimes as diffused masses. 

 With regard to the colourless fat-globules, they must necessarily 

 undergo a metamorphosis within the cells, since very little free fat 

 is generally found in the bile. From certain microscopical observa- 

 tions which I made in reference to the morphological contents of 

 the hepatic cells of dogs and rabbits at different periods after 

 taking food, it seems to follow that their physical characters vary 

 with the stage of the digestive process. These and other histo- 



