SECT. 1 6 1.] ARRANGEMENT OF HEPATIC CELLS. 347 



slight interstices between the cells and the basement membrane. 

 According to my view, the spaces which are seen in an injected liver 

 are not natural ; and there can be no doubt that the bile is trans- 

 mitted from cell to cell till it arrives to the smallest real ducts, 

 whose communications with the network of cells will be described 

 in the following paragraph. 



Such a conduction through closed cells is, as vegetable physiology 

 sufficiently shows, not impossible, only it will not, of course, take 

 place so rapidly as in places where true canals subserve this purpose. 

 Since the bile, as the more recent observations show more and more 

 distinctly, is not merely secreted from the blood, but really formed 

 in the liver, and, at the same time, is the most complex of the secre- 

 tions, it may be supposed, that the peculiar arrangement of the 

 secerning parenchyma in the liver has a very intimate relation with 

 the above circumstances. In fact, the blood-plasma, when it has to 

 pass through many cells, and suffer their metabolical influences, 

 must undergo entirely different changes before it arrives at the ex- 

 cretory canals, than when it is separated from the canals of the 

 glands only by a simple layer of cells and one or two structureless 

 coats. The necessary slowness of the process in these circumstances, 

 is compensated by the elaboration of the secretion and the size of 

 the organ. 



If nitric acid be added to the hepatic cells, they become, as Backer also 

 mentions, greenish-yellow coloured. Sugar and sulphuric acid render them red. 

 Water produces in the cells an abundant precipitate of dark granules, which 

 generally dissolve readily and completely in acetic acid, so that the cells 

 become more or less pale, as is also the case when only the acid is added. When 

 the liver is boiled, the parenchyma becomes hard, and the cells appear con- 

 tracted and granular. Diluted caustic alkalies quickly attack and dissolve the 

 hepatic cells of animals; in man, the cells resist longer : still, they immediately 

 swell up to double their previous size, become quite pale, and at length also 

 disappear. Ether and alcohol, as also sulphuric and nitric acids, render the 

 cells smaller and granular. The inference from these and the above- 

 mentioned facts is, that the hepatic cells contain a considerable quantity of 

 nitrogenous substances, bile-colouring matter, fat, and perhaps, also, the acids 

 of the bile. The sugar, which more recent investigations have shown to 

 be present in the liver, is, perhaps, to be considered as being formed in the 

 parenchyma, in the cells accordingly, and not merely in the blood. The liver- 

 cells of young mammalians are, according to the observations of Oluge and 

 myself, very often found full of fat, so that the livers of such animals have 

 the greatest resemblance with fatty livers. 



^ 16 1. Efferent Biliary Passages. — The hepatic duct, with its 

 branches, accompanies the portal vein and hepatic artery, so that 

 a branch of the portal vein has always, on one side, a much nar- 



