THE BILIARY CANALS OF THE LOBULES. 15 



of its borders. Wherever, consequently, in a completely in- 

 jected lobule, the planes of two hepatic cells are seen in profile, 

 that is, as a straight line, a biliary duct may, with few excep- 

 tions, be observed, either presenting a circular or oval section 

 which lies in the centre of this line, or in rare cases at one of 

 its extremities, or offering its lateral surface to the observer, and 

 then appearing as a small rod which runs parallel to the line, 

 and, according to the focussing of the microscope, is situated 

 just above or beneath it. 



If it be borne in mind how the hepatic cells are arranged 

 between the capillaries, it becomes evident that when in fine sec- 

 tions only a single series of cells is visible between two radial 

 capillaries, the biliary ducts must appear partly in section 

 within the transverse lines which, as profile views of the line 

 of junction of two cells, run from one capillary to the other, 

 and must partly present their lateral aspect more or less fore- 

 shortened as canals that are approximatively parallel to the 

 capillaries, and intervene between them. But if in these sec- 

 tions the hepatic cells appear in the form of an epithelium 

 then the biliary ducts will constitute a plexus with polygonal 

 meshes, each of which includes an hepatic cell (fig. 120). 

 Again, if in thin sections the radially arranged capillaries are 

 seen to be transversely divided, the biliary ducts will be partly 

 seen in transverse section, and for the most part within the lines 

 which, as profile views of the line of junction of two cells, unite 

 two capillaries together; or more rarely they will form points 

 where the surfaces of several cells are applied to each other; 

 and finally in part in the form of a plexus, each mesh of which 

 is occupied by a capillary vessel (fig. 121). 



The above description has been drawn up from the appear- 

 ances presented by injected preparations. The liver of Man, 

 which at the earliest can only be investigated some hours after 

 death, has by that time become so altered from incipient coagu- 

 lation of the hepatic cells that the biliary canals of the lobules 

 can no longer be injected. Nevertheless they are still accessible^ 

 even without injection, to observation, and with very high 

 powers it will then be found that their arrangement is pre- 

 cisely similar to that of other Mammals. After I had given a 

 detailed description of the biliary ducts of the liver of the 



