THE LIVER AND BILIARY APPARATUS. 197 



fades, until at length it would be difficult to even locate the 

 original seat of the capillary. I have verified this over and 

 over again. The capillary walls seem to be structureless ; at 

 least with a power of 1,400 diameters I have been unable to 

 detect any structure. The membrana propria of the inter- 

 lobular bile-ducts is continued on to the capillaries within the 

 lobule. 



Hering, Henle, and others do not believe that the bile-capillaries possess 

 walls of their own, but suppose them to be contained within the boundary- 

 surface of the liver-cells, the latter taking the place of the epithelium of the 

 interlobular bile-ducts. Henle further quotes Schweigger-Seidel (in the Archiv 

 far path. AnaL und Phys., XXVII., 505, 1863), who injected the bile-capillaries 

 with faintly colored gelatine, and showed that by warming the slide the gela- 

 tine dissolved without leaving any residue whatever. From what has been 

 said of artificial injections, and recognizing the extreme delicacy of the bile-cap- 

 illaries, it is not surprising that this result was obtained after injecting a warm 

 solution of gelatine into the capillaries. The walls of these capillaries are 

 homogeneous and exceedingly delicate, so that they are destroyed by a mod- 

 erate degree of heat. Very soon after death they undergo a sort of liquefac- 

 tion, and what was before a vessel with true walls is now an open channel, 

 through which an artificial fluid can be made to force its way. 



At first the elimination of the indigo-carmine takes place 

 in the bile- capillaries on the external border of the lobule, 

 and somewhat later the capillaries about the central vein be- 

 come filled. Neither the protoplasm of the liver-cells nor their 

 nuclei ever become stained with the blue solution during the 

 process of elimination ; such coloring would be the result of 

 post-mortem diffusion. But the cylindrical epithelium of the 

 glands is colored blue, and indubitably these glands excrete 

 the indigo-carmine, as do the cells of the convoluted tubules of 

 the kidney. Whether they secrete any substance during life, 

 or what that substance may be, has not yet been determined. 



Theile, Kolliker, and Kiernan suppose that these glands secrete a mucous 

 substance which becomes mixed with the bile. Henle regards these glands 

 and excavations as reservoirs which are occasionally filled with bile. From 

 what has been said above it would appear that the cylindrical epithelium of 

 the glands eliminates the indigo-carmine, and hence we may suppose that 

 they secrete some fluid or substance during life. 



The gall-bladder. The walls of the gall-bladder are about 



