THE LIVER. 



149 



human liver the epithelial cells of the parenchyma form a plexus 

 lying in the meshes of the capillary network of the interlobular 

 vessels. 



It requires an eifort of the imagination to conceive of a third plexus 

 within the lobule, but such a plexus exists, being formed of the 

 radicles of the gall-duct. These are minute channels situated 

 between contiguous epithelial cells, each of which is grooved upon 

 its surface to form half of the tiny canal. The cells themselves 

 have fine channels running from the bile-capillaries into their cyto- 

 plasm and ending there in little rounded expansions. It is difficult 

 to detect these bile-capillaries in ordinary sections of the liver, 

 unless they have been previously injected through the main duct ; 

 but with a high power their cross-sections may sometimes be clearly 

 seen, appearing as little round or oval spaces at the junction of two 



FIG. 127 



FIG. 128. 





Fig. 127. Perivascular lymphatic of the human liver. (Disse.) c, capillary in longitudinal 

 section ; a, lymphatic space between the capillary and row of epithelial cells ; b, wall 

 of the lymphatic space, slightly separated from the liver-cells and drawn a little em- 

 phatically; I, liver-cells; d, bile-capillaries in cross-section, with their intracellular 

 ramifications. 



Fig. 128. Bile-capillaries between the liver-cells, with minute channels penetrating the cells 

 and communicating with secretory vacuoles within the cytoplasm. Injected liver of the 

 rabbit. (Pfeiffer.) 



epithelial cells, midway between the nearest capillary bloodvessels. 

 Throughout their Avhole course they appear to be separated from 

 the nearest bloodvessels by a distance approximately equal to half 

 the diameter of one of the epithelial cells. It is this fact that makes 

 it so difficult to frame a mental picture of their distribution in the 

 lobule (Fig. 128). 



The nerves supplying the liver ramify in extremely delicate, non- 



