452 A. B. MACALLUM. 



longitudinally. The meslies of this network are irregular and 

 greater or less in area than that of a hepatic cell, and the fibrils 

 are very fine, without varicose swellings, and with a violet tint 

 appearing quite distinct against the duller tint of the back- 

 ground formed by the hepatic cells. This perivascular plexus 

 is in direct continuation with the fibres of the coarse inter- 

 lobular plexus, and is therefore of a nervous nature. Whether 

 it belongs to the walls of the capillary channels or to the 

 hepatic cells bordering on these, or to both, I do not know. 

 Sometimes it appears to belong to one, sometimes to the other. 

 I cannot even say whether it is distinct from the intercellular 

 network. The latter, also, is formed of fine fibrils, which are 

 commonly seen unconnected with each other, but which in good 

 preparations show anastomoses enclosing a varying area and 

 extending between the hepatic cells. The finest of these fibrils 

 possess varicosities regularly arranged and observable only with 

 homogeneous immersion lenses such as a -j^ inch. 



All my efforts to find a further resolution of the fibrils of the 

 perivascular plexus availed nothing in the result. They might, 

 as Kolatschewsky found in one or two cases, terminate in the 

 nuclei of the capillary wall, but as to this I can bring no 

 observations either for a negative or for an affirmative view, since 

 in my preparations the capillary walls and their nuclei, unstained 

 by gold chloride, appeared under high magnifying power as a 

 hyaline refracting membrane. The perivascular plexus may, 

 as I have already pointed out, serve as origin to the intercellular 

 plexus. 



From the fibrils of the intercellular netvv^ork ex- 

 cessively minute twigs are given off which terminate 

 each in a delicate bead in the interior of the hepatic 

 cells near the nucleus. In a section such as that given in fig. 

 1 one often suspects such intracellular terminations, but the use 

 of homogeneous immersion objectives does not demonstrate them 

 satisfactorily, and only a careful search of very thin sections 

 gave in five or six cases results not at all doubtful. I found, 

 indeed, in some specimens excessively fine fibrils of a violet 

 colour passing from the capillary side of the hepatic cell to the 



