STRUCTURE OF THE LIVER. 



317 



To take the distribution of the portal vein first : In 

 its course through the liver this vessel gives off small 

 branches, which divide and subdivide between the lobules 

 surrounding them and limiting them, and from this cir- 

 cumstance called inter-lobular veins. From these small 

 vessels a dense capillary network is prolonged into the 

 substance of the lobule, and this network gradually gather- 

 ing itself up, so to speak, into larger vessels, converges 

 finally to a single small vein, occupying the centre of the 

 lobule, and hence called i;ira-lobular. This arrangement 

 is well seen in fig. 86, which represents a transverse sec- 

 tion of a lobule. The smaller branches of the portal vein 

 being closely surrounded by the lobules, give off directly 

 Fig. 86.* 



i?iter-lobular veins (see fig. 85) ; but here and there, espe- 

 cially where the hepatic artery and duct intervene, branches 



* Fig. 86. Cross section of a lobule of the human liver, in which 

 the capillary network between the portal and hepatic veins has been fully 

 injected (from Sappey) -. I. Section of the witfro-lobularvein ; 2, its 

 smaller branches collecting blood from the capillary network ; 3, inter- 

 lobular branches of the vena portse with their smaller ramifications 

 passing inwards towards the capillary network in the substance of the 

 lobule. 



