DIGESTION. 



275 



merous fatty molecules, and some yellowish-brown grannies of bile-pig- 

 ment. The cells sometimes exhibit slow amoeboid movements. They 

 are held together by a very delicate sustentacular tissue, continuous with 

 the interlobular connective tissue. 



To understand the distribution of the blood-vessels in the liver, it 

 will be well to trace, first, the two blood-vessels and the duct which en- 

 ter the organ on the under surface at the transverse fissure, viz., the 

 portal vein, hepatic artery, and hepatic duct. As before remarked, all 

 three run in company, and their appearance on longitudinal section is 

 shown in Fig. 206. Kunning together through the substance of the 

 liver, they are contained in small channels called portal canals, their 

 immediate investment being a sheath of areolar tissue (Glisson's capsule). 



d a 



FIG. 205. FIG. 206. 



FIG. 205. A. Liver-cells. B. Ditto, containing various-sized particles of fat. 



FIG. 206. Longitudinal section of a portal canal, containing a portal vein, hepatic artery and 

 hepatic duct, from the pig. p, branch of vena portae, situate in a portal canal formed amongst the 

 lobules of the liver, I Z, and giving off vaginal branches; there are also seen within the large portal 

 vein numerous orifices of the smallest interlobular veins arising directly from it; a, hepatic artery; 

 fc, hepatic duct. X 5. (Kiernan.) 



To take the distribution of the portal vein first : In its course 

 through the liver this vessel gives off small branches which divide and 

 and subdivide between the lobules surrounding them and limiting them, 

 and from this circumstance called ^Wer-lobular veins. From these small 

 vessels a dense capillary network is prolonged into the substance of the 

 lobule, and this network gradually gathering itself up, so to speak, into 

 larger vessels, converges finally to a single small vein, occupying the 

 centre of the lobule, and hence called aWra-lobular. This arrangement 

 is well seen in Fig. 207, which represents a transverse section of a lobule. 



The small intra-lobul&r veins discharge their contents into veins 



