GLANDULAR SECRETIONS. 



89 



lobules is a miniature gland, containing all the component elements 

 of which' the gland is made up, viz. : branches of the hepatic artery 

 and vein, branches of the portal vein, branches of the hepatic ducts 

 and secreting cells. These lobules are connected together by means 

 of areolar tissue and anastomoses of blood-vessels. The hepatic 

 artery is distributed in a capillary form upon the walls of the hepatic 

 ducts, and upon the trunks 



and branches of the portal Fig. 21.* 



and hepatic veins ; it is 

 therefore probably destined 

 for the nutrition of the or- 

 gan and not to supply ma- 

 terials for the biliary secre- 

 tion, at least until it has be- 

 come venous by traversing 

 the capillary system. From 

 the capillary network the 

 blood passes into branches 

 of the portal vein, and thence 

 into the hepatic veins ; for 

 when fine injection was 

 thrown by Mr. Kiernan into 

 the hepatic artery, the por- 

 tal veins became filled, but not the hepatic. The venaportcB ramifies 

 in a capillary form between the lobules, and hence is called the 

 interlobular vein, sending capillary twigs inwards, which converge 

 towards the centre of the lobule, to form the hepatic or intralobular 

 vein. (Fig. 21.) These 



latter terminate in the 

 larger trunks,which pass 

 along the bases of the 

 lobules, collecting from 

 them their venous blood; ^ 

 these are called by 

 Mr. Kiernan sublobular 

 veins. The main trunk 

 of the hepatic vein ter- 2; 

 minates in the ascend- 

 ing vena cava. The he- 

 patic ducts also form a 

 plexus, which surrounds 



Fig. 22.t 





* Horizontal section of three superficial lobules, showing the two principal systems of 

 blood-vessels; 1, 1, intralobular veins, proceeding from the hepatic veins; 2, 2, interlobular 

 plexus, formed by branches of the portal veins. 



t Horizontal section of two superficial lobules, showing the interlobular plexus of biliary 

 ducts; 1, 1, intra-lobular veins; 2, 2, trunks of biliary ducts, proceeding from the plexus 

 which traverses the lobules ; 3. interlobular tissue ; 4, parenchyma, of the lobules. 



8* 



