GLISSON'S CAPSULE PORTAL VEIN. 517 



" Each lobule is composed of a plexus of biliary ducts, of a venous 

 plexus formed by branches of the portal vein, of a branch (intra- 

 lobular), of an hepatic vein, and of minute arteries ; nerves and 

 absorbents, it is to be presumed, also enter into their formation, but 

 cannot be traced into them." " Examined with the microscope, a 

 lobule is apparently composed of numerous minute bodies of a yel- 

 lowish colour, and of various forms, connected with each other by 

 vessels. These minute bodies are the acini of Malpighi." " If an 

 uninjected lobule be examined and contrasted with an injected 

 lobule, it will be found that the acini of Malpighi in the former 

 are identical with the injected lobular biliary plexus in the latter, 

 and the blood-vessels in both will be easily distinguished from the 

 ducts." 



Glisson's capsule is the cellular tissue which envelopes the hepatic 

 artery, portal vein, and hepatic duct, during their passage through 

 the right border of the lesser omentum, and which continues to 

 surround them to their ultimate distribution in the substance of the 

 lobules. It forms for each lobule a distinct capsule, which invests 

 it on all sides with the exception of its base, connects all the lobules 

 together, and constitutes the proper capsule of the entire organ. But 

 " Glisson's capsule," observes Mr. Kiernan, " is not mere cellular 

 tissue ; it is to the liver what the pia mater is to the brain ; it is a 

 cellulo- vascular membrane in which the vessels divide and subdivide 

 to an extreme degree of minuteness ; which lines the portal canals, 

 forming sheaths for the larger vessels contained in them, and a web 

 in which the smaller vessels ramify ; which enters the interlobular 

 fissures, and with the vessels forms the capsules of the lobules ; and 

 which finally enters the lobules, and with the blood-vessels expands 

 itself over the secreting biliary ducts." Hence arises a natural 

 division of the capsule into three portions, a vaginal, an interlobular, 

 and a lobular portion. 



The vaginal portion is that which invests the hepatic artery, 

 hepatic duct, and portal vein, in the portal canals ; in the larger 

 canals it completely surrounds these vessels, but in the smaller is 

 situated only on that side which is occupied by the artery and duct. 

 The interlobular portion occupies the interlobular fissures and spaces, 

 and the lobular portion forms the supporting tissue to the substance 

 of the lobules. 



The Portal vein, entering the liver at the transverse fissure, rami- 

 fies through its structure in canals which resemble, by their surfaces, 

 the external superficies of the liver, and are formed by the capsular 

 surfaces of the lobules, " all their canals being," as it were, " tubu- 

 lar inflections inwards of the superficies of the liver." These are 

 the portal canals, and contain, besides the portal vein with its rami- 

 fications, the artery and duct with their branches. 



In the larger canals, the vessels are separated from the parietes 

 of the cavity by a web of Glisson's capsule ; but, in the smaller, the 

 portal vein is in contact with the surface of the canal for about two- 



