112 SPECIAL HISTOLOGY. 



connected together throughout the whole organ. Nevertheless, 

 it would be very erroneous to suppose that the secreting paren- 

 chyma of the liver is everywhere homogeneous. Ultimate seg- 

 ments may be observed in it, which have a certain independence, 

 although they are in nowise isolated. These hepatic lobules, as 

 they may be called, if the term be used in its most general sig- 

 nification, or hepatic islets, are thus produced : 1. The smallest 

 branches of the afferent and efferent blood-vessels, the venue 

 inter- and intra-lobulares (Kiernan) are distributed at pretty 

 equal intervals through the whole liver, so that a portion of he- 

 patic substance of J — \ — 1'" in diameter, is always found to 

 give origin in its interior, to a small twig of the hepatic vein 

 receiving externally a certain number of the minutest branches 

 of the portal vein and of the hepatic artery ; and, 2. The hepatic 

 ducts do not commence irregularly in the parenchyma, but are 

 so disposed that they invariably arise at a distance of ~ — J'" 

 from the origins of the hepatic veins and take the same course 

 as the finest ramifications of the portal vein. In this manner 

 little masses, containing only secreting parenchyma, capillaries 

 and the origins of hepatic veins, are marked out in the liver; 

 whilst in their interspaces, together with parenchyma and 

 capillaries, lie the ultimate branches of the portal vein and 

 hepatic artery and the origins of the hepatic ducts, which, as 

 they do not approach the masses from one, but always from 

 many sides, and are also supported and partially united by 

 connective tissue, form, if not complete, at all events partial 

 zones around them. 



[The livers of those animals which present lobes (Polar 

 Bear, /. Midler, Pig), are of the greatest value in compre- 

 hending the structure of the organ and I therefore here subjoin 

 an account of the structure of the Pig's liver. If we examine 

 this organ in sections or otherwise, it is always seen to be 

 divided into numerous small, rounded, polygonal, not very regular 

 arece of tolerably uniform size, (i — 1 J'") which consist of the 

 proper parenchyma of the liver and are bordered by whitish 

 partitions, readily visible to the naked eye. If a cut surface 

 be scraped with the handle of a scalpel, angular masses of liver, 

 equal in size to these arece, are detached, the capsules which 

 surrounded them remaining behind as empty compartments, 

 like a honeycomb. These become still more distinct if a thin 



