Mr. Beale on the Anatomy of the Liver of Vertebrate Aiiimals. 469 



In some animals these communications are so numerous, that a 

 complete network is formed at the portal aspect of the lobule, or 

 around a small branch of the portal vein. 



Not only are the right and left hepatic ducts connected together 

 by intermediate branches in the transverse fissure of the liver, as 

 E. H. Weber long ago demonstrated, but the branches coming off 

 from these communicate with each other as well as with the trunks 

 from which they come off. These branches are very numerous, and 

 form an intimate network of irregular branched ducts. Similar 

 communications occur between the branches in the portal canals, 

 but they are not so numerous. This arrangement occurs to a less 

 extent in the dog and in the calf, but it is not present in all animals. 

 The author has not been able to demonstrate it in the pig, seal, rab- 

 bit, horse, cat and monkey, although he is not prepared to say that, 

 absolutely, no communications take place between the ducts near 

 their origin, in these animals. 



Of the glands of the ducts. — The so-called glands are small cavi- 

 ties of a rounded or oval form, or more or less branched, which com- 

 municate with the cavity of the duct by a very constricted neck. 

 The simple glands are for the most part situated in the coats of the 

 ducts, so that, when injected, they scarcely project beyond the ex- 

 ternal surface. These cavities or glands are most easily demon- 

 strated in the pig. 



When a small duct from the human liver is laid open, two lines 

 of orifices are seen opening upon the internal surface, as Kiernan 

 described. The great majority of these, however, are not the open- 

 ings of glands, but almost all of them are the orifices of branches of 

 the duct which communicate with each other in its coats, or just at 

 the point where they leave it. Very few of them are the openings 

 of caecal cavities, which are very rare in the smaller ducts of the 

 human subject. 



Vasa aberrantia. — There are many curious branches of communi- 

 cation between the ducts in the transverse fissure of the liver, which 

 have been well named " vasa aben-antia " by Weber. Theile looks 

 upon all these ducts as anastomosing mucus-glands. The author 

 has seen these ducts in the portal canals, down to those not more 

 than one-eighth of an inch in diameter. They present the same 

 characters as the branches in the transverse fissure, but are not so 

 numerous. The coats of the vasa aberrantia are thinner than those 

 of the ordinary ducts, and, like them, are lined with epithelium, 

 principally of a subcolumnar form. These branches are always sur- 

 rounded by areolar tissue, in which lymphatics are very numerous. 

 The arrangement of the vessels about the vasa aberrantia is pecu- 

 liar. The arteries and veins form a network, and each small branch 

 of the artcrjf lies between two branches of the vein, which com- 

 municate with each other at frequent intervals by numerous trans- 

 verse branches, some of which pass over and some under the artery. 

 The author observes that this beautiful arrangement of the vessels 

 occurs in the gall-bladder, in the transverse fissure, and in the portal 

 canals. This disposition of the veins has the effect of ensuring free 



