24 THE LIVER, BY EWALD BERING. 



It is invested externally by another layer of connective tissue, 

 and where the surface of the gall-bladder is exposed this is 

 again covered by the peritoneum. The bloodvessels, and es- 

 pecially the veins of the gall-bladder, are both numerous and 

 large. The arteries, according to Beale, are each accompanied 

 by two veins that frequently communicate by short branches 

 passing over or under the artery, so that the whole venous sys- 

 tem closely resembles the usual arrangement of the lymphatics. 

 Numerous large subserous lymphatics are distributed on the 

 free surface of the bladder ; but minute lymphatic vessels have 

 not been demonstrated, either in this part or between the 

 several layers of which it is composed. According to Luschka,* 

 the parietes of the gall-bladder contain small isolated mucous 

 glands, like those of the cystic and hepatic ducts, and the 

 ductus communis choledochus. From a consideration of its 

 structure, the cystic duct must be regarded as a prolongation 

 of the gall-bladder. 



E. H. Weber described the plexiform and anastomosing biliary 

 ducts situated in the transverse fissure under the term vasa aber- 

 rantia, because he considered them to be ducts, the parenchyma 

 belonging to which had not been developed. He took a similar view 

 of the nature of other ducts that may be found lying externally to 

 the proper substance of the liver. Theile,f on the other hand, in 

 consequence of his discovery of the glands of the biliary ducts, 

 regarded all these ducts of the transverse fissure as plexiform anas- 

 tomosing mucous glands, as well as that plexus of biliary ducts he 

 found in the capsule of Glisson. But he considered the ducts found in 

 the ligamentum triangulare sinistrum (Ferrein, Kiernan), those found 

 in the connective tissue that sometimes forms a bridge over the in- 

 ferior vena cava between the right lobe and the lobulus Spigelii 

 (Kiernan, Theile), those in the fossa for the umbilical vein (Kiernan, 

 Weber), and those at the sides of the gall-bladder, to be biliary ducts, 

 which have lost their proper lobular substance by atrophy. That 

 this is correct in regard to a portion of these ducts, at least, may be 

 concluded from the circumstance that in old people the sharp edge 



* Henle and PteuSer'sZeitschriftfurBationetteMedicin., 1858, Bandiv., 

 p. 189. 



t Rud. Wagner's Handworterbuch, der Physiologie, Band ii., 1844. 



