CHAP.XXXIII.] GALL BLADDER. 471 



these branches leave the ducts and anastomose with each other 

 just outside the trunk from which they are given off. 



Many of the small ducts about the -^ of an inch in diameter, 

 have numerous ccecal pouches connected with them, arranged 

 pretty close together, gradually becoming shorter as the duct 

 becomes smaller, and giving off branches composed of basement 

 membrane only. These irregular ducts with coecal pouches are 

 very numerous in the transverse fissure of the liver, where they 

 form an intricate network connected with the larger branches 

 of the duct in this situation. They were described by Theile as 

 branching mucous glands, but were first noticed and named vasa 

 aberrantia by Weber, who also described the anastomosis between 

 the right and left hepatic ducts in the transverse fissure, by the 

 intervention of these irregular branches. 



In the portal canals, the vasa aberrantia occur as already men- 

 tioned, but in diminished number. Dr. Beale considers these 

 cavities, or irregular branches, connected with the ducts, as little 

 reservoirs in which the bile in ducts with thick coats is brought 

 into closer proximity with the numerous vessels surrounding them, 

 by which means it loses some of its water, and probably undergoes 

 other changes. He observes, that the arrangement of the vessels 

 around these ducts, both in the transverse fissure of the liver and 

 in the portal canals, is similar to that which exists in the coats of 

 the gall bladder. A small cavity with a narrow neck seems scarcely 

 adapted for pouring out viscid mucus; moreover, the bile of animals, 

 in which these so-called glands are very few in number, as in the 

 rabbit, seems to contain as much mucus as that of the pig, in which 

 animal the glands are very numerous and well developed. Accord- 

 ing to this view of their office, these cavities may be regarded in 

 the light of little gall bladders. 



The coats of the larger ducts appear to be principally composed 

 of condensed fibrous tissue, but there is reason for supposing, that, 

 at least in some of them, there are a few muscular fibre cells, 

 although they do not form a distinct layer or muscular coat. 



The epithelium of the larger ducts is of the columnar variety. 

 The cells are large and well-formed, often exhibiting a distinct 

 nucleus. They are frequently tinged with yellow colouring matter, 

 and often contain yellow granules. In the smaller ducts, this 

 epithelium becomes shorter, until, in the smallest branches, it 

 approaches more nearly to the tesselated variety. 



Gall Bladder. The gall bladder may be looked upon as a 

 diverticulum of the hepatic duct. It lies in a fossa underneath the 

 liver. It is of a pear shape, and its fundus is directed downwards 



