394 THE PANCREAS. 



In the duplicature of peritoneum forming the left lateral ligament of 

 the liver, and also in the two fibrous bands which sometimes bridge 

 over the fossa for the vena cava and the fissure of the umbilical vein, 

 there have been found biliary ducts of considerable size which are not 

 surrounded with lobules. These aberrant ducts as they are called, 

 were described by Ferrein and afterwards l)y Iviernan ; they anastomose 

 together in form of a network, and are accompanied by branches of the 

 vena portie, hepatic artery, and hepatic vein. 



Structure of tlie Gall-bladder. — Besides the peritoneal investment 

 and the mucous lining, the gall-bladder possesses an intermediate mus- 

 cular and connective tissue coat, of considerable strength. This con- 

 sists mainly of bands of dense shining white fibres, which interlace in 

 all directions. Intermingled with these are plain muscular fibres, which 

 have principally a longitudinal direction, but some run transversely. 

 This coat forms the framework of the organ, and supports the larger 

 blood-vessels and lymphatics. The nerves form a gangliated plexus in 

 it ; partly also immediately beneath the serous coat (L. Gerlach). 



The mucous memirane, which is generally strongly tinged with bile, 

 is elevated upon its inner surface into very numei-ous small ridges, 

 which, uniting together into meshes, leave between them depressions 

 of different sizes and of various polygonal forms. This gives the 

 interior of the gall-bladder an alveolar aspect, which is similar to what 

 is seen on a smaller scale in the vesiculo3 seminales. These alveolar 

 intervals become smaller towards the fundus and neck of the gall- 

 bladder ; and at the bottom of the larger ones, other minute depres- 

 sions, which may be seen with a simple lens, lead into numerous 

 mucous recesses. The whole of the mucous membrane is covered by 

 columnar epithelium, and it secTctes an abundance of viscid mncus. 



At the places where the neck of the gall-bladder curves on itself there 

 are strong folds of its mucous and areolar coats projecting into the 

 interior. 



In the ci/st'fc duct, the mucous membrane is elevated internally in a 

 similar manner into a series of crescentic folds, which are arranged in 

 an oblique direction, and succeed closely to each other, so as to present 

 very much the appearance of a continuous spiral valve. When dis- 

 tended, the outer surface of the duct appears to be indented in the 

 situation of these folds, and dilated or swollen in the intervals, so as to 

 present an irregularly sacculated or twisted appearance. In the structure 

 of its wall, the cystic duct resembles the gall-bladder. 



THE PANCREAS. 



The 2K()icreas (fig. 282, h i) is a long, narrow, flattened gland of a 

 reddish cream colour, larger at one end than at the other, and lying 

 across the posterior wall of the abdomen, behind the stomach, and 

 opposite the first lumbar vertebra. Its larger end, the ]iead, turned 

 to the right, is embraced by the curvature of the duodenum, whilst its 

 left or narrow extremity, the tail, reaches to a somewhat higher level, 

 and is in contact with the spleen. 



The pancreas varies considerably, in different cases, in its size and weight. It 

 is usually from 6 to 8 inches long, about 1^ inch in average breadth, and 

 from half an inch to an inch in thickness, being thicker at its head and along its 

 upper border than elsewhere. The weight of the gland, according to Ea-ause and 



