400 DISEASES OF THE OASTRO-1NTESTINAL TRACT. 



them, however, there is seen under the microscope the atypical 

 structure characteristic of the neoplasm, and not liver-tissue. 

 Secondary carcinoma of the liver is quite common, occurring 

 generally in the form of rounded and umbilicated, pinkish 

 nodules, varying in size from a pea to that of an apple, and 

 often so numerous as to produce an enormous enlargement 

 of the organ. The liver- cells surrounding such a nodule 

 are greatly flattened and atrophied. Microscopically, their 

 structure usually recalls that of the primary tumor. 



Echinococcus cyst is the most important parasitic disease of 

 the liver, and is produced by the larvaB of the tsenia echino- 

 coccus. There may be one or more cysts, varying in size up 

 to that of a man's head. They consist of a connective-tissue 

 capsule, inside of which is the parasitic cyst-wall proper, from 

 which originate smaller vesicles brood- capsules and the 

 heads of the immature tapeworms. As long as the parasite is 

 alive the cyst contains a clear non-albuminous fluid, in which 

 are found scolices, the size of a millet- seed, and characteristic 

 booklets. 



THE BILE-DUCTS AND GALL-BLADDER. 



Inflammation of the bile-ducts is generally secondary to an 

 inflammation affecting the mucous membrane of the duodenum. 

 It may also be produced by the presence of a gall-stone or an 

 intestinal parasite which has crept into the common duct. 

 The result is an obstruction to the outflow of bile, and conse- 

 quent absorption of bile-pigment, giving rise to the condition 

 known as obstructive jaundice. (A non-obstructive jaundice 

 may arise from increased haemolysis in various severe infec- 

 tious diseases as yellow fever.) 



Inflammation of the gall-bladder is quite common, and has a 

 tendency to end in suppuration. It may result from extension 

 of an inflammation from the bile-ducts, or be due to the 

 presence of gall-stones or retained bile. 



Stenosis of the bile-ducts may arise from the pressure ex- 

 ternally of an aneurism, a tumor, or an inflammatory proc- 

 ess around the duct. Congenital atresia sometimes occurs. 



Primary carcinoma of the gall-bladder is occasionally met ; 

 the irritation produced by the presence of gall-stones is looked 

 upon as a possible cause. 



