=Gangrene= of the peritoneum may result from intussusception or hernial incarceration of some portion of the bowel, when the part will appear as a softened, dark, offensive mass, limited by a band of highly congested tissue. =Ascites.= Dropsical accumulations in the abdominal cavity, may result from obstructed circulation, caused by disease of the liver, kidneys, heart or lungs; or from pressure upon the vena cava, or portal vein, by some abnormal growth. The fluid effused may be nearly colorless, or present various shades of yellow, red or green, and usually coagulates on the application of heat. The peritoneum may appear unchanged, or it may present a thickened, opaque, white or macerated appearance, in chronic cases. Blood may be found in the peritoneal cavity, as a result of wounds, rupture of some of the abdominal or pelvic organs, or bursting of an aneurism. =Morbid Growths.= =Tubercular Deposits=, of the miliary form, are not unfrequent in the peritoneum. They may be diffused over the whole membrane, as semi-transparent, gray granules, but more frequently are found on the under surface of the diaphragm, in the neighborhood of the spleen, and on the viscera generally, while the parietal layer is more free. The tubercles, acting as foreign bodies, give rise to inflammation, usually of a chronic form, but sufficient to result in exudation of lymph, and the formation of adhesions between the adjoining surfaces. Softening of the tubercular deposits sometimes takes place, and perforation of the intestinal wall results, leading to an effusion of the intestinal contents into the peritoneal cavity. =Cancer= of the peritoneum, is sometimes seen as a primary affection, yet it more frequently extends to this membrane from some of the deeper parts. The encephaloid variety may be met with, but the colloid form is that most frequently seen. The omentum is the occasional seat of this form of cancer, the membrane in such cases becoming enormously increased in size. =Tumors= of various kinds, including _fibrous_, _fatty_, and _cystic_, may be found in the peritoneal cavity, generally having had their origin, however, in the sub-peritoneal tissues. _Fatty_ tumors may originate within the substance of the omentum or mesentery, while _cystic_ tumors may be found within the broad ligaments of the uterus or ovaries. Section II. OF THE STOMACH.