In this group the bacterial infection is of a much more virulent nature than in the catarrhal form. The inflammation originating in the mucosa of the appendix at once involves all its lay-en, including the serosa. Necrobiotic processes and formation of pus take place quite early. The peritoneum is also very soon involved, either in the immediate neighborhood of the appendix or in its entirety. Ulcerations and gangrenous processes may lead to the destruction of a part of the appendix, thus causing perforation, or to a total necrosis of the entire appendix. As a result of this process the latter may be cast off from the caecum and be found free in the peritoneal cavity or embedded in pus.

1 P. Guttmann: Verhandlungen des Vereins fur innere Medicin zu Berlin, 1883-84, p. 301.

The way in which the peritoneum is involved is quite variable. There may be an adhesive type of peritonitis leading to a matted and agglutinated condition of the appendix, or a circumscribed or diffuse peritonitis without adhesions. The contents of the appendix may. be emptied into the abdominal cavity or hemmed in by adhesions. The size, location, and direction of the abscess differ greatly. The location and length of the appendix and the portion perforated play an important part in this respect. In the great majority of cases the abscess is at first intraperitoneal, but very soon extends toward the surface or above or below Poupart's ligament. Again it may penetrate into the bladder, vagina, small intestine, or rectum. In some instances it reaches the diaphragm and from there perforates into the pleural cavity.

In some very grave cases there is no abscess but a diffuse peritonitis. Here we often meet with a paretic condition of the intestine, the latter being filled with gas; the serous layer is shiny and red, while there is an absence of any exudation. In other cases a small quantity of a purely serous or bloody serous exudation is found. The condition just described may be discovered either in operations undertaken very early or at autopsies in cases which terminate fatally at the beginning of the disease. In still another group of cases which is a comparatively very small one, the general peritonitis may assume a more protracted and chronic form. In these cases mattings and adhesions are formed over more or less large areas of the abdominal cavity, and in these accumulations of pus may be found.

Appendicitis due to tuberculosis is of comparatively rare occurrence and shows a great tendency to the formation of fistulae. Recently actinomycosis has been found to be the cause of some cases of appendicitis with the formation of abscesses. In these cases the actinomycosis fungi can easily be demonstrated.