The arterial supply to these parts is great enough to get them into trouble in those people who are imprudent eaters, and it is also great enough to save the parts when diseased if the patient has the proper treatment. For the benefit of the lay reader I will say that the blood-vessels represented in the cut are the arteries; there are also veins, nerves, and lymphatics imbedded in the folds of the peritoneum, accompanying and paralleling the arteries, but they are not shown in the cut. The peritoneum is the lining membrane of the peritoneal cavity. It is well to remember that there is nothing in the peritoneal cavity except a little serum. The layman will say that the bowels are in this cavity, but they are not; they project into the cavity, and their outside covering is the lining membrane of the peritoneal cavity, but they are truly on the outside of the cavity, and to enable the layman to understand the anatomy so that he can apply it when reading of the disease, I shall describe the course of an ulcer: If an ulcer starts in the bowel it first eats through the mucous coat which is the lining membrane of the bowel then through the submucous coat, which is the second layer or coat of the bowel, then through the muscular coat, which is the third layer of the bowel; this brings the ulcer to the serous coat or peritoneum. When the peritoneum is eaten through it is called perforation, for it means that there is an opening into the peritoneal cavity, and, unless the cavity is cut into, cleaned and properly drained death will take place in a very short time. I say death is inevitable without surgical treatment. In this I appear to be more radical than the most radical, for the best authors have much to say about perforation, diffuse peritonitis, and of patients who live after perforation, as though it were a common occurrence; I say they are mistaken. CHAPTER II _History: _Appendicitis did not become popularly known until about twenty years ago--not till it was christened and baptized in the blood of the surgical art. Of course the appendix has always been subject to inflammation, just as it is now, but in former years the disease we call appendicitis bore various names, depending upon the diagnostic skill of the attending physician. Typhlitis and perityphlitis were the names used to designate the disease now covered by the word appendicitis. The diseases that appendicitis may be confounded with and must be differentiated from are obstruction, renal colic, hepatic colic, gastritis, enteritis, salpingitis, peritonitis due to gastric or intestinal ulcer, enterolith, obstipation, invagination or intussusception, hernia, external or internal, volvulus, stricture and typhoid fever. The old text-book description of typhlitis and perityphlitis is so similar to the description of the present day appendicitis that it is not necessary to reproduce it. The symptoms given show conclusively that they are really one and the same.