2. The ileum, 6, opens into the cecum, all of the bowel below the
opening being cecum, the opening of the appendix, 3, is in the lower
part of the cecum.

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,