terminates at the surface of the body (Figs. 2, 71 and 73). It has three
divisions, known as the cæcum, the colon, and the rectum.

[Fig. 73]


Fig. 73—*Passage from small into large intestine.* At the ileo-cæcal valve
is the narrowest constriction of the food canal.


_The cæcum_ is the pouch-like dilatation of the large intestine which
receives the lower end of the small intestine. It measures about two and
one half inches in diameter and has extending from one side a short,
slender, and blind tube, called the _vermiform appendix_. This structure
serves no purpose in digestion, but appears to be the rudiment of an organ
which may have served a purpose at some remote period in the history of
the human race. The cæcum gradually blends into the second division of the
large intestine, called the colon.

_The colon_ consists of four parts, described as the ascending colon, the
transverse colon, the descending colon, and the sigmoid flexure, or
sigmoid colon. The first three divisions are named from the direction of
the movement of materials through them and the last from its shape, which
is similar to that of the Greek letter sigma (Σ).

_The rectum_ is the last division of the large intestine It is a nearly
straight tube, from six to eight inches in length, and connects with the
external surface of the body.

The general structure of the large intestine is similar to that of the