makes its appearance, with a kind of valvular opening into it, of such a nature that everything that passes along it having reached the blind or closed end, must return in order to escape; or rather the office of the cæcum is to permit certain alimentary matters and all fluids to pass from the ileum, but to oppose their return.

The

colon

is

[an]

intestine of very large size, being one of the most capacious, as well as one of the longest, of the large intestines. It commences at the

cæsum caput coli,

and soon expands into a cavity of greater dimensions than even that of the stomach itself. Having attained this singular bulk, it begins to contract, and continues to do so during its course round the cæcum, until it has completed its second flexure, where it grows so small as scarcely to exceed in calibre one of the small intestines; and though, from about the middle of this turn, it again swells out by degrees, it never afterwards acquires its former capaciousness; indeed, previously to its junction with the rectum, it once more materially differs in size.

At the upper part of the margin of the pelvis the colon terminates in the

rectum