Evacuation.= Much of the misconception about
constipation arises from the mistaken idea that this is a disorder of
the whole intestine or at least of the whole colon. As a matter of
fact, the trouble is almost wholly in the rectum. There is no trouble
with the general traffic movement, but only with the unloading at the
terminus. In my experience, the patient reports that he feels the
fecal mass in the lower part of the rectum, but that he is unable to
expel it. Examination by finger or by X-ray reveals a mass in the
rectal pouch. If there is a piling up of freight further back on the
line, it is only because the unloading process has been delayed at the
terminus.

So long as the bowel-content is in the region of automatic control,
there is very little likelihood of trouble. An occasional case of
organic trouble--appendicitis, lead-colic, mechanical obstruction, new
growths or spinal-cord disease--may cause a real blockade, but in
ninety-nine cases out of every hundred there is little trouble so long
as the involuntary muscles, working automatically under the direction
of the subconscious mind, are in control. By slow or rapid stages, on
time or behind time, the bowel-content reaches the upper part of the
rectum and passes through a little valve into the lower pouch. Here is
where the trouble begins.

=Meddlesome Interference.= In the natural state the little human, like
the other animals, empties his bowel whenever the fecal mass enters
the lower portion of the rectum. The presence of the mass in the
rectum constitutes a call to stool which is responded to as
unthinkingly as is the desire for air in the taking of a breath. But
the tiny child soon has to learn to control some of his natural
functions. At the lower end of the rectum there is a purse-string
muscle called the _Sphincter-ani_, an involuntary muscle which may
with training be brought partly under voluntary control. Under the
demands of civilization, the baby learns to tighten up this muscle
until the proper time for evacuation. Then, if he be normal, he lets
go, the muscles higher up contract and the bowel empties itself
automatically, as it always did before civilization began.

There is, however, a possibility of trouble whenever the conscious
mind tries to assume control of functions which are meant to be
automatic. Under certain conditions necessary control becomes
meddlesome interference. If the child for one reason or another takes
too much intere