or sufficiently appreciated
among physicians, that the mass of fecal matter normally evacuated from
the bowels comes mainly from the blood; and that this mass is not, as
it is usually supposed to be, the residue of the food that has been
left unassimilated. Embedded in the mucous membrane of the colon are
tubular glands under the control of the nervous system. When these
glands become unduly excited through local inflammation and irritation,
the normal flow from them is increased to such an extent that a rapid
waste of precious tissue occurs throughout the system, and the vital
force--which had taken perhaps years to store--is depleted to the point
of exhaustion, sometimes even in a few hours. Almost every one has had
some experience of exhaustion following diarrhea.

The increased flow of blood to the mucous membrane of the colon
furthers this extraordinary secretion by the glands. As has been
pointed out, inflammation, septic poisoning, intestinal foulness, or
retained feces, act as irritants on the mucous membranes, thereby
drawing the blood to the colon where it is excreted and exhaustion
follows. The great danger in diarrhea, therefore, is the rapid
depletion of the vital force. But when the small intestines are
affected the consequences may be still more deplorable. Then the
unassimilated food is hurried along too quickly for absorption and the
body receives but little nourishment to restore its powers. Thus
another draught is made upon the sufferer's reservoir of vitality, and
hence additional exhaustion. But this waste of tissue, loss of vital
force, non-assimilation and non-supply, are not so grave as the
positive danger of the permanent destruction of the millions of small
absorbing vessels (villi) of the small intestine by a continuance of
this abnormal irritation. Of course the secretory and excretory glands
of the colon also suffer, and we then have costiveness resulting from
lack of absorption and excretion.

Abnormal irritability of the bowels is necessarily involved in the
inflammatory process known as proctitis and colitis. Increase this
irritability to a certain point and diarrhea takes the place of
constipation--a much more alarming symptom. Diarrhea is more alarming
because the intensified local activity of the excretory glands of the
bowels brings on, as has been said, a general exhaustion of the vital
powers.

The severity of diarrheal symptoms is much increased by the character
and abundance o