DIURETICS, the name given to remedies which, under cer tain conditions, stimulate an increased flow of urine. Some are absorbed into the blood and stimulate the kidneys directly, causing an increased flow of blood; others act through the nervous system. A second class act in congested conditions of the kidneys by diminishing the congestion. Another class (saline diuretics) are effectual by virtue of their osmotic action. A fourth class are diuretic by increasing the blood pressure within the vessels in general, and the Malpighian tufts in particular,—some, as digitalis, by increasing the strength of the heart's contractions, and others, as water, by increasing the amount of fluid circulating in the vessels. Some remedies, as mercury, although not diuretic them selves, when prescribed along with those which have this action, increase their effect. The same substance may act in more than one way; e.g., alcohol, besides stimulating the secretory organs directly, is a stimulant to the circulation, and thus increases the pressure within the vessels. Caffeine acts in nearly every way mentioned above. Together with digitalis it is the most efficient remedy for cardiac dropsy. A famous diuretic pill, known as Guy's pill, consists of a grain each of mercurial pill, digitalis leaves and squill, made up with extract of henbane. Digitalis, producing its diuretic effect by its action on heart, vessels and kidneys, is much used in the oedema of mitral disease, but must be avoided in chronic Bright's disease, as it increases the tension of the pulse, already often dangerously high. Turpentine and cantharides are not now used as diuretics, as they are too irritating to the kidneys.