DIURETICS (from δια, through, and oυpεω, to pass urine) are remedies which, under certain conditions, produce an increased flow of urine. Their mode of action is various. Some, as turpentine and cantharides, are absorbed into the blood, are carried to the secretory organs (the kidneys), aud stimulate them directly, causing an increased flow of blood to them; others act as stimulants through the nervous system. A second class act in congested conditions of the kidneys by diminishing the congestion; this is supposed to be one of the modes of action of digitalis. Another class, such as the 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 themselves, when prescribed along with those which have this action, increase their effect. The same remedy 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. It is stated above that remedies have a diuretic action under “certain conditions.” These relate to—1st, the state of the kidneys themselves; 2d, the condition of other organs; 3d, the surroundings of the patient; 4th, the dose and mode of administration of the remedy. In illustration of each of these—1st, a dose of cantharides, which in a patient with the kidneys healthy would be diuretic, would in one with the kidneys acutely congested have the reverse effect; 2d, if there were much ...