It was believed for a long time that drugs radiated from the seat of application throughout the system, by the nerves; this is known now to be false, and, instead, we recognize the blood to be the common carrier; thus the blood has to take up the drug in solution before there will be other than a local effect, and when once dissolved in it the periodic rounds of circulation are made regularly with this impregnation, so that the system, as a whole, responds to the medicine's influence. As proof of this, we find that blood taken from any portion of the body, near or far from the point of application, contains the drug; also the blood of persons poisoned when injected into others produces similar poisonous symptoms; if you interrupt the blood-circulation to any part, no poison will he transmitted to that part; as other secretions are nourished by the blood, you would expect them also to have similar medical properties, and such is the case - milk, sweat, urine, etc.; if we inject medicines directly into the blood (a dangerous process), we soon have characteristic action. The blood is enabled to absorb these through the intervention of the veins, lymphatics, and lacteals; while it eliminates them, even to the extent often of irritation, through the excretory organs, kidneys, bowels, skin, etc.