Any therapeutic measure claiming efficacy in a given disease or condition should fulfil at least this primary condition: It should be proved beyond a reasonable doubt that this measure, and this alone, produced the given result. As a corollary to the main proposition, it may be fairly demanded that any maneuver claiming to be more effective than another should show that the former measure is definitely and measurably superior to the latter.
In 1920, Allen1 published a paper in which he asserted that a greater restriction in salt intake in cases of hypertension would produce a much greater reduction in pressure, a greater relief in symptoms, a speedier clearing up of retinal hemorrhages, etc., without other restriction in diet, exercise, etc., than other methods of treatment. He advocated limiting the intake of salt to 0.5 gm. a day instead of the usual 2 gm. His claim, if true, would have