The idea that the development of arterial hypertension may be instituted by chemical substances coursing in the blood stream has long been an engaging one. It is more appealing than any purely mechanical hypothesis of the genesis of high blood pressure yet formulated; and there is a seemingly corroboratory analogy in the demonstrable hypertensive effects that known chemical substances can actually bring about when they are introduced into the circulation intentionally. Alcohol and tobacco, tea and coffee, all have at times been brought into consideration, usually by enthusiasts imbued with the purpose of the reformer. In addition to such exogenous potent substances there remains the possibility of endogenous products either fundamentally abnormal or merely normal constituents of the organism but arising for some reason in abnormally augmented amounts.
It is obviously desirable that the claims against each suspected engenderer of harm should be critically considered; for the discovery of the