Abstract

The physiological action of the chemical substance depends, in a great measure, on the living substance upon which it is to act. Effects found in actions on one tissue are not applicable, without special tests, to the other tissues of the same animal or to the same tissues of other animals. Effects found for simple tissues are not applicable to complex organs and effects found for organs are not applicable to entire animals.

The order of toxicity of the four chlorides under discussion was found in experiments on animals (dogs) to be magnesium, calcium, potassium, sodium. Magnesium was twice as toxic as calcium, potassium three times less toxic than the latter, while sodium was many times less toxic than any of the others. The dominant view that potassium is the most toxic was derived mostly from experiments upon the isolated heart.

For the dog, and perhaps for all mammals, the toxicity of the alkalies and alkali earths existing as constituents of the animal body is in inverse proportion to the quantities in which they are present in the serum of that animal; the smaller this quantity the more toxic it is in intravenous injections.

The convulsions produced by intravenous injections of sodium chloride may be toxic in character and have the same origin as the twitchings and rhythmical contractions observed in frog muscles when immersed in solutions of sodium chloride. On the other hand, the early stoppage of the respiration might have its cause in the curare-like action which sodium chloride exercises upon the motor nerve endings.