I have already mentioned (p. 29) that one can hardly look for a general relation between the atomic weights of metals and their lethal activity, so that what we want is really a knowledge of the particular relationship of each group of elements to the organs and tissues of the body.

In such an investigation it seems natural to take the muscles first, then the motor nerves, afterwards the nerve-centres and individual organs. A number of experiments have been made by

Cash and myself in order to do this for the alkalis and alkaline earths, and we have found that the contractile power of muscle as shown by the height of the curve, is increased by rubidium, ammonium, potassium, and caesium. It is slightly increased or unaffected by sodium, excepting in large doses, and is almost invariably diminished by lithium.

The duration of contraction, as shown by the length of the curve, is increased by rubidium in large doses, ammonium, sodium, and caesium. It is shortened by ammonium, lithium, rubidium in small doses, and by potassium.

The contracture, or viscosity, is increased by rubidium in large doses, ammonium, lithium, and sodium. It is diminished by rubidium in small doses, ammonium, caesium, and potassium.

Both ammonium and rubidium have two actions on muscle of an opposite character, sometimes increasing and sometimes diminishing both the duration of the contraction and of the contracture, or viscosity, which remains after the ordinary contraction has ceased. In the case of rubidium this appears to depend upon the dose, but we were not satisfied that it was so entirely in the case of ammonium salts.

In regard to the action of the alkaline-earths and earths, we found that the contractile power of muscle is increased by barium, erbium, and lanthanum. It is sometimes increased and sometimes diminished by yttrium and calcium. It is diminished by didymium, strontium, and beryllium.

The duration of contraction is increased by barium, calcium, strontium, yttrium, and erbium. It is unaffected, or slightly diminished, by beryllium, didymium, and lanthanum.

Contracture is increased by barium, calcium, strontium, yttrium, and beryllium.

The contracture produced by barium is enormous, resembling that produced by veratrine. It is, like that of veratrine, diminished by heat, cold, and potash, and may be abolished by these

Increase or diminish after action or contracture.

Increase. O Diminish.

Increase or diminish altitude

Increase or diminish altitude.

Diminish. O Increase.

Shorten or lengthen curve

Shorten or lengthen curve.

Lengthen. O Shorten.

agents. It is by no means so well marked when the drug-is injected into the circulation as when locally applied to the muscle.

The action of some of the more important of those drugs can be graphically represented by a spiral

The action of some of the more important of those drugs can be graphically represented by a spiral, the terminal members of which are potassium and barium, and these two are, to a certain extent, connected by ammonium as an intermediate link.

The effect of one member of one of these groups may be diminished or increased by the subsequent application of another. Potassium shortens the elongated curves caused by barium, calcium, sodium in large doses, and lithium, and reduces the contracture which these substances cause. The veratrine-like curve of barium is counteracted by almost all the substances which produce a shorter curve than itself.