Abstract: The generally held view that Ca²⁺ is synergistic to the action of cardiac glycosides, has been shown to be true only for a few glycosides. According to the results of the present experiments on guinea pigs, the toxicity of divasid, a glycoside-preparation from Strophanthus divaricatus Hook et Arn with divaricoside as the main constituens, showed no dependence on Ca²⁺, a circumstance similar to ouabain. In another experiment, it has been observed that Ca²⁺ nullified the antiarrhythmic action of tetrandrine on divasid and ouabain.