Views and results of investigations made by various specialists are given. A description of digitalis mechanism over the heart is explained showing reaction of calcium and sodium ions across the cell membrane during deplorisation. Mechanism of release of free calcium ions to the contractile proteins is explained. The positive inotropic action of digitalis is mediated through membrane and sarcoplasmic adenosinetriphosphatase system causing increased availability of calcium to the contractile proteins. It is the linkage between myosin cros bridges and reactive sites on the action filament in the presence of calcium troponin-tropomyosin complex which facilitates contractility.