SummaryBy oral as well as by parenteral route, the digitalic glucosides penetrate into all the tissues of-the body. They are concentrated less in the heart than in other organs. Their steroid nucleus is hydroxylated in the body. The glucidic side chain may also be progressively lost by hydrolysis. The extent of these two metabolic processes may vary from one heterosid to another. The catabolic derivatives are able to produce cardiotonic effects. The rates of fecal and urinary excretion as well as the duration of action of each glucoside depend on the nature and the quantity of the various catabolites formed by hydroxylation or by hydrolysis.