1. A steroid glycoside obtained from Digitalis purpurea that has no cardiac action; used as a reagent in the determination of plasma cholesterol and steroids having a 3-hydroxyl group in beta configuration. 2. A mixture of four different steroids found in the seeds of Digitalis purpurea; a strong hemolytic poison. They can act as nonionic detergents in the solubilization of membrane proteins.