Abstract
(First paragraph) From plants of the Apocynaoiac and Scrophulariaceae order, substances are extracted which are heart poisons. Small doses of such substances stimulate deseased heart to a greater contractional activity and the result is a decrease in the rate and an increase in the intensity of the heart beat. These substances are made of a complicated polynuclear radical of the steroid type called aglucon or genin and a chain of sugars such as glucose rhammose, digitoxose, cymarose, digitalose etc. attached to the aglucon by a glucosidic linkage. These types of substances are called cardiac glycosides. The glycosides of therapeutic value are found in the digitalis plant commonly known as fox glove.