Medicinal plants. Historical artwork of foxglove plants (Digitalis sp., left and right) and herb paris (Paris quadrifolia, centre). Both plants are extremely toxic, but can be used in medicinal treatments. Tincture of herb paris is an arsenic antidote and the juice of the berries can cure eye inflammations. The leaves of the foxglove contain digitalin, which is a heart muscle stimulant. High doses cause disorganised pumping of the heart. However, small quantities can be used as a drug to treat heart failure, for example in cases of heart attack (myocardial infarction). From Hortus Eystettensis, by Basilius Besler, published in 1613.