Fagge and Stevenson recognized that the action of Strophanthus was similar to that of Digitalis, a foxglove plant. Thomas R. Fraser, Professor of material medicals and therapeutics in Edinburgh also worked on frogs, birds and mammals with that "Kombe arrow poison". He found that the primary action was on the heart, but noted that voluntary muscles were gradually impaired.
Fagge and Stevenson noted a resemblance between Strophanthus' effects and those of Digitalis, a foxglove plant. Thomas R. Fraser, Professor of material medicals and therapeutics in Edinburgh also examined the properties of "Kombe arrow poison" on frogs, birds, and mammals, finding that the primary impact was on the heart but also impairing voluntary muscles.