In 1910, a systematic pharmacological investigation of a series of aliphatic and aromatic amines (Barger & Dale, 1910) revealed a number of compounds that had properties similar to those of epinephrine. These compounds elicited physiological responses of varying degree similar to functional stimulation of the sympathetic nervous system. From this work the term sympathomimetic amine was coined. Prior to this (in the 1880's), ephedrine, the active principle of the Chinese herb Ma Huang, had been studied and was discarded as being too toxic. Upon reinvestigation by Chen and Schmidt (1924), the pharmacological importance of ephedrine as a sympathomimetic was recognized. Publication of this work stimulated new interest in these amine compounds, especially the phenylethylamines and the phenylisopropylamines, the chemical nucleus structures of epinephrine and ephedrine, respectively.