The interval of the electrocardiogram from the termination of the S wave to the end of the T wave is being investigated by various observers in order to establish the method of its production and the significance of the variations from the normal. This interval is designated the S-T interval.
The present interpretation of the phenomena of the S-T interval rests, fundamentally, on the observations of a few workers. The foremost among these is Galvani1 who, in 1786, discovered electric currents in the muscles of the frog. The flow of electric current from points of higher potential to points of lower potential was first observed by Nobili,2 in 1824, shortly after his invention of the galvanometer. Kölliker and Müeller,3 in 1855, while pursuing investigations similar to those of Galvani, found each beat of the frog's heart to be accompanied by a definite electric current. The next great advance was made