On the electrical phemomena of the excitatory process in the heart of the frog and of the tortoise, as investigated photographically.

See No. 824. This paper contains several tracings of the heart's electrical activity recorded with a capillary electrometer, the earliest graphic recorder of bioelectric signals. These were the "first undistorted tracings of the electrical activity of the heart" (Burch & Depasquale, A history of electrocardiography, 1990, 102).