Luigi Galvani's pioneering work in the late 1700s set the stage for studying the electrical excitability of muscles and neurons. In the first half of the 19th century, Jean Pierre Flourens pioneered the experimental method of carrying out localized lesions of the brain in living animals describing their effects on motricity, sensibility and behavior. In 1843 Emil du Bois-Reymond demonstrated the electrical nature of the nerve signal,[1] whose speed Hermann von Helmholtz proceeded to measure,[2] and in 1875 Richard Caton found electrical phenomena in the cerebral hemispheres of rabbits and monkeys.[3] Adolf Beck published in 1890 similar observations of spontaneous electrical activity of the brain of rabbits and dogs.[4] Studies of the brain became more sophisticated after the invention of the microscope and the development of a staining procedure by Camillo Golgi during the late 1890s.