HELMHOLTZ, HERMANN von. - B. on 31 Aug. 1821 at Potsdam, d. at Charlottenburg on 8 Sept. 1894. He graduated in medicine in 1842 with a work on microscopic anatomy in which he discovered the cellular structure of the nerve ganglia.
He studied various biological phenomena, including putrefaction and the causes of fermentative phenomena, animal heat, muscular contraction, the speed of transmission of nervous stimulation, etc. In the field of physics he remained famous (together with Mayer and Thomson) for the application of the law of conservation of energy to electrical and magnetic phenomena. He studied the sense organs by carrying out fundamental experiments in the experimental physiology of sensations; his accurate data, the aid of instruments which his skill perfected or devised, and the keen critical spirit with which he interpreted and assessed the results, made his researches classical.
His most notable works: Über die Erhaltung des Kraft (1847), Beschreibung eines Augenspiegels zur Untersuchung des Netzhaut im lebenden Auge (Berlin 1851), Handbuch der physiologischen Optik (Leipzig 1866).
Giorgio M. Biffoni