HERMANN VON HELMHOLTZ. — Born on 31 August 1821 in Potsdam, died on 8 September 1894 in Charlottenburg. He earned his medical degree in 1842 with a paper on microscopic anatomy in which he discovered the cellular structure of nerve ganglia.
He studied various biological phenomena, including putrefaction and the causes of fermentation, animal heat, muscle contraction, and the speed of transmission of nervous stimulation, among others. In the field of physics he became renowned (alongside Mayer and Thomson) for applying the law of the conservation of energy to electrical and magnetic phenomena. He investigated sense organs, conducting fundamental experiments in experimental physiology of sensations; his precise data, the aid of instruments which his skill perfected and invented, and the acute critical spirit with which he interpreted and weighed results, rendered his research classic.
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. Baffoni