Nestor Gréhant
Nestor Louis François Gréhant (2 April 1838 in Laon – 26 March 1910) was a French physiologist. In 1864 he received his medical doctorate in Paris, where he later earned a doctorate in natural sciences (1870). He served as a préparateur to Claude Bernard at the faculty of sciences in Paris, and subsequently became director of the laboratory of general physiology at the École pratique des Hautes Études. In Paris, he also served as a professor of physiology at the Muséum d’Histoire Naturelle. In 1905 he became a member of the Académie de médecine. He is best remembered for  his studies of blood and blood circulation (measurement of cardiac output in animals) and respiration. He also made contributions in his research of the nervous system, of muscle activity, toxicology, anaesthesia and experimental hygiene. He developed a number of devices that he used in research, including a "grisoumètre" (firedamp detector) that was still in use in coal mines up until 1950.