Cytochrome

Studying the muscles of a horse botfly, Keilin noticed absorption bands that disappeared after shaking but reappeared afterward. He suggested that there must be a substance responsible for absorbing oxygen in cells, discovered it, and named it cytochrome. This finding enhanced understanding of cellular oxygen absorption processes.
 David Keilin England 1924 Cytochrome

Studying the muscles of a horse botfly, Keilin noticed absorption bands that disappeared after shaking but reappeared afterward. He suggested that there must be a substance responsible for absorbing oxygen in cells, discovered it, and named it cytochrome. This finding enhanced understanding of cellular oxygen absorption processes.