Used with
permission of Maiken Naylor, University at Buffalo, Buffalo, NY, USA,
http://ublib.buffalo.edu/libraries/units/sel/exhibits/stamps
Louis Pasteur (1822-1895) advanced the field of stereochemistry with his studies of optical isomers and methods of separating them. He went on to develop vaccines for rabies and anthrax, and the process now known as pasteurization, in which microorganisms which cause spoilage of products such as wine or milk are killed by the application of heat. His work helped to disprove the theory of spontaneous generation, which was still current in the 1860's: it was believed that living organisms could spontaneously arise from inanimate matter, such as maggots from meat. Pasteur excluded invisible airborne organisms from samples by means of S-shaped necks on flasks.