In 1688, Francesco Redi (1626 – 1678), an Italian physician who
disapproved the idea of spontaneous generation, showed that
rotting meat carefully kept from flies did not spontaneously
produce maggots.
In 1836, Theodor Schwann (1810-1882) helped develop the cell
theory of living organisms, namely that that all living organisms
are composed of one or more cells and that the cell is the basic
functional unit of living organisms.
In 1861, Louis Pasteur’s (1822-1895) famous experiments with
swan-necked flasks finally proved that microorganisms did not
arise by spontaneous generation.