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of plant cells. It was Raspail who in 1825 coined the Latin phrase
omnis cellula e cellula
—every cell is derived from another cell. Raspail
combined chemical analysis with microscope work by adding iodine-
starch color reaction to the cell. He used this technique to examine
processes within cells, such as how the membrane of the cell wall
serves as a selective gateway: “[Cell walls] thus have the property of
Dutch manufacturer Anton van Leeuwenhoek ground precision lenses for microscopes.
His instruments achieved powerful magnification, permitting scientists to clearly see
and identify living bacteria, various body cells, and tiny protozoa.
