Early scientists were conflicted about the mechanism by which cells were created, with some scientists holding the viewpoint that cells were spontaneously crystallized in what was known as free cell formation. Robert Remak discovered ways to fix and observe cell membranes in various stages of cell division. These findings led Rudolf Virchow to proclaim in 1855, Omnis cellula e cellula (every cell comes from another cell), thus completing the tenets of cell theory.