Who proposed the principle that all cells arise from pre-existing cells?

The principle that all cells arise from pre-existing cells was proposed by Rudolf Virchow in 1855. This principle, also known as the "Cell Proliferation" principle, builds upon the earlier cell theory stating that all living organisms are made up of cells and that the cell is the basic unit of life. The cell proliferation principle adds that new cells are formed by the division and differentiation of pre-existing cells. This principle was a significant contribution to the cell theory and is considered one of the cornerstones of modern cell biology.