Virchow expanded Scheiden’s cell theory and stated that cells arise from pre-existing cells.
The cell theory was given by Schleiden and Schwann, which was later modified by Rudolf Virchow. The three principles of cell theory are:
- All living organisms are composed of one or more cells.
- Cell is the basic structural and functional unit of living organisms.
- All cells arise from pre-existing cells.
Cell theory was expanded by Virchow in 1855 by suggesting that all cells arise from pre-existing cells All animals and plants are composed of cells, which serve as the units of structure and function and all cell arise from pre-existing cells. This is called the Cell Theory. It was propounded by Matthias Schleiden and Theodor Schwann in 1839 later on Rudolf Virchow added to this in 1858.