The cell theory scientists were Theodor Schwann and Matthias Jakob Schleiden. Schleiden suggested that all the different parts of plants are made of cells. Schwann came to the same conclusion as Schleiden and stated further that animals were also composed of cells.
Schleiden further suggested that cells were made by a crystallization process either within other cells or from the outside. However, this theory was later refuted by scientists Rudolf Virchow, Robert Remak and Albert von Kölliker.
Nevertheless, Rudolf Virchow later made contributions to Schleiden’s and Schwann’s work. He proposed that living cells must develop from pre-existing cells. However, this idea had already been proposed by Robert Remak, who further published observations on cell division disapproving Schwann’s and Schleiden’s generation schemes. Remak stated that binary fission was how new animal cells were made. No further contributions were made on cell theory.
The modern interpretation of cell theory states:
- All living cells arise from pre-existing cells by division
- All known living things are composed of one or more cells
- Energy flow occurs within cells
- All cells have the same chemical composition in organisms of the same species
- The activity of an organism depends on the total activity of independent cells
- The cell is the fundamental unit of structure and function in all living organisms