- Schleiden (1804-1881) and T. Schwann (1810-1882). Schleiden was botanist. While Schwann was an animal anatomist. Schleiden and Schwann though that each body of plant and animal consisted of cell.
- Felix Dujardin (1835) said that the most important part of living cell was the liquid that always resided in every living cell (protoplasm).
- Johannes Purkinje and Hugo van Mohl (1840) introduced the term of protoplasm.
- Max Schultze (1825-1874) though thatprotoplasm was the primary structure of living organisms that make all living process.
- Rudolf Virchow (1858) though that every cell came from the prior cell (omnis cellula e cellula).
- Robert Brown, R. Strasburger, and C. Bernard succeded in finding nucleus. Starsburger said that each nucleus came from the prior cell formed through division. Meanswhile, Bernard said that nucleus managed cell function, and it was the most important structure of cell.
Scientists, later, found out that there were chromosome and gene in cell as heredity units. Therefore, new cell theory came out and stated that cell was a heredity unit. From the explanation, we can conclude that cell is a structural, functional, and growt unit of living organism.