1. According to Jean Brachet (1961), the cell is the basic structural unit of an organism.
2. According to Loewy & Siekevitz (1963), a cell is a unit of biological function which is surrounded by a permeable membrane and is self-reproducing.
3. According to C. P. Hickman (1970), the cell is the unit of biological structure and function and is the smallest biological unit capable of self-regulation and reproduction.
4. According to Swanson and Webster (1978), the cell is the basic unit of physical existence of life.
5. According to De Roberties (1979), the cell is the basic structural and functional unit of an organism.
6. According to the Merriam Webster dictionary, a cell is a microscopic lump of protoplasm covered by a semipermeable membrane, containing one or more nuclei and other cell organelles and their components, capable of performing the basic functions of life either singly or by interaction with other cells, and is the smallest independent functioning structure of life. constitutes a unit.
