In 1665, Robert Hooke, a British scientist examined thin slice of cork tissue under the compound microscope and found that the cork consisted of many neatly arranged little chamber or cavities. Since each chamber was enclosed by walls similar to cell of honey combs, he named the chamber cells.
In 1835, Dujardin, a French biologist, examined thin slice of living plants under much improved microscope and discovered that cells have content. He named the content sarcode, later named protoplasm by Purkinje in 1839 and von Mohl in 1846.
In 1839,Mathias Schleiden was a German botanist discovered that all plants are made up of cells.
In 1839, Theodor, a German zoologist examined bits of animals under a microscope and observed that animals were composed by cells.
In 1839, Schleiden and Theodor Schawann jointly stated what is now known as the cell theory, namely that all living things are made up of cells. After the statement of the cell theory, in 1846, Hugo Von- Mohl fisrt applied the term protoplasm to the the living substances in the cell, the name by which it si still known till today. In 1858 Rudolf Virchow stated that cells come from pre- existing cells.
The cell Theories
1.All living things are made up of a cell or cells
2.The cell is the structural and functional unit of all living things
3.New cells arise from pre-existing cells by cell division
4.There is no life apart from the life of cell
5.All living things are either single cell or a group of unicellular or multicellular
CELL AS A LIVING THING UNIT OF AN ORGANISM
A cell is defined as the basic structural and functional unit of a living organism. In other word, the cell is the simplest, smallest and basic unit of life because it can carryout all life activities