in 1838 , matthias schleiden , a german Botanist , announced that every plant is made up of a large number of cells.
In 1839 , Theodar Schwann , a german zoologist declared that all animals and plants are composed of cells which serve as the units of structure and function.
Rudolf Virchow in 1858 made an addition to the celll theory by saying that all cells arise from pre existing cells.
the cell theory states 3 major points :
* the cell is the smallest unit of structure of all living things.
* the cell is the unit of all living things.
* all cells arise from pre existing cells.