Schleiden proposed that all plants are composed of cells.
He stated that the different parts of the plant organism are composed of cells. Schleiden and Schwann became the first to formulate what was then an informal belief as a principle of biology equal in importance to the atomic theory of chemistry.
Stated that animals are made up of cells
He was the first scientist to prove that cells can only form from pre-existing cells.
Virchow completes cell theory.
Rudolph Virchow suggested that all cells come from pre-existing cells. He also stated that not all plants are made up of cells,which eventually lead to the creation of the cell theory.