Schwann discovered that all animals are made of cells! However, Schleiden made a similar discovery.
Each one of these plants is made out of cells!
Schleiden discovered that all plants are made of cell. The last part of Cell theory comes from Rudolf Virchow.
These cells are dividing! That must mean all cells come from preexisting cells!
Virchow discovered that all cells come from each other!
Those were many of the people who developed cell theory! So as you can see, All organisms are composed of one or more cells, cells are the basic unit of structure and function, and all cells come from preexisting cells