History of the Cell Theory Cells, the make-up of all living things. Some cell are complete organisms, such as unicellular bacteria and protozoa. Other types of cells are called multicellular, such as nerve cells and muscle cells. Withen the cell is genetic material, Deoxyribonucleic Acid (DNA) containing coded instructions for the behavior and reproduction of the cell. The cell was first discovered by the 1665 English scientist Robert Hooke, who studied the dead cells of cork with a crude microscope. Robert Hooke was born on the isle of Whight and educated at the University of Oxford. Hooke could not have discovered the cell without the microscope which was developed by