When:January 01, 1653. when looking at a piece of cork he Discovered empty spaces contained by walls, and termed them pores and cells therefore gaining credit for the discovery of cells. He didn't grasp the full effect of his discovery at the moment.
Anton van Leeuwenhoek
When: 1670 described cells in a drop of pond water using a microscope that he created
When:1839. reached the same conclusion as Schleiden about animal tissue being composed of cells, ending speculations that plants and animals were fundamentally different in structure.
When: 1838 concluded that all plant tissues are composed of cells and that an embryonic plant arose from a single cell. He declared that the cell is the basic building block of all plant matter.
When:1855 added a third tenet to the cell theory: Omnis cellula e cellula, or all cells develop only from existing cells.