Robert Hooke (1665) named the boxlike compartments of cork as “cellulae”. (only 30 x )2. Antonie van Leeuwenhoek (1670) observed living cells with lens that could magnify 300x.3. By 1830, the microscopes had been improved to observe 1 micrometer.4. Robert Brown discovered “nucleus” at 1830s while examining plant cell.5. All plant tissues were composed of cells---- Mattthis Schleiden (plant) in 1838,Theodeor Schwann (animal) in1839.