cell theory By 2012krispykreme 335 Aristotole founded his own school in Athens Jan 1, 1590 First microscope invented by Zacharias Janssen Jan 1, 1634 Jan Baptist van Helmont discovers trees don't eat soil Jan 1, 1665 Robert Hooke discovered a honeycomb-like structure in a cork slice Jan 1, 1673 Anton van Leeuwenhoek helps microbioligy Jan 1, 1802 Lorenz Oken animals into 5 classes Jan 1, 1833 Robert Brown discovers nucleus of plant cells Jan 1, 1838 Matthias Schleiden proposes that cells are building blocks of cells Jan 1, 1839 Theodor Schwann discovered pepsin Jan 1, 1840 Albrecht von Roelliker discovers that sperm and eggs are also cells Jan 1, 1842 Louis Pasteur discovered the principles of vaccination Jan 1, 1855 Rudolf Virchow added 3rd part of cell theory
