Cell Theory

• Robert Hooke - improved the design of the existing compound microscope; used three lenses and a stage light
• Robert Hooke - the cork looked as if it was made of tiny pores, which he came to call “cells” because they reminded him of the cells in a monastery
• Antonie Van Leeuwenhoek - a master microscope maker and perfected the design of the simple microscope (which only had a single lens)
• Antonie Van Leeuwenhoek - saw with these microscopes was bacteria and protozoa, but he called these tiny creatures “animalcules.”
• Antonie Van Leeuwenhoek - the first to observe and describe spermatozoa in 1677
• Theodore Schwann and Mathias Schleiden - proposed the cell theory
• Matthias Jakob Schleiden - discovered that plant tissues were made up of cells
• Rudolf Virchow - stated that all cells come from preexisting cells
• Theodor Schwann - discovered that animal tissue is also composed of cells
• Rudolf Virchow - he formally enunciated in his powerful dictum that, “Omnis cellula e cellula“, which is translated as “All cells only arise from pre-existing cells“
• MODERN CELL THEORY

  1. Cells are the smallest complete living things—they are the basic units of organization of all organisms
  2. All organisms are composed of one or more cells in which all life processes occur.
  3. Cells arise only from preexisting cells through the process of cell division.
  4. All of today’s existing cells are descendants of the first cells formed early in the evolutionary history of life on earth.