Cell Theory

  • 1350 BCE

    Aristotle

    Through his study of embryos he articulated principles of generation. He made up spontaneous generation. The notion of life arising from non-living things.
  • Zacharias Jansen

    He invented the compound optical microscope which made it easier and more practical to observe cells. His invention helped deny the theory of Spontaneous Generation. Scientists used his microscope to look at cells.
  • Jan Baptist van Helmont

    He helped make an early contribution to photosynthesis. He noticed that maggots only appeared on the uncovered meant which helped disprove spontaneous generation.
  • Robert Hooke

    While observing through his microscope he discovered plant cells. It helped disprove spontaneous generation.
  • Antoni van Leeuwenhoek

    He discovered the existence of single celled organisms. He helped disprove spontaneous generation.
  • Lorenz Oken

    He stated that all living organisms originate from and consist of cells. That may have been the first statement of cell theory. His experiments helped disprove spontaneous generation even though he believed in it himself.
  • Robert Brown

    His discovery of the nucleus in cells contributed to cell theory. This helped further disprove spontaneous generation because it is the second half of cell theory.
  • Matthias Schleiden

    He concluded that all plants are made of cells. Helped disprove spontaneous generation.
  • Theodor Schwann

    He stated that plant tissue was made up of cells. He demonstrated the same fact but for animal tissue. He then figured out that all tissue is made up of cells. His studies of yeast fermentation provided evidence against spontaneous generation.
  • Albrecht von Roelliker

    He discovered that sperm and eggs are also cells. This helped disprove spontaneous generation.
  • Carl Heinrich Braun

    He changed the cell theory defining cells as the basic unit of life. It helped disprove spontaneous generation.
  • Rudolf Virchow

    He made the discovery that cells arise from pre-existing cells. His work helped with the study of disease in the cellar level. He helped disprove spontaneous generation.
  • Louis Pasteur

    He disproved spontaneous generation and learned that cells would only grow on broth if it was exposed to air.