The Development of the Cell Theory by Shefali Samtani

  • Invention of the microscope - Janssen brothers

    Invention of the microscope - Janssen brothers
    The first microscope was invented around 1595 by two Dutch lens-makers, Hans and Zacharias Janssen. They created the microscope using a two-lens system of an eyepiece, ocular lens, and an objective lens. This was the first "compound" microscope.
  • Robert Hooke's microscope

    Robert Hooke's microscope
    In 1665, Robert Hooke used a self-made microscope with a three lens system and a beam of light that focused by passing light through a glass flask filled with water. With his handmade microscope, Robert Hooke was able to view plants, animals, and non-living objects. While he was examining a cork with his microscope, he saw thousands of empty chambers, which he later named cells. The term “cells” is still used today.
  • Anton Van Leeuwenhoek's microscope

    Anton Van Leeuwenhoek's microscope
    In around 1665, Anton Van Leeuwenhoek was the first person to view the movement of different types of single cells, which is now known as living microorganisms such as bacteria, sperm, and unicellular protozoa.
  • Theory of spontaneous generation - Francesco Redi

    Theory of spontaneous generation - Francesco Redi
    In 1668, Francesco Redi questioned the belief that maggots formed from raw meat spontaneously. He set up an experiment by setting out flasks that contained raw meat; some were sealed, covered in gauze, and some were open to the air. The maggots were only found in the flasks that were open and available to flies so they could lay their eggs. This disproved the theory of spontaneous generation (life could emerge from non-living matter).
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    Development of the achromatic lens

    Early compound microscopes were ineffective compared to single lens microscopes because the images were often blurry. Throughout the 18th century, a combination of lenses known as the achromatic lens was developed to improve the amount of detail that could be seen.
  • Cell wall - Karl Rudolphi and J.H.F. Link

    Cell wall - Karl Rudolphi and J.H.F. Link
    In 1804, Karl Rudolphi and Johann Heinrich Friedrich Link proved that cells were independent of each other and that they each had their own cell walls.
  • Robert Brown and the cell theory

    Robert Brown and the cell theory
    The importance of the cell a was recognized in 1830. Microscopist Robert Brown identified the nucleus during his study of orchids. He was the first one to recognize that this cell structure was related to the importance of the cell function.
  • Joseph Jackson Lister

    Joseph Jackson Lister discovers that using multiple weak lenses together at different distances provides clear magnification.
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    The Cell Theory

    The cell theory states that every living thing is either made up of one or more cells, they are the smallest of all units of life, and pre-existing cells produce all new cells.
  • Matthias Schleiden and Theodor Schwann

    Matthias Schleiden and Theodor Schwann
    In 1838, Matthias Schleiden made an observation that all plants were composed of cells and he stated that the nucleus was responsible for the development of the rest of the cell. Theodor Schwann who was studying animal physiology believed that plant and animal tissue must have similarities. He found related structures between the plant tissue, animal tissue, and the nucleus. They suggested that plants and animals were composed of cells and that cells were the basic unit of all organisms.
  • Louis Pasteur

    Louis Pasteur
    Boiling meat broth in a flask, Louis Pasteur heated the neck of the flask and bent it into the shape of an "S" so that only air could reach the broth. Nothing grew in the broth, providing evidence that spontaneous generation didn't occur and that micro-organisms are found in the air.
  • Rudolf Virchow and the cell theory

     Rudolf Virchow and the cell theory
    Rudolf Virchow extended the cell theory with his statement that all cells only appear from pre-existing cells.
  • Richard Zsigmondy

    Richard Zsigmondy invents the ultramicroscope which enables observation of specimens below the wavelength of light.
  • Gerd Binnig and Heinrich Rohrer

    3-D images possible with the invention of the scanning tunneling microscope by Gerd Binnig and Heinrich Rohrer.