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Jan 1, 1200
Roger Bacon used a convex lens as magnifying glass
Roger Bacon used a convex lens as magnifying glass -
Period: Jan 1, 1200 to
Historical Development of the Cell Theory
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Jan 1, 1485
Leonardo da Vinci used glass lenses to study small objects
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Two spectacle-makers, Hans and Zacharias Janssen, constructed the first compound microscope using two lenses inside a tube
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Robert Hooke further developed the compound microscope, including the use of the iris diaphragm. Hooke kept a detailed record of his observations. He first described cells in his description of a slice of cork under the microscope. He described it as 'all
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Anton van Leeuwenhoek described unicellular organisms from his observations of a drop of stagnant rainwater as 'animalcules'. Leeuwenhoek also soaked some peppercorns in water for several days. When he examined a drop of this water under his microscope, h
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Leeuwenhoek discovered bacteria from his observations of saliva
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Rene Dutrochet stated that all animals and plants are made up of cells
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Robert Brown noted that the cells of orchids he was observing under the microscope contained a structure inside the cell. He called this the 'nucleus'
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Matthias Schleiden and Theodor Schwann formulated the cell theory that all living matter is composed of small units called cells
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Rudolf Virchow stated that 'where a cell exists there must have been a pre-existing cell, just as the animal arises only from an animal and the plant only from a plant'
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Ernst Ruska built the first electron microscope. Transmission electron microscopes and scanning electron microscopes were developed in the following decades. Details of internal cell structures were revealed