1) Hans and Zacharias Janssen were known for inventing the compound optical microscope. This contributed to the cell theory by making it easier and more practical to observe cells. 3)Hans and Zacharias Janssen Cell Theory was first discovered after they developed the microscope.
Zacharias Janssen. Related items. Optical microscope Electron microscope. 18th century microscopes from the Musée des Arts et Métiers, Paris. A microscope (from the Ancient Greek: μικρός, mikrós, "small" and σκοπεῖν, skopeîn, "to look" or "see") is an instrument used to see objects that are too small for the naked eye.
The cell theory states that 1. cells are the unit of structure of all living things 2. cells are the unit of function of living things--they carry out life processes 3. all cells come from pre--existing cells.
Robert Hooke, an English scientist, discovered a honeycomb-like structure in a cork slice using a primitive compound microscope. He only saw cell walls as this was dead tissue. He coined the term "cell" for these individual compartments he saw.
Anton van Leeuwenhoek is another scientist who saw these cells soon after Hooke did. He made use of a microscope containing improved lenses that could magnify objects almost 300-fold, or 270x. ... Leeuwenhoek named these “animalcules,” which included protozoa and other unicellular organisms, like bacteria.
Matthias Jakob Schleiden (5 April 1804 – 23 June 1881) was a German botanist and co-founder of the cell theory, along with Theodor Schwann and Rudolf Virchow. ... He also recognized the importance of the cell nucleus, discovered in 1831 by the Scottish botanist Robert Brown, and sensed its connection with cell division.
Virchow is credited with several very important discoveries. His most widely known scientific contribution is his cell theory, which built on the work of Theodor Schwann. He was one of the first to accept the work of Robert Remak, who showed the origins of cells was the division of pre-existing cells
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In 1838 Matthias Schleiden had stated that plant tissues were composed of cells. Schwann demonstrated the same fact for animal tissues, and in 1839 concluded that all tissues are made up of cells: this laid the foundations for the cell theory. Schwann also worked on fermentation and discovered the enzyme pepsin.