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400 BCE
Aristotle
Came up with the theory of "Abiogenesis," which is the original evolution of life or living organisms from inorganic or inaminate substances. https://www.khanacademy.org/test-prep/mcat/cells/cell-theory/v/history-and-development-of-cell-theory -
Zacharias Janssen
Believed to be the first investigator to invent the compound microscope. (https://micro.magnet.fsu.edu/optics/timeline/people/janssen.html) -
Anton van Leeuwenhoek
He invented his own version of the microscope, he used this microscope to discover small animal-like creatures and called them "animacules". These animacules were actually bacteria. https://www.khanacademy.org/test-prep/mcat/cells/cell-theory/v/history-and-development-of-cell-theory -
Jan Baptista van Helmont
Helmont not only discovered the concept of gases, especially carbon dioxide, but experimented and discovered the process called photosynthesis. https://www.britannica.com/biography/Jan-Baptista-van-Helmont -
Robert Hooke
He looked through a microscope and discovered small rooms that he called cells. https://www.khanacademy.org/test-prep/mcat/cells/cell-theory/v/history-and-development-of-cell-theory -
Francesco Redi
Redi was one of the first people to question spontaneous origin of living things. He devised experiments that all pointed to the same conclusion: if flies are excluded from rotten meat, maggots do not develop. https://www.britannica.com/science/biology/The-study-of-the-origin-of-life#ref498796 -
Lazzaro Spallanzani
Spallanzani repeated tests over spontaneous origin of life and published his findings and claimed Needham hadn't heated his tubes long enough, nor had he sealed them in a satisfactory manner. -
Robert Brown
Brown described two plants adapt to different enviornmental condition, as well as the plant nucleous and analyzed sexual processes in higher plants. https://www.khanacademy.org/test-prep/mcat/cells/cell-theory/v/history-and-development-of-cell-theory -
Lorenz Oken
Asserted that there are fundamental units of life in which he called "infusoria" and anticipated the subsequent identification of the cell and development of the cell and development of cell theory. https://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/lorenz-oken#:~:text=Lorenz%20Oken%2C%20a%20proponent%20of,cell%20and%20development%20of%20cell -
Matthias Schleiden
He discovered that all plants have similar structure and discussed the topic with Theodor Schwann. https://www.khanacademy.org/test-prep/mcat/cells/cell-theory/v/history-and-development-of-cell-theory -
Theodor Schwann
Theodor Schwann discovered that all animals had similar structure and extended the idea of cellular theory to include animals. In 1837 he discussed this topic with Matthias Schleiden, and in 1838 published a book stating all living things are composed of cells. https://www.khanacademy.org/test-prep/mcat/cells/cell-theory/v/history-and-development-of-cell-theory -
Albrecht von Roelliker
Roelliker discovered through powerful microscopes that the sperm and egg are composed entirely of cells, which contributed to the idea of cell theory. He also discovered that humans are formed of cells from beginning to end. https://www.sutori.com/item/untitled-d27b-e6b4#:~:text=of%20Cells%20Timeline-,1840%20Albrecht%20von%20Roelliker%2C,cells%20from%20beginning%20to%20end -
Rudolf Virchow
He studied bacteria through a microscope and found out that one bacteria divides into two that are identical (binary fission), and stated that "Every cell originates from a cell like it." https://www.khanacademy.org/test-prep/mcat/cells/cell-theory/v/history-and-development-of-cell-theory
Virchow also first expressed that cellular reproduction is the basis of the continuity of life. https://www.britannica.com/science/zoology/Methods-in-zoology -
Louis Pasteur
Pasteur first did Swan-neck bottle experiment and came up with the theory that all microorganisms that came from suitable media came from microorganisms in the air not the air itself, he earned support to this theory in 1876. He showed the world that microbes are an immense and varied component of the organic world, which helped to contribute to the study of fermentation and biochemistry. https://www.khanacademy.org/test-prep/mcat/cells/cell-theory/v/history-and-development-of-cell-theory
