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384 BCE
Aristotle
He was the first to theorize that each germ came from another. -
Zacharias Jansen
Invented the first compound microscope, allowed scientists to observe cells and stated that, "all living things are made of cells." -
Jan Baptist Van Helmont
Partially discovered the process of photosynthesis. -
Robert Hooke
He was the first person to observe cells, coined the term "cell" while observing a piece of cork. Cells came from the term cell, which is a monk's living quarters. He also said, "All living things are made of cells." -
Antoni Van Leeuwenhoek
Invented a lens for the microscope to magnify 270%. He first did it to see spermatozoa (a sperm cell) and protozoa(an informal term for a group of single-celled eukaryotes.) His findings supported cell theory as a whole. -
Lorenz Oken
He said,"All living things originate and consist of cells." He developed a new system of animal classification based on evolution. He also believed in both the ideas that all living organisms have cells and cells are formed by pre-existing cells. -
Robert Brown
He observed plants, discovered/named the cell nucleus, stressed its importance in reproduction and recognized its significance as an essential organelle. He also said, "All living things are composed of cells." -
Matthias Schleiden
He observed plants on a microscopic level, said all plant tissues are composed of cells. He also said Embryonic plants arise from single cells and that cells are the building blocks of plant matter. He believed that new cells in plants were formed from the nucleus of the old cell. -
Theodor Schwann
He reached the same conclusion Schleidan did but in animals. He ended the controversy that plants and animals were fundamentally different. He examined the cellular structure in animal cartilage and determined that cells are the basic unit of life. -
Albrecht Von Roelliker
He discovered through the help of powerful microscopes that the sperm and egg were composed of cells and that humans are formed of cells from the beginning to end. -
Rudolf Virchow
He said, "Every cell stems form another cell." He was the first to demonstrate that the cell theory applies to both normal and diseased cells. He added cell theory and strengthened the theory that cells exist from pre-existing cells. -
Louis Pasteur
He conducted experiments similar to Neddham but used it to disprove spontaneous generation. He used S shaped beakers to trap microorganisms and prevent them from entering broth. Pasteur postulated the germ theory which states that microorganisms cause infectious diseases. He also, proved the cell theory by showing that spontaneous generation does not exist and all cells are formed by pre-existing cells.
