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Aristotle observed preformation and epigenisis when theorizing how animals and plants developed. Preformation is the theory that a sperm or other cell is a miniature version of the animal and will grow when properly stimulated.
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Zacharias Janssen creates the first compund microscope. It allows us to see cells
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Jon Baptist van Helmont recognized descrete gases. He identified carbon dioxide.
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Robert Hooke looked through a microscope at a cork & noticed cells. He was the first person to use the word cell to describe microscopic structures.
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Francesco Redi performed an experiment to see if rotting meat changed into flies. He discovered that only flies to could make more flies, thus disproving the theory of spontaneous generation.
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Anton Van Leeuwenhoek used a microscope to view pond organisms, bacteria, and blood cells.
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John Needham discovered that soup that had been exposed to the air contained micro organisms. He theorized that a life force was present in all inorganic matter including air and oxygen that could cause spontaneous generation.
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Lazzaro Spallanzani discovered that soup that was kept sealed did not contain the micro organisms that appeared in soup open to the air. He determined that micro organisms get into the soup from the air.
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"All living organisms originate from and consist of cells" was a quote by Lorenz Oken.
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Robert Brown discovers the nucleus of the cell. He stresses its importance in fertilization.
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Matthias Schleiden and Theodor Schwann create cell theory. The theory states that all living things are made up of one or more cells. Schwann conducts experiments to help disprove spontaneous generation once and for all.
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Albrecht von Roelliker discoveres that sperm and eggs are also cells
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Rudolf Virchow writes and publishes his aphorismomnis "cellula e cellula". This means every cell stems from another cell. He theorized that all forms of disease come from changes in normal cells
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Mendel is later known as the father of genetics for his work in tracking genetic information in peas.
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Rudolf Virchow heartily endorses cell division and the role it plays in pathology
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Charles Darwin wrote and published The Origin of Species which explains heredity and variations in different species.
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Pasteur was a French chemist and biologist who proved the germ theory of disease and invented the process of pasteurisation.
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Upon examination of these cells, he finds rods that he calls chromosomes.
