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384 BCE
Aristotle
He established methods for investigation and reasoning and provided a theory on how embryos generate and develop. He originated the theory that an organism develops gradually from undifferentiated material, later called epigenetic. -
Zacharias Janssen
He invented the compound microscope which helped to be able to observe tiny cells through magnification. He rejected the idea of spontaneous generation -
Jan Baptist van Helmont
He partially discovered photosynthesis in 1643, and he thought that water would create more wood. He supported spontaneous generation. -
Robert Hooke
The first cells from an organism (cork) were observed by Hooke in 1685. These ideas led to cell theory, which states that all organisms are made of cells. He rejected spontaneous generation -
Anton van Leeuwenhoek
In 1678 he observed cells through a microscope, and saw little animal like figures. He rejected spontaneous generation -
Francesco Redi
He was the first person to challenge the theory of spontaneous generation by demonstrating that maggots come from eggs of flies. This image shows the experiment that he did to discover what he did. -
Lorenz Oken
He stated in 1805 that "All living organisms originate from and consist of cells." Oken believed that these infusoria, later paralleled to cells, were primitive matter in which all things were organized and in themselves had the capacity to produce more life. Rejected spontaneous generation. This image demonstrates the breakdown of how different organisms create other ones. -
Robert Brown
His discovery of the nucleus in 1831 and its role helped to put together the cell theory, which states that all living organisms are composed of cells, and cells come from pre-existing cells. He helped disprove spontaneous generation. This image shows where the nucleus would be located in a cell. -
Matthias Schleiden
In 1838, he concluded that all plant tissues are composed of cells and that an embryonic plant arose from a single cell. He declared that the cell is the basic building block of all plant matter. He thought that spontaneous generation was true. This image shows the structure of the cell. -
Theodor Schwann
He defined a cell as the basic unit of animal structure. He also discovered pepsin which was the first digestive enzyme prepared from animal tissue, and experimented to disprove spontaneous generation. He rejected spontaneous generation. -
Albrecht von Roelliker
In 1840, he realized that sperm cells and egg cells are also cells. This image shows the different parts of an individual sperm cell. -
Albert von Kolliker
He helped to confirm the view that cells arise only from other cells and cannot be generated from non-cellular material. He also advocated the view that tissue should be studied and understood as a mass of individual cells. -
Robert Remak
He discovered that the origin of cells was by the division of pre-existing cells. As well as several other key discoveries. -
Rudolph Virchow
He concluded that all cells arise from pre-existing cells in 1858. He rejected spontaneous generation. Virchow used the theory that all cells arise from pre-existing cells to lay the groundwork for cellular pathology, or the study of disease at the cellular level. This image shows the different cells that come from the other cells before them. -
Louis Pasteur
In 1859, he contributed to the cell theory by disproving spontaneous generation. He was the first scientist to prove that cells can only form from pre-existing cells. He did this by creating an experiment that showed cells would only grow in broth if air was exposed. He rejected spontaneous generation. This image shows his discovery about sealing containers and he found that mold grew if something wasn't sealed up tightly. -
Walther Flemming
He was the first person to conduct a systematic study of chromosomes during division and called this process mitosis. This image shows different chromosomes.
