cell theory

• All living organisms are composed of one or more cells, and the products of cells. This basic building block concept was first proposed by German botanist Matthias Jakob Schleiden

  in 1838 based on his observations of plants.
• The cell is the basic unit of life. German physiologist Theodor Schwann extended Schleiden's idea to animals in 1839, recognizing the cell as the fundamental unit of all living things.
• New cells arise only from pre-existing cells. This concept, often phrased as "Omnis cellula e cellula" (Latin for "All cells come from cells"), was formulated by German physician Rudolf Virchowin 1855. He disproved the theory of spontaneous generation, which held that life could arise from non-living matter.
• Matthias Jakob Schleiden (1804-1881):A German botanist, Schleiden proposed the first postulate of cell theory in 1838 based on his observations of plants. He concluded that all living organisms are composed of one or more cells, and the products of cells.
• Theodor Schwann (1810-1882):A German physiologist, Schwann extended Schleiden's idea to animals in 1839. He recognized the cell as the fundamental unit of all living things.
• Rudolf Virchow (1821-1902):A German physician, Virchow formulated the third postulate in 1855. He disproved the theory of spontaneous generation, which held that life could arise from non-living matter. His contribution to cell theory is the concept that new cells arise only from pre-existing cells, often phrased as "Omnis cellula e cellula" (Latin for "All cells come from cells").