Class 11th Biology - Historical Background and Discovery of Cell

Class 11th Biology - Historical Background and Discovery of Cell

Historical Background and Discovery of Cell

• Robert Brown (1773- 1858) discovered nucleus in the center of all cells. He established that the nucleus was the fundamental and constant component of the cells.
• In 1838, a German botanist Mathias Jacob Schleiden (1804-1881) put forth the idea that cells were the units of structure in the plants. In 1839, his co-worker, a German Zoologist, Theodor Schwann applied Schleiden’s thesis to the animals. Both of them postulated that the cell is the basic unit of structure and function in all life forms. This simple, basic and biological generalization is known as Cell Theory or Cell Doctrine.
• In later years the cell theory was extended and refined further. Nageli(1817-1891) showed in 1864 that plant cells arise from the pre-existing cells. In 1855, a German pathologist Rudolf Virchow (1821-1902) confirmed Nageli’s principle of the cellular basis of life’s continuity. His statement was that the cells arise only from the pre-existing cells, thus he established the significance of cell division in the reproduction of organisms.
• In 1858, Virchow published his classical textbook Cellular Pathology and in it, he correctly asserted that as functional units of life, the cells were the primary sites of diseases and cancer.
• Later, in 1865, Louis Pasteur in France gave experimental evidence to support Virchow’s extension of the cell theory.
• An English plant micro anatomist Nehemiah Grew (1641-1721) published accounts of the microscopic examination of sections through the flowers, roots, and stems of plants and clearly indicated that he recognized the cellular nature of plant tissues.
• In 1807, Mirbel stated that all plant tissues were composed of cells. French biologist, Rene Dutrochet, concluded in 1824, that all animal and plant tissues were “aggregates of globular cells”.

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