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150 Years of the Discovery of the Laws of the Heredity SI

150 Years of the Discovery of the Laws of the Heredity

Gregor Johann Mendel (1822-1884) born on the 20th July 1822 in Heinzendorf bei Odrau (currently Hynčice, Czech Republic) within a family of farmers. After completing the secondary education in Opava, he attended the Institute of Philosophy in Olomouc (1840-1843), where he studied mathematics, physics, philosophy and ethics. In Olomouc, Johann Karl Nestler (1783-1842), who had conducted the research on the hereditary characteristics of animals and plants directed the Department of Natural History and Agriculture. In 1843, on the recommendation of his physics’s teacher, Friedrich Franz (1783-1860), and against his father’s wishes, who wanted him to be in charge of the family farm, he entered the S. Tomás Monastery. By becoming an Augustinian monk, the name Gregor was added to his Christian name. During that period, the monastery was a cultural centre of the region, connecting therefore with research and education of its members and gaining access to the extensive library of the monastery and its premises.

Following his entrance into the S. Tomás monastery, he studied Theology in Brno (1845-1848). After which he was ordained as priest (1847) and appointed as a substitute teacher in Znojmo and Brno (1849-1851). He also attended the Vienna University (1851-1853) where he studied physics, mathematics and natural history, and where he attended not only the experimental physics courses by Christian Doppler (1830-1853) but also the courses on plant anatomy and physiology by Franz Unger (1800-1870).

The building of a greenhouse in the S. Tomás Monastery in 1854 allowed him to work with peas (Pisum sativum) during about ten years. Here he carried out a study on the hereditary transmission of certain characteristics, such as the color and the seed roughness, the cotyledons color, the color of the flowers, the shape and the color of the string beans, among others. On the 8th February and on the 8th March 1865 he announced for the first time before the Society’s Natural History Association of Brno (in which he was a co-founder in 1861) his experiences findings. At these meetings he has introduced the concepts of the dominant and recessive “factors” and explained his results by using the formulation of two laws: the law of the segregation and the law of independent segregation. In accordance with the former law, despite an individual inherits two factors from his/her parents, only one is transmitted to the following generation. According to the latter, factors relating to different characteristics are transmitted independently. These important results, which formed the basis of the modern genetics, were then published in 1866 («Versuche über Plflanzen-hybriden», Verhandlungen des naturforschenden Vereines in Brünn, Bd. IV für das Jahr 1865, 1866, Abhand-lungen, 3–47).

In 1868, after the death of the Abbot C. F. Napp (1792-1867), Mendel became Abbot in the S. Tomás Monastery and, with the new administrative responsibilities, his scientific work has slowed considerably. In spite of the discovery of the laws of the hereditary being his more significant work, Mendel committed himself to other scientific activities, carrying out astronomic and meteorological observations for several years.

When Mendel died on the 6th January 1884 (Brno, Austria), the importance of his work had not yet been recognized. One would have to wait until the early twentieth century for the botanists Hugo de Vries (1848-1935), Carl Correns (1864-1933) and Erich von Tschermak (1871-1962) to give him the deserved credit for the discovery of the laws of the hereditary.

Francisco Malta Romeiras Inter- University Centre of History on Science and Theology, Faculty of Science, Lisbon University 

Technical Details

Issue Date: 04.08.2015
Designer: Atelier Design&etc / Elizabete Fonseca
Printer: Bpost
Process: Offset
Colours: 4 Colours
Size: 30.6 x 40 mm
Values: €0.45, €1
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