In 1880, he established that starch is both a source of stored energy for plants and a product of photosynthesis. Andreas Franz Wilhelm Schimper (1856-1901) was a French then German botanist (Figure 6). A, Hugo von Moh B, Arthur Meyer (CC BY-NC 4.0) C, Andreas Schimper. ![]() Hugo von Mohl (1805-1872), a German botanist (Figure 6), gave the first detailed description of “Chlorophyllkörnern” (chlorophyll granules) in green leaves in 1837.Īrthur Meyer (1850-1922), a German botanist, cell biologist and pharmacognosist (Figure 6), was the first to name and describe chlorophyll-containing structures in chloroplasts (which Meyer called “autoplasts”) known as grana.įigure 6. A, Joseph Bienaimé Caventou B, Pierre Joseph Pelletier Chlorophyll was isolated in 1816 by the French chemists and pharmacists Joseph Pelletier (1788-1842) and Joseph Caventou (1795-1877) who gave it its name in reference to the green (chloro) colour of the leaves (phyllum) (Figure 5). After developing air analysis techniques, he demonstrated – around 1860 – that the volume of gaseous oxygen released and the volume of CO2 absorbed are almost identical. Jean-Baptiste Joseph Dieudonné Boussingault (1802-1887), French chemist, botanist and agronomist, is considered the founder of modern agricultural chemistry (Figure 4). These observations are reinforced by those of Nicolas-Théodore de Saussure (1767-1845), a Swiss chemist, biochemist and botanist (Figure 5): de Saussure shows that plants need carbon dioxide, but also water, nitrogen compounds and mineral salts to ensure their nutrition and growth. He showed that plants absorb carbon dioxide and produce oxygen in the presence of light and published a book in 1783 entitled “ Research on the influence of sunlight in transforming fixed air into clean air by vegetation”. Jean Senebier (1742-1809), a Swiss naturalist, meteorologist and pastor (Figure 4), studied gas exchanges between plants and the atmosphere. A century later, Lavoisier demonstrated that the carbon dioxide released by animal respiration, or by burning a candle, is made up of carbon and oxygen. A, Jean Senebier B, Nicolas-Théodore de Saussure C, Jean-Baptiste Boussingault (Schultz etching from a photo by Pierre Petit )In the 17 th century, Van Helmont had identified the “gas sylvestre” as a product of charcoal combustion: it was in fact carbon dioxide. Bacteria density was highest in the areas illuminated by the blue and red lights. (3) all living parts of the plant “damage” the air, but the extent of air restoration by a green plant far exceeds its harmful effect.Ī century later, Theodor Wilhelm Engelmann (1843-1909), a German physiologist (Figure 3), demonstrated the role of the colour of light in an experiment with filamentous algae (spirogynous type) illuminated with coloured spots, then with a prism, in which aerobic bacteria* serve as an indicator of oxygen production. (2) only the green parts of the plant are involved in this restoration (1) Light is necessary for the plant to restore air (photosynthesis) Having placed plants in the water in light and dark, he finds that : Lehmann in 1909 In 1779, Jan Ingen-Housz (1730-1799), Dutch physician and botanist (Figure 3), extended Priestley’s observations and demonstrated the role of light in the production of oxygen by plants. Engelmann, date and authors unknown, published in Munich by J.F. Left, Jan Ingen-housz, Unknown author Right, Prof. It gives the name of oxygen to the gas involved. ![]() Ī few years later, in 1777, Antoine Laurent de Lavoisier (1743-1794), French chemist, philosopher and economist (Figure 2), replaced the theory of phlogistics with the “general théorie of combustion ”. At the time of Priestley, it was not yet a question of oxygen, but of the theory of phlogistics. This was actually oxygen, a gas which he co-discovered (1774) with Carl Wilhelm Scheele (1742-1786), a Swedish chemist (Figure 2). A, Carl Wilhelm Scheele Okänd (1742-1786) – 1700-tal B, Joseph Priestley by Ozias Humphrey (1742-1810) C, Antoine de Lavoisier explaining to his wife the result of his experiments, Joseph Priestley (1732-1804), a British chemist and theologian (Figure 2), showed that plants restore a property in the air that is necessary for animal life, but destroyed by it ( i.e. It should also be noted that Van Helmont also scientifically demonstrated the existence of “gases”, around 1610, and gave them this name. Jean-Baptiste Van Helmont (1579-1644), an alchemist, chemist, physiologist and physician from the Netherlands (Figure 1), measured the amount of water absorbed by a willow tree under controlled growing conditions and showed that water contributes to plant growth.
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