Jan IngenhouszBiography — Famous Biologists
Jan Ingenhousz was born in 1730 in the city of Breda in what is today the southern Netherlands, was trained as a doctor at the Catholic University of Louvain in Belgium. After graduation, he practiced for several years in London (1765-1768), where he became a proponent of variolation, an early method of smallpox vaccination that involved inoculating patients with smallpox virus taken from patients with a mild form of the disease. In 1768 he traveled to Vienna and successfully inoculated the Austro-Hungarian Empress, Maria Theresa, and the rest of the imperial family, which gained him far more fame in his lifetime than did his discovery of photosynthesis. This feat secured his professional career since he became, as a result, Court Physician to the Empress. Discovery of photosynthesis
In the experiment leading to his discovery, he placed plants underwater in a transparent container and saw that the undersides of their leaves made bubbles in sunlight. However, when the same plants were placed in darkness, the bubbles eventually stopped forming. He was also able to see that the leaves and other green (chlorophyll-containing) parts of the plants were the sites where the gas was produced. He collected this gas and conducted a series of tests to determine its identity. He eventually found that a smoldering candle would burst into flame when exposed to the unknown gas, which showed it was oxygen. In recognition of his discovery, Ingenhousz was elected to the Royal Society of London that same year. Brownian motion In 1785, Ingenhousz reported that under a microscope he had observed irregular movement of coal dust on the surface of alcohol. He thus described Brownian motion at a much earlier date than did Robert Brown (1827), the English investigator for whom the phenomenon is named. Ingenhousz died and was buried in 1799 at Calne.
Notes:
Jan Ingenhousz, 1779. Experiments upon vegetables, discovering their great power of purifying the common air in the sun-shine, and of injuring it in the shade and at night. To which is joined, a new method of examining the accurate degree of salubrity of the atmosphere, London.
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