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Jan Ingenhousz | |
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| Born | 8 December 1730 |
| Died | 7 September 1799 (aged 68) Calne, Wiltshire,Great Britain |
| Nationality | Dutch |
| Alma mater | Catholic University of Leuven |
| Known for | Photosynthesis |
| Scientific career | |
| Fields | Physiology |
Jan IngenhouszFRS (8 December 1730 – 7 September 1799) was a Dutch-British[1]physiologist,biologist andchemist.
He is best known for discoveringphotosynthesis by showing that light is essential to the process by which green plants absorb carbon dioxide and release oxygen.[2][3][4] He also discovered that plants, like animals, havecellular respiration.[5] In his lifetime he was known for successfully inoculating the members of theHabsburg family inVienna againstsmallpox in 1768 and subsequently being the private counsellor and personal physician to the Austrian EmpressMaria Theresa.[6]
He was born into the patricianIngen Housz family inBreda inStaats-Brabant in theDutch Republic. From the age of 16, Ingenhousz studied medicine at theUniversity of Leuven, the Protestant Universities were not then open to Catholics like himself,[7] where he obtained his MD in 1753. He studied for two more years at theUniversity of Leiden, where he attended lectures by, among others,Pieter van Musschenbroek, which led Ingenhousz to have a lifelong interest in electricity. In 1755 he returned home to Breda, where he started a general medical practice.
Following his father's death in July 1764, Ingenhousz intended to travel through Europe for study, starting in England where he wanted to learn the latest techniques ininoculation againstsmallpox. Via the physicianJohn Pringle, who had been a family friend since the 1740s, he quickly made many valuable contacts in London, and in due time became a master inoculator. In 1767, he inoculated 700 village people in a successful effort to combat an epidemic inHertfordshire. In 1768, EmpressMaria Theresa read a letter by Pringle on the success in the fight against smallpox in England, whereas in theAustrian Empire the medical establishment vehemently opposed inoculations. She decided to have her own family inoculated first (a cousin had already died), and requested help via theEnglish royal house. On Pringle's recommendation, Ingenhousz was selected and requested to travel to Austria. He had planned to inoculate the Royal Family by pricking them with a needle and thread that were coated with smallpox germs taken from the pus of a smallpox-infected person. The idea of the inoculation was that by giving a few germs to a healthy body the body would develop immunisation from smallpox. The inoculation was a success and he became Maria Theresa's court physician. He settled in Vienna, where in 1775 he married Agatha Maria Jacquin.
In the 1770s Ingenhousz became interested in gaseous exchanges of plants. He did this after meeting the scientistJoseph Priestley (1733–1804) at his house inBirstall,West Yorkshire, on 23 May 1771. Priestley had found out that plants make and absorb gases. Ingenhousz' travelling party in northern England includedBenjamin Franklin. They then stayed at the rectory inThornhill, West Yorkshire with the polymath and botanist Rev.John Michell.
In 1779, Ingenhousz working at his rented country house in Southall Green,[8] discovered that, in the presence of light, plants give off bubbles from their green parts while, in the shade, the bubbles eventually stop.[9][10] He identified the gas asoxygen. He also discovered that, in the dark, plants give offcarbon dioxide. He realised as well that the amount of oxygen given off in the light is more than the amount of carbon dioxide given off in the dark. This demonstrated that some of the mass of plants comes from the air, and not only the water and nutrients in thesoil.
In addition to his work in the Netherlands and Vienna, Ingenhousz spent time in France, England, Scotland, and Switzerland, among other places. He carried out research in electricity,heat conduction, and chemistry, and was in close and frequent correspondence with bothBenjamin Franklin andHenry Cavendish.[11] In 1785, he described the irregular movement of coaldust on the surface of alcohol and therefore has a claim as discoverer of what came to be known asBrownian motion. Ingenhousz was elected aFellow of the Royal Society of London in 1769 and a member of theAmerican Philosophical Society[12] in 1786.In 1799, Ingenhousz died atBowood House, nearCalne inWiltshire, and was buried in the churchyard of St Mary the Virgin, Calne. His wife died the following year.[13]
On 8 December 2017, aGoogle Doodle commemorated his 287th birthday.[14]
