'Jan Ingenhousz' or 'Ingen-Housz' (
December 8,
1730 -
September 7,
1799) was a
Dutch-born
British physiologist,
botanist and
physicist. He is best remembered for showing that
light is essential to
plant respiration,a vital step in the discovery of
photosynthesis.
Ingenhousz discovered that, in the presence of light, plants give off bubbles from their
green parts while, in the shade, the bubbles eventually stop. He identified the
gas as
oxygen (for this discovery he is known affectionately as "the Oxygen man"). He also discovered that, in the dark, plants give off
carbon dioxide. He realized 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
soil.
In
1785, he described the irregular movement of
coal dust on the surface of
alcohol and therefore has a claim as discoverer of what came to be known as
Brownian motion.
External links
★
Entry at the Catholic Encyclopedia