Ingenhousz

INGENHOUZ, Jan (Jan Ingen-Housz, 1730-1799), physician and natural scientist, of Dutch origin. Although I. was widely known as a physician, his main significance for science is based on his research on gas exchange in plants. Here I. continued the experiments of Priestley, who discovered (1772) that plants can 'purify' air spoiled by animal respiration (make it suitable again for respiration and combustion). I. refined Priestley's experiments and proved that this 'purification' is carried out only by the green parts of the plant and only in the light, whereas in the dark plants 'spoil' air just like animals. With this research, the foundation was laid for the most important chapter of plant physiology—the doctrine of photosynthesis. However, I. himself did not yet understand the significance of the phenomenon he had established for plant nutrition. He saw here only a special air-purifying apparatus. A collection of I.'s works was published under the general title 'Miscellanea physico-medica' (Vienna, 1795).