Jan Ingenhousz.

Dutch Physician 1730-1799

Jan Ingenhousz made major contributions to plant physiology as well as human medicine. He was born in the Netherlands, received a medical degree in 1753, and went on to further study in Leiden, Paris, and Edinburgh, finally aiding in the discovery of a new smallpox inoculation procedure. For a time he lived in England, where he befriended Benjamin Franklin and Joseph Priestley. After his success with the smallpox vaccine, however, Empress Maria Theresa of Austria called Ingenhousz to the Austrian court. There he served as personal physician to the empress for twenty years. He returned to in England in 1778.

Ingenhousz had an early interest in gases, which led to his interest in photosynthesis. The results of his work demonstrated both the disappearance of gas and the production of oxygen during photosynthesis. Ingenhousz disproved the belief that carbon comes from the soil by...