A MISPLACED CHAPTER IN THE HISTORY OF PHOTOSYNTHESIS RESEARCH - THE 2ND PUBLICATION (1796) ON PLANT PROCESSES BY DR INGENHOUSZ,JAN, MD, DISCOVERER OF PHOTOSYNTHESIS - A BICENTENNIAL RESURRECTION

In 1779, the Dutch physician Jan Ingen-Housz (1730-1799) obtained a le ave-of-absence from his post as Court Physician to Empress Maria There sa of Austria in order to do research (in England) on plants during th e summer months. He performed more than 500 experiments, and described the results in his exceptional book Experiments Upon Vegetables (1779 ). In addition to proving the requirement for light in photosynthesis, Ingen-Housz established that leaves were the primary sites of the pho tosynthetic process. Later, Ingen-Housz published research papers on v arious subjects but aside from his 1779 book, he published only one mo re communication on photosynthesis and plant physiology. This was enti tled 'An Essay on the Food of Plants and the Renovation of Soils'. The essay was published in 1796 as an appendix to an obscure British gove rnment report, which is rare and virtually unknown. The present paper describes the 1796 essay, which is particularly interesting in that it shows how Ingen-Housz's concepts were modified by new interpretations of chemical phenomena described in Lavoisier's great and revolutionar y book Traite Elementaire de Chimie (1789). Ingen-Housz not only disco vered photosynthesis, but plant respiration as well, and the 1796 essa y is testimony to his remarkable insights.