Comments on: 2.1 outline the progress that occurred in the 17th and 18th centuries towards understanding plant growth by identifying: the observation of van Helmont that soil was not primarily responsible for a plants change in mass as it grew Stephen Hales’ proposal that plants extract some of their matter from air the work of Priestley in identifying that plants could ‘restore the air’ used by a candle and his subsequent discovery of oxygen Ingen-Housz’s demonstration of the importance of sunlight for oxygen production by plants Senebier’s demonstration of the use of carbon dioxide during photosynthesis Saussure’s conclusion that water was also necessary for photosynthesis. index.html Just another WordPress site hourly 1 http://wordpress.org/?v=3.5