Estimation of diffusive resistance of bundle sheath cells to CO2 from modeling of C4 photosynthesis

This account is focused upon the early part of my career in order to illuminate the logistics and the culture of our science in the period 1936 to 1949. A roundabout path took me from a farm in Pennsylvania to a PhD under George Burr at Minnesota in 1939. In studying the photosynthetic competence of chlorophyll formed by the green alga Chlorella in darkness, I stumbled upon the phenomenon of photoinhibition. In a two-year postdoctorate at the Smithsonian Institution, I worked under E.D. McAlister. Our major accomplishment was in making simultaneous recordings of fluorescence and CO₂ uptake during the induction period. Variations in photosynthetic behavior of Chlorella led to a study of culture conditions and a recognition of the changing conditions which occur in batch cultures. A continuous culture apparatus (turbidostat) was developed as a means of attaining steady-state growth and production of uniform experimental material. I exploited the device in work at my first (and only) position at The University of Texas in 1941 and subsequent years. Study of the CO₂/O₂ gas exchange ratio led to the recognition of the important role of nitrate in the photosynthetic metabolism of algae. The account ends with the 1949 American Association for the Advancement of Science symposium.Invited and edited by Govindjee