1934 



KINETICS OF PHOTOSYNTHESIS 



CHAP. 37d 



Brown and Webster (1953) made a similar study of the blue-green alga 

 Anahaena, in which respiration during 10-20 min. periods of illumination 

 proved to be subject to much stronger changes in response to light than 



38 



36 



34 



CO 

 C/1 



< 



30 



28 



30 



27 - 



CVJ 



cn 



< 



2 I 



26-18 



40 60 



MINUTES 



Fig. 37D.20. Oxygen and carbon dioxide metabolism of Chlorella in light and in 

 darkness (Brown 1953). Cells cultured in Knop's solution. 110 fA. cells in 5 ml. M/15 

 potassium phosphate, pH 6.7, 20.9°C. White fluorescent light. Shaking, 195 oscilla- 

 tions per minute at 19 mm. excursion. Gas phase: helium, oxygen (isotope-enriched), 

 carbon dioxide. Ordinates are partial pressures in arbitrary units. Total volume, 28.8 

 ml. To obtain volume (N.T'.P.) of gas in milhliters, multiply by 13.4 for masses 32 or 

 34; by 18.5 for mass 44. Mass 44 (CO2) value corrected for buffer retention. 



was found before with Chlorella. These changes ranged from complete 

 suspension of respiration in light to an enhancement by up to a factor of 2.5. 

 The sign and extent of the effect seemed to be related to two factors: 

 light intensity and oxygen tension (fig. 37D.21). Inhibition occurred in 

 weak and moderate light intensity (expressed through the ratio P/R, 



