QUANTUM YIELD 



1959 



logarithmically, with a decay constant of about 20 min.-^ so that a steady 

 rate of respiration, characteristic of dark-adapted aerobic suspensions, is 

 reached only after several hours. In alternating hght, this course is re- 

 peated again and again, starting each time at a higher initial rate, until the 

 steady respiration rate of light-adapted suspension is reached. Brackett 

 et al. suggested that the respiration increase in light also follows a logarith- 



4 ' ^ ' 6 ' l6 ' 1^ ' Ki ' 16 ' 18 ' ^b ' 2^ ' ^4 ' ^6 ' ^b 30 ' 32 ^4 



TIME-MINUTES 



Fig. 37D.31. Plot of slopes derived from experimental data, of the type shown in 

 preceding figures, by constructing the tangent T in every point (after Brackett et al. 

 19532). Six minute cycles. Two runs with the same suspension show the same time 

 course, including minor details. (In one run, the second dark period is extended to >12 

 min.) Dashed line represents interpolated main trend of respiration (for a 6 min. cycle 

 of the intensity used). 



mic course, and interpolated the respiration curves over the light periods as 

 indicated by dashed lines in fig. 37D.32 (the "burst" of oxygen consump- 

 tion, observed in the first 1-2 minutes of the dark periods, is disregarded in 

 this interpolation!). Using the so interpolated respiration values, the rate 

 of photosynthesis Avas computed point-by-point; the result is shown by the 

 uppermost curve in the figure. 



Calculated in this way, photosynthesis appeared constant except for an 

 induction period, declining in duration with the repetition of the cycle. 



