10 14 

 Minutes 



Figure i. Effect of anions on oxygen evolution by illuminated 

 chard chloroplast fragments. Curve I, effect of Cl~; Curve II, effect 

 of Br~; Curve III, effect of N0 3 -; Curve IV, effect of I~; Curve V, 

 NaF; Curve VI, control. Values for sulfate, thiocyanate, and acetate 

 coincided with those for the control. A potassium salt of each re- 

 spective anion was added to give a concentration of io~ 2 M in the 

 manometer vessel, except that the fluoride was added as NaF. Re- 

 action mixture: a chloroplast suspension containing 0.5 mg. of chlor- 

 ophyll, M/15 phosphate buffer, quinone as oxidant. Illumination at 

 flask level approx. 28,000 lux. t = 15° C. Other details of technique 

 were similar to those previously described. — Arnon and Whatley 



(71). 



