PRIMAHY llYI)U()(ii;\ ACCKl'TOR ISOLA'I'IOX ,'{2!) 



ester reeognizable by this separation. The top trace in Fig. 1 rep- 

 resents a separation in which the leaves were darkened for a short 

 time before extraction. Darkening for as short an interval as 2 or o 

 seconds is sufficient to produce the difference exhibited between the 

 upper and lower traces. 



Table I illustrates the changes in ratio these substances undergo 

 under diflferent conditions. That 5a is directly related in level to the 

 intensity of the illumination is illustrated by the first five experi- 

 ments — the brighter the illumination, the higher the level of 5a o\er 

 a very wide range of intensities. It is not yet known over what range, 

 if any, the relationship is linear. Exposure to two G.E. #50 flash buibs 

 gave about twice as high a level as exposure to one. These bulbs 

 deliver 110,000-lumen seconds of light in about 50 milliseconds. Thus 

 it is not necessary for the illumination to be spread over a long period 

 of time to produce the unknown, 5a. These experiments were done by 

 triggering the bulb at the same time as the leaves were thrust into 

 boiling ethanol. 



TABLE I. Ratio of 5a (Reduced) to 5b (Oxidized) Extractable after Exposure 

 of Barley Leaves to Different Conditions 



Condition Ratio 



Air, light 2000 ft-c 1:10 



Air, light 2000 ft-o, 2 sec dark 0: 10 



Air, light 10,000 ft-c 2:10 



Air, light 1 #22 flash bulb 5: 10 



Air, light 2 #50 flash biilbs 15: 10 

 Air, dark 0:1 



N2, dark 1:0 



Vacuum, 2000-ft-c, 30 sec 5 : 10 



N2, 2000 ft-c, 5 min 10:10 



CO-CO.2, 1000-ft-c, red 15 min 15:10 



CO-CO2, 1000 ft-c, red 2 hr V2: Vj 



CO-CO2, 1000 ft-c, yellow 15 min V?: 10 



Note: Leaves were exposed to P^'' for 24-36 hr in a light-dark-light sequence 

 before exposure to the above conditions. Figures in the ratio represent the ap- 

 proximate P'- content of each fraction ol)taineil by inspection of the recorder 

 trace. The first two experiments are those represented in the figure. 



If the light le^'el remains the same and the plant is exposed to 

 anaerobic conditions, the build-up of 5a is rapid. Subjection of the 

 leaf to a 30-second evacuation results in production of 5a in about a 

 third of the maximum attainable amount. Five minutes under nitro- 



