699 



William Arnold and J. B. Davidson 



I 



The data, over the region of 0.65 milliseconds to 0.9 seconds, which were 

 token with the phosphoroscope has been combined with two other sets of 

 points, determined on older, slower equipment. The ordinates of the different 

 decay curves have been multiplied by constants so that they match at the 

 points of overlap. White light was used for illuminating the cells. All points,, 

 with the possible exception of those at the shortest times, were taken at "light 

 saturation. " It should be emphasized that throughout the entire decay of the 

 delayed light, the intensity of the exciting light needed to give a maximum 

 signal is increased as the time in the dark is decreased. 



Figure 1 also shows that over the range of 6.5 X 10~'* to 4X10*^ seconds 

 the delayed light signal is approximately proportional to l/t. 



Figure 2 is also a decay curve for delayed light from Chlorella at 25° C. 

 Here the exciting light was blue as obtained from a tungsten lamp through a 

 filter of 10 cm of saturated copper sulfate. The lamp was operated so that 

 the delayed light signal was proportional to exciting light intensity. A red 

 filter eliminated the exciting light from the photomultiplier. 



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 TIME (sec) 



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