DISCUSSION 423 



also sec the li,t;lui()-clark. part, whicii is somctliing new. W'c also sic that 

 both the slow and the fast iiicUiction eiletts are due to chan<;es in the 

 ehloro|}hvll complex. 



Dr. Kok: 1 would like to add that at least in our later experiments with 

 inonochroniatie actinic li,t;ht the intensities— e\ en usint; wide slits— were 

 extremely weak. W'c certainly could not apj^roadi photosynthetic saturation, 

 let alone photoinhihitory phenomena. 



Dr. jAC.KNnoRK: I woidd like to comment on the physiological significance 

 ol high light intensity in respect to phosphorylation with pyocyanine. Dr. 

 .\vron finds that he doesn't reach saturation of photopho.sphorylation luitil 

 15.000 foot candles, using Swiss chard chloroplasts. 



Dr. Strehler: Apropos oi Dr. Commoner's and Dr. Rabinowitch's remarks 

 about the induction period. I would like to point out that the luminescence 

 of green plants (following their illumination) also shows a diphasic decay 

 phenomenon which has somewhat diflerent time constants, howe\er, from 

 those Dr. Connnoner has observed. We have simultaneously measured the 

 luminescence intensity from plants and absorption spectrum changes at 

 r)15 m/i and have also measured the degree to which the absorption phe- 

 nomenon is suppressed in the dark after illumination and have found close 

 kinetic correspondences between the absorption spectrum changes and the 

 luminescence. It would be interesting to tie these three phenomena, the 

 absorption spectrum, the luminescence of the chloroplasts, and the electron 

 spin resonance changes, together. 



