i;eac'TI()N patterns ix photosynthesis 



81 



urements of fluorescence. Therefore it is interesting to make a com- 

 parison of changes in absorption and fluorescence. We made such 

 measurements on the same object (Fig. 7). The plot cf both with 

 respect to time shows conformities as if both changes belong to reac- 

 tions with the same substance. Because the change of fluorescence be- 

 longs to chlorophyll, it is likely that the change of absorption also 

 belongs to chlorophyll or to a substance which reacts directly with 



ISW'sec 



time 



Fig. 7. First picture: Change of absorption of Chlorella at 515 m^ as function of 

 time. Second picture: Change of fluorescence of Chlorella at 700 ni/u as function 

 of time, —ti = 1.5 second, /d = 0.8 second. 



chlorophyll. If so, the change of absorption at 475 m;u and 515 m/x 

 characterizing the unknown substances X and Y must be attributed 

 to a chlorophj'll complex or to a substance directly reacting with 

 chlorophyll.* 



These changes of absorption at 515 m/x and 475 niju are found also 

 in chloroplasts separate from the living cell. It is of interest that the 

 decline of the change of absorption in the dark time after the flash 

 is nearly the same, whether there is a Hill reaction (with quinone or 



* The typical change of fluorescence was described 12 years ago bj' H. Kautsky 

 and U. Franck on Ulva lacluca (Biochem. Z., 315, 156 (1943)). 



