48 A. G. FERRARI, B. L. STREHLER, W. E. ARTHUR 



(1) Dark Reaction (0): 



J. I (0H-) I I 



(a) H— C— C=0 + O, > HOOC— C=0 



I I 



R R 



II II 



(h) HO— OC— C=0 + RCHO + HoO > HO— C— C=0* + 



I I 



R R 



H2O + RCOOH 



(2) Light-Activated Reaction: 



I 1 (0H-) r n 



(a) HO— C— C=0 + H,,0 , HOCH COOH 



R R 



(b) HOCH- COOH + h^ + O3 > HOCOOH COOH 



R R 



(c) HO— C— O— OH COOH + RCHO + H2O > 



R 



HOCOOH CO*OH + H2O + RCOOH 



R 



It cannot at present be stated whether these chemiluminescences 

 bear a direct relationship to the process in vivo. Such a relationship, if 

 it exists, could be established through the isolation of identical inter- 

 mediates in the two processes. Possibly, these findings may be of in- 

 terest only from the standpoint of chlorophyll chemistry. But they 

 certainly lend support to the hypothesis that chlorophyll can be 

 directly excited by reactions in which it is involved or which take 

 place in its vicinity. 



Acknowledgments. Thanks are due to Dr. Hans Gaffron and Dr. James 

 Smith for stimulating discussions of some of the results here presented, and 

 to Mr. Charles Soderquist and Mr. John Hanacek for invaluable assistance 

 in the construction of apparatus. 



This work was supported in part by a grant from the U.S. Atomic Energy 

 Commission. 



Discussion 



Liunry : Did j^ou get the emission spectrum? 



Strehler: The emission spectrum is very close to that of chlorophyll. It may 



