BERNARD L. STREHLER 233 



ume increase. The observations just noted will be included in the 

 following section on the mechanism of bacterial luminescence where 

 an attempt will be made to present a coherent picture of all the facts 

 thus far presented. 



Mechanism of Bacterial Extract Luminescence 



Physical Considerations 



Before proceeding with a proposed specific chemical mechanism 

 deri\'ed from the above experiments and inferences therefrom, it is 

 important to state a number of restrictions imposed on any model 

 mechanism of luminescence by physical considerations of various 

 types. 



First of all there is the restriction imposed by the thermodynamic 

 aspects of the reaction. The light emitted corresponds to between 

 52 and 60 kcal at the maximum energy region of the spectrum. Thus 

 it would seem unlikely that any reaction furnishing less than around 

 50 kcal of energy would be capable of producing luminescence in the 

 extracts. Second, the rate of the reaction must also be sufficient to 

 account for the observed yields of 1/100 to 1/1000 light quanta pro- 

 duced per oxygen consumed and the real activation energy of any 

 given step cannot be so high that the observed rates are prohibited 

 (Cormier and Strehler, 1954). If the apparent activation energies are 

 higher than would permit such a reaction to proceed at a reasonable 

 rate, it must be concluded that some artifactual influence produces 

 the extremely high observed activation energies. 



Although it is theoretically possible for a reaction liberating only 

 around 50 kcal to emit light of somewhat more energetic character, 

 this is a rather anomalous occurrence, and it is the instinct and expe- 

 rience of physical chemists to expect an even larger release of energy 

 by a considerable number of kilocalories to be prerequisite to the 

 occurrence of a chemiluminescent reaction. 



Discussion and Conclusions 



With these preliminary thermodynamic and kinetic considerations 

 in mind, we would hke to present the scheme illustrated in Fig. 14 

 which furnishes a framework for interpreting the observations which 



