J. W. HASTINGS AND W. D. McELROY 261 



ship between irradiation dosage and degree of stimulation when an 

 irradiated 20-30% (NH4)2S04 fraction is added to the reaction mix- 

 ture is shown in Fig. 4. 



Studies concerning the utiHzation of this factor ( McElroy, Hastings, 

 Sonnenfeld, and Coulombre, 1954) indicated that it is destroyed dur- 

 ing luminescence and could therefore be considered as bacterial lucif- 

 erin, analogous to Cijpridina and firefly luciferins. 



IRRADIATION TIME -HOURS 



IRRADIATION TIME - HOURS 



Fig. 3. Effect of irradiation dosage Fig. 4. EflFect of ultraviolet dosage 

 upon activity of enzyme fraction, upon stimulation of luminescence 



both with and without added by 20-30% (NH4)2S04 fraction. 



FMN. 



Since long-chain aldehydes will substitute for the factor produced 

 by ultraviolet treatment, it seems possible that a photochemical pro- 

 duction of aldehyde occurs during irradiation. This possibility has 

 not been investigated. However, it has been found (McElroy and 

 Green, 1954) that the aldehyde is utilized for light production in the 

 same way as is the factor derived from irradiation. The total light 

 emitted by a reaction mixture is proportional to the amount of alde- 

 hyde added (Fig. 5). This evidence is not in accord with Strehler's 

 results which indicate (personal communication) that aldehyde acts 

 only by accelerating the luminescent oxidation of FMNH2. It is pos- 

 sible that the different results may be ascribed to the fact that Strehler 

 has used crude acetonized powders rather than a purified enzyme 

 fraction. With the crude powders it is possible that products of the 

 aldehyde reaction may be reconverted into active aldehyde or that 



