ENERGY EXCHANGE IN PHOTOREACTIONS 53 



body Radiation. Black-body radiation probably plays no significant 

 role in biological processes except in the very general sense in which it 

 controls the temperature of the earth's surface. It has been suggested 

 that olfaction is the result of absorption by smelled substances of 

 the black-body radiation from nerve endings (Beck and Miles, 1947). 

 Mechanically produced luminescence has been noted, in passing, in the 

 discussion of meteor light (Sect. 4-3). In this section, chemiluminescence 

 need be given but summary treatment in view of the exposition of the 

 preceding sections. 



Chemiluminescence has figured in biological research primarily in the 

 investigations of fireflies and certain luminescent algae and bacteria. It 

 plays a considerable role in the survival ability of these organisms, and 

 much has been learned about the behavior of proteins by its study. 

 Harvey (1940), Drew (1939), Johnson (1947), and others have put the 

 chemiluminescence of various organisms to good use. The luminescence 

 intensity gives a direct measure of the velocity of certain enzyme- 

 catalyzed reactions in the intact organism, permitting the in vivo study 

 of the effect of a variety of substances and physical conditions such as 

 pressure and temperature on these processes. The reader is referred to 

 the more complete discussion given in a book by Johnson et al. (1954). 



Numerous organic molecules react with oxidizing agents to produce 

 intense chemiluminescence: 



NH 



2 







II 



c 



Oxidant (H2O2; rerricyanide, etc.) + 



^N— H 



I —^hv-\- products. 



.N— H 



O 



Luminol 



(1-46) 



Indeed, Audubert (1936), usmg very sensitive light-detection equipment, 

 observed that light is produced during the course of a number of chemical 

 reactions not usually considered to be luminescent. Some examples are 

 neutralization of strong acids by strong bases, oxidation of glucose by 

 permanganate, potassium sulfate reaction with oxygen, sodium amalgam 

 reaction with water, and the oxidation of ethanol by chromic acid. The 

 question of the existence of natural rays (mitogenetic radiation) excited 

 fierce controversy for a number of years. It is probable that at least 

 some of the positive results reported were due to the type of reactions 

 studied by Audubert and hence to normal chemiluminescence. 



