44 THE NATURE OF ANIMAL LIGHT 



The sensitivity of our eye is largely responsible for 

 lie detection of so small an energy change. As we have 

 leen, recent determinations have proved that the dark 

 idapted eye can detect 18 X lO"^" ergs per second. From 

 he heat of complete oxidation of pyrogall^ol it is 

 )ossible to calculate the amount of pyrogallol neces- 

 lary to give 18 X 10'^** ergs if completely oxidized. This 

 luantity is infinitesimally small. When pyrogallol is 

 )xidized by K4Fe(CN)6 and H2O2, it is not completely 

 )xidized and probably only a small amount of the energy 

 s converted into light ; otherwise we should be able to see 

 ;he luminescence of a very much weaker concentration 

 )f pyrogallol. As the reaction luciferin ^ oxyluciferin 

 s so easily reversible, very little energy must be liberated, 

 ind,as experiments indicate, very little heat, if any, accom- 

 janies light production. Even though this be true, it is 

 itill possible for a very small amount of luciferin to pro- 

 iuce a very large amount of light. 



A very small amount of lucif erase only is necessary be- 

 ;ause it behaves as an enzyme and follows the general rule 

 ;hat catalysts act in minute concentrations. 



On the assumption that luciferase is an enzymej an 

 )rganic catalyst oxidizing luciferin with light production, 

 ve may appropriately inquire into the relation between thg 

 joncentration of luciferin and luciferase and intensity 

 md duration of luminescence. Oxygen tension, hydrogen 

 on concentration and temperature must be maintained 

 jonstant as these all affect both intensity and duration of 

 uminescence. Before considering luciferin and lucife- 

 rase, however, let us study a few well-known chemilumi- 

 lescent oxidations with special reference to concentration 

 jf reacting substances and temperature. 



