174 PHYSICAL CHEMISTRY 



Japanese animals luminous secretions and extracts that are free 

 from particles. According to Raphael Dubois (1913), these 

 secretions contain "luciferase" which can be replaced by potas- 

 sium permanganate and "luciferin," of unknown chemical nature. 

 Harvey (1916) finds that various oxidases may be substituted 

 for luciferase. 



Coblentz (1912) photographed the spectrum of the light emit- 

 ted by two species of firefly of the genus Photinus. The light 

 contains only from yellowish green to orange rays. It is a cold 

 light and is also lacking in rays of short wave length. He found 

 the temperature of the luminous organ to be only a fraction of 

 a degree above that of the same organ when not emitting light. 

 It is probable but not certain that this heat is produced by the 

 oxidation of the photogenic substance, as the admission of oxygen 

 to the organ would naturally result in cell respiration. 



Note: In Abderhalden's table, p. 175, for Na 

 read Na 2 0; for K read K 2 ; for H,P0 4 read P 2 0,. 



