126 THE NATURE OF ANIMAL LIGHT 



firefly or Cypridina lucif erase with boiled extracts of non- 

 luminous forms, or of distantly related luminous forms, 

 are probably caused by photophelein in the boiled extract. 



Like the plant peroxidases, Cypridina lucif erase is not 

 readily affected by the action of chloroform, toluol, etc. 

 Unlike the plant peroxidases, it will not oxidize {i.e., 

 produce coloration) in either presence or absence of 

 H2O2, any of the hydroxyphenol or aminophenol com- 

 pounds, such as pyrogallol, a-naphthol, para-diamino-ben- 

 zine, gum guaiac, etc., commonly used as peroxidase rea- 

 gents. Neither will lucif erase produce light with any sub- 

 stances, such as oils, lophin, pyrogallol, gallic acid, escu- 

 lin, etc., which we know to be capable of oxidation with 

 light production by other means. The luciferases are 

 very highly specific and act only upon the lucif erins of the 

 same or closely related species. They must be placed by 

 themselves in a new class of oxidizing enzymes. 



According to Dubois, Pholas luciferase is rather 

 readily destroyed by chloroform and my own observa- 

 tions indicate that this is true also of firefly luciferase, 

 so that a certain amount of variation exists in the group 

 of luciferases. 



None of the luminescent animals which I have studied 

 are at all affected by cyanides. The luminescence con- 

 tinues in extracts of Cypridina, firefly, and Cavernularia, 

 or in Noctiluca and luminous bacteria after addition of 

 small or high (m/40) concentrations of KCN. In this 

 respect the luciferases are very different from many types 

 of oxidizing enzymes which are inhibited by exceedingly 

 weak concentrations of cyanide. It should be borne in 

 mind, however, that while KCN inhibits catalase and the 



