138 PHOTOGENIC REACTION IN CYPRIDINA 



many of the characteristics of an enzyme and certainly as much 

 right to be called an enzyme as the peroxidases of plants which are 

 also used up in the oxidation process. The Cypridina luciferase re- 

 action appears to be specific to an extraordinary degree. Of many 

 tried I have found no substances or plant or animal extracts which 

 can take the place of luciferase^ nor any substances^ or plant or ani- 

 mal extracts^ which can be oxidized with light production by luci- 

 ferase. The light recorded with various extracts of luminous and 

 non-luminous animals in my former paper is to be referred to the 

 presence of photophelein, the third substance concerned in light 

 production which probably acts by assisting the luciferin-luciferase 

 reaction in the manner already suggested. Let us now turn to the 

 oxidation product or products of luciferin. 



When luciferin is oxidized it must be converted into some substance 

 or substances and I believe this change involves no fundamental 

 destruction of the luciferin molecule, as it is a reversible process. I 



^ I have tried the blood or extracts of many species of animals or plants in- 

 cluding those containing strong oxidizing enzymes both with and without H2O2 

 and have always failed to obtain light with Cypridina luciferin. Among others 

 the juice of Indian pipe {Monotropa), potatoes, and turnips (containing strong oxi- 

 dases and peroxidases), the blood of the ox and a worm (Arenicola) (containing 

 hemoglobin), the blood of the squid (Loligo), Limulus and Sycotopus (containing 

 hemocyanin), and extracts of Choetoptenis (a luminous annelid), and the mollusc, 

 Unio, (rich in manganese) were tried. Dubois reports that he has obtained hght 

 on mixing Pholas luciferin with the blood of divers molluscs and marine crus- 

 taceans {Ann. Soc. Linn. Lyons, 1913, xl). I can confirm this statement for an 

 extract of Unio, but obtained no light with Limulus blood, Sycotopus blood, squid 

 {Loligo) blood, or turnip or potato juice and Pholas luciferin. Evidently Pholas 

 luciferin is much more readily oxidized with light production than Cypridina 

 luciferin. 



''The following oxidizable substances have been tested: aesculin, lophin, berga- 

 mot oil, pyrogallol, gallic acid, aniline, adrenalin, phenol, a-napthol, /?-phenylene- 

 diamine, ortol, orcinol, hydrochinone, resorcinol, pyrocatechol, tannin, benzi- 

 dine, gum guaiac, amidol, a-napthylamine, and the chromogen of the false in- 

 digo plant {Baptisia). Luciferase, with or without H2O2, will not accelerate the 

 oxidative color change in any of the above compounds. 



* I have regularly obtained a fair light on mixing luciferase well shaken with 

 chloroform to set free any bound luciferin and boiled potato or turnip juice or 

 boiled Limulus blood. The light is especially marked about the coagulum in 

 the boiled Limulus blood. The significance of these results is not apparent. 



