THE CHEMISTRY OF LIGHT PRODUCTION 125 



an albumin associated with some heavy metal as iron, 

 copper or manganese is uncertain. From analyses of 

 whole Cypridina, kindly made for me by Prof. A. H. 

 Phillips of Princeton University, all three of these metals, 

 which we know to be associated with biological oxidations, 

 are present, and it is quite possible that one of them is 

 concerned with the oxidation of lucif erin. 



Although I have tested a great many oxidizers, organic 

 and inorganic, and a large number of oxidizing enzymes 

 from blood and tissue extracts of animals rich in iron, 

 copper and manganese, I have found no material which 

 is capable of taking the place of Cypridina luciferase. 

 Peroxidases or oxidases of plants, haemoglobin, haemo- 

 cyanin, extracts of mussels, manganese containing blood 

 of various marine Crustacea and mollusks will give no light 

 on mixing with luciferin. Such active oxidizers as 

 KMn04, H.Os, BaOo, and many others, will not oxidize 

 Cypridina luciferin with light production, although they 

 can oxidize Pholas luciferin with light production. 



The action of Cypridina luciferase is very highly 

 specific. It is found only in the luminous organ of Cypri- 

 dina hilgendorfii, not in non-luminous parts and not 

 in a non-luminous species of Cypridina closely related 

 to hilgendorfii. 



Lucif erins and lucif erases from closely allied luminous 

 forms will mutually interact to produce light, but no light 

 appears if these substances come from distantly related 

 forms. Thus firefly (Photuris) luciferin will give light 

 with Pyrophorus luciferase and vice versa, but Cypridina 

 luciferin will give no light with firefly (Luciola) luciferase 

 or vice versa, nor with Pholas luciferase or vice versa. 

 The faint luminescences sometimes observed on mixing 



