132 THE NATURE OF ANIMAL LIGHT 



tract of Pholas. He now regards it as identical with 

 his coluciferase. 



I have not been able to demonstrate that a Cypridina 

 extract will reduce methylene blue, or nitrates to nitrites, 

 either with or without the addition of acetaldehyde. This 

 may be due to the fact that oxyluciferin, which is also 

 present, may be reduced more readily than either nitrates 

 or methylene blue, and so is reduced first. 



We can also reduce oxyluciferin by means which do not 

 involve the use of animal extracts. Perhaps the best of 

 these is reduction by palladium black and sodium hypo- 

 phosphite. The latter is oxidized in presence of palla- 

 dium and nascent hydrogen is set free. The nascent 

 hydrogen reduces any easily reducible substance which 

 may be present, such as methylene blue or oxyluciferin. 

 Oxyluciferin is not reduced by palladium alone or hypo- 

 phosphite alone, but methylene blue is reduced by palla- 

 dium black alone. 



If hydrogen sulphide is passed through a solution of 

 methylene blue the dye is very quickly reduced and be- 

 comes colorless. If the H2S is driven off by boiling the 

 colorless methylene-blue solution, the blue color again 

 returns on cooling. Oxyluciferin can also be reduced 

 by H^S. 



If one adds some Mg powder to oxyluciferin and then 

 dilute acetic acid in successive additions as the acetic 

 acid is used up in formation of Mg acetate, the oxylucif- 

 erin will be reduced relatively quickly. Nascent hydro- 

 gen is produced in the reaction and is no doubt the active 

 reducing agent. 



Dilute acid favors the reduction of oxyluciferin. If 

 one saturates an oxyluciferin solution with CO2 or adds 



