On the Cnemistry of Light Production in Luminous Organisms. 85 
erase is found only in luminous animals it does not seem likely that a 
coluciferase would be widespread, but we do know that a reducing 
enzyme occurs in milk and tissue extracts—in fact is widespread. It 
seems more logical to interpret the above experiments as due to the 
reduction of an oxyluciferin to luciferin rather than the conversion of a 
proluciferin to luciferin. 
Indeed, we can reduce oxyluciferin by means which do not involve the 
use of animal extracts and consequently are free from the objection that 
‘“‘eoluciferase’’ may be responsible for the result, but which, neverthe- 
less, are perfectly well-known reducing methods. Perhaps the best of 
these is reduction by palladium black and sodium hypophosphite. The 
latter is oxidized in presence of palladium and nascent hydrogen is set 
free! The nascent hydrogen reduces any easily reducible substance 
which may be present, such as methylene blue or oxyluciferin. Oxy- 
luciferin is not reduced by palladium alone or hypophosphite alone, but 
methylene blue is reduced by palladium black alone. 
If hydrogen sulphide is passed through a solution of methylene blue 
the dye is very quickly reduced and becomes colorless. If the H25 is 
driven off by boiling the colorless methylene-blue solution, the blue 
color again returns on cooling. Oxyluciferin can also be reduced to a 
certain extent by H.S. Sulphur dioxide or oxides of nitrogen (prepared - 
by the action of HNO; on Cu) had no reducing action on either methy- 
lene blue or oxyluciferin. 
Dilute acid favors the reduction of oxyluciferin. If one saturates an 
oxyluciferin solution with CO, or adds a little dilute acetic acid and 
allows the solution to stand for 24 hours, a certain amount of reduction 
will occur. No reduction occurs if the solution is saturated with pure 
hydrogen and allowed to stand 24 hours. If one adds some Mg 
powder to oxyluciferin and then dilute acetic acid in successive addi- 
tions as the acetic acid is used up in formation of Mg acetate, the 
oxyluciferin will be reduced relatively quickly. Nascent hydrogen is 
produced in thereaction and is no doubt the active reducing agent, while 
theacid accelerates the reduction. Soured milk also has quite a marked 
reducing action. Acid thus favors reduction and hinders oxidation, 
while alkali favors oxidation and hinders reduction of the oxyluciferin. 
While I have not studied the properties of oxyluciferin as fully as 
those of luciferin, so far as I can judge both substances give the same 
general reactions and possess identical properties. If we make a 
concentrated hot-water extract of Cypridina, it will contain all the 
substances of the animal soluble in hot water and not coagulated by 
heat and may be spoken of as crude luciferin solution. If air is 
bubbled through this solution for some time, all the luciferin is oxid- 
ized and it may then be spoken of as crude oxyluciferin solution. 
Both crude luciferin and crude oxyluciferin solution are yellow in 
1 Bach, Chem. Ber., 1909, xlii, 4463. 
