On the Chemistry of Light Production in Luminous Organisms. 107 
liver, etc., or by bacteria; by Schardinger’s enzyme of milk; by H.S or 
the nascent hydrogen from the action of acetic acid on magnesium; 
and by palladium black and sodium hypophosphite, all well-known 
reducing methods. The reaction luciferin<—- oxyluciferin is a reversible 
one and reduction of oxyluciferin no doubt occurs in animals which burn 
luciferin within the cell, thus tending for conservation of material. 
Reduction of oxyluciferin will occur even in presence of luciferase if 
oxygen is absent. Dilute alkali favors oxidation and dilute acid favors 
the reduction. 
So far as I have been able to determine, luciferin and oxyluciferin 
have identical chemical properties. Neither is digested by the enzymes 
malt diastase, ptyalin, yeast invertase, pepsin, trypsin, steapsin, amy- 
lopsin, rennin, erepsin, urease, or enzymes occurring in the water 
extracts of dried spleen, kidney, or liver. Of the above enzymes tried, 
luciferase is destroyed only by pepsin (probably), trypsin, erepsin, and 
something in spleen and liver extract. Further properties of Cypridina 
luciferin and Cypridina luciferase may be noted from the accompanying 
tables. 
Luciferase is unquestionably a protein and all its properties agree 
with those of the albumins. Although used up in oxidizing large quan- 
tities of luciferin, it behavesin many ways like an enzyme and may be so 
regarded. 
Luciferin, on the other hand, is not digested by proteolytic enzymes, 
is dialyzable, almost but not completely precipitated by saturation with 
(NH,4)2SOQu,, and is soluble in absolute alcohol, acetone, and some other 
organic solvents, but not in the strictly fat-solvents like ether, chloro- 
form, and benzol. There are, however, certain CO-NH linkages which 
are not attacked by proteolytic enzymes and some peptones soluble in 
absolute alcohol, so that these two characteristics do not bar it from the 
group of proteins. Luciferin, in fact, has many properties in common 
with the proteoses and peptones and may be provisionally placed in a 
new group of natural proteins on the borderland between the proteose 
and peptones. 
