On the Chemistry of Light Production in Luminous Organisms. 95 
glycogen are nearly if not completely precipitated by saturating their 
solution with (NH,)2SO,. But the polysaccharides are not precipitated 
by the phosphotungstic acid, whereas luciferase is completely precipi- 
tated and luciferin very nearly completely precipitated (see p. 98). 
The evidence from salting-out experiments indicates that both lucif- 
erin and luciferase are proteins, the former on the border-line between 
proteoses and peptones, the latter a more complicated protein but not 
a globulin. Dubois! finds Pholas luciferin completely precipitated by 
saturation with (NH,4).SO,, but not by MgSO, or NaCl. 
ALCOHOL AND ACETONE. 
If strong ethyl alcohol or acetone is added to a solution of crude 
luciferase an abundant precipitate forms. This precipitate is found 
to contain the luciferase, which is separated completely from solution 
by alcohol between 50 and 60 per cent and by acetone between 70 and 
80 per cent. We are dealing in both cases with a precipitation and 
not a coagulation of luciferase. The precipitates partially redissolve 
in water, and if the solution is filtered luciferase is found in the filtrate. 
Indeed, the precipitates from addition of alcohol or acetone to crud? 
luciferase may stand under alcohol (95 per cent) or acetone (90 per cent) 
respectively for 35 days without complete destruction of the luciferase, 
but there is always a diminution of activity which is no doubt eventu- 
ally complete. The alechol or acetone precipitate may be washed and 
dried and will give light whenever luciferin is added. 
If strong ethyl alcohol or acetone is added to a solution of crude 
luciferin a precipitate also forms, but it is not nearly so voluminous, 
since the heat-coagulable proteins are absent from the luciferin solution. 
With alcohol the precipitate is very fine; with acetone it is flocculent 
and clumps together readily. 
The precipitates washed once with 95 per cent alcohol and acetone 
respectively dissolve completely in water, but these solutions give only 
a faint or no light if luciferase is added. On the other hand, the filtered 
alcohol and acetone solutions contain considerable amounts of luciferin. 
The absence of luciferin in the alcohol and acetone precipitates is only 
apparent. It is really partly precipitated by alcohol and acetone, but 
is largely oxidized during the process of testing. Experiments indicate 
that oxyluciferin is present in the precipitates and can be reconverted 
into luciferin by appropriate methods. These experiments indicate 
that alcohol and acetone only partially precipitate luciferin, but com- 
pletely precipitate luciferase. 
They are confirmed by extracting the dried, powdered Cypridinz 
with alcohol or acetone solutions of various strengths. Luciferin is 
soluble in all strengths, even in absolute alcohol and acetone, although 
it is sparingly soluble in the latter. Luciferase is only sparingly soluble 
1 Dubois, Ann. Soc. Linn. de Lyons, 1914, Ixi, 161. 
