282 STUDIES ON BIOLUMINESCENCE. IX 



If we extract dried Cypridincc, which have previously been thor- 

 oughly extracted with benzene, with 800 cc. of boiling absolute alco- 

 hol for an hour, filter the alcohol extract through blotting paper and 

 hardened filter paper, quickly evaporate the filtrate to dryness on the 

 water bath, and dissolve the residue in a small quantity of water sat- 

 urated with CO2, we obtain a yellow opalescent solution which gives 

 a bright light with luciferase. This solution contains some protein 

 or protein derivatives as it gives a very faint Millon reaction, a good 

 positive ninhydrin test, reddish blue in color, but no biuret reaction. 

 It precipitates with tannic and phosphotungstic acids but not with 

 picric, acetic, trichloroacetic, or chromic acids or on saturation with 

 (NH4)2S04. The phosphotungstic precipitate is not due to the 

 presence of calcium. The extract gives a faint Molisch reaction for 

 carbohydrates. As the evidence points to the presence of some 

 protein material in the absolute alcohol extract of Cypridince, it is 

 possible that this protein is luciferin. It should be emphasized, how- 

 ever, that the Millon reaction was very faint although the ninhydrin 

 was quite marked. 



Alkaloidal Reagents. 



A solution of phosphotungstic acid added to crude luciferase solu- 

 tion gives a voluminous precipitate which, if washed quickly in 

 running water on the filter and then suspended in water, does not 

 completely dissolve but gives a good Kght if luciferin is added. It 

 dissolves if a trace of dilute NH4OH solution is added. The filtrate 

 gives no light with excess luciferin, even though it contains some 

 material which will precipitate on addition of more phosphotungstic 

 acid. 



Tannic acid added in slight excess to luciferase gives an abundant 

 precipitate which contains luciferase and will give a good light with 

 luciferin if suspended in water. It does not completely dissolve, 

 even on addition of dilute NH4OH solution. The filtrate gives a 

 very faint light on addition of an excess of luciferin, even though an 

 excess of tannic acid was used to precipitate and all precipitable 

 material was thrown down. 



Saturated aqueous picric acid added in equal volume to crude 

 luciferase solution gives a not very abundant precipitate which if 



