280 STUDIES ON BIOLUMINESCENCE. IX 



struction of the luciferase, but there is always a diminution of activity 

 which is no doubt eventually complete. The alcohol or acetone pre- 

 cipitate 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 solu- 

 tion. With alcohol the precipitate is very fine; with acetone it is 

 fiocculent and clumps together readily. The precipitates washed 

 once with 95 per cent alcohol and acetone respectively dissolve com- 

 pletely 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 ab- 

 sence 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 re- 

 converted into luciferin by appropriate methods. These experiments 

 indicate that alcohol and acetone only partially precipitate luciferin, 

 but completely precipitate luciferase. Boiling absolute alcohol will 

 extract a considerable amount of luciferin and such a solution is quite 

 stable even if exposed to air provided the alcohol is not allowed to 

 evaporate. In alcohol-water and acetone-water mixtures the luciferin 

 oxidizes readily and disappears in the course of a day or so. 



Solubility in Organic Solvents. 



The solubility of luciferin and luciferase in a number of pure or- 

 ganic solvents was tested by extracting the dried powdered Cypridince, 

 filtering, and then testing the filtrate by the addition of luciferase and 

 luciferin, respectively. Small pieces of the photogenic gland will 

 sometimes pass through ordinary filter paper, but can always be 

 recognized as isolated brightly luminous dots appearing when the sol- 

 vent is tested for photogenic material. A heavy blotting paper holds 

 back these fine particles and was used for filtering except in the case 

 of very viscous solvents. The results are summarized in Table II. 



It will be noticed that luciferase is not extracted by any of the sol- 

 vents tried, whereas luciferin is soluble in a considerable number of 



