286 STUDIES ON BIOLUMINESCENCE. IX 



Neutral lead acetate solution was added to crude luciferase solution, 

 drop by drop, until no further precipitate formed. The filtrate was 

 clear and gave no further precipitate on adding more lead acetate. 

 It gave a good light with excess of luciferin. The precipitate sus- 

 pended in water does not dissolve, but upon addition of luciferin gives 

 a bright light. 



Basic lead acetate added drop by drop gives a bulky precipitate 

 leaving a clear filtrate which gives no further precipitate on addition 

 of more basic lead acetate. This filtrate gives no light with excess 

 luciferin but the precipitate washed once with water on the filter 

 gives a bright light. 



Saturated HgCl2 solution was added drop by drop to luciferase so- 

 lution until no further precipitate occurs. The filtrate is perfectly 

 clear and gives a bright light with luciferin although it gives no 

 further precipitate with HgCl2. The precipitate washed on the 

 filter for 20 hours in running water is suspended in water. It does 

 not dissolve but on addition of luciferin gives a fair light. 



Luciferase therefore is completely precipitated by basic lead 

 acetate, nearly completely precipitated by neutral lead acetate, but 

 not precipitated by mercuric chloride. 



If a saturated solution of HgCl2 is added drop by drop to luciferin 

 solution a precipitate forms. If this is filtered off, washed with dilute 

 HgCl2, and suspended in water, it does not completely dissolve but 

 gives a good light if an excess of luciferase is added. The opalescent 

 filtrate which gives no further precipitate with HgCl2 gave a fair 

 light on adding an excess of luciferase. Mercuric chloride and 

 acetic acid almost completely precipitate luciferin from solution. 



Neutral lead acetate solution added to luciferin gives a heavy pre- 

 cipitate. The solution filters cloudy at first even though no further 

 precipitate forms on adding lead acetate, but soon filters clear. This 

 clear filtrate containing some Pb gives a bright light on addition of 

 excess of luciferase. The precipitate was washed several times on the 

 filter and by decantation with dilute Pb acetate, and suspended in 

 water. It does not completely dissolve but gives a good light with 

 luciferase. Lead acetate and acetic acid give no good precipitate with 

 crude luciferin. 



