THE CHEMISTRY OF LIGHT PRODUCTION 117 



reason for this is that luciferin oxidizes even in absence 

 of lucif erase and will then no longer give light with lucif e- 

 rase. This spontaneous oxidation, which occurs without 

 light production, can be prevented by keeping the luciferin 

 in a hydrogen atmosphere or by the addition of acid. 

 Under these conditions the luciferin can be boiled without 

 destruction or preserved for months without deteriora- 

 tion. The rapid disappearance of luciferin from neutral 

 or alkaline solution on boiling in the air is entirely due 

 to the more rapid oxidation at the boiling point. As the 

 oxidation product, oxyluciferin, can be readily recon- 

 verted into luciferin again, we can not consider luciferin 

 unstable in the sense that its molecule is actually destroyed 

 as is the case when lucif erase is boiled. 



Not only is luciferin stable on boiling but it will 

 actually withstand boiling for 10 hours with 20 per cent. 

 HCl (by weight, sp. gr. = 1.1) or with 4 per cent. H2SO4. 

 After one day of boiling with 20 per cent. HCl the luciferin 

 was completely destroyed and with 4 per cent. H2SO4 

 destruction was almost complete. In these cases there 

 was no question of a mere oxidation to oxyluciferin, as 

 no oxyluciferin could be demonstrated, after boiling with 

 such strong acids. An actual destruction, probably an 

 hydrolysis of the luciferin molecule, occurred. We shall 

 have occasion to refer to this again in considering the 

 protein nature of luciferin. It must be borne in mind 

 that many proteins require four or five days ' boiling with 

 20 per cent. HCl for complete hydrolysis to amino-acids. 

 Luciferin forms a solution in water, probably colloidal, 

 although the luciferin will dialyze through parchment 

 or collodion membranes. It is rather readily adsorbed 

 by various finely divided materials such as bone black, 



