THE CHEMISTRY OF LIGHT PRODUCTION 139 



Acid and light favor reduction while alkali and dark- 

 ness favor oxidation in the lucif erin ;=± oxylucif erin reac- 

 tion. Whether the lueif erin be really oxidized by removal 

 of H2 or whether by addition of oxygen is, of course, uncer- 

 tain, but the analogy with methylene blue is striking and 

 may serve as a working hypothesis until the composition 

 of lucif erin and its oxidation product are known. 



While I have not studied the properties of oxylucif erin 

 as fully as those of luciferin, so, far as I can judge, both 

 substances give the sarhe general reactions and possess 

 identical properties. Both crude luciferin and crude 

 oxyluciferin solution are yellow in color, but I do not be- 

 lieve that either pure luciferin or oxyluciferin are yellow 

 in color, because an ether or benzine extract of Cypridina 

 is also yellow, although luciferase, luciferin, and oxylucif- 

 erin are insoluble in ether and benzine. The yellow pig- 

 ment which can be observed to make up part of the 

 luminous gland of Cypridina is not luciferin or luciferase. 

 It may be a pigment related to urochrome. 



When tests are applied and precipitating reagents 

 are added to crude luciferin and crude oxyluciferin solu- 

 tion, they give identical results in each case. A more 

 complete account of the chemistry of luciferin has been 

 given in this chapter, and there is no need of duplicating 

 these statements regarding oxyluciferin. Like luciferin, 

 the oxyluciferin will pass porcelain filters, dialyze 

 through parchment or collodion membranes, and is 

 undigested by salivary diastase, pepsin HCl, Merck's pan- 

 creatin in neutral solution, and erepsin. The salivary 

 diastase and the pancreatin (containing amylopsin, tryp- 

 sin, and lipase) were allowed to digest for four days at 

 38° C. without showing any evidence of digestive action. 



