The Chemistry of Light-Production in Luminous Organisms. 233 



6. Ether and chloroform have no effect on the light-production. 



7. The oxidase is not a true catalyzer, but is used up in transferring 

 oxygen from H 2 2 to the pyrogallol. 



8. The reaction has nothing to do with the production of light by 

 luminous animals. 



GENERAL CONCLUSIONS. 



We may be very certain that in all luminous animals a definite sub- 

 stance undergoes chemical change, and if free oxygen is present light 

 is produced. This oxidizable substance may conveniently be called 

 photogenin. In some forms it is oxidized within the cell, in others 

 without. In some forms the oxidation goes on continuously, in others 

 only after stimulation, using the word "stimulation" in the same sense 

 in which it is used in referring to muscle contraction. In some forms 

 photogenin occurs as granules, in others it may be obtained in a solu- 

 tion which will pass the finest porcelain filters. In some forms we can 

 demonstrate the existence of a second substance necessary for light- 

 production, photophelein; in others this can not be demonstrated. 

 There are definite quantitative relations between photogenin and 

 photophelein, and in those animals in which the two substances can 

 not be demonstrated they are possibly present in equivalent amount. 

 Photogenin is colloidal and probably a protein ; photophelein is crystal- 

 loidal and of wholly unknown composition. Neither of the two are 

 soluble in fat solvents. Photogenin is found only in luminous glands, 

 photophelein throughout the organism and in non-luminous animals. 

 Photopheleins from different species of luminous or non-luminous 

 animals will give light with various photogenins if the animals are 

 nearly related, but only a very faint light if distantly related. The 

 connection between photogenin and photophelein resembles most 

 that between the zymase ( = photogenin) and cozymase ( = photo- 

 phelein) of yeast-juice. Both of the former substances must be pres- 

 ent for the fermentation of sugar by yeast, just as both of the latter 

 must be present for the production of light by luminous animals. 

 As regards destruction by heat and dialyzability even the properties 

 of the two corresponding substances are similar. Here the parallel 

 ceases, at least so far as our knowledge is concerned. It is possible 

 that a mixture of photogenin and photophelein oxidizes a third sub- 

 stance, just as zymase-cozymase oxidizes sugar, but we know of no 

 third oxidizable substance. We do know that whenever photogenin 

 and photophelein in solution are exposed to free oxygen, light is pro- 

 duced and both substances disappear. This is the present extent of 

 our knowledge and only additional experimental work can give us a 

 more definite idea of the nature of these substances. 



