390 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 3 8 



benzaldehyde by peroxid formation, is that diphenylamine (a nega- 

 tive catalyst for the oxidation of benzaldehyde) has no effect on the 

 luminescence of a luciferin-luciferase reaction (Harvey, 1918, 1928). 



Alkali, within limits, favors the oxidation of luciferin to oxylucif- 

 erin (by luciferase) with the resultant production of light, while acid 

 favors the reduction of oxyluciferin to luciferin with the consequent 

 decrease in the glow. These facts are in accord with oxidations and 

 reductions in general. 



The activity of aerobic oxidases is destroyed by cyanid concentra- 

 tions of the order of M/10,000. On the other hand, the activity of 

 anaerobic oxidases (oxidases which do not accelerate oxidations pro- 

 duced by molecular oxygen) and of dehydrogenases are not affected 

 by cyanid except in relatively high concentrations of the latter. 

 M/5,000 KCN reduces the luminescence of luminous bacteria to only 

 20-25 percent but KCN (even M/250) does not influence the lumi- 

 nescence of Cypridina luciferin-luciferase. M/20 KCN, while it 

 does not extinguish the luminescence of the Cypridina preparation, 

 diminishes its brightness — i. e., presumably decreases the mass of 

 active luciferase (Harvey, 1916a and b, 1917b, 1932). The reason 

 for the almost nil effect of KCN on the action of luciferase — quite 

 apparently an aerobic oxidase — is problematical. Since it has not 

 been possible to prepare luminous extracts of bacteria, fungi, or 

 medusae (Harvey, 1924, 1926b) and since it is known that the bacterial 

 dehydrogenases are closely bound up with cell structure, Harvey (1935) 

 has suggested that luciferase may be a specialized type of dehydro- 

 genase in which oxygen is absolutely required as a specific hydrogen 

 acceptor. 



3. Luciferins and luciferases. (a) Properties. — To Dubois belongs 

 the credit for the fundamental discovery of the presence of the sub- 

 strate, luciferin, and the enzyme, luciferase, involved in luminescence. 

 In 1885 he found that an aqueous extract of the photogenic organ of 

 a beetle will luminesce in the presence of air and that cellular structure 

 is thus not essential for the production of light (exceptions to such a 

 discovery have been noted above). Such an extract was, however, 

 continuously luminescent so long as it endured, there being no peri- 

 odicity in the production of light. From what has been said concern- 

 ing the mechanism of flashing, the reason for this is quite apparent. 

 In 1887 (a and b) he showed that bioluminescence requires the presence 

 of at least four substances, the following three of which had already 

 been recognized: (1) Air [oxygen] (Boyle); (2) water (Spallanzani, 

 1794); and, of course, (3) a photogenic substance(s). By dialysis 

 through celloidin, two separate solutions were obtained from an 

 aqueous extract of the photogenic organs of fireflies. Neither the 

 dialysate nor the residual solution luminesced. When both solutions 

 were mixed light was reproduced. This at once established the 



