E. NEWTON HARVEY 143 



of heat on oxidation we have further evidence in support of that 

 presented in a previous paper, that no carbon dioxide is produced 

 during luminescence of luciferin. The energy change involved is 

 very small indeed. It is on first thought surprising that so bright 

 a luminescence as that of Cypridina should result from a reaction 

 involving only a very small amount of heat. If we recall, however, 

 that the eye is an extraordinarily sensitive instrument (responding 

 to 10~^ ergs per second), which can detect light so weak, that, if 

 it were converted into heat, would take 60,000,000 years to raise 

 1 gm. of water 1°C., we may realize that, after all, a very small heat 

 production during oxidation of luciferin may be sufiiciently great to 

 account for its luminescence. 



It gives me pleasure to acknowledge the kindly interest and assis- 

 tance in setting up apparatus of Dr. W. Weniger of the Nela Research 

 Laboratory. 



