98 THE NATURE OF ANIMAL LIGHT 



The average rise in temperature is no doubt due to 

 heat from friction in mixing of the liquids and breaking 

 of the glass tube. The difference in the average rise of 

 control and of luciferin experiments is so small (.0006° C.) 

 as to have little significance. We may therefore conclude 

 that if any temperature change occurs during the lumines- 

 cent reaction it is certainly less than 0.001° C. and prob- 

 ably less than 0.0005° C, too small to be measured by 

 this method. 



To prepare the luciferin solution, two grams of dried 

 Cypridina were dissolved in 20 c.c. hot water and 10 c.c. 

 of this 10 per cent, solution was used in the thermos bottle 

 in the above experiments. If we assume that 1 per cent, 

 of the dried Cypridina is luciferin, 0.01 gram of luciferin 

 on oxidation was not able to raise the temperature of the 

 10 c.c. (in reality 11 c.c, since 1 c.c. luciferase solution 

 was mixed with the 10 c.c. luciferin solution) .001° C. 

 This means that 1 gram luciferin liberates at least less 

 than 10 calories during the luminescence accompany- 

 ing oxidation. 



Since 1 gram glucose liberates 4000 calories on com- 

 plete oxidation to COg and HjO, it will be seen that the 

 oxidation of luciferin is a very different type of reaction 

 from the oxidation of glucose. As we shall see, it i^ 

 probably similar to the oxidation of reduced haemoglobin 

 or the oxidation of leuco methylene-blue to methylene 

 blue. According to Barcroft and Hill (1910), 1.85 calories 

 are produced per gram of haemoglobin oxidized. I have 

 been unable to find figures for the heat exchange during 

 oxidation of leuco-dyes, but it is no doubt also small. 

 Since luciferin evolves no measurable amount of heat on 

 oxidation, we have very good evidence in support of that 



