140 STTJDIES ON BIOLUMINESCENCE. XI 



this tube could be broken and the luciferase and luciferin solutions 

 mixed. 



It was found that even after the luciferase and luciferin solutions 

 came to the same temperature within the thermos bottle, this was 

 not necessarily the same as that of the room, and a slow rise or fall 

 occurred as indicated by a slow drift of the galvanometer coil. Read- 

 ings of each thermo-couple on the galvanometer scale were therefore 

 taken at 1 minute intervals for some time before and after mixing 

 the luciferin and luciferase solutions and plotted as curves. Control 

 experiments were also carried out in exactly the same manner as the 

 luciferin-luciferase experiments but water was placed in the two 

 tubes instead of luciferin and luciferase. Figs. 2 and 3 give typical 

 experiments with water and with luminescent solutions respectively. 

 As can be seen from the curves, the rise in temperature in each 

 case figured is 0.006°C., or two scale divisions. 



With both control (water) and luciferin experiments there was 

 a slight rise in temperature on mixing the liquids in the two tubes. 

 The average rise of five control (water) experiments was 0.0054°C. 

 and the average rise of five luciferin experiments was 0.0048°C. 



In one control experiment there was no change in temperature 

 on mixing and in one luciferin experiment there was a sHght drop in 

 temperature (0.0045°C.) on mixing. The average rise in temperature 

 is no doubt due to heat from friction in the mixing of the liquids and 

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

 control and of luciferin experiments is so small (0.0006°C.) as to have 

 little significance. We may therefore conclude that if any tempera- 

 ture change occurs during the luminescent reaction it is certainly 

 less than O.OOrC. and probably less than 0.0005°C.; too small to be 

 measured by this method. 



To prepare the luciferin solution, 2 gm. of dried Cypridina were 

 dissolved in 20 cc. of hot water and 10 cc. of this 10 per cent solution 

 were used in the thermos bottle in the above experiments. If we 

 assume that 1 per cent of the dried Cypridina is luciferin, 0.1 gm. of 

 luciferin on oxidation was not able to change the temperature of the 

 10 cc. (in reahty 11 cc, since 1 cc. of luciferase solution was mixed 

 with the 10 cc. of luciferin) of solution 0.001°C. This means that 

 1 gm. of luciferin liberates less than 0.1 calorie during the luminescence 

 accompanying oxidation. 



