STUDIES ON BIOLUMINESCENCE. 



XL Heat Production during Luminescence of Cypridina 



LucirERiN. 



By E. NEWTON HARVEY. 



{From the Nela Research Laboratory, National Lamp Works oj the General Electric 



Company, Cleveland.) 



(Received for publication, September 5, 1919.) 



Dubois^ obtained some evidence of infra-red radiation given off dur- 

 ing the flash of the West Indian firefly, Pyrophorus. Langley and 

 Very2 ^\^q 2^1 first observed a slight heating of their bolometer from 

 the Hght of the same insect, but in a later investigation, Langley^ was 

 unable to detect any heating of his bolometer whatsoever. Coblentz/ 

 using a vacuum thermopyle, could detect no infra-red radiation 

 from the American firefly, Photinus. Ives^ also, using a phosphor- 

 photographic method, found no infra-red radiation in the light of 

 Photinus. We must attribute the earlier evidence to experimental 

 errors and conclude that the light of luminous animals contains no 

 rays of wave-length longer than the visible. 



This does not mean, however, that no heat is produced by the 

 reaction which produces the luminescence. A temperature change 

 of a few thousandths or hundredths of a degree would evolve no 

 measurable radiation. Coblentz* first studied the problem of 

 heat production in the firefly, using a thermo-couple as the measuring 

 instrument. He came to the conclusion that the temperature of 

 the insect was slightly lower than the temperature of the air and 

 that the luminous segments were slightly hotter than the non-lumi- 



^ Dubois, R., Bull. Soc. Zool. France, 1886, xi, 1. 

 2 Langley, S. P., and Very, F. W., Am. J. Sc, 1890, xl, series 3, 97. 

 ^ Langley, S. P., Am. Astrophys. Obs., 1902, ii, 5. 



^ Coblentz, W. W., Carnegie Institution of Washington, Publication No. 164, 

 1912. 



^ Ives, H. E., Phys. Rev., 1910, xxxi, 637. 



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