PHYSICAL NATURE OF ANIMAL LIGHT 



55 



Fig. 11. — Spectral energy curves of various fireflies and the carbon glow lamp (after 



Coblentz) . 



light of A xrrz 0.565/x will then be the theoretically most effi- 

 cient possible, when we consider the energy radiated in 

 relation to the sensitivity of our eye. This is the usual 

 method of determining the luminous efficiency of artificial 



5 



