PHYSICAL NATURE OP ANIMAL LIGHT 



55 



FiQ. 11. — Spectral energy curves of various fireflies and the carbon glow lamp (.afttr 



Coblentz), 



light of A ^ 0.565/^ 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 



