56 



THE NATURE OF ANIMAL LIGHT 



lights and is obtained from a knowledge of the radiated 

 energ}^ and the visual sensibility. Eeduced luminous effi- 

 ciency = light {radiated energy X visual sensibility) or 

 luminosity -f- total radiated energy. 



Si 

 a> 



> 

 > 



0.64 0.68 



Reeves 



Ives 



0.48 0.52 0.56 0.60 



Author 



Coblentz & Emerson 



Nutting 



Fio. 12. — Visibility curves of various investigators obtained by different methods {ajter 



Hyde, For sy the and Cady). 



The spectral energy curve for the firefly has been 

 worked out by Ives and Coblentz (1910), using a pho- 

 tographic method in which the intensities of different 

 wave-lengths of the firefly (PJwtlnus pyralis) light is com- 



