THE CANADIAN ENTOMOLOGIST. 



359 



plate is very sensitive in the region of .59/x, and it is difficult to eliminate 

 this effect in the fire-fly curves. The hump in the curve of the light from 

 the glow worm and of Photimis consa7iguinetis at .59/x is, therefore, not 

 considered of real significance. The curves of these two samples were 

 obtained from the photographs taken with the small spectrograph. 



Knowing the distribution of energy in the spectrum of the glow lamp, 

 given in fig. 26, it is possible to determine the spectral energy distribution 



Fig. 26. — Spectral energ}- curves of fire-flies and glow lamp. 



of the fire-fly by multiplying the energy values of the glow lamp by the 



ratio of densities, lilri^Tiffe, ^t each wave length. The resultant curves 

 are given in figs. 26 and 27. In fig. 26 the spectral energy curve of the 

 Photuris peimsylvanica and of the Photi?ius pyralis are plotted to the 

 same scale in the blue-green. An integration of these two curves shows 

 that for the same emissivity in the blue the energy curve of the Photinus 

 pyralis is 2.83 times that of the pennsylvanica. To the eye it is apparent 

 that the illuminating power of the Photinus is far greater than that of the 

 Photuris. 



