PHYSICAL NATURE OF ANIMAL LIGHT 



43 



BUNSEN FLAME LINES 



PLUCKER TUBE LINES 



Source 



Mercury 



Hydrogen 



Helium 



Color 



Yellow 



Green 



Blue 



Violet 



Red 



Blue 



Red 



Yellow 



Green 



Blue 



Violet 



Wave-lengths (/iAt = 



1000' 



579.0, 576.9 

 546.1 



491.6, 435.8 

 407.8, 404.7 

 656.3 



486.1, 434.1 



728.2, 706.5, 667.8 

 587.6 



504.8, 501.6, 492.2 



471.3, 447.2 

 438.8, 402.6, 388.8 



to A = 0.44At). Young (1870) first recorded the limits of 

 the firefly spectrum as a little above C (A ^ .6563/^) to 

 F {\ = .4861ai). Since then a number of luminous forms 

 have been examined and all are found to give short con- 

 tinuous spectra (not crossed by light or dark bands or 

 lines) lying in different color regions. Thus, Conroy 

 (1882) examined the glowworm {Lampyris noctiluca) 

 light and observed a band extending from A = 0.518ju. to 

 A = 0.656At. Dubois (1886) states that the spectrum of 

 Pyrophorus noctilucus, the West Indian "Cucullo,'' ex- 

 tends from slightly further than the Fraunhofer B line 

 to the F line, while Langley and Very (1890), working 

 on the same form, placed the limits at A = 0.468/>t to 



