PHYSICAL NATURE OF ANIMAL LIGHT 53 



is similar in absorption properties to complex carbohy- 

 drates. Transparency of the integument to the ultra- 

 violet was not studied. 



Although photographs of the spectrum of firefly {Pho- 

 tinus) light show that it extends only to the beginning 

 of the blue, Forsyth (1910) reports ultra-violet radiation 

 in luminous bacteria. He exposed a plate for 48 hours to 



— -r- r 1 ■ ! " 1 



so 



a 

 g 40 



a 



.Si30 



a 

 o 



SO 



in 



a 



10 - 



Wave lengths in^=.00lmm. 



In X . o IX ■ o XI X , 



l234Sei.78 9ft 



Fig. 10. — TransmisBivity of the integument of fireflies to infra-red radiation (after Coblente.) 



the spectrum of bacterial light dispersed by a quartz prism 

 and got a continuous band from A, = 0.50/* (the lower limit 

 of sensitivity of the plate) to A^0.35ai. However, Mc- 

 Dermott (1911 d) was unable to observe fluorescence of 

 p-amino-ortho-sulpho-benzoic acid, which responds to the 

 ultra-violet light. Molisch (1904, book) photographed bac- 

 terial and fungnis light through glass and through a piece 

 of quartz and found no difference in density on the plate. 

 As the exposure was brief, to avoid saturation, and as the 

 ultra-violet, which passes quartz but not glass, has a much 



