16 THE NATURE OF ANIMAL LIGHT 



phospliine is not known as a decomposition product of 

 organized matter. Methane (CH4), a well-known decom- 

 position product of organic matter and abundantly formed 

 in swamps, will burn with a pale bluish flame and some 

 have thought the Ignis fatuus to be the result of this gas. 

 As methane is not self-inflammable there remains the 

 difficulty of explaining how it becomes lighted. Although 

 still a mystery, it is possible that this light is also of 

 electrical origin or that in some cases large clusters of 

 luminous fungi have been observed. 



The flashing of flowers, especially those of a red or 

 orange color, like the poppy, which many observers have 

 noticed during twilight hours, is a purely subjective phe- 

 nomenon due to the formation of after images in eyes 

 partially adapted to the dark. This flashing, first ob- 

 served by the daughter of Linnseus, is never observed in 

 total darkness or in the direct field of vision, but only in 

 the indirect field as during a sidelong glance at the plant. 



There are some cases of luminosity on record in con- 

 nection with man himself. (See Heller, 1854). Before 

 the days of aseptic and antiseptic surgery, wounds fre- 

 quently became infected with luminous bacteria and 

 glowed at night. The older surgeons even supposed that 

 luminous wounds were more apt to heal properly than non- 

 luminous ones. We know that luminous bacteria are 

 non-pathogenic, harmless organisms and the presence of 

 these forms even on dead fish or flesh never accompanies 

 but always precedes putrefaction. As recorded by Robert 

 Boyle, no harm has come from eating luminous meat, 

 unless it may also have become infected with patho- 

 genic forms. 



A few cases of luminous individuals have been noted 



