THE 

 NATURE OF ANIMAL LIGHT 



CHAPTER I 



LIGHT-PRODUCING OEGANISMS 



The fact that animals can produce light must have 

 been recognized from the earliest times in countries where 

 fireflies and glowworms abound, but it is only since the 

 perfection of the microscope that the phosphorescence of 

 the sea, the light of damp wood and of dead fish and flesh 

 has been proved to be due to living organisms. Aristotle 

 mentions the light of dead fish and flesh and both Aristotle 

 and Pliny that of damp wood. Robert Boyle in 1667 made 

 many experiments to show that the light from all three 

 sources, as well as that of the glowworm, is dependent 

 upon a plentiful supply of air and drew an interesting 

 comparison between the light of shining wood and that of 

 a glowing coal. Boyle had no means of finding out the 

 true cause of the light and early views of its nature were 

 indeed fantastic. Even as late as 1800 Hulme concludes 

 from his experiments on phosphorescent fish that the 

 light is a ** constituent principle of marine fishes'' and 

 the *^ first that escapes after the death of the fish." It 

 was only in 1830 that Michaelis suspected the light of 

 dead fish to be the result of some living thing and in 

 1854 Heller gave the name Sarcina noctiluca to the sus- 

 pected organism. In 1875 Pfliiger showed that nutrient 

 media could be inoculated with small amounts of luminous 

 fish and that these would increase in size, like bacterial 



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