The Nineteenth Century 243 



works, Dubois published over fifty papers on bioluminescence, sev- 

 eral of which are of a general nature. 



The second part of Dubois's Legons was entitled " Production de la 

 Lumiere et des Radiations Chemiques par les £tres Vivants." After 

 describing luminescence in each group of organisms, Dubois empha- 

 sized his belief in the importance of " granulides " as fundamental 

 structures for light production and described his experiments to 

 demonstrate the luminous materials, luciferin and luciferase, in both 

 Pyrophorus and Pholas. He gave the methods of purifying these 

 substances and stated that the " Chemical nature of luciferin should 

 be easy to establish. It is only a question of time and quantity from 

 where we stand today " (p. 524) . Luciferin was regarded as " cer- 

 tainly not living as it withstands temperatures incompatible with 

 life." On the other hand the nature of luciferase presented greater 

 difficulties. It existed only in the luminous regions of animals in 

 the form of " bioplastes, plastidules, microzymes, etc., which one 

 can consider as made up of infinitely small granulations, actually 

 alive \a I'etat vivant]." 



Raphael Dubois was professor of general physiology at the Uni- 

 versity of Lyons and Director of the Marine Laboratory at Tamaris- 

 sur-mer, where much of the biolimiinescence study was made. His 

 interests were indeed broad, covering every field of comparative 

 physiology and biochemistry, ranging from narcosis to animal pig- 

 ments and animal behavior. 



His great contribution was to place the chemical investigations 

 of bioluminescence on a firm foundation. By demonstrating the 

 existence of luciferin and luciferase he brought the production of 

 light by animals and plants in line with other biological processes 

 which are enzyme controlled. 



With the work of Dubois, the history of bioluminescence has 

 arrived at the modern period. The chemical structure of all the 

 luciferins and the luciferases are not yet completely known and 

 details of the mechanism of light emission remain to be filled in, 

 but the broad outlines are understood. The phosphorescence of the 

 sea and the shining of wood, fish, and flesh are no longer mysterious, 

 but due to the light of living microorganisms. Like the larger marine 

 and terrestrial animals, their light production is also a chemilumi- 

 nescence, in which a compound manufactured within living cells 

 and given the general name of luciferin, oxidizes in the presence of 

 an enzyme, luciferase. In some cases accessory substances are also 

 necessary. 



