1 86 THE SEAS 



most diverse animals and is displayed in many different 

 ways, yet the actual production of light is the result of a 

 chemical process which is identical in all cases. As long 

 ago as 1667 the great chemist Robert Boyle found that 

 bio-luminescence could only take place in the presence of 

 air while, owing to the work very largely of an American 

 physiologist, Professor E. Newton Harvey, we now know 

 that the light is produced as a result of the oxidation of a 

 substance called luciferin. When this combines with 

 oxygen, light is produced, the luminescent reaction being 

 probably represented by the following equation : — 

 Luciferin -|- Oxygen = Oxy-Luciferin + water (-f- light). 



The reaction is essentially the same as any other oxidation, 

 for example that which occurs when a candle is burnt, but 

 the energy produced takes the form of light only. This is 

 one of the most striking properties of this animal light — 

 it is cold, being unaccompanied by heat of any kind and is 

 consequently more efficient than any of the forms of light 

 which we can artificially produce, in all of which there is 

 an invariable waste of energy owing to the accompanying 

 production of heat. 



But besides the luciferin, a second substance known as 

 lucif erase is invariably present when light is produced. 

 This is an enzyme or ferment — belonging to the same 

 class of substance as the ferments which enable us to digest 

 our food — and takes no direct part in the. production of 

 light but acts as a kind of chemical lubricant assisting in 

 some mysterious fashion in the union of the luciferin with 

 the oxygen. Both luciferin and lucif erase can be isolated 

 from the animals which produce them so that it is possible 

 to produce animal light in the laboratory and experiment 

 with it in various ways. When the two substances are 

 placed in a test-tube together, there is a momentary glow 

 near the surface, where alone- there is available oxygen, 



