CHAPTER XVIII 

 PHOTOGENIC BACTERIA 



Introduction. There are certain species of saprophytic 

 bacteria which possess the power of throwing off light when the 

 requisite conditions are provided. Bacteria of this character 

 are called photogenic. 



The power of luminosity, or phosphorescence, is due in all 

 probability to the combustion of various food materials and 

 to cell respiration, just as the phosphorescence of insects is a 

 combustion process. Luminosity itself is of no physiological 

 importance. 



Distribution. The majority of photogenic bacteria are 

 found in salt water and on the fresh and decomposing flesh of 

 marine animals, such as fish. The phosphorescence of the sea 

 is due in a large part to bacteria and also to phosphorescent 

 protozoa. 



It has been known for some time that the light often noted 

 emanating from decomposing willows and other trees, and 

 particularly from decaying stumps of trees, is due to a fungus. 

 This fungus is in some cases similar to a mold, and in other 

 cases photogenic bacteria have been found. The much re- 

 nowned "will-o'-the wisp" phenomenon is caused by saprogenic 



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