252 NUTRITION AND METABOLISM 



known to lose the power of light production as the chromogenic bacteria 

 may lose the power of pigment production. Phosphorescence has, like 

 pigmentation also, no bearing upon the development of the cell, and the 

 light-giving compounds may be regarded as incidental waste products. 

 Certain chemical bodies stimulate light production, while others favor 

 the growth only. One of the most important factors in the production 

 of light is sodium chloride. 



