80 GENERAL BIOLOGY 



Static electricity is probably always developed by 

 both animals and plants, as a universal concomitant 

 of vital activity, but in some forms, such as the 

 electric eel and electric ray (Torpedo), an arrange- 

 ment of muscle fibers, in the structure of a galvanic 

 pile, permits of the accumulation of a charge, so 

 that such an animal can give a severe shock. 



FIG. 29. Phosphorescence in Noctiluca. A portion of the body is 

 represented, with numerous scintillating dots. (From Calkins, after 

 Quatrefages.) 



Light. The energy transformations of metabo- 

 lism also occasionally take the form of light. This 

 is often called phosphorescence, owing to the fact 

 that the light usually resembles the glow of phos- 

 phorus. As a matter of fact it has nothing to do 

 with phosphorus, which in its free and luminous 

 state is an active poison to all living protoplasm. 

 Phosphorescence is a special characteristic of many 

 minute organisms of the sea and of the bacteria 

 that develop in decaying wood and fish. Some of 

 the more complex animals are provided with special 

 light-giving organs that flash in the dark like torches. 

 Certain insects show a remarkable development in 



