18 LIVING LIGHTS. 



and muscular zone of the body, and cavity of the stomach ; 

 the rest of the animal showing no luminosity. The light 

 seemed to proceed from a viscous liquid, a secretion which 

 oozed to the surface. One Aurelia that he squeezed in 

 twenty-seven ounces of milk rendered the whole so lumin- 

 ous that a letter was read by the light, this being one of the 

 first practical results of the investigation of marine phos- 

 phorescence. Humboldt experimented with Aurelia aurita, 

 and, having placed it upon a tin plate, observed, that, when- 

 ever he struck it with another metal, the slightest vibration 

 of the tin rendered the animal completely luminous. He also 

 observed that it emitted a greater light when in a galvanic 

 circuit. 



