118 EMISSION OF LIGHT 



The interesting Synchata Baltica (fig. 18) be- 

 longs to the tribe of Hydatinea, of which many 

 individuals are common in our ditches and stag- 

 nant freshwaters. 



The largest of these phosphorescent Infusoria 

 described by Ehrenberg, are about one-eighth 01 

 a line, the smallest are from a forty- eighth to 

 a ninety-sixth of a line in size. They offer a 



Tig. 18. 



magnificent spectacle when placed under the mi- 

 croscope in a dark room. 



Ehrenberg has likewise studied certain species 

 of Photocharis, marine animalcules which resemble 

 Nereis among the worms ; and, when seen under 

 the microscope, appear like minute strings of 

 lighted sulphur. The phosphoric light they emit 

 is of a greenish-yellow, similar to that of the com- 



