116 EMISSION OF LIGHT 



highly magnified; 2, less magnified; 3, as seen 

 with a pocket lens on the surface of a glass of 

 water; 4, as they descend through the water, 

 glowing with phosphorescent light, when the 

 glass is shaken.) 



In the year 1830, Michaelis, a distinguished 

 professor at Kiel, was, according to Humboldt, the 

 first to make known the existence of Phosphoric 

 Infusoria. He first observed the phenomenon 

 of phosphorescence in a species of the genus 

 Peridinium (fig. 15), a ciliated animalcule, and 



Fig. 15. 



afterwards in Prorocentrum micausj* and in the 



* It is exceedingly probable that this animalcule will be placed 

 among the Khizopodes; and the same remark may apply to 

 many now-called Infusoria. In this microscopic class of ani- 

 mals, as it undergoes fresh investigations, the species are con- 

 tinually being removed and placed in higher genera, families or 

 classes. Thus the Rotifera are now classed among the Annelides. 



