112 EMISSION OF LIGHT 



shall call attention to the most remarkable of 

 them. Their zoological descriptions, i.e. their 

 nature and habits, can be found in other works. 



A vast number of these inferior organisms 

 render the waters of the ocean luminous in every 

 latitude. The little beings classed in the genus 

 Noctiluca, which resemble the larger kinds of In- 

 fusoria, but belong in reality to the class of Wdzo- 

 podes, play an important part in the illumination 

 of the sea. Polypes , Medusae, a whole host of In- 

 fusoria, some Worms, and some small Crustaceans, 

 contribute also to the beauty of this phenomenon. 



In the years 1749 and 1750, Vianelli and Grix- 

 ellini, two Venetian naturalists, discovered in the 

 waters of the Adriatic, considerable quantities of 

 an animalcule evidently possessed of luminous pro- 

 perties. They immediately attributed to this sin- 

 gular being, the cause of the phosphorescence of 

 the sea, a phenomenon which to that day had re- 

 mained a mystery. This animalcule received from 

 Linnasus the name of Nereis noctiluca. 



In 1776, Spallanzani was made aware of the 

 self-luminous properties of a Mediterranean blub- 

 ber, Pellagia phosphorea, and at the commence- 

 ment of the present century Yiviani made known 

 the following fifteen species of phosphoric animals, 

 Asterias noctiluca, Gy clops exiliens, Gammarus 

 caudisetus, G. longicornis, G. truncatus, G. hetero- 

 j G. crassimanus, Nereis mucronata, N. radi- 



