112 EMISSION OF LIGHT 
shall call attention to the most remarkable of 
them. Their zoological descriptions, 7.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 Rhizo- 
podes, play an important part in the illumination 
of the sea. Polypes, Medusce, 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 
Linneeus 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 Viviani made known 
the following fifteen species of phosphoric animals, 
Asterias noctiluca, Cyclops exiliens, Gammarus 
caudisetus, G. longicornis, G. truncatus, G. hetero- 
clitus, G. crassimanus, Nereis mucronata, N. radi- 
