THE PYROSOMA. O/ 



sea by the combined contractions and dilations of the 

 aggregate of individuals which enter into its compo- 

 sition. Several species are described, as pyrosoma 

 atlanticum, pyrosoma elegans, pyrosoma giganteum, etc. 



Enveloped in a flame of bright phosphorescent light, 

 gleaming with greenish lustre, the pyrosoma presents 

 a most brilliant spectacle : when quite at rest, however, 

 the light is but sparingly given out, increasing when the 

 water in which it floats is agitated, or when the animal 

 is taken into the hand. A shoal of these animals not 

 only illuminates the sails of a vessel, but a book 

 may be read near the windows of the stern cabin, and 

 the sea-birds which hover around, are enabled to search 

 for their finny prey. The splendour of the pyrosoma 

 fades and vanishes with death, the general colour being 

 then a dull yellowish white. 



From what has been said, the reader will collect 

 enough to discover that the luminousness of the ocean 

 is not owing to one, but to various causes ; that the paler 

 but more extensive efiiilgence of its waters is generally 

 to be attributed to putrescent animal substances, while 

 the more brilliant but defined illumination, spread in 

 patches or long lines, is produced by masses of luminous 

 animals, and chiefly by the pyrosoma. Nor let us pass 

 hastily from the conclusion at which we have arrived. 



