CHAPTEE XXIII. 



THE LUMINOSITY OF THE SEA. 



Nature of the Phenomenon — Phosphorescence a Misnomer — Classification of 

 Luminous Phenomena — Sparks always visible — Their Cause — Luminous 

 Sheath to Ship— Singapore Harbour — Simon's Bay — NoctilucEe— Scene 

 on the Chinese Coast — Moon-shaped Patches of Light — Not caused by 

 Medusae — Often spontaneous — Probably Pyrosomas — Recurrent Flashes — 

 Colour and Appearance spontaneous — Depth of the Animals — Examples 

 of Recurrence — Milky Sea ; its Rarity — Conditions of Luminosity — Non- 

 luminous Animals — Rationale of Luminosity — A Correlative of some 

 other Force — Contractility — Luminous Envelopes — Range of Luminosity 

 among Animals. 



There are few subjects of study more interesting than tlie 

 luminous appearances presented by the sea under various 

 circumstances, and the least observant person cannot fail to 

 be struck with the remarkable phenomena which in the 

 course of a long voyage he must perforce sometimes witness. 

 That the sea, the great extinguisher of fire, should be turned 

 into flame — that the darkness of night should be illuminated 

 by the luminous glow which bathes every ripple, and breaks 

 over every wave — that globes of light should traverse the 

 ocean, or that lightning flashes should coruscate no less in 

 the billows of the sea than in the clouds of the air — are all 

 facts which seize upon the imagination, and enforce attention 

 and consideration. Nor is the interest lessened by the 

 knowledge that all these phenomena are produced by ani- 

 mals, whose home is in the great waters — that not only do 

 the fiery bodies of large animals give out steady patches of 

 light, but that of the myriad animalcules with which the sea 



