470 GENERAL CHARACTERS OF ACALEPH^E. LUMINOSITY. 



change of place in search of food. None of them, however, can 

 endure a rough sea. Although in calm weather they float in 

 countless myriads upon the surface, they sink, on the slightest 

 disturbance of it, into the depths of the ocean. For the same 

 reason, they prefer the open sea to the neighbourhood of the 

 coast ; and in fact to approach the land is almost fatal to them. 

 They are often driven by the winds and currents which they 

 cannot resist, against the hard shore, and there they are soon 

 beaten to pieces by the waves ; or they are left dry by the tide, 

 which they have not the power of following, and speedily melt 

 like the spangled hoar-frost beneath the sun-beam. 



1029. The voyager in the open sea, however, often encoun- 

 ters whole fleets of these animals, extending, as far as the eye 

 can reach, basking as it were in the sunshine that illumines the 

 surface, and reflecting its rays with all the gorgeousness of the 

 most brilliant iridescent hues. Most of the Acalephae seem 

 inclined thus to associate ; and in tropical regions, where they 

 exist in the greatest abundance, the voyager, after passing through 

 a fleet of one species, will in a short time encounter an equally 

 extensive collection of another kind. It is not by day only, 

 however, that these animals delight the eye of the mariner. It 

 is chiefly to them that the phosphorescence of the sea is due, which 

 is occasionally observed on our own coasts, but only in a degree 

 which affords a faint idea of the extraordinary nature of this 

 phenomenon as it presents itself in warmer latitudes. The whole 

 surface of the ocean displays a diffused luminosity, like that of the 

 Milky- way on a clear night. The path of the ship is marked by 

 a brilliant line of glowing light. The waves, as they gently curl 

 over one another (this phenomenon is never seen with a rough 

 sea), break into brilliant spangles. The oars of a boat rowing 

 over them, seem dripping with pearls when raised from the 

 water; and every stroke is marked with anew line of brightness. 

 And amidst this general splendour, varied forms of more glowing 

 lustre are seen to move some like ribands of flame some 

 like globes of living fire some gently gliding through the still 

 ocean, others more rapidly moving just beneath its surface. 

 Now, although other marine animals such as the Pennatula 



