PRINCIPAL DIVISIONS OF THE OCEAN 41 



heavens. Farther south, the sea is seldom phosphorescent, 

 probably owing to the s,carcity of organic beings in that 

 part of the ocean. The same torn and irregular particles of 

 gelatinous matter seem, in the Southern as well as in the 

 Northern Hemisphere, to be the common cause of this phe- 

 nomenon. The particles were so minute as easily to pass 

 through fine gauze, yet many were distinctly visible by the 

 naked eye. The water, when placed in a tumbler and agi- 

 tated, gave out sparks, but a small portion in a watch-glass 

 scarcely ever was luminous. All these particles retain a 

 certain degree of irritability. My observations gave a dif- 

 ferent result. Having used the net one night, I allowed it 

 to become partially dry, and twelve hours after, having 

 occasion to use it again, I found the whole surface sparkle 

 as brightly as when first taken out of the water. It does 

 not appear probable, in this case, that the particles could 

 have remained so long alive. When the waves scintillate with 

 bright green sparks, it is generally owing to minute shell- 

 covered animals ; but there can be no doubt that very many 

 other pelagic animals, when alive, are phosphorescent. The 

 phenomenon is the result of the decomposition of the or- 

 ganic particles, by which process the ocean becomes purified.'' 



Having briefly glanced at some of the most important 

 features of the world of waters, it may not be amiss to call 

 attention to some of its principal divisions, and these are 

 ^YQ'. the Atlantic, Pacific, Indian, Arctic, and Antarctic 

 Oceans. Although no one portion is completely set off from 

 the rest, it has been found desirable to arrange it into these 

 divisions. 



The extreme breadth of the Atlantic system is about five 

 thousand miles, and its narrowest part about sixteen hun- 

 dred miles. The extent of its shores is immense — above 

 fifty thousand miles — several thousand more than the Pacific 

 and Indian Oceans combined. The Atlantic, from its relation 

 to civilized countries, and as the most frequented highway 



