204 



THE OPAL SEA 



The violet 

 rays. 



Other 



liphts in 

 the depths. 



Liphtinp 

 power, of 

 lumines- 

 cence- 



trates opaque substances and travels where the 

 ordinary sunlight is turned back, reflected. Is 

 it not possible that this same ray may reach 

 through sea water to the lowest depths? And 

 is it not further possible that the great watch- 

 crystal eyes of, say, the lantern fishes were es- 

 pecially constructed to receive just that beam? 

 Besides there may be still other lights — more 

 lights than we have dreamt of in our philosophy 

 — down there under the wave. The sperm 

 whale that sees so indifferently upon the sur- 

 face, goes down to the depths in his search for 

 the octopus. By what light does he see his 

 prey? Or does he scent the strong musk of the 

 octopus and guide his course by that alone?* 



As for the phosphorescence or luminescence 

 with which many of the deep sea fishes are en- 

 dowed, there is little known about either its 

 extent or its use. It may have no more illu- 

 minating power in the sea than a candle in a 

 cave. And as a candle is used by a human being 

 to prowl about with in the night, so the lumi- 

 nescence of the fish may be only an individual 

 light that enables its possessor to go in and 

 out of dark places. It is assumed by naturalists 



* Mr. Charles H. Townsend, the director of the New 

 York Aquarium, tells tae it is doubtful if whales ever 

 descend to very great depths. 



