DWELLERS IN THE DEEP 



203 



the depths have eyes — highly organized and 

 very sensitive eyes — and it is not believable that 

 nature made them without purpose. That is 

 quite contrary to her practice. And she some- 

 times eliminates a member if unused. The 

 stream-fish in the waters of the Mammoth Cave 

 are blind, became blind by being plunged in 

 continual darkness; but not so the majority of 

 fish that live in the deep sea. From which it 

 would seem that the dwellers in the ocean 

 depths have eyes that are in continual use — 

 eyes that are perhaps adapted to another kind 

 of light than sunlight. 



It is explained by naturalists that there is 

 phosphorescence or luminescence in the depths, 

 that the fishes themselves possess it and flash 

 it at will, and that their eyes are adapted to it. 

 Very likely they can see by it to some extent; 

 but is that the only light, is that sufficient to 

 account for the marvellous telescopic e3^es of 

 some of the octopuses ? We may be wrong about 

 sunlight not penetrating to the great depths, 

 never reaching beyond a hundred or more fath- 

 oms of water. We keep thinking of our sun- 

 light, of the yellow, red and blue rays that make 

 up white sunlight ; but what of the far end of 

 the spectrum — the X rays that were discov- 

 ered only a few years ago ? The dark ray pene- 



The prob- 

 lem of 

 light. 



How do the 

 bottom 

 dwellers 

 aeef 



Phosphor- 

 escence and 

 lumiriea- 

 cence. 



