THE HAUNTS OF LIFE 93 



tophores, this denizen of the great depths had only one, 

 ' a rhombic chromatophore between the two fins '. The 

 arms bore some normal suckers, but each had thirty-six 

 others of minute size, flattened and without sucking disc, 

 and showing in each case in the long spindle-shaped and 

 clumsy stalk a curious structure which may be a lumines- 

 cent organ and reflector. 



The eyes are of interest, in illustration of the subtlety 

 of life. There are Deep-Sea cuttlefishes with small eyes, 

 as one might expect, but this is the only case, recorded 

 as yet (1914), in which the actual structure of the eye is 

 involved. For this cuttlefish is blind ! The eye is minute, 

 without a lens, with a very degenerate retina and optic 

 nerve. Nature is economical, as we say in metaphor ; 

 but here she seems to have been parsimonious to a degree 

 almost hazardous. The degeneration of thisCephalopod's 

 eye has gone further than in many blind vertebrates. It 

 is adaptive, apparently, to conditions of abyssal darkness ; 

 but surely it remains sensitive to the luminescent sparkles 

 of its own arms and the prey they grope for. 



Problems of Deep -Sea Fauna. 



There are many unsolved problems in the Deep Sea, 

 and one of the most obvious of these is the frequent occur- 

 rence of 'phosphorescence'. It is seen in animals of high and 

 low degree ; it is exhibited by sedentary animals and by 

 free swimmers ; it is associated with a great variety of 

 highly specialized organs ; and these are occasionally 

 situated on most extraordinary places near the end of the 

 tail, on the tip of a long flexible rod, inside the mantle- 

 cavity of a cuttlefish, or inside the gill-chamber of a crusta- 



