THE PHYSICAL CONDITIONS OF THE ABYSS 27 



the bottom of the deep sea, but it is quite probable 

 that it does in some places, and hence the well- 

 developed eyes and brilliant colours of some of the 

 deep-sea animals. 



On the other hand the entire absence or rudimen- 

 tary condition of the eyes of a very considerable pro- 

 portion of deep-sea animals seems to prove that the 

 phosphorescent illumination is not universally dis- 

 tributed, and that there must be some regions in 

 which the darkness is so absolute that it can only be 

 compared with the darkness of the great caves. 



It is difficult to believe that the eyes of such 

 animals as crabs and prawns for example would 

 undergo degeneration if there were a glimmer of light 

 in their habitat, a light even so faint as that of a star- 

 light night in shallow water. With the faintest light 

 the eyes would be of use to them in seeking their 

 prey, avoiding their enemies, and finding their mates, 

 and any diminution in the keenness of this sense 

 would probably be of considerable disadvantage to 

 them and tend to their ultimate extinction. 



It might be argued that the animals of the abysses 

 of the ocean probably feed chiefly upon the carcases 

 of pelagic animals that have fallen from the upper 

 regions of the sea, and that the sense of smell is 



