THE PHYSICAL CONDITIONS OF THE ABYSS 43 



that below a hundred fathoms no organisms, except- 

 ing a few parasitic fungi, are to be found that can be 

 included in the vegetable kingdom. While then the 

 researches of recent times have proved beyond a doubt 

 that there is no depth of the ocean that can be called 

 azoic, they have but confirmed the perfectly just 

 beliefs of the older naturalists that there is a limit 

 where vegetable life becomes extinct. It is not diffi- 

 cult to see the reason for this. All plants, except a 

 few parasites and saprophytes, are dependent upon 

 the influence of direct sunlight, and as it has been 

 shown above that the sunlight cannot penetrate 

 more than a few hundred fathoms of sea- water, 

 it is impossible for plants to live below that 

 depth. 



The absence of vegetable life is an important 

 point in the consideration of the abysmal fauna, for 

 it is in consequence necessary to bear in mind that 

 the food of deep-sea animals must be derived from 

 the surface. It is possible that deep-sea fish, in 

 soTue cases, feed upon one another and upon deep-sea 

 Crustacea, that deep-sea Crustacea feed upon deep-sea 

 worms, that deep-sea echinoderms feed upon deep- 

 sea foraminifera, and so on through all the different 

 combinations ; but the fauna would soon become 



