46 J'HE DEPTHS OF THE SEA. [chap. i. 



upon which animals can feed. This process is, how- 

 ever, so far as we are at present aware, constantly 

 effected under the influence of light. There seems 

 to he little or no light at the bottom of the sea, 

 and there are certainly no plants except such as 

 may sink from the surface, bat the bottom of the 

 sea is a mass of animal life. At first sight it 

 certainly seems difScult to account for the main- 

 tenance of this vast animal population living with- 

 out any visible means of support. Two explanations 

 have been suggested. It is conceivable that certain 

 animal forms may have the power of decomposing 

 water, carbon dioxide, and ammonia, and re-com- 

 bining their elements into organic compounds without 

 the agency of light. Dr. Wallich supports this view, 

 and in doing so he states that " No exceptional law 

 is invoked, but, on the contrary, that the proof of 

 these organisms being endowed with the power to 

 convert inorganic elements for their own nutrition 

 rests on the undisputed power which they possess 

 of separating carbonate of lime or silica from waters 

 holding these substances in solution." ' This, how- 

 ever, seems scarcely satisfactory. All the substances 

 employed in the nutrition of animals are offered to 

 them finally in solution in water, and the abstraction 

 of these from their watery solutions cannot be re- 

 garded as a ' chemical separation.' The broad dis- 

 tinction still remains, that when carbon dioxide in 

 solution is presented to a green plant in the sun- 

 shine it can decompose it, while an animal cannot. 



I believe we have a simpler explanation. All 

 sea-water contains a certain quantity of organic 

 ' North Atlantic Sea-bed, p. 131. 



