164 THE OCEAN FLOOR 



nutriment for marine animals. This may be true 

 especially in the deep sea, where the influx of dissolved 

 organic matter is dependent on the movement of water 

 masses. It is of particular interest to find at the greatest 

 known depths sufficient bacteria to contribute to the 

 nourishment of bottom-feeding animals. It is equally 

 interesting to note that most of the animals found on 

 the deep-sea floor are types adapted to feed on very 

 small particles like bacteria. 



Earlier investigations of marine bottom deposits 

 collected from different parts of the world have 

 demonstrated the occurrence of bacteria capable of 

 attacking virtually all kinds of organic compounds. 

 Such bacteria are believed to play an important part 

 in the mineralization of organic matter in the sea and in 

 the formation of carbon dioxide, ammonium sulphate, 

 phosphates, and other plant nutrients. 



Large numbers of bacteria that reduce sulphates 

 to hydrogen sulfide are commonly found in bottom 

 deposits. The activities of such bacteria are often 

 responsible for the vitiation of water in stagnant basins. 

 By catalyzing the transformation of both organic and 

 inorganic constituents of marine mud, bacteria appear 

 to be the principal dynamic agencies that affect its 

 hydrogen-ion concentration and oxidation-reduction 

 potential; this fact may have a pronounced effect on 

 the composition, chemical reactivity, diagenesis, color, 

 biological population, geochemistry, and other proper- 

 ties of recent sediments. 



