152 THE OCEAN 



as round dots, rods, or threads ; they are 

 colourless and contain no chlorophyll, and 

 have an envelope or capsule of cellulose or 

 allied substance. They multiply by division 

 or by spores. Life as a whole could not con- 

 tinue without bacteria ; they do not originate 

 life, but supply life with the necessary mate- 

 rial. Plants without chlorophyll and animals 

 dissipate the energy accumulated by chloro- 

 phyllous plants, which derived this energy 

 wholly from the rays of the sun. 



Bacteria and decomposing organic matter 

 are always associated, so that the presence 

 of bacteria throughout the whole mass of the 

 ocean — even in the greatest depths and in the 

 coldest water — was inferred long before their 

 presence was detected by actual observations. 



The vast majority of bacteria cannot live 

 unless they have organic substances both 

 carbonaceous and nitrogenous at their dis- 

 posal. They include those which produce 

 fermentation (decomposition of non-nitrogen- 

 ous substances) and those which produce 

 putrefaction (decomposition of nitrogenous 

 substances). The excretions and dead bodies 

 of animals, the fragments of tissues and cells, 

 the waste of domestic and industrial life, all 

 eventually find their way into the soil and 

 into the ocean. Generally these substances 

 are not in a fit chemical state to be utilised 



