194 BRITISH FISHERIES 



a ton of corn, or two or three hundredweight of 

 meat or cheese. The same area at the bottom 

 of the sea yields a greater weight of food to the 

 persevering fishermen every week in the year."^ 



According to Brandt,^ the fishermen of Northern 

 European countries take from the North Sea about 

 nineteen million kilogrammes of nitrogen, in the 

 form of edible fish, every year. At any one 

 moment there is about double this quantity 

 present in the North Sea. Since this withdrawal 

 of nitrogenous food-material continues year by 

 year, the loss of nitrogen (and of course the 

 other food-forming elements) must be made up. 

 The nitrogen taken from the sea in the shape of 

 fish is returned to it as nitrogenous compounds 

 washed down from the land by rivers. On the 

 death and decomposition of the bodies of animals 

 and plants, the organic material of which they are 

 composed is resolved, by the action of putrefactive 

 bacteria, into compounds of nitrogen (ammonia, 

 and salts of nitric and nitrous acid), carbonic acid, 

 water, and other substances. The nitrogenous 

 substances, being easily soluble in water, are soon 

 washed into the sea by the agencies of rain and 

 rivers. It has been computed that all the rivers 

 of the world convey in this way no less than thirty 

 billion grammes (about twenty-nine million tons) of 



^ p. 26 (8vo edition). 



* Wissensch, Meeresunt, Kiel Kommission, Bd. iv., Abth. Kiel, 

 1899. 



