292 THE CIRCULATION OF NITROGEN [PART III 



proportion to the surface of the Atlantic, than does the North 

 Sea coast-line to the surface of that water mass. But we ought 

 also to consider the catchment area of the rivers as well as the 

 relations between ocean surface and coast-line. Apparently these 

 considerations do not help towards a solution of our question. 

 We know that many other substances enter the sea in greater 

 amount than are taken fi'om it. Salt is carried down to the sea 

 in the rivers, bat then salt is probably taken from the sea in the 

 evaporated water vapour. Silica and lime are also added to the 

 sea, but both substances are accumulated there : silica in the form 

 of diatom ooze, sponge spicules, flints, and radiolarian ooze ; and 

 lime in the form of calcareous oozes, coral reefs, shelly sands and 

 gravels, nullipore formations, &c. Potassium and phosphoric acid 

 are also added, but the former element accumulates at the sea 

 bottom as glauconite, while phosphoric acid accumulates in the 

 form of phosphatic nodules. Magnesium, manganese, iron, &c. 

 are also added to the sea but all these elements accumulate 

 there in certain forms. No permanent deposits of nitrogenous 

 materials are however known to occur, or to have occurred, in the 

 sea bottom deposits. There are no insoluble inorganic nitrogen 

 salts, and the insoluble organic nitrogenous substances that we do 

 know cannot resist bacterial activity. There are deposits of 

 nitrates on the land — the S. American beds of Chili saltpetre for 

 instance, and the potassium nitrate accumulations elsewhere. But 

 these substances can only accumulate in hot and dry climates. 

 Their permanent disposition in the ocean is obviously an impossi- 

 bility. 



It has indeed been suggested that organic matter is being laid 

 down at the sea bottom, forming a stratum that may at some 

 future time become available for the nutriment of terrestrial 

 plants. One can hardly say that this is not possible, for organic 

 remains must sink to the bottom of the deep seas, and at the very 

 low temperature which prevails there bacterial activity, and conse- 

 quently putrefactive decomposition, may be practically arrested so 

 that nitrogenous matters may accumulate. Nevertheless there is 

 no direct evidence in favour of this purely a priori hypothesis. 

 Natterer^ again revived, in 1894, an older view of Schlossing to the' 



^ Denkschr. Akad. Wien, Bd. lxi. 1894. 



