Masterpieces of Science 



erosive work. Were it not for this system of 

 alluvial storage and decay, the seas could not be 

 supplied with the debris essential for the main- 

 tenance of the life which they contain; for that 

 life, unlike the life of the land, does not depend 

 on the soil of the ocean floors, but upon the dis- 

 solved matter contained in the water, from which 

 the marine animals and plants take all their 

 store of nutrition. This nutrition comes mainly 

 from the land- waste brought to the sea in the 

 state of solution by the streams, and, as we have 

 just seen, the comminution and solution of this 

 waste/ depend upon the work which goes on in 

 the laboratories of the alluvial plains. 



It is true that a portion of the mineral matter 

 contributed by the land to the sea comes from 

 the seashore, and yet another portion from vol- 

 canic ejections which are poured out from the 

 numerous vents of oceanic islands. The material 

 taken from the seashore into solution by the sea- 

 water is, however, small in quantity, and this for 

 the reason that the ocean water has usually but a 

 small amount of free carbonic acid to aid in its 

 solvent work. The material contributed from 

 volcanoes is larger in quantity than that won by 

 the ocean waves from the coast line. A large 

 part of this volcanic waste is, however, borne 

 to the ocean from the land on which it falls, by 

 the streams, which readily remove the incoherent 

 volcanic waste by the action of their waters, 

 and bear it to the sea. 



152 



