1 8 TOILERS IN THE SEA. 



as a dwelling-place, at the same time contains an 

 enormous store of nourishment for them. The same 

 thing must take place in all seas. In the shallower 

 regions which immediately surround continents and 

 islands, great masses of Algae grow wherever there 

 are rocks and stones. In the warmer seas there is 

 an enormous floating Sargasso-life. Only a small 

 portion of these plants is directly eaten by animals, 

 or thrown upon the shore. Most of them die where 

 they have lived, or, after they have been carried 

 away by currents and winds, lose the gases which 

 make them lighter than sea-water, sink down, and 

 become finally decomposed into a soft mass. With 

 the sinking organic materials are, of course, inter- 

 mixed the remains of Testacea, and the fine in- 

 organic soil constituents of the higher regions, which 

 the currents of flood and ebb and the waves are 

 unceasingly triturating. This muddy mixture must 

 move down towards the deeps upon the sloping 

 sea bottom in the neighbourhood of the coasts, 

 from purely mechanical causes, until the weight and 

 mutual adhesion of the individual particles present 

 so much resistance to the pressure of the masses 

 following them from above that equilibrium is pro- 

 duced." And again, "dead plants, fragments of 

 shells, and sand, are heaped one upon the other to 

 a height of feet or fathoms. The alternation of 

 flood and ebb, and the winds, keep the upper strata 



