THE OYSTER. 9 



is continually breaking down and wearing away the 

 hard rocks, and carrying the fragments down to lower 

 levels to form the fertile land of the hillsides and 

 valleys and meadows. As the roots of the plants 

 penetrate this loose material they gather up the mineral 

 food which is dissolved by the rain, and convert it into 

 their own substance, and as their leaves fall and their 

 trunks decay, the decaying vegetable matter gradually 

 builds up the leaf-mould and the meadow-loam which 

 are so well adapted for supporting vegetable life. 

 Each year, however, the heavy rains wash great quan- 

 tities of this light, rich soil into the rivers, which in 

 times of flood cut into their banks and carry the arable 

 land, which has been built up so slowly, down to lower 

 levels, until at last it finds its way to the ocean and is 

 lost, so far as its use to man is concerned. 



In a long, flat river-valley it may be arrested for a 

 time, so that man may make use of it, but its final 

 destination is the ocean, and as this has already been 

 enriched by the washings through untold ages, all 

 that is most valuable for the support of life is now dis- 

 solved in its waters, or deposited upon its bottom, 

 where man can make no use of it. 



We love to dream of the shipwrecked treasures 

 which lie among the bones of the sailors on the sea- 

 bottom ; of the galleons sunk and lost with their pre- 

 cious cargoes of bullion and jewels from the treasure- 

 chambers of the Incas and the palaces of Asia ; but all 

 these, and all the " gems of purest ray serene, the 

 dark, unfathom'd caves of ocean bear " ; all the thous- 

 3 



