§ 486. THE SALTS OF THE SEA. 255 



ocean. Out of it, coral islands and coral reefs of great extent — 

 marl-beds, shell-banks, and infusorial deposits of enormous mag- 

 nitude, have been constructed by the inhabitants of the deep. 

 These creatures are endowed with the power of secreting, appa- 

 rently for their own purposes only, solid matter, which the waters 

 of the sea hold in solution. But this power was given to them 

 that they also might f;ilfill the part assigned them in the economy 

 of the universe. For to them, probably, has been allotted the 

 important office of assisting to give circulation to the ocean, of 

 helping to regulate the climates of the earth, and of preserving 

 the purity of the sea. The better to comprehend how such crea- 

 tures may influence currents and climates, let us again suppose 

 the ocean to be perfectly at rest — that throughout, it is in a state 

 of complete equilibrium — that, with the exception of those tenants 

 of the deep which have the power of extracting from it the solid 

 matter held in solution, there is no agent in nature capable of dis- 

 turbing that equilibrium — and that all these fish, etc., have sus- 

 pended their secretions, in order that this state of a perfect aque- 

 ous equilibrium and repose throughout the sea might be attained. 

 In this state of things — the waters of the sea being in perfect equi- 

 librium — a single mollusk or coralline, we will suppose, com- 

 mences his secretions, and abstracts from the sea water (§ 465) 

 solid matter for his cell. In that act this animal has destroyed 

 the equilibrium of the wholo ocean, for the specific gravity of that 

 portion of water from which this solid matter has been abstract- 

 .ed is altered. Having lost a portion of its solid contents, it has 

 become specifically lighter than it was before ; it must, therefore, 

 give place to the pressure which the heavier water exerts to push 

 it aside and to occupy its place, and it must consequently travel 

 about and mingle with the waters of the other parts of the ocean 

 until its proportion of solid matter is returned to it, and until it at- 

 tains the exact degree of specific gravity due sea water generally. 

 486. How much solid matter does the whole host of marine 

 Solid matter secreted p^^uts and auimals abstract from sea w^ater daily ? 

 ^^ *^^'°' Is it a thousand pounds, or a thousand millions of 



tons ? No one can say. But, whatever be its weight, it is so 

 much of the power of gravity applied to the dynamical forces of 

 the ocean. And this power is derived from the salts of the sea, 

 through the agency of sea-shells and other marine animals, that 



