THE WORK OF ORGANISMS IN ROCKS. 11 



solution. In river water, calcium salts always greatly 

 exceed sodium salts, whereas in the sea, sodium pre- 

 ponderates over calcium. Other elements, too, show 

 discrepancies, but not in so marked a degree as those 

 quoted. 



The composition of sea water depends on two factors 

 — (1) the action of water in dissolving out and carrying 

 material from the land to the sea, and (2) the action of 

 certain agents in removing some of these substances out 

 of solution. 



It is owing to the fact that some salts are 

 precipitated out of solution and others are not that the 

 discrepancies occur. 



The relative proportions of the elements in the ocean, 

 therefore, have always been changing. Some have 

 increased and others have remained stationary or almost so.* 

 This is almost exclusively the work of organisms. How they 

 accomplish this is our next query ; but before attempting 

 to answer it let me remind you of an observation made 

 during the course of one of the excursions of this Society 

 to Widnes some years ago. We found the great heaps of 

 chemical waste supporting a very scanty flora, only 

 hardy and adaptable forms could exist on so inhospitable 

 a soil. The Moss Polytrichum was seen to assume a fleshy 

 habit, and its stem when pressed by the fingers was found 

 to be hard and prickly. I collected some of these speci- 

 mens, and found crystals in the tissues, which, on analysis 

 by Mr. Rhodes, proved to be selenite. The plant has no 

 selective power in absorbing water from the ground, and 

 here it was compelled to take up water charged with large 

 quantities of sulphuric arid and salts of lime. 



-The Pal geochemistry of the Ocean has been dealt with in an 

 exhaustive manner by Professor Macallum (Trans. Canad. Inst., 

 Vol. VII., p. 535), and I need not further discuss the question. 



