ancient guise. Briefly then, fresh-water was a bar- 

 rier seemingly only to the progress of the higher 

 form; however, in the case of the primitive type, 

 it offered no obstacle to growth, but actually ap- 

 peared to foster it. 



This puzzling paradox seemed hopelessly in- 

 volved and utterly without explanation when, 

 like a flare in the night, there flashed upon my full 

 consciousness certain statistics, memorized long 

 ago and which were until that moment still 

 smoldering somewhere in the recesses of my brain : 

 The age of the ocean, since the earth assumed its 

 present form, is presumed to be somewhat less 

 than 100,000,000 years. It is known that there 

 exists at present, in solution in the sea, 4,800,000 

 cubic miles of salts; more than enough to cover 

 the surface of the United States one and one-half 

 miles deep. It is further known that the sea re- 

 ceives from the land, in addition to other elements, 

 more than 60,000,000 tons of sodium every year. 

 This substance, dissolved out of the rocks by rains 

 and carried in solution by rivers and underground 

 streams to the ocean, there combines with chlorine, 

 and this chemical union forms the salt of the sea. 

 Consequently, as we go farther and farther back 



[104] 



