146 THE SEA. 



Bank, that rises like a vast mountain of rock from 

 the very edge of the plateau. 



Professor Bailey, who examined these deposits, 

 assumes that these countless hosts of animalcules did 

 not die, much less live, on the spot where they are 

 found. It is probable that at that vast depth total 

 darkness reigns perpetually, no ray of light from the 

 sun having power to struggle through a layer of water 

 two miles in thickness. Could they bear this priva- 

 tion? It is scarcely supposable that their tender 

 tissues could sustain the pressure of so great a column 

 of water, equal to the weight of four hundred atmo- 

 spheres. In all probability they lived near the sur- 

 face, perhaps finding their range of motion and their 

 support in the immense fields of floating weed, the 

 Sargassum, that cover the area of the Gulf Stream, 

 that wondrous mighty river of warm water that 

 pursues its unerring track through the broad Atlantic, 

 as steadily, and within as well-defined bounds, as the 

 Thames through the plains of Middlesex, or the 

 Amazon through the forests of Brazil. Here, on the 

 countless stems and leaves and vesicles of the yellow 

 weed, amidst a vast profusion of other animal life, 

 they probably sported, enjoying the genial influences 

 of tropical light and heat, and carrying with them, in 

 the warm surface-waters of the Gulf, the same favour- 

 able conditions of existence, long after the swiftly 

 speeding stream had carried them beyond the tropical 

 latitudes. 



But, day by day, hour by hour, ten thousand times 



