280 TOILERS IN THE SEA. 



vations show that thousands of deep-sea corals, and 

 of other lime-secreting animals, flourish on deep-sea 

 deposits, at depths much greater than those at which 

 true reef-building species are found. The dead 

 remains of these deeper-living animals, as well as the 

 dead shells of pelagic species, that fall from the sur- 

 face waters, build up submarine elevations towards 

 the sea-level. Again, the reef-building coral will 

 grow upon its own debris, rising, as men, morally 

 and spiritually, are said by the poet to do, 



"'On stepping-stones of their dead selves to higher things.' 



This small error told for much ; for if coral could 

 grow on deep-sea deposits when lifted up, and if 

 it could also grow seaward, when once established, 

 upon its own dead and sunken masses, then sub- 

 marine elevations, and not submarine subsidences, 

 might be the true explanation of all the facts. But 

 what of the lagoons, and the immense areas of sea 

 behind the fringing reefs? How could these be 

 accounted for? It was these which first impressed 

 Darwin with the idea of subsidence. They looked 

 as if the land had sunk behind the reef, leaving a 

 space into which the sea had entered, but in which 

 no fresh reefs could grow. And here we learn the 

 important lesson, that an hypothesis may adequately 

 account for actual facts, and yet, nevertheless, may 

 not be true. A given agency may be competent to 



