274f THE OCEAN. 



of fresn water would be detrimental to the health 

 of a polype formed for living in the sea, and there- 

 fore the openings here might have been expected. 

 But this effect is increased by the sediment deposited 

 as has already been observed in speaking of the 

 coral islands. The little green wooded islets, which 

 serve as gateways here as in the former case, are 

 susceptible of ready explanation. Where a river 

 empties itself, a great quantity of vegetable matter, 

 rubbish, and earth, is perpetually carried down, and 

 this would naturally be deposited at the shallows on 

 either side, where the stream met the boiling waves 

 of the Ocean. The heap would very soon be raised, 

 by accumulations, above the surface of the tide, 

 decomposition would take place, seeds washed down 

 would spring up, and, under a tropical climate, the 

 young soil would speedily be clothed with trees and 

 shrubs. In the small islets where there is no efflux 

 of fresh water, the process would be more protracted, 

 but not essentially different : the current driven in 

 through the aperture would bring sea-weeds, and the 

 floating matters washed off the land, and when the 

 soil was once raised above the surface, though com- 

 posed of but sand and pulverised coral, the cocoa- 

 nut would gi-ow and thrive. It is remarkable to see 

 this graceful palm rising from the very sea-sand, 

 where its roots are daily wet with salt water, yet 

 towering to the height of seventy feet, throwing out 

 its elegant plumose fronds, and producing its clusters 

 of flowers and fruit, as luxuriantly as if it were 

 growing in the rich alluvial valleys of the interior. 

 These little fairy islets, so useful as well aa 



