THE COCOA-NUT PALM. 227 



ful cocoa-nut palm. This tree is exceedingly hardy, 

 and is found growing on reefs which are so low 

 that at a distance the trees seem to be standing on 

 the surface of the water. Indeed many of them 

 spring out of the pure white sand, and their roots 

 are washed perpetually by the salt spray. Never- 

 theless, the fruit of such trees is sweet and good. 



Coral islands of the kind we have just described 

 seldom rise more than a few feet above the level of 

 the sea ; but most of them are clothed with luxu- 

 riant vegetation. 



We might easily fill a volume on the subject of 

 the ocean's inhabitants, small and great ; but we 

 think the few to which we have made reference is 

 sufficient for the purpose of showing that one set 

 of creatures accounts for that strange luminosity of 

 the ocean which is seen at times in all marine parts 

 of the globe, while another set accounts not only for 

 the sudden appearance of coral islands in the sea 

 where no such islands existed in days of old, but 

 also, partly, for that circulation of the waters of the 

 ocean which is absolutely necessary to the well- 

 being of all the creatures on this earth. 



There are other animals in the sea, besides me- 

 dusse, which assist in giving luminosity to its waters ; 

 and there are other insects, besides corallines, which 

 extract its lime, destroy its equilibrium, and assist 

 in causing its perpetual motion ; but the two spe- 

 cies which we have described are the best types of 

 the respective classes to which they belong. 



