66 THE UNIVERSE. 



spread. But these obscure artisans, as modest as they are 

 laborious, frequently conceal themselves from the eye ; to 

 see them we must have recourse to the magnifying-glass. 



It is principally in the South Sea and the Red Sea that 

 the constructions of these Polypi abound. At the ap- 

 proaches to the Maldive Islands they form extraordinary 

 masses, of not less extent than the Alps, according to the 

 accounts of travellers. The American traveller Dana states 

 that the larger coral islands of the Pacific are at present 

 290 in number, with a total area of 20,000 square miles, 

 an enormous work, equal perhaps to an eighth part of the 

 surface of all the other islands of this vast sea. 



After having described the methods by which the Polypi 

 raise their dangerous reefs so fatal to mariners, Owen thus 

 sums up as to the immensity of their labors : " The pro- 

 digious extent of the combined and unintermitting labors of 

 these little world-architects must be witnessed in order to 

 be adequately conceived. They have built up a barrier 

 reef along the shores of New Caledonia for a length of 400 

 miles ; and another which runs along the northeast coast of 

 Australia 1000 miles in extent." This represents, adds the 

 illustrious zoologist, a mass compared with which the walls 

 of Babylon and the Pyramids of Eg}^pt are but children's 

 toys. And these edifices of the Polypi have been reared in 

 the midst of the ocean waves, and in defiance of tempests 

 which so rapidly annihilate the strongest works of man. 



Notwithstanding their extreme minuteness, the Polypi 

 have nevertheless, by their calcareous buildings, brought 

 about important changes on the crust of the terrestrial 

 globe. They have modified it in two ways: by raising the 



