125 



CHAP. VII. 



MAKINE VEGETATION. 



Analogy between Marine and Terrestrial Vegetation. Variety 

 of the Algse. Marine Botany, its Classification. Specimens 

 of the three Subdivisions in which our Sea-weeds are compre- 

 hended. 



THE ocean is not to be regarded merely as a vast 

 kingdom replete with an inexhaustible variety of 

 living forms, but as rivalling the land itself in 

 the profusion of its vegetable productions. The 

 bottom of the sea is in many respects analogous 

 to the surface of the dry land, for it is diversified 

 with level plains, deep valleys, caverns and rocks, 

 hills and mountains, submerged beneath the 

 liquid element, as the plains, valleys, and moun- 

 tains of the land are covered by the great aerial 

 ocean at the bottom of which we live. And the 

 analogy is no less strict between the vegetable 

 productions of the sea and the land. The general 

 distinction is only such as necessarily obtains 

 from the difference between the circumambient 

 fluids in which they have their abode. Thus the 

 stems of marine plants are slender, because they 

 are sufficiently supported by the dense element 

 in which they grow and do not require to be 



