OCEAN LIFE. 3 



organized matter, and vegetables on unorganized. For the sup- 

 port of animal life, therefore, we require vegetables to change 

 the mineral constituents of the surrounding media into suitable 

 nutriment. In the sea this office of vegetation is almost exclu- 

 sively committed to the Algae, and we may judge of the complete- 

 ness with which they execute their mission by the fecundity of 

 the animal world which depends upon them. Not that I would 

 assert that all, or nearly all, the marine animals are directly 

 dependent on the Algae for their food ; for the reverse is noto- 

 riously the case. But in every class we find species which derive 

 the whole or a part of their nourishment from the Algae ; and 

 there are myriads of the lower in organization which do depend 

 upon them altogether. Among the higher orders of Algae feeders 

 I may mention the Turtles, whose green fat, so prized by Alder- 

 manic palate, may possibly be colored by the unctuous green 

 juices of the Caulerpae, on which they browse. But without 

 further notice of those that directly depend on the Algae, it is 

 manifest that all must ultimately, though indirectly, depend on 

 whatever agency in the first instance seizes on inorganic matter, 

 and converts it into living substance suitable to enter into the 

 composition of animal nerve and muscle. And this agency is 

 assuredly the office of the vegetable kingdom, here confined in the 

 main to Algae ; proving that they are indispensable to the con- 

 tinuance of organic life in the sea. They also keep pure the 

 water in which they vegetate, and yield a considerable portion 

 of oxygen gas to the atmosphere. 



The Algae have served as food both for man and cattle ; and 

 have been much employed in agriculture and the arts. But they 

 have proved most valuable to man, in affording substances which 

 prove highly beneficial in the treatment of disease. 



