6 THE OYSTER. 



restrial animals, and all naturalists know that it is 

 equally true of sea-food. The blue-fish preys on 

 smaller fishes ; many of these on still smaller ones ; 

 these in their turn upon minute Crustacea ; these upon 

 still smaller animals ; and these pasture on the micro- 

 scopic plants which swarm at the surface of the ocean. 

 However long the chain may be, all animals, those of 

 the water as well as those of the land, depend on plants 

 for food, although most of the vegetable life of the 

 ocean is of such a character that its existence is known 

 only to naturalists. 



If there were no plants all animals would starve, for 

 no animal is a direct food-producer. It can furnish 

 nothing except what has come to it from plants. 



Now, for the purposes of animal life a small plant 

 is as effective as a large one, since however small it 

 may be, it still has the power, which is possessed by no 

 animal, to gather up the inorganic matter of the earth, 

 and to turn it into vegetable matter fit for the nourish- 

 ment of animals. Microscopic plants can do this work 

 as well as great forests of lofty trees, if they are 

 numerous enough, for size counts for nothing. 



Every one knows that the sea is rich in animal life ; 

 that it contains great banks covered with cod and had- 

 dock ; miles and miles of water crowded full of mack- 

 erel and herring, and great monsters of the deep such 

 as the whales and sharks. To the superficial observer 

 the vegetation of the sea appears to be very scanty, 

 and, except for the fringe of sea-weeds along the shore, 

 the great ocean seems, so far as plant life is concerned, 



