THE OYSTER. 7 



lutely invisible to the unaided eye, and even when they 

 are gathered together in a mass, it looks like slimy 

 discolored water and presents no traces of structure. 

 They seem too insignificant to play any important 

 part in the economy of nature, but the great monsters 

 of the deep, beside which the elephant and the ox and 

 the elk are small animals, owe their existence to these 

 microscopic plants. 



Their vegetative power is wonderful past all expres- 

 sion. Among land plants, corn, which yields seed 

 about a hundredfold in a single season, is the emblem 

 of fertility, but it can be shown that a single marine 

 plant, very much smaller than a grain of mustard seed, 

 would fill the whole ocean solid in less than a week, 

 if all its descendants were to live. 



This stupendous fact is almost incredible, but it is 

 capable of rigorous demonstration, and it must be 

 clearly grasped before we can understand the life of 

 the ocean. As countless minute animals are con- 

 stantly pasturing upon them, the multiplication of 

 these plants is kept in check, but in calm weather it is 

 no rare thing to find great tracts of water many miles 

 in extent packed so full of them that the whole surface 

 is converted into a slimy mass, which breaks the waves 

 and smooths the surface like oil. The so-called "black 

 water" of the Arctic and Antarctic oceans, the home 

 and feeding ground of the whale, has been shown by 

 microscopic examination to consist of a mass of these 

 plants crowded together until the whole ocean is dis- 

 colored by them. Through these seas of " black 

 water" roam the right whales, the largest animals on 

 earth, gulping at each mouthful hundreds of gallons 



