INTERNAL ECONOMY OF THE SEA 87 



by animals they are raised to a still higher incar- 

 nation as animal proteins. But when the plant or 

 animal dies the complex organic substances are 

 broken down through the agency of bacteria into 

 simple constituents once more, and some of these 

 being utilized by plants may enter again into the 

 circle of life. Shakespeare, with his prescience, 

 spoke of what might happen to the dust of Caesar, 

 but it was only a vague vision that he can have 

 had of the long nutritive chains, with quaint 

 sequences like those of " The House that Jack 

 built," which connect Diatoms and debris with 

 fishes and man. As Professor Herdman tells us, 

 man eats the cod, which in turn may feed on the 

 whiting, and that on the sprat, and the sprat feeds 

 on Copepods, which again depend on Peridinians 

 and Diatoms. Most of the nutritive chains bring us 

 through Copepods to sea-grass and seaweeds, to 

 Diatoms and debris. For so the world goes round, 

 and such are the incarnations of the sea. 



