INTERNAL ECONOMY OF THE SEA 83 



Danish naturalists, Petersen and Jensen, show that 

 the organic matter of the sea-floor in the sheltered 

 waters of fjords and bays is mainly due not to the 

 sinking down of the minute Plankton organisms, 

 but to the detritus of the sea-grass (Zostera) and 

 its associates in shallow water. This is of enormous 

 practical importance, since it is in man's hands to 

 cultivate, if need be, the littoral vegetation, and 

 thus cast bread upon the waters, to be gathered 

 again after many days. But aquiculture is not yet 

 a pressing need. 



As to a heresy started some years ago by Profes- 

 sor Putter, that sea-water contains large quantities 

 of dissolved organic matter a sort of fundamental 

 " stock "of the sea-soup and that this accounts 

 for the sustenance of many marine animals whose 

 food supply has been confessedly difficult to dis- 

 cover, it cannot be said to have been confirmed 

 by further investigation. In fact, recent work by 

 Professor Benjamin Moore and others at Port Erin 

 Biological Station is quite against it. The prob- 

 ability is that sufficient importance has not been 

 attached to the nutritive role played by the organ- 

 isms of the Dwarf Plankton (Nanno-plankton), 

 which abound beyond telling in the open sea, and are 

 so extremely minute that they pass through the 

 invisible pores of the finest silk cloth used in tow- 

 netting. There is thus no reason to depart from 

 the conclusion that the producers in the economy 

 of the sea are the chlorophyll-possessing plants, 

 both of high and low degree, and such small animal 



