METHODS OF PLANKTON RESEARCH. 545 



the surface itself. Thus the coastal plankton is made up 

 of very diverse forms, partly always plankton, partly 

 plankton during only certain periods in the life history. 

 Out on the high seas, where the ocean floor is a waste as 

 far as fixed living plants are concerned, and the water is 

 2,000 or more fathoms deep, the plankton contains no 

 forms arising from the bottom. Thus the oceanic 

 plankton is subjected to different 'conditions of existence, 

 and the absence of these forms in general from our coasts 

 is probably due to their failure to compete with the 

 abundant pelagic life of the shallower waters. The ocean, 

 according to the figures provided by the oceanic quantita- 

 tive plankton expeditions, may be considered as a desert, 

 receiving its life from all sides, and from this producing 

 forms that are peculiar to it, and have in the struggle for 

 existence been driven further out. 



It is now obvious that the most important regions for 

 the employment of quantitative methods are areas like 

 the North Sea and the Irish Sea, or coastal water 

 generally, where, since the plankton is of great import- 

 ance as the food of fishes and contains the eggs and 

 larvae of the latter, the results may be applied to the 

 elucidation of problems in fishery work. It is necessary, 

 also, to determine to what extent the plankton is 

 dependent upon the various hydrographical conditions, 

 and also what variations occur during the year. Since 

 the year 1901, Great Britain, Germany, Norway, Sweden, 

 and other countries in Europe bounding the North Sea 

 and Baltic, have together investigated the hydrographical 

 and biological conditions of these two areas. Grants have 

 been given by the Governments concerned and suitable 

 steamers provided, and an International Committee has 

 drawn up a programme in accordance with which various 

 stations are visited four times a year, and scientific 



