124 THE SEAS 



of the animals and plants of the plankton by large ooeano- 

 graphical expeditions which have been sent out by different 

 countries during the last fifty years, and it is fairly estab- 

 lished that all the waters of the globe are inhabited by them. 

 Just as on land, the various species of plants and animals 

 have their own distribution, some living in tropical climes 

 and others in the far north or south, so it is noticed that 

 many members of the plankton are to be found only in 

 certain regions and may give the catches made in those 

 localities a characteristic appearance. Amongst diatoms, 

 for instance, there are species that are normally only found 

 in coastal regions, others that occur only in the open ocean 

 waters of tropical and sub-tropical regions, and others 

 again that characterize the catches of northern waters. 

 But while species of these little drifting plants are to be 

 found almost anywhere in the oceans all over the world, the 

 cool temperate and the cold arctic and antarctic waters are 

 now known to carry this diatom life in quantities far 

 exceeding the other regions. The waters that bathe the 

 shores of the British Isles, of Holland, Sweden, Denmark, 

 Norway and Iceland, on the east, and of Greenland, New- 

 foundland and the Gulf of Maine in America on the west, 

 possess a richer pasturage of microscopic plant life than is 

 to be found in any other locality in the North Atlantic 

 Ocean. The significance of the plankton plants in the 

 general economy of the sea will then become at once 

 apparent, when it is realized that it is precisely these 

 regions, the North Sea, the Baltic, the Norwegian and 

 Greenland Seas, and the banks of Newfoundland, that give 

 rise to the greatest fisheries in the Atlantic, and in fact in 

 the whole world. 



Dependent on the diatoms are, of course, the small 

 animals of the plankton, and it is natural to suppose that 

 where the plant life is most abundant there will be found 



