92 SEA FISHERIES 



vegetable and animal forms having common attributes, 

 and of which it is convenient to estimate the degree of 

 evaluation. Neritic plankton is by definition distinct from 

 oceanic plankton : however, it often happens that the two 

 become mingled and interpenetrated. There is a great 

 analogy between the pelagic flora and fauna of the 

 subtropical Atlantic and those of the Mediterranean. 

 The water of the glacial regions, charged with its 

 peculiar plankton, reaches the Mediterranean and perhaps 

 even the Red Sea. The dead plankton which falls from 

 the surface is absorbed by the creatures at the bottom. 

 These latter, moreover, develop according to the direction 

 of the currents, and their number is in direct proportion 

 to the quantity of plankton carried by the currents. 



The opinion which I have just cited namely, that 

 there are centres of pelagic dispersion is supported by 

 the well attested fact that there are local accumulations 

 of plankton. There is such an accumulation in the 

 Red Sea. Along the Norwegian coast, in May and June, 

 the plankton is scanty ; but shortly afterwards large 

 accumulations of diatoms appear, which give the sea a 

 brown tint. They are developed from spores contained 

 in the icebergs which come down from the North at this 

 season. This is one of the means by which "pelagic 

 swarms " are formed. Another means is the encounter of 

 two currents loaded with plankton. Such swarms have 

 been observed off Concarneau by the Princess Alice. 

 They consisted of bands of plankton parallel to the line 

 of the swell and to one another. Each belt was from 

 2 to 3 feet wide, 25 to 30 feet long, and 3 feet in depth. 

 In the open ocean, thousands of miles from any land, 

 colossal agglomerations of pelagic fish are found, which 

 cover whole seas. Here is another example, which will 

 serve as a synthesis of the preceding data. In the 



