622 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



(3) the veroGHrrents (the littoral ciirreiits or local coast currents); aud 



(4) the zoocurrents (the local phmktoiiic streams or very crowded animal 

 roads). 



Ralicur rents or ocean streams. — The unequal distribution of plank-. 

 ton in tiio ocean is in great part the direct result of the oceanic 

 currents. In general the proposition is recognized as true that tlie 

 great ocean streams, which we briefly designate as halicur rents, effect 

 a greater accunuilation of swimming organisms and thereby are 

 richer in i:)lankton than the /m^/.stesa or "still streams,'' the extensive 

 regions which are inclosed by them and relatively free from currents. 

 For a long time (lie richness in i)lankton which characterizes the Giilf 

 Stream on the east coast of Xorth America, the Falkland Stream on 

 the east coast of South America, and the Guinea Stream on the west 

 coast of Central Africa, has been known. Less understood and investi- 

 gated thaji these Atlantic streams, but also very rich in varied plankton, 

 are the great streams of the Indian and Pacific oceans, the Monsoon 

 Stream on the south coast of Asia, the Moziunbique Stream on the east 

 coast of South Africa, the Black Stream of Japan, the Peru Stream on 

 the west coast of South America, etc. 



It is very difficult, from the numerous scattered accounts of the 

 pelagic fauna and flora of these great ocean currents, to form a general 

 picture of them, but it is now possible to draw Irom them the conclu- 

 sion that generally the i)lanktou of the halicurrents, qualitatively as 

 well as quantitatively, is richer than the plankton of the haUstasa, or 

 the great oceanic sea basins around which flow the great streams and 

 counter streams, and which meet the first glance on every recent map 

 of the marine currents.* 



In defending this proposition I rely especially upon the rich experi- 

 ence of the two most iraportaut plankton expeditions, of the (JhaUcnfjer 

 (6) and of the Vettor Pisani (8), and also upon my own comparative 

 study of several hundred plankton samples, which were collected in 

 part by Murray, iu part by Capt. Rabbe, in the most diverse parts of 

 three great oceans. The planktonic wealth of the great halicurrents is 

 most remarkable at the place where they are narrowest, when the 

 masses of swimming animals and plants are most closely pressed 

 together. Highly remarkable here is the opposition which the rich 

 pelagic fauna and flora of the stream forms iu qualitative and quanti- 

 tative relation to the sparse population of the immediately adjacent 

 halistase. As the temperature and often even the color of the sea 



* The systeni.itic biologioal investigation of the hnJisinsa seems to uie to form one 

 of the nearest and most pressing problems of planlitology, and also of oceanography. 

 Apart from the smaller and little investigated Arctic and Antarctic regions, iu all 

 five great areas of quiet water ought to ho distinguished, namely: (1) the North 

 Atlantic licdisiasc (with the Sargasso Soa) ; (2) the South Atlantic (between Benguela 

 and Brazil streams); (3) the Indian (between Madagascar and Australia); (4) the 

 North Pacific (between California and China), and (5) the South Pacific halistasq 

 (between Chili and Tahiti). 



