194 THE OCEAN RIVER 



the Ocean River and of the complex patterns of life within it. 

 The drift of water both aided and hindered Columbus in his 

 voyage of exploration; and it plays its part today in the great 

 migrations of fishes. Some of these great mass movements are 

 dedicated to feeding and others to breeding. Some are local, 

 like those of the Icelandic cod fishery, but others put even 

 Columbus into the shade by the length of time they take and 

 the danger involved. Their migrations are still in many ways a 

 great puzzle to science. Not the least of these mysteries is how 

 the fish is able to find its way along a well-defined path of hun- 

 dreds or even thousands of miles through water that it may 

 never have experienced before. The greatest of these travellers 

 are the eels and the salmon, though the tunas follow them 

 closely. 



The most adventurous journey of all is that of the fresh- 

 water eel, which we have mentioned already in connection 

 with the lost land of Atlantis. For many years men have 

 wondered how eels were able to grow and multiply in rivers 

 and streams and ponds, for nobody had ever seen their eggs 

 or very young stages. Izaak Walton expressed contemporary 

 opinion in 1653 when he wrote, ''. . . eels are bred of a par- 

 ticular dew, falling in the months of May or June on the 

 banks of some particular ponds or rivers . . . which in a few 

 days are, by the sun's heat turned into eels." Even more 

 curious ideas had their vogue, and the truth had not been 

 discovered even when Pasteur exploded the old ideas of 

 spontaneous generation, whereby life was supposed to arise 

 from mud or putrefaction. The only clue was that suddenly, 

 at certain times of the year, enormous numbers of elvers or 

 young eels appear in the mouths of rivers and begin to swim 

 upstream. The strange story of whence they come was not 

 unravelled until 1922, when Johannes Schmidt, a Danish 

 scientist, finally pieced together scattered evidence and found 

 the solution to the mystery. Since, unlike Columbus, the eels 

 keep no log books of their travels, and since we cannot follow 



