THE IMPENETRABLE SEA 



canines for fighting their rivals. So, faithful to each 

 other and with the male fighting off any interfering 

 rivals, the couples battle their way onward against swift 

 currents, often tearing their flesh against sharp stones, 

 climbing cataracts and leaping unbroken falls of con- 

 siderable height. 



The shrinking of their stomachs from the time they 

 leave tide-water is accompanied by a narrowing of their 

 throats. These remarkable changes are gradual, but they 

 increase until all desire for food is gone, and any tempta- 

 tion to turn back to the rich feeding grounds of the salt 

 waters vanishes. The great reserve of flesh and blood 

 which they bring with them from the ocean enables them 

 to keep their vital organs active until their strange mission 

 up the fresh-water streams is accomplished. 



This is one of the ocean's greatest mysteries. The fish 

 face colossal hazards. They fight against the strong 

 currents. They climb cataracts and are dashed back 

 again and again — yet still they persist. As they ascend 

 the American rivers, and those of other countries, they 

 are caught by gill nets, fyke nets, pounds, weirs, seines, 

 wheels, and other devices. 



Before they enter the rivers they are fiercely attacked 

 by seals and sea-lions, and many other natural enemies 

 meet them on their way up-stream, apart from their 

 greatest enemy, man, with his fishing rods and ingenious 

 traps. 



The force which drives them onward is the sexual 

 instinct. But this fact deepens rather than lessens the 

 mystery, for it does not explain why they have to go such 

 long distances up-stream to the places where they were 

 born to gratify it — nor how they remember the locations 

 all their lives and are able to identify them again. We 

 only know that they do return to their parent streams. 



After their arrival, the female salmon pours out her 

 eggs in vast quantities, and while this is happening the 

 eggs are fertilized (outside the female's body) by the milt 



36 



