1 68 THE HAUNTS OF LIFE 



like many other animals, probably die after 

 the eggs are safely deposited, for none of 

 them ever reappear at the coasts or in the 

 rivers after spawning. 



There are only a few species of eel which 

 enter fresh water; the great majority of the 

 family spend their whole lives in the sea, 

 many of them in deep water. Moreover, 

 some individuals, even of the common eel, do 

 not enter the rivers, but probably remain 

 about the estuaries till it is time to return to 

 deeper water. 



On the other hand, some yellow eels do not 

 return to the sea. They may have settled 

 down in ponds which they found it easy to 

 reach when they were little elvers, but dif- 

 ficult to escape from later, or they may lack 

 the impulse to migrate. Such eels may live 

 a long time and grow to a great size, but they 

 never produce eggs. 



All these facts justify the conclusion that 

 the common eel is descended from ancestors 

 which were entirely sea-fish, and that it has 

 taken to a fresh-water life. Whether it will 

 go farther in the same direction, we have no 

 means of knowing. 



We have followed this story at some length, 



