PAST AND PRESENT 79 



response. It infers further that they know that 

 winter is coming, an inference equally unwarranted. 

 If they are birds of the year they have never ex- 

 perienced a winter. If they are migratory, their 

 parents, for countless generations before them have 

 left the north before winter has materialised. How 

 can they possibly arrive at the knowledge of the very 

 existence of such a thing as a northern winter? If 

 they do not know that it is coming, they can surely 

 not flee from it. It assumes still further that they 

 can intelligently distinguish north from south. 

 Why should they proceed south! Why not east or 

 west or north again? Whatever the solution, the 

 performance is not peculiar to birds. Sea-lions 

 annually make infallible return to their breeding 

 grounds from mid-ocean without any landmarks 

 to steer by. Like travelling penguins, their eyes 

 are at water level and their field of vision is negligi- 

 ble. Various fish find their way back to the same 

 spawning streams year after year. The European 

 eel, which breeds only once in its life, crosses the 

 vast Atlantic from Europe to the West Indies to 

 spawn there and then die. The larvae, minute 

 elvers, may take three years to make the return pas- 

 sage, but they spend their lives in European inland 

 waters after traversing 3000 miles of ocean that 

 they have never before seen. Their parents are 

 dead. There can be no question of guidance. 



