Habits and Adaftatlons 261 



different from the adult as the caterpillar is from the butter- 



The preliminaries were now over, and the stage was set 

 and waiting for the entrance of the master mind. This turned 

 out to be a Dane named Johannes Schmidt. He had two 

 clues to work with: the adult eels left the rivers and went 

 out to sea, and the young larvae came in from the sea. Obvi- 

 ously the eels spawned at sea, but was it in the open ocean, 

 or off some unknown coast or island? Did they go to dif- 

 ferent places, or did they all spawn at the same place? 

 Schmidt burned with a great desire to find out. To follow 

 the adults was impossible j they disappeared into the sea and 

 were never seen again. But the little larval forms could be 

 picked up by towing nets at the surface of the ocean. And 

 the larvae were growing, at the same time that they were 

 moving from their birthplaces toward their future fresh- 

 water homes. Therefore, the smaller the larvae found in any 

 part of the ocean, the nearer that part of the ocean must be 

 to the spawning grounds. Schmidt's reasoning was simple 

 enough in theory, but its practical application was stupendous. 



In 1906 he put to sea, and for fifteen years he towed nets 

 up and down the ocean. From the English Channel to Chesa- 

 peake Bay, from Greenland to Puerto Rico, he collected and 

 surveyed and mapped, and correlated sizes and seasonal 

 numbers. And at last his maps began to make sense. For he 

 found that as he went westward from the European coast 

 the larvae grew progressively smaller, and the same thing 

 happened as he went south and southeast from the Ameri- 

 can coast. And he was finally able to announce with absolute 

 certainty that the spawning grounds of both species are be- 

 tween 20 and 30 degrees north and 50 and 70 degrees west, 

 with the European spawning-beds to the east of the Ameri- 

 can. This area lies northeast of Puerto Rico, southeast of 

 Bermuda. It is for all practical purposes the area of the 



