26o The Life Story of the Fish 



change, bass, pickerel, and even trout, make many a meal 

 off young eels. 



On the other side of the Atlantic the same animal exists — 

 although set off in a different species because it has an average 

 of 1 14 vertebrae in its backbone to only 107 for the American 

 — but the situation is different. The European has always 

 looked upon the eel as a highly desirable food. For centuries 

 he has been intent upon its capture and has, therefore, been 

 interested in its mode of life. And for centuries its method of 

 propagation baffled him, for it disappeared from his rivers in 

 the adult stage, and reappeared in the young stage, but no 

 ripe eels and no eggs were ever seen. Folklore provided the- 

 ories ranging all the way from spontaneous generation to 

 the transformation of horsehairs into little eels. The actual 

 solution of the problem is an illustration of how halting the 

 steps of progress sometimes are, and of the way in which 

 different men in different lands at different times can un- 

 knowingly work together to write a complete scientific 

 detective story. 



The first step was taken by a German named Kauf in 

 1846. He discovered in the sea a little ribbon-like fish with 

 a tiny head which he labeled Leftocefhalus brevirostris. 

 Science looked at this small animal without undue excite- 

 ment, put it away in a bottle of alcohol, and forgot about it. 



Fifty years elapsed before the next chapter was written. 

 This time the collaborator was an Italian named Grassi, 

 and the scene was the Mediterranean. Here Grassi found, 

 in 1896, specimens of KauPs little fish which were busily 

 engaged in ceasing to be Leftocefhali. They were in transi- 

 tion stages, and he succeeded in proving to his own aston- 

 ished eyes, and to those of other scientists as well, that what 

 they were doing was turning themselves into little eels. 

 Kauf's Leftocefhdus was the larva of the eel, almost as 



