Evolution Going On 109 



The Romance of the Eel 



Early in summer, at dates varying with the distance of the 

 rivers from the open Atlantic, crowds of young eels or elvers 

 come up-stream. Sometimes the procession or eel-fare includes 

 thousands of individuals, each about the length of our first finger, 

 and as thick as a stout knitting needle. They obey an inborn 

 impulse to swim against the stream, seeking automatically to 

 have both sides of their body equally stimulated by the current. 

 So they go straight ahead. The obligation works only during the 

 day, for when the sun goes down behind the hills the elvers 

 snuggle under stones or beneath the bank and rest till dawn. In 

 the course of time they reach the quiet upper reaches of the river 

 or go up rivulets and drainpipes to the isolated ponds. Their 

 impulse to go on must be very imperious, for they may wriggle up 

 the wet moss by the side, of a waterfall or even make a short excur- 

 sion in a damp meadow. 



In the quiet-flowing stretches of the river or in the ponds they 

 feed and grow for years and years. They account for a good 

 many young fishes. Eventually, after five or six years in the case 

 of the males, six to eight years in the case of the females, the well- 

 grown fishes, perhaps a foot and a half to two feet long, are seized 

 by a novel restlessness. They are beginning to be mature. They 

 put on a silvery jacket and become large of eye, and they return 

 to the sea. In getting away from the pond it may be necessary to 

 wriggle through the damp meadow-grass before reaching the 

 river. They travel by night and rather excitedly. The Arctic 

 Ocean is too cold for them and the North Sea too shallow. They 

 must go far out to sea, to where the old margin of the once larger 

 continent of Europe slopes down to the great abysses, from the 

 Hebrides southwards. Eels seem to spawn in the deep dark 

 water; but the just liberated eggs have not yet been found. The 

 young fry rises to near the surface and becomes a knife-blade-like 

 larva, transparent all but its eye. It lives for many months in this 

 state, growing to be about three inches long, rising and sinking 



