194 SALMONIA. 



nicating with the Danube, though some of 

 these lakes and morasses are wonderfully 

 fitted for them, and though they are found 

 abundantly in the same countries, in lakes 

 and rivers connected with the ocean and 

 the Mediterranean. Yet, when brought 

 into confined water in the Danube, they 

 fatten and thrive there. As to the instinct 

 which leads young eels to seek fresh water, 

 it is difficult to reason : probably they pre- 

 fer warmth, and, swimming at the surface 

 in the early summer, find the lighter water 

 warmer, and likewise containing more in- 

 sects, and so pursue the courses of fresh 

 water, as the waters from the land, at this 

 season, become warmer than those from the 

 sea. Mr. J. Couch (Lin. Trans, tit. xiv. 

 p. 70) says the little eels, according to his 

 observation, are produced within reach of 

 the tide, and climb round falls to reach 

 fresh water from the sea. I have sometimes 

 seen them, in spring, swimming in immense 

 shoals in the Atlantic, in Mount Bay, making 

 their way to the mouths of small brooks and 

 rivers. When the cold water from the 



