ON THE FOOD OF FISH. 113 



certainly appears possible that the character of the 

 fish may have changed by degrees, through succes- 

 sive generations, and owing to being bred and fed 

 in a different manner from the other fish. I have 

 placed trout from one stream into another, and after 

 years could very easily distinguish them from their 

 compeers of the stream. But it is doubtful if their 

 progeny would show and retain their special charac- 

 teristics, though if they interbreed with the fish 

 of the stream, as they would be pretty sure to, the 

 breed might possibly be improved by the infusion 

 of fresh blood. 



Few experiments of any note have been tried in 

 the feeding of fish, this being as yet almost untrodden 

 ground j but I once heard of an experiment being 

 tried in the following manner: — Equal numbers of 

 trout were confined for a certain time by gratings to 

 three several portions of the same stream. The fish 

 in one of the divisions were fed entirely upon flies ; 

 in another, upon minnows; and in the third, upon 

 worms. At the end of a certain period, those which 

 had been fed on flies were the heaviest and in the 

 best condition; those fed on minnows occupied the 

 second place; while those fed on worms were in 

 much the worst order of the three. The probability 

 is, that had another pen been set off, and the fish 



I 



