SECOND DAY.] VARIETIES OF TROUT. 67 



and in the goose and duck, not only is the colour of 

 the feathers changed, but the form of the muscles of 

 the legs and wings, those of the wings, being little 

 employed, become weak and slender, those of the 

 legs, on the contrary, being much used, are strong 

 and fleshy. And it is well to know this, as, in the 

 young birds, the muscles of the legs and thighs are 

 the best parts for the epicure, a large quantity of 

 flesh being developed there, but not yet hardened or 

 rendered tough by exercise. These facts are of the 

 same kind and depend on the same principles, as the 

 peculiarity of the breeds or races in trout s. Fish in 

 a clear cool river, that feed much on larvae, and that 

 swallow their hard cases, become yellower, and the 

 red spots increase so as to outnumber the black ones ; 

 and these qualities become fixed in the young fishes, 

 and establish a particular variety. If trout from a 

 lake, or another river of a different variety, were 

 introduced into this river, they would not at once 

 change their characters ; but the change would take 

 place gradually. Thus I have known trout from a 

 lake in Scotland, remarkable for their deep red flesh, 

 introduced into another lake, where the trout had 

 only white flesh, and they retained the peculiar 

 redness of their flesh for many years. At first they 

 all associated together ' in spawning in the brook 

 which fed the lake, but those newly introduced were 



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