16 OLD FLIES IN NEW DRESSES 



seen a trout which refused a fairly accurate 

 imitation of the flies which were on the 

 water rise at and take below the surface a 

 swan's feather. There are also many other 

 much more extraordinary but similar cases 

 on record. Thus, the fact that these trout 

 took an abnormally coloured fly is not a 

 conclusive proof that they mistook it for 

 the natural fly, particularly as this experi- 

 ment was made during the May-fly season, 

 when the trout sometimes appear to be 

 quite mad, but are at any rate always 

 much less shy than at any other time of 

 the year. 



The experiment, too, was made upon a 

 private water, and I think that there is 

 great doubt that the same result would 

 have occurred had it been made upon a 

 well-fished water where the trout were 

 more shy and better educated. 



We must then consider whether, in what 

 we know of the natural history of fish, 

 there are any facts which point towards 

 the probability of their being able to dis- 

 criminate between different colours. Here 

 we find that there are cases in which 

 in certain species the males are more 



