14 THE WAY OF A TROUT WITH A FLY 



in the sunshine, and varying in colour at every motion as 

 rays of light strike it at different angles ?" 



Now, accepting for the sake of argument this presenta- 

 tion of the action and appearance of the larva as correct, we 

 have to reconcile it with the fact that this shy, keen-sighted 

 fish does not infrequently take the artificial fly of the angler, 

 floating, sunken, or semi-submerged, at times and under 

 conditions which can leave no doubt in any reasonable mind 

 that he takes it for the natural fly which it feebly pretends 

 to represent. What is the inevitable conclusion ? Un- 

 doubtedly that the eyesight of the trout, though perfectly 

 adapted for all his purposes except defence against the wiles 

 of man, is defective in some direction or directions, since 

 it permits him to make such fatal mistakes. But how can 

 we know the nature and extent of these defects in his eye- 

 sight ? There are two ways of getting at it. One is by 

 microscopic examination of the trout's eye by a skilled 

 oculist or optician — a method beyond me; the other is by 

 reasoning from the innumerable data which a prolonged 

 experience of trout-fly fishing gives to every observant 

 angler. 



The first point to which I invite attention is that a trout 

 is a predaceous animal, and his eye may be expected to 

 evince the peculiarities of the eyes of other predaceous 

 animals whose business it is to catch their prey in motion. 

 One naturally turns to the cat for a familiar example. If 

 anyone has watched a cat at play, he may guess to what I 

 am leading up. For a moving object her sight is of amazing 

 quickness, but she is far more stupid than the dog at finding 

 a stationary object, unless guided by the sense of smell. Is 

 this true of the trout ? Let us follow the inquiry further. 

 The cat not only sees things in motion, it sees them 

 moving in the dark. The trout also has a faculty for seeing 

 — at any rate in his own element — in the dark, and even 



