Fish-hooks. 41 



From the nature of the case it appears so extremely 

 probable that with all created things which rely upon 

 eyesight to guide their conduct the eye must act in sub- 

 stantially the same way, that it would seem far more 

 rational to accept it as a fact than to question it in the 

 absence of cogent proof to the contrary. 



Few artificial flies even approximately duplicate any 

 living insect. In most of them, when on or in the water 

 and viewed from beneath its surface, the wing, or the 

 hackle, or some other part is more conspicuous than the 

 rest of the fly. The fly enters the range of vision of the 

 fish without previous warning, as a surprise. Time for 

 critical inspection and analysis of detail is not allowed. 

 The more conspicuous portion arrests their attention, 

 the less conspicuous parts are overlooked. They get at 

 first but a general impression, which they confound with 

 the nearest similar familiar impression, and on this they 

 act. The discrepancies, which close approach might 

 make sufficiently obvious, are overlooked in the ardor of 

 pursuit. And so, if the first impression excites the ap- 

 petite, and nothing gives rise to suspicion or alarm, the 

 fly is taken. 



This, it seems to me, or something very like this, must 

 be why it is possible to lure trout with the artificial fly. 

 It may be a mere theory, or call it a mere hypothesis 

 not rising to the dignity of a theory in certitude, still it 

 has this in common with many generally accepted theo- 

 ries, that it is consistent with and explains the observed 

 facts. 



Returning, now, to the Black-Fairy fly. Through 

 three or four feet of ordinary clear water, lighted from 

 above by strong daylight but not direct sunshine, the 

 body, while it could be seen, was very inconspicuous. 



