Flies and Fly-fishing. 383 



distance of twelve or fifteen inches. It is absolutely cer- 

 tain that had his eyes acted in the normal manner, noth- 

 ing could prevent the formation of a perceptible image, 

 except the absorption of the light proceeding from the 

 object by the water. As the water was clear, it is obvi- 

 ous that a stratum of twelve or fifteen inches was quite 

 inadequate to produce that result, since the bottom can 

 be distinctly seen in only moderately clear water at a 

 much greater depth. 



That the eye of the trout is different from ours is a 

 frequent remark. That it is different in size and differ- 

 ent in color is true ; but that it is different in function, 

 different in its relation to the reflection and refraction 

 of light, is a mere supposition, resting, I believe, as at 

 present advised, upon no foundation whatever. It may 

 be more sensitive to light than ours ; it may render ob- 

 jects visible to them through a stratum of water which 

 would totally obscure them to us. But even this I know 

 no reason to believe, notwithstanding the fact that will 

 here occur to every one of the incessant rise of trout 

 long after the shades of evening have fallen, and after a 

 fly can no longer be distinguished by us upon the water. 

 The difference of background towards which they look 

 sufficiently accounts for this to my mind. 



It may be that some of the rays composing the beam 

 of light which are incompetent to excite vision in us, 

 and of the presence of which we only become aware 

 as they evidence their existence by heat or chemical 

 action, may be visible to them ; but if we are prepared 

 to grant this, and I for one can see no reason so to 

 do, it but prolongs the spectrum in one or both direc- 

 tions. It is too improbable even for mere surmise, in 

 absence of direct proof, that they can see both ends of 



