22 THE WAY OF A TROUT WITH A FLY 



that, with their eyes concentrated on the nymphs and 

 duns coming down to them, they could not see me without 

 a special effort, or without some special cause attracting 

 attention ? If one supposed that for reasons of self- 

 protection, or for some other sound natural cause, the eye 

 of the trout had a wide range of focus, so that he could see — 

 even behind him — to quite a distance out of water when 

 not intent on his food, and that when food was toward 

 that focus shortened to a few — perhaps a very few — inches 

 to deal with the business in hand, would not that explain 

 his comparative unconsciousness of the angler's presence 

 far better than the supposition that appetite was so strong 

 upon him as, without diminishing the acuteness of his 

 vision, to cast out fear ? It is worth thinking about. 



The human eye focuses itself upon an object, and it sees 

 that object clearly — its immediate surroundings clearly 

 enough; but those which are not the object of attention are 

 often blurred and impressionist in outline and effect. If 

 the object of attention be near, the effect of distant objects 

 is blurred and lost. Imagine a like result in the eye of a 

 trout, and allow for a denser medium than air. While the 

 attention is focused on the food, feet or inches off, it may 

 well be that the mechanical effect on the lens of the eye is 

 to blur or even to shut out altogether comparatively long- 

 range objects, such as an angler in the rear extending forty 

 feet or forty-five feet of line in his direction. It might 

 even be that, with the focus of his eye shortened, a trout 

 becomes incapable of seeing through water on one side 

 when the light is in a particular direction, while remaining 

 quite capable of seeing distinctly what is behind him on 

 the other side. In earlier pages I have endeavoured to 

 show that the vision of the trout is defective, at any rate 

 as regards the form of the fly, while attentive to colour and 

 size. The mouth of the trout is large, and when he takes 



