92 The American Salmon-fisherman. 



of throwing some light on the question. They are not 

 the best nor the most conclusive methods I could devise, 

 though they are the best and most conclusive methods my 

 limited time and facilities permitted. Of these experi- 

 ments I propose to give some account. Upon the facts 

 the reader may rely. On the value of my deductions 

 from these facts every one can pass for himself. 



How the fly really appears to the salmon seemed to me 

 to lie at the root of the matter, and to ascertain this, if 

 possible, I addressed my attention. 



Though we cannot say with the absolute certainty of 

 mathematical demonstration that a rock or snag in a 

 river-bed appears to a salmon as what we know and de- 

 scribe as a rock or snag, since we cannot change ourselves 

 into that fish; still the probabilities seem to me so over- 

 whelmingly in its favor, that, in the absence of direct 

 and incontrovertible proof to the contrary, I see no other 

 course open to a reasonable man than to conclude that 

 such is the fact. If this is true as to rocks and snags, it 

 must also be true as to flies, since the same principles 

 govern in both cases. 



In my former volume, "Fly-Rods and Fly-Tackle," I 

 gave my reasons for this view at some length, concluding 

 thus : " Light is light, and by its aid all animated beings 

 see, and in its absence all alike are blind. The laws of 

 nature operate equally and invariably both above and 

 below the water ; and until it is demonstrated to be other- 

 wise, I cannot think that trout see in any different man- 

 ner or by any different means than do we. There is 

 probably a difference in degree, but I cannot believe in 

 kind." 



As far as my limited skill as an anatomist enables me 



