12 THE WAY OF A TROUT WITH A FLY 



the case of smaller soft-hackled patterns the case is only a 

 shade less wonderful, and even in the cases where the imita- 

 tion or representation of the natural fly is most lifelike, it 

 cannot be suggested that the likeness is so precise that it 

 could for a moment deceive the eyesight of man. 



In the matter of the trout's colour perception there has 

 been much divergence of opinion among anglers. Some 

 have gone so far as to suggest that the trout is colour-blind. 

 Some say he perceives tone only and not colour. Others 

 would have you believe that he sees colour precisely as does 

 man. I am not of the school which would class the trout 

 as colour-blind. I am assured by a man of science who has 

 studied the subject that in the retina of the trout, the seat 

 of colour vision, no differences in quality from that of man 

 are to be found. The same elements are to be found in 

 human beings and in the trout. These are, of course, 

 structural differences. The medium, water, in which the 

 trout lives renders a spherical lens behind a flat cornea 

 necessary. The method of adjustment of focus differs from 

 that of man, the eye of the fish being accommodated for near 

 vision, and the entire retina of the trout's eye appears to be 

 sensitive, instead of merely one spot. But, allowing for 

 these differences of mechanism, there is no obvious or 

 apparent essential difference. And I am asked to infer from 

 this that trout see colour precisely as do men. It may be 

 so. I do not know. But I would ask whether an examina- 

 tion of the retina of a man who is wholly or partially colour- 

 blind shows any differences from the retina of a man of 

 entirely normal vision. If no differences are shown, why 

 may not the trout, notwithstanding his similar retina, be 

 partially colour-blind without the fact being betrayed by his 

 retina ? The lines of the spectrum are numerous, and I 

 would ask, is it not conceivable that the trout may have a 

 faculty of perceiving some to which man is insensitive and 



