103 



aided by a glass water-tank of large dimensions, specially con- 

 structed to facilitate the investigation ; and having regard to the 

 exhaustive nature of his experiments, so much more complete in 

 every respect than my own, I cannot do better than, with Mr. 

 Wells' permission, give my readers in a condensed form the result 

 of his investigation, leaving them to form their own judg- 

 ment on his results and to test them in practice for themselves if 

 disposed. 



It would .'; seem, then, to result from Mr. Wells' experiments 

 that the question of the color or stain of gut in its relation to light, 

 and to fish-vision may, when rightly apprehended, prove to be 

 both important, and the subject of laws which it would be 

 greatly to the fly-fisher's advantage to study. 



Mr. Wells primarily bases his experiments, and of course the 

 deductions drawn from them, on the probable general similarity 

 between fish vision and human vision. 



" The eye, whether of fish or flesh, is but a lens refracting rays of light, and 

 converging them to form a picture on a screen the retina. In this respect, 

 and as far as the mechanical principles of construction are concerned, it has its 

 exact counterpart in the camera of the photographer." 



" 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 beneath the water ; and until it is demonstrated to be otherwise I 

 cannot think that trout see in any different manner, or by different means than 

 do we. There is probably a difference in degree, but I cannot believe in 

 kind." 



The differences which do exist as in regard to size, colour, 

 sphericalness of form, and absence of the power of contraction 

 and expansion are indicated by Mr. Wells, and it is shown that 

 they would naturally produce, under ordinary conditions, a less 

 perfect vision than our own.* 1 



* The rise of fish at flies after nightfall, and after the flies have long ceased 

 to be visible to us, is explained by the difference of background against which 

 they are looked at. 



