The Senses and the 'Nervous System 95 



telling one from another, but also extremely good judgment 

 of distance. To be sure, we have all seen a trout miss a fly 

 that it rose for, but it must be remembered that the fish is 

 moving, the water is moving, and the fly is sometimes mov- 

 ing also. The preponderant number of times that the trout 

 does take the fly seems to me proof of its ability to judge 

 distance. Its eye may have technical faults, but it does the 

 work. 



To sum up, we find that the testimony of these three spe- 

 cies refutes the charges against the fish. The acuteness of its 

 vision is considerable, at least at close range, and it seems 

 probable that distinctness of vision at long range is not im- 

 portant, for even in the clearest water light travels but a 

 comparatively short way, and far objects are hidden from 

 sight. Of what use is the ability to distinguish things a quar- 

 ter of a mile away if there is such a haze that they become 

 invisible at a distance of one hundred feet? It may well be 

 that the fish cannot focus properly for long range, and that 

 distant objects are blurs which become evident to it only 

 by their movement. Certainly movement plays a very im- 

 portant part in attracting its attention — as is true of all ani- 

 mals, including ourselves. In any case, once it has become 

 aware of a distant object, it approaches it; and once it has 

 come close to it, it is able to see it very distinctly. For ex- 

 tremely close work its vision is apparently better than ours, 

 for it seems to see clearly an object within an inch of its nose, 

 which we do not. And this is important to it, for it must 

 bring its eyes very close to whatever it eats. 



As to judgment of distance the testimony is not so clear, 

 but it is still favorable. And, after all, consider a bird like 

 the phoebe. The location of its eyes and their connections 

 with the brain are very much the same as the fish's, and yet 

 no one doubts its distance judgment because its eyes are not 

 arranged the way ours are. Birds are easier to observe than 



