Reighard. — Senses and Learning in Fishes 159 



eye sees clearly the near objects not obscured by the haze 

 in the water. When need comes it adjusts the eye to the 

 more distant and less visible objects, fleeing prey or ap- 

 proaching enemy. It does not need to be always alert 

 to objects at a distance in the water for these move 

 through the dense medium with relative slowness, and 

 they are more or less obscured by the opacity of the water. 

 It is probable that the degree of contraction of the muscle 

 which moves the lens aids the fish to appreciate the dis- 

 tance of objects from it. 



C. Color Vision in Fishes. The experience of 

 anglers with artificial flies indicates strongly that fish 

 discriminate between colors. On the other hand there 

 are scientific investigators who hold that fish do not see 

 colors at all — but are totally color blind (e.g. Hess, 1911) . 



To the totally color-blind person there are no green 

 trees or red flowers. He sees the world in blacks and 

 whites and grays. So we see objects in an uncolored pho- 

 tograph and tell them apart by size and form and by 

 their varying shades of the one color. To the totally 

 color-blind the world appears much as in such a photo- 

 graph. He tells objects apart, not by color, but by form, 

 size or shade. If he is shown little skeins of colored 

 yarn all of the same size and shape and is asked to put 

 together those of the same color, he matches blues and 

 reds and greens. They all look gray to him, and he puts 

 together those skeins that to his eye have the same shade 

 of gray. 



When a fish looks at an artificial fly, he sees, according 

 to one view, no color at all. The fly seems to him to be 

 made up of white, black and grey parts. According to 

 this view he tells the flies apart only by their size and 

 shape and by the size, shape and shade of the different 

 grey, black or white patches that make up their patterns. 

 If this view is correct the gaudy colors of our flies and 

 other lures are useless so far as their effect on fish is 

 concerned. They catch our eyes only. 



Whether this view, that fish are color-blind, is correct 

 is then a matter of some interest to makers and users of 



