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American Fisheries Society 



lures. How may we test it? A human being may tell 

 us whether two objects of like size and shape, but of 

 different colors look alike to him. If he can learn to tell 

 them apart we know that he is not color-blind. The prob- 

 lem with the fish is then to find some way of making it 

 tell us whether two objects identical except for color, 

 look alike to it. After several years work, Miss Cora 

 D. Reeves (1917), a student in my laboratory has suc- 

 ceeded in doing this. 



Figure 4. Ground plan of aquarium for testing color vision in fish. 



The fish (common sunfish and horned dace) is placed 

 in an aquarium (Fig. 4), divided into two compartments 

 by an opaque partition. The fish is placed in the smaller 

 compartment which communicates with the larger by a 

 door. At the far end of the larger compartment are two 

 plates of opal ground glass illuminated, the one with blue 

 the other with red light. The door is now opened and 

 the fish sees in the larger compartment the blue and red 

 plates. He has previously been trained to come to a blue 

 plate to be fed. If now the fish goes to the blue plate he 



