488 GEKTRUDE MAREAN WHITE 



and yellow, the blue component must be assumed to be lacking. 

 These results seem to be explained equally well according to the 

 four-color theory of Hering and the three-color theory of Young- 

 Helmholtz. 



EXPERIMENTS IN THE DISCRIMINATION OF PATTERNS 



Mast ('14) and Sumner ('11) have shown that certain flat fishes 

 adapt the color markings of their skin to the background against 

 which they rest. Such an adaptation would be frequently of 

 protective value. According to Mast, such stimulation is re- 

 ceived through the eye. One naturally inquires whether rec- 

 ognition of differences in the configuration of their environment 

 is of use to fishes in seeking their food. Experiments with a view 

 to ascertaining whether this is the case were carried out on the 

 stickleback and the mudminnow. 



Mudminnows no. 27 and no. 40 which had given positive re- 

 sults in the color experiments were tested in several ways to 

 discover whether they could form associations of food and paper 

 with various patterns. On the center of a round piece of card- 

 board 7 cm. in diameter was pasted a five-pointed star of black 

 paper. A ring of black paper 5.3 cm. in diameter and 1 cm. wide 

 was pasted to a similar white card. When the star was held 

 above the tank containing the fish, forceps containing food were 

 presented, while the circle signified gray paper which matched 

 the food. As in the color tests, the fishes were made to leap out 

 of water to obtain the bait. Mudminnow no. 40 when sub- 

 jected to this test exhibited during twelve days no signs of form- 

 ing an association with the patterns. 



Dots and stripes were the test next applied. Black stripes 

 1 cm. wide were pasted on white cardboard 1 cm. apart. On 

 another white cardboard were pasted black dots 1.8 cm. in di- 

 ameter and the same distance apart. Except for the designs 

 on the cards the test was in all respects similar to the previous 

 one, and the results were similar, for mudminnows no. 27 and 

 no. 40 to which it was applied attempted to take food in the 

 same manner when either card was held above them. 



