LIGHT OF DIFFERENT WAVE-LENGTHS BY FISH 59 



stimulus patches were presented to Large Sunfish there 

 were many records of peculiar behavior. One such record 

 from my notes follows (see fig. 17): 



"As the slide-door went up, the sunfish made straight for the opening, went about 

 one-third the distance to the stimulus patches; halted six seconds (position I), 

 then went up toward the blue (position 2) . Food was released and fell close in front 

 of its mouth. The fish did not snap at it. It was a piece of angle worm and nearly 

 white against the black floor. Then followed a movement of retreat to the further 

 end of the stimulus compartment in front of the door^. The same fish then returned 

 nearly to its former position (2) in front of the blue. I let a piece of worm fall 

 through the water, but it was not touched. The fish circled around to the red side 

 (position 3). There followed a swift dart toward position 4 indicated by the dotted 

 line in figure 17. This was not like the usual slow swimming up toward the stimulus 

 patches, nor like the retreat around the outer edge of the retention compartment 

 which followed it and is indicated in the figure (positions 5, 6, and 7). During all 

 these movements except the swift dart from 3 to 4 and in all positions except 4 the 

 head was toward the red plates." 



Avoiding reactions toward red were observed with all 

 widths of slit, even those so narrow that the light trans- 

 mitted was very weak. They were not so vigorous with 

 weak red light as the reaction just described, but they 

 showed, at least, that intensity was not the only factor 

 in their conditioning. Besides this peculiar response to 

 red there was noted an equally interesting mode of be- 

 havior of the sunfish toward blue. Large Sunfish, even 

 in the same tests in which it was giving this vigorous avoid- 

 ance reaction toward red, repeatedly came close to the 

 margin of the blue patch of light and remained there, some- 

 times with the head just above the margin of the stimulus 

 plate. Often at such times the body of the sunfish was 

 turned slightly on one side so that the sagittal plane formed 

 an angle of about 30° with the vertical. My notes fre- 

 quently record, " Cocked its eye at the blue." This was 

 frequent behavior for the other sunfish also. 



(2) Minnows. — Peculiar behavior toward red was less 

 marked in minnows than in sunfish but was occasionally 

 quite striking. 



Pimephalcs. — Some nearly full-grown minnows which 

 had been one week in a stock aquarium, and were not yet 

 tame, were tested as to first responses toward blue-red 

 and also toward blue-gray patches which were matched 

 in brightness. Seven Pimephales notatus were tested. Each 

 fish was presented with the matched blue-gray patches 



