LIGHT OF DIFFERENT WAVE-LENGTHS BY FISH 



29 



During the following weeks a separate series ot tests 

 with the red at maximum value was made for each fish. 

 The percentages of blue choices for each ten trials were: 



For H: 80, 90, 80, 60, 40, 90, 70, 30, 60, 70 per cent. 



For Md: 85, 50, 70, 70, 70, 80, 50, 80, 70, 90, 100 per cent. 



The variations in the records from day to day, as shown 

 in the above percentages and in the graphs, indicate that 



Fig. 12 

 Path of Md going from the discrimination tank to the blue illuminated area, p. 28 



uncontrolled factors modified behavior. In figure 13, at. 

 the left over the heading " Red Maximum " the records 

 of these fish are shown in graphs plotted from the average 

 percentages of correct choices in each twenty successive 

 trials. In the graphs of Md and H the first 20 preliminary 

 trials are also included. During the period covered by 

 this series there were variations in the quality of the water 

 supplied to the aquarium, due to changes in the filter 

 cores, which become porous, and variations in the light 

 due to changes in the electric current, which affected the 

 intensity of the ceiling light. Besides these external vari- 

 ables some manifestations of breeding behavior indicated 



