LIGHT OF DIFFERENT WAVE-LENGTHS BY FISH 97 



choices at various red intensities are 

 shown in figure 15, p. 39. The graphs 

 have the same general form as those 

 of the dace so that the statements of 

 sec. 22 apply to them. 



c. Blue-gray 



24. A brief series of trials was made before 

 blue and gray plates of matched 

 brightness for the human eye, with 

 blue as the positive plate, with two 

 horned dace. One went to the gray 

 and blue with about equal frequency: 

 the other chose blue in 13 out of 17 

 trials, (p. 49 and Table II.) 



25. A brief series of trials was made before 

 blue and gray plates of matched bright- 

 ness, with the blue as positive plate, 

 with three sunfish previously trained 

 to go to blue for food. Seventeen out 

 of tw^enty choices were to the blue 

 plate, (p. 49 and Table II.) 



E. Unlearned responses 

 1 Breathing rate 



a. Umbra limi 



26. After stimulation with red light a mud- 

 minnow. Umbra limi, was found pant- 

 ing rapidly. The red was the only 

 unusual factor in the environment, 

 (p. 57.) 



b. Notropis cornutus 



27. The breathing rate of a shiner, Notropis 

 cornutus, increased by one-fourth when 

 the illumination of white light to which 

 it was accustomed was increased by 

 the addition of a carbon lamp. But 

 when this increased illumination was 

 lessened by a red filter the breathing 

 rate more than doubled, (p. 58.) 



