38 



ROBERT M. YERKES 



date. On April 28th, by the elimination of general illumination, 

 darkness adaptation was effected, and the results again, as on 

 April 22nd, favored the green. 



TABLE 5 

 Results of Experiments with Chromatic Stimuli 

 Dove Number 3, 9 Dove Number 4, tf 



From these four series of ten reactions with doves numbers 

 3 and 4, it may be inferred that under the condition of general 

 illumination in which these doves had been trained to distin- 

 guish the light stimulus patch from the dark and to react posi- 



