A STUDY OF COLOR VISION IN THE RING-DOVE 



27 



back to the starting point at A, where is it allowed to feed for 

 a definite interval. In case, however, the subject enters the 

 other compartment, it is not allowed to pass into the alley, 

 but instead, either with or without the use of the electric shock, 

 according to the experimenter's previous decision, it is required 

 to retrace its steps and again attempt to distinguish the stim- 



FlG. 1. Reaction-box for Ring-doves. A, entrance chamber; B, discrimination 

 compartment; D, screen-door; M, sliding partition moving in A and B; E, E, 

 stimulus compartments; P, partition between E and E; F, F, doors between 

 stimulus compartments and alleys G, G,; H, H, slide-doors between G and A; 

 I, I, pulleys for cords attached to F, F; S, S, stimulus apertures. 



ulus which demands positive reaction from that which demands 

 negative reaction. 



In the case of the observations about to be described, achro- 

 matic stimuli were obtained by placing a two candle power 

 carbon incandescent lamp 86 cm. from the stimulus area. Thus, 



