A STUDY OF COLOR VISION IN THE RING-DOVE 39 



tively to the lighter of the two, the spectral red and green stimuli 

 appeared of about the same intensity to the female dove, whereas 

 to the male, the red appeared the more intense. One naturally 

 infers that both birds, as a result of their previous training, 

 would go to the stimulus patch which appeared the lighter of 

 the two, supposing that an appreciable difference existed. The 

 series of observations on April 22nd and 28th with darkness 

 adaptation indicate that green appeared considerably lighter for 

 both birds than without adaptation. Green was chosen more 

 frequently by number 3 than by number 4, apparently because 

 the two stimuli were of more nearly the same value in general 

 illumination for this bird than for the male. 



From these few observations, and naturally only a few obser- 

 vations could be made of preference, we may conclude that 

 spectral red and green stimuli of approximately the same energy 

 values did not appear markedly different to the female dove 

 in general illumination, whereas without general illumination the 

 green seemed the more intense. For the male, on the contrary, 

 the red seemed somewhat more intense than the green, and 

 darkness adaptation rendered the two of practically the same 

 intensity. 



Hess 4 has already demonstrated the Purkinje phenomenon in 

 chickens and doves, by a method radically different from that 

 of the writer, while Lashley 5 has more recently demonstrated 

 it in the game bantam by the method of this investigation. 

 There seems to be no reason for doubting that the observations 

 described above also constitute a satisfactory demonstration of 

 the modification of stimulating value by adaptation. 



A series of observations was now instituted, beginning on 

 April 29th, on the development of the ability to distinguish 

 red from black and of the habit of reacting positively to red and 

 negatively to black. Supposing that red appeared light and 

 black dark, it would seem that both doves, merely as the result 

 of their light-dark training with colorless stimuli, should select 

 red uniformly and avoid the black. The results, however, as 

 they appear in table 5, do not wholly justify this expectation. 



4 Hess, C. Untersuchungen iiber das Sehen und uber die Pupillenreaction von 

 Tag- und Nachtvogeln. Archiv. fur Augenheilkunde, 1908, Bd. 59, S. 143. 



. Vergleichende Physiologie des Gesichtssinnes. Jena, 1912, 



Bd. 4, S. 9. 



5 Watson, J. B. Behavior. New York, 1914, p. 350. 



