CHAPTER IX 



THE SENSE OF SIGHT: COLOR VISION 



Is the dancing mouse able to discriminate colors as we 

 do? Does it possess anything which may properly be 

 called color vision? If so, what is the nature of its ability 

 in this sense field ? Early in my study of the mice I attempted 

 to answer these and similar questions, for the fact that they 

 are completely deaf during the whole or the greater part of 

 their lives suggested to me the query, are they otherwise 

 defective in sense equipment? In the following account of 

 my study of color vision, I shall describe the evolution of my 

 methods in addition to stating the results which were obtained 

 and the conclusions to which they led me. For in this case 

 the development of a method of research is quite as interest- 

 ing as the facts which the method in its various stages of 

 evolution revealed. 



Observation of the behavior of the dancer under natural 

 conditions caused me to suspect that it is either defective 

 in color vision or possesses a sense which is very different 

 from human vision. I therefore devised the following extremely 

 simple method of testing the animal's ability to distinguish 

 one color from another. In opposite corners of a wooden 

 box 26 cm. long, 23 cm. wide, and u cm. deep, two tin boxes 

 5 cm. in diameter and 1.5 cm. deep were placed, as is shown 

 in part I of Figure 18. One of these boxes was covered on 

 the outside with blue paper (B of Figure 18), and the other 

 with orange l (O of Figure 18). A small quantity of " force' 1 



1 These were the Milton Bradley blue and orange papers. 



