140 The Dancing Mouse 



Without further mention of the many experiments which 

 were necessary for the perfecting of this method of testing 

 color vision, I may at once present the final results of the tests 

 which were made with reflected light. These tests were 

 made with the discrimination apparatus in essentially the 

 same way as were the brightness discrimination tests of 

 Chapter VII. 



In all of the color experiments, unless otherwise stated, 

 a series of ten tests each day was given, until satisfactory 

 evidence of discrimination or proof of the lack of the ability 

 to discriminate had been obtained. The difficulties of getting 

 conclusive evidence in either direction will be considered in 

 connection with the results themselves. For all of these 

 tests with reflected light the Milton Bradley colored papers 

 were used. These colored papers were pasted on white 

 cardboard carriers. I shall designate, in the Bradley nomen- 

 clature, the papers used in each experiment. 



With colored cardboards inside the electric-boxes as well 

 as at their entrances (see Figure 14 for position of cardboards) 

 blue-orange tests were given to Nos. 2 and 3 until they dis- 

 criminated perfectly. The papers were Bradley's blue tint 

 No. i and orange. Number 2 was perfect in the twelfth 

 series (Table 17), No 3 in the fourteenth and again in the 

 sixteenth. They were then tested with a special brightness 

 check series which was intended by the experimenter to 

 reveal any dependence upon a possible brightness difference 

 rather than upon the color difference of the boxes. 



The nature of this brightness check series, as well as the 

 results which No. 2 gave when tested by it, may be appre- 

 ciated readily by reference to Table 18. Tint No. i of the 

 blue, which is considerably brighter, in my judgment, than 

 the Bradley blue, was replaced at intervals in this series by 

 the latter. For it was thought that in case the mouse were 



