Role of Sight in Daily Life of Dancer 179 



of it has already appeared in earlier chapters. That from 

 the fourth source will constitute the bulk of the material of 

 this chapter. 



My observation of the behavior of the mice has furnished 

 conclusive evidence of their ability to see moving objects. 

 But that they do not see very distinctly, and that they do 

 not have accurate perception of the form of objects, are 

 conclusions which are supported by observations that I have 

 made under both natural and experimental conditions. In 

 Chapters VII, VIII, IX, and X, I have presented n abun- 

 dance of evidence of brightness vision and, in addition, indica- 

 tions of a specific sensitiveness to -wave length which may be 

 said to correspond to our color vision. It is noteworthy, 

 however, that all of the experimental proofs of visual ability 

 were obtained as the result of long periods of training. Sel- 

 dom, indeed, in my experience with them, have the dancers 

 under natural conditions exhibited forms of activity which 

 were unquestionably guided by vision. 



It is claimed by those who have experimented with blinded 

 dancers that the loss of sight decreases the amount and 

 rapidity of movement, and the ability of the animals to avoid 

 obstacles. 



By means of the discrimination method previously used in 

 the preliminary experiments on color vision, a full descrip- 

 tion of which may be found in Chapter IX, p. 133, the 

 dancers' ability to perceive form was tested. Immediately 

 after the two males A and B had been given the "food-box" 

 tests, whose results appear in Table 15, they were tested in 

 the same apparatus and by the same method for their ability 

 to discriminate a rectangular food-box from a round one. 

 In the case of the color discrimination tests, it will be remem- 

 bered that the circular tin boxes 5 cm. in diameter by 1.5 cm. 

 in depth, one of which was covered with blue paper, the 



