MAZE STUDIES WITH WHITE RAT 283 



elusions can be asserted with confidence. Some interpretations 

 must be regarded as suggestive. 



Vision has a sensitive function. This statement means that 

 the various objective alterations sometimes affected the animal's 

 behavior through the medium of vision; in ordinary language 

 we would say that the changes were perceived through the eye. 

 The sensitivity of the eye is sufficiently proven by the third 

 class of experiments in which the disturbances were limited to 

 those animals with vision. Obviously these alterations were 

 sensed wholly through the eye. 



Most of these alterations may be sensed entirely through 

 some other sense avenue than vision. The novel sensory con- 

 ditions in the hunger experiment were obviously intraorganic 

 in character. Vision can hardly be concerned in a sensitive 

 way. In most of the experiments, the blind animals were 

 affected; these blind animals must have sensed the novel con- 

 ditions by means of other sense avenues than vision. 



The normal animals probably utilized both of the above 

 sensory means in reacting to the novel features in the fourth 

 class of experiments. They possess both sensory capacities. 

 The alteration can be perceived thrbugh this other sense modal- 

 ity since the blinds were affected. The alterations certainly 

 possessed optical features. The differential sensitivity of blind 

 and normal rats indicates that these changes were sensed wholly 

 or in part through vision. The normal rats exhibited the greater 

 degree of susceptibility or sensitivity to the alterations. The 

 percentage of animals affected among the normals was equal to 

 or greater than that for the blind rats with the exception of 

 one experiment, — rotation of the cage. Obviously, this excep- 

 tion can not be explained on the hypothesis that the blind rats 

 possessed modes of sensitivity not belonging to normal animals : 

 it can be explained, however, in terms of principles to be de- 

 veloped later. 



Vision possesses a corrective and adaptive function. The 

 presence of eyes in some way increases the ability of the animal 

 to adapt to these changes. Normal animals resist and over- 

 came the disturbances better than do the blinds. The effect 

 of this function is found in the greater rapidity of adaptation, 

 a smaller error record, and a larger percentage of perfect runs. 

 The best illustration of the operation of this function is found 



