300 * HARVEY CARR 



cleansing of the maze, and 14 errors occurred in the first trial. 

 After the regular series of tests were completed, both cage and 

 maze were rotated simultaneously in the hope of inducing more 

 serious effects; error scores of 40, 5, and 1 were secured in three 

 of the 10 trials. Rotation of cage and cleansing the maze were 

 the only tests which induced disturbances, and it is possible 

 that these results may have been due to chance irregularities. 

 Granted the validity of the results, the question arises as to the 

 sense avenue through which the changes were instituted. The 

 changes resulting from cleansing the ma' e may well have been 

 perceived through the sense of contact, for undoubtedly the 

 contact values of the bottom of the runways were altered. 

 Rotation of the cage may have affected the animal by means of 

 its sensitivity to heat as the cage was located in the proximity 

 of a steam radiator. 



The practical insensitivity of the blind and anosmic animal 

 considered in conjunction with the sensitivity of all other groups 

 including those animals which were blind and partially anosmic 

 indicates that all of these alterations are sensed almost wholly 

 through smell and vision. This conclusion does not warrant 

 the assumption that the rat does not possess any other efficient 

 avenues of sensitivity. The statement merely means that smell 

 and vision are the only senses adapted to the detection of these 

 particular alterations of the environment. 



Since vision and smell are the only effective senses in our 

 conditions, it follows that all disturbances manifested b}^ the 

 anosmic group must have been instituted by means of vision, 

 and that we can utilize the data of this group in determining 

 the function of vision. This hypothesis is supported by the 

 facts, for the results are in harmony with the conclusions as to 

 the function of vision previously derived from the differential 

 records of the blind and normal animals. All experiments in- 

 volving an alteration of the optical environment were very effec- 

 tive upon the anosmic animals; this group of tests comprised 

 rotation of environment, rotation of uncovered maze, and a 

 change in the position of the living cage. On the other hand 

 those experiments involving a minimal optical element, such as 

 cleansing the maze and rotation of the covered maze, had little 

 effect upon this group of rats. Moreover, the anosmic group 

 when disturbed exhibited powers of adaptability on a par with 



