190 The Dancing Mouse 



changing the position of the labyrinth, placing smoked paper 

 on the floor, or by introducing a new odor at some point. 

 The exclusion of the possibility of guidance by smell and 

 touch did not seriously interfere with the animal's ability to 

 follow the path. 



The results which have just been considered seemed to be 

 of sufficient interest and importance to justify the further use 

 of the labyrinth method in the investigation of the role of 

 vision. A series of experiments with labyrinth B was there- 

 fore planned so that the importance of sight, touch, and 

 smell in connection with this form of habit should be more 

 satisfactorily exhibited. Does the dancer follow the path by 

 sight, touch, smell, by all, or by no one of them ? 



This series of tests with labyrinth B, whose several pur- 

 poses may best be explained in connection with the various 

 kinds of tests enumerated below, consisted of: 



I. A preliminary test in which the dancer was permitted 

 to wander about in the labyrinth, without being shocked, 

 until it finally escaped to the nest-box by way of the exit. 

 Thus the animal was given an opportunity to discover that 

 escape from the maze was possible. 



II. This was immediately followed by a series of tests at 

 the rate of about one per minute, with an electric shock as 

 punishment for every mistake. This was continued without 

 interruption until the path had been followed without error 

 five times in succession. 



III. The labyrinth was now moved about 3 cm. to one 

 side so that it covered a new floor area, and a test was given 

 for the purpose of ascertaining whether the mouse had been 

 following a trail on the floor. 



IV. Tests with smoked paper on the floor were now 

 alternated with tests in which the floor was plain. The 

 alternation was rendered necessary by the fact that the paper 



