196 The Dancing Mouse 



errors in the first darkness test and the number of the first 

 test in which no mistakes occurred. 



No more disturbance of the dancer's ability to follow the 

 path which it had learned resulted from washing the labyrinth 

 thoroughly than from darkening the room. Indeed it is clear 

 from Column VI that the path was not followed by the use of 

 smell. However, the test in darkness, after the odor of the 

 box had been removed, proved conclusively that in most 

 cases the mice could follow the path correctly without visual 

 or olfactory guidance. 



The behavior of 18 individuals as it was observed in laby- 

 rinth B makes perfectly evident three important facts, (i) In 

 following the path which it has learned, the dancer in most 

 instances is not guided to any considerable extent by a trail 

 (odor or touch) which has been formed by its previous 

 journeys over the route; (2) sight is quite unnecessary for 

 the easy and perfect execution of the labyrinth habit, for even 

 those individuals which are at first confused by the darken- 

 ing of the experiment room are able after a few tests to follow 

 the path correctly; (3) and, finally, smell, which according to 

 current opinion is the chiefly important sense of mice and rats, 

 is not needful for the performance of this habitual act. 



At this point we may very fittingly ask, what sense data 

 are necessary for the guidance of the series of acts which 

 constitutes the labyrinth habit? I answer, probably none. 

 A habit once formed, the senses have done their part ; hence- 

 forth it is a motor process, whose initiation is conditioned 

 by the activity of a receptive organ (at times a sense receptor), 

 but whose form is not necessarily dependent upon immediate 

 impressions from eye, nose, vibrissae, or even from internal 

 receptors. These are statements of my opinion; whether 

 they express the truth, either wholly or in part, only further 

 experimentation can decide. 



