210 0 1 2 0 212 2 2 0 0 214 0 1 -- 0 220 2 4 2 0 410 1 3 2 1 420 2 4 1 4 Averages 1.2 2.5 1.2 0.8 FEMALES 211 2 2 0 0 213 2 2 -- 3 215 0 1 2 2 225 3 2 0 0 415 1 3 2 1 425 1 7 0 0 Averages 1.5 2.8 0.7 1.0 That covering the floor with smoked paper forced the mice to relearn the path, in large measure, is evident from the results of Column IV. An average of ten tests was necessary to enable the mice to follow the path correctly. It is almost certain, however, that the interference with the perfectly formed labyrinth habit which this change in the condition of the floor caused was not due to the removal of important tactual sense data. As Column V shows, the number of errors in total darkness is very small. Some individuals gave no sign of being disturbed by the absence of visual guidance, others at first seemed confused. I have given in the table the number of 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 labyrinth B makes perfectly evident three important facts, (1) 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 darkening 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.