USELESS HABITS IN TWO BRITISH NEWTS. 



163 



time occupied in traversing the labyrinth at the first trial 

 from ten minutes to one minute twenty seconds in the 30th 

 trial. After this greater irregularity and an increase in time 

 are shown. The table must be supplemented by the following 

 observations : During the first few trials the Newt wandered 

 about the troughs aimlessly, eventually getting out by chance. 

 At the end of the 15th trial the delay at the ends of the troughs 

 where it " nosed" the barrier was less, and it had made a useless 

 habit of wandering up and down a. Having once entered b, 

 however, it walked to the end, and had formed a sure habit of 

 turning left and so back along the side and into c and out at the 

 exit. This behaviour was not owing to the fact that the animal 



Fig. 2. — Diameter = 4 in. ; greatest diameter of hole in each disk = 1 in. 



merely followed the wall of the labyrinth all the way, as it 

 frequently turned from the left to the right corner, and vice versa, 

 at the end of b before finally going back by turning left. At the 

 end of the 31st trial the Newt learnt to turn directly into c 

 without going to the end of b, but it is interesting to observe 

 that the habit grew gradually, by a process of "accretion," as 

 Dr. E. M. Yerkes has called it,* i. e. the distance that it went 

 beyond the opening to c towards the end of b became gradually 

 less and less. This process is shown in Fig. 1 ; the routes 



* Yerkes, R. M. : " Habit Formation in the Tortoise" (' Popular Science 

 Monthly,' vol. lviii. p. 19). 



o2 



