HABIT FORMATION IN THE FIDDLER CRAB 237 



it did not turn before reaching the end of the alley, it was 

 charged with a closed trial. If it did turn, however, and lib- 

 erated itself from the alley by going to the open corner, the 

 attempt was recorded open. The results are given in the fol- 

 lowing table, 5 : 



TABLE 5 



From the above data it is evident that the animal was guided 

 by its sense of sight in liberating itself from the alley. It should 

 be borne in mind that the fiddler crab is positively thigmo- 

 tactic, and under ordinary circumstances it has a strong tendency 

 to follow the sides of the box. The animals which were subjected 

 to this test had already learned to free themselves from the 

 trap, and therefore knew the direction of escape. They were, 

 therefore, able to avoid the side which led to the blind end of 

 the alley. 



The crabs were given a rest of ten days, at the end of which 

 they were tested for habit retention. Unfortunately, five of 

 the animals died during the interval, and two of the remaining 

 ones were too sluggish to give results. Those which were 

 tested gave the following records, table 6 : 



TABLE 6 



No. Closed Open % Closed % Open 



13 7 30 70 



3 1 9 10 90 



4 2 8 20 80 



These three crabs were now tried for unlearning. The corner 

 which had been closed was opened, and the open one closed. 

 Each animal was tried for five days, being given twenty trials 



