HABIT FORMATION IN THE FIDDLER CRAB 233 



glass, it began to move to the opposite corner. In the begin- 

 ning the animal would go half way and turn back, trying to 

 climb again. Finally it would venture all the way across, run 

 out through the opening into the adjoining box, and enter one 

 of the burrows. If an individual showed too much stubborness, 

 by remaining at the closed corner even after it had given up 

 its climbing, the experimenter gently drove it in the direction 

 of the open corner. The crab was allowed to remain in this 

 burrow for about a minute, after which it was taken out and 

 again placed in the triangular chamber, the experimenter taking 

 up the same position as before. It usually took the animal 

 about one minute to recover its composure before making a 

 second trial. With successive trials it seemed to learn that 

 there was one corner which afforded an exit, for no sooner than 

 it reached the closed side, it reversed its direction, and liberated 

 itself from the trap. Sometimes a crab would start off in the 

 direction of the closed corner, but before reaching it, would 

 turn and go to the open. Occasionally an animal ran directly 

 to the center and remained there for a few seconds, often running 

 first in one direction and then in another, before making its 

 final choice. Gradually movements to the open corner became 

 more frequent, attaining almost perfection at the end of ten 

 days, with an average of twenty trials per day. 



Following, in table 3, are the records of ten* individuals: 



* Nos 1, 2, 3, 4 and 10 were experimented with at Cold Spring Harbor. The 

 remaining five were tried at Hunter's Island, New York City. 



