Carr and Watson, Orientation in the White Rat. 33 



eral conditions must be observed in the experiment: (i) The 

 alleys of the maze into which the rats are introduced should be 

 relatively long and should differ markedly in their length. (2) 

 When placed in the maze, the animals naturally tend to spring 

 from the hand on the run, and go for a short distance before 

 attempting to adjust themselves to the situation. This tendency 

 should be minimized as much as possible by holding them in posi- 

 tion for a short time, or by allowing them to nibble a crumb of 

 bread when released. (3) Since, with successive attempts, the 

 rats w^ill gradually learn to make immediate orientation, only a 

 few trials for each position should be given. The series of tests, 

 the results of which are given in the paper previously referred to, 

 are faulty in the first and third respects. We have repeated the 

 experiment in order to eliminate these possible sources of error. 

 In order to meet the conditions required under (i), a new maze 

 was constructed the plan and dimensions of which are represented 

 in the cut. The alleys are six inches wide and six inches deep. 

 Finished lumber was used, the cracks in the floor were filled with 

 putty, and the whole maze w^as given three coats of white paint. 

 The maze was constructed so that it could be sawed across at the 

 dotted lines and divided into three sections for the purpose of the 

 second experiment. The maze was not so divided until the first 

 experiment was completed. The cut represents the maze as 

 used, with the exception that the opening into the cul-de-sac B 

 was closed. The experiment was conducted out of doors in an 

 enclosed yard. The rats were introduced into the maze at the 

 positions .v^, x., and x.,. Two of these alleys are seven and one-half 

 feet long, while the third is two feet shorter. This allows the 

 animals to run a distance of two and one-half to three and one- 

 half feet in either direction from the starting place before a turn 

 is possible or necessary. The experiment was started with twelve 

 rats, but four became sickly and unreliable in conduct and were 

 discarded. The group consisted of three normal males, two 

 blind males and three normal females. After the rats had been 

 thoroughly trained, the experiment was started each day by giving 

 them a prehminary run through the maze and then introducing 

 each rat separately at x^ with wrong orientation, at x. with 

 correct orientation, and at Xg with wrong orientation. By "wrong" 

 orientation, we mean that the rats were headed back towards the 

 starting box, 0. This procedure was followed the second day 



