298 WALTER S. HUNTER 



The preceding analysis makes the following answer necessary: 

 Those birds that passed from confusion to lack of confusion, 

 or vice versa, with a change in the degree of rotation of the 

 maze, must in some manner have changed the system of cues 

 upon which they were depending. Pigeon no. 5, e. g., must 

 have been relying upon visual sensations from without the 

 maze at the time when the 90° rotation was made, because 

 only on this basis could the inter-connection of cues have been 

 disturbed by the change. During the tests at the 90° rotation, 

 in place of filling in the gaps (however large or small) in his 

 system of cues with other external visual "landmarks" or with 

 the old ones now reconstructed, pigeon no. 5 did one of two 

 things: He either left the gap unfilled and relied upon the re- 

 maining cues, or else he filled it with visual cues from within the 

 maze. Hence when the 270° rotation was made, his reactions 

 were not confused. 



The case of pigeons nos. i, 2 and 7 is slightly different. What 

 seems the most probable explanation of their behavior is as 

 follows : In the normal position of the maze, these birds relied 

 upon visual cues from within the labyrinth and upon some 

 from without. These latter were of such a nature as not to 

 be noticeably changed by the 90° rotation. (An example of these 

 would be the screen behind which the experimenter sat. An 

 inspection of fig. 4 will aid in understanding the statement that 

 all of labyrinth B was not behind the screen — a part projected 

 to the north, without, however, exposing the experimenter to 

 the bird's view. This being the case, a 90° rotation would not 

 change the relative position of the screen and the maze nearly 

 so much as a 270° rotation.) Hence there was little confusion, 

 if any, at this position. However, at 270° the external visual 

 cues, e. g., the screen, were so changed in relation to the maze 

 as to cause much disturbance in the birds' reactions. Again, 

 two alternatives were open to the birds : they might either re- 

 place the changed "landmarks" with partially or entirely new 

 ones, or they might fall back upon the cues that yet remained. 

 Which was done cannot be stated. 



How, now, are the perfect records for all the birds at the 360° 

 rotation to be explained ? The present experiments unfortu- 

 nately do not provide data for a complete answer to this question. 

 Tw^o explanations seem equally possible to the writer: (i) The 



