The Behavior of Xoddy and Sooty Terns. 255 



Third trial: Given this bird on the early morning of the following day. 

 No full errors were made, but the bird showed a clearly marked tendency 

 to turn in the old direction. Time: 0.25 minute. 



NODDY I. 



First trial: Perfect. Time: 0.16 minute. 



Second trial: Is confused and hesitant. Tries at two points to turn in 

 the old direction. Time : 0.43 minute. 



NODDY II. 



First trial: Hesitancies, but no error. Time: 0.41 minute. 

 Second trial: Confusion evident. Tendency to turn in the old direc- 

 tion very marked. Time : 0.56 minute. 



NODDY III. 



First trial: Badly confused at H. Tries in vain at first to find the exit 

 from H. Runs full length of L, then out and up I into F and comes to O 

 by long way. Time: 0.91 minute. 



Second trial: Runs full length of L, starts to run into S, but withdraws 

 head, turns and goes up I, turns into Z and goes full length, comes back 

 down I, runs into R, turns and goes up E on wrong way to O. Time: 

 2.43 minutes. 



From these experiments we are justified, I think, in concluding that there 

 are some data used by these birds in this reaction which are not clarified by 

 applying the term " visual " to them.' Porter's results on the English spar- 

 rows and other birds, obtained by testing trained birds in the reversed maze, 

 are very similar to the ones reported here. My own experiments on normal, 

 blind, and anosmic rats when tested in a similar way gave results which 

 corroborate the above.^ 



An explanation of the disturbances in the reactions of the birds which 

 ensue upon changes in the directions of the alleys of the maze can not be 

 made until a more complete and better controlled method of experimentation 

 is at hand. 



'There are two possible sources of error in this experiment. In the first place, 

 the "environment" was not rotated with the maze; in the second place, the rotating 

 of the maze changes its position with respect to the two sources of light. Owing to 

 the conditions under which I worked. I could not control these defects. Porter in his 

 work on the reversed maze (op. cit., p. 256) makes no mention of either of these two 

 possibilities of error. 



'Op. cit., p. 86. 



