447 



direction to that on the lower disk. With ahnost no confusion the 

 ants, both coming and going, led out over the old trail. The disk 

 has been removed i hour and to minutes. 



January 26. — 8:17 A.M. I remove disk B again. 



11:17 A.M. 1 replace disk B so that the direction of the trail 

 extends at an angle of 90 degrees from the one on the lower disk. 

 Without hesitation the ants start out from the stem over the old trail, 

 but the first three from each direction go only two thirds of the 

 way to the circumference and then turn back. The fourth ant from 

 above goes over the edge, hesitating a little, and meets the ant on 

 the under side. After that the ants go on as before. The disk has 

 been removed 3 hours. 



1 1 :20 A.M. I remove the lower disk, A. 



5 130 P.M. I so replace disk A that the trail on it extends in the 

 opposite direction from that on the other disk. The first ants that 

 reach the disk appear lost and wander about, but still seem to recog- 

 nize the trail faintly when they cross it. In about a minute, one ant 

 on the upper side of the disk follows the trail to the edge and goes 

 to the under side, where it follows the trail on to the nest. Not all 

 the ants seem to be able to recognize the trail, and many wander 

 about over both surfaces of the disk, sometimes following it for a 

 short distance and then leaving it. 



5:55 P.M. Eleven ants wandering on the upper surface and nine 

 on the lower surface. Every once in a while an ant goes from one 

 surface to the other on the trail. 



5 158 P.M. Sixteen ants wandering on the upper surface. 



January 2"/. — 8:00 A.M. The trail which the ants are using this 

 morning does not coincide exactly with the old trail. It goes over 

 the edge of the disk at the same point, but at an intermediate point 

 between the circumference and the stem it is about ^ inch to the 

 side of the old trail. The disk has been removed 6 hours and 10 

 minutes. 



January 26. — 6:00 P.M. I remove disk B. 



January 21. — 8:05 A.M. I replace disk B. The ants can still fol- 

 low the trail, but it is evidently very indistinct to them. The first 

 ants from either direction start out over the trail, very slowly how- 

 ever. They move a little way, stop, go on, turn around and go back 

 to the stem and then wander about over the disk, apparently search- 

 ing for a more distinct trail. Nearly all those that go over the edge 

 of the disk, however, do so at the point where the old trail goes over. 

 The ants follow the trail quite closely on the under side, although 

 they move very slowly. I think the ants feel less like wandering 



