36 



about on the lower surface because of their inverted position, and 

 they therefore "smell" their way much more carefully. 



8 :45 A.M. The ants are still wandering about on the upper sur- 

 face of the disk. A number of them cross and recross the trail many 

 times without seeming to notice it. On the lower side they are fol-' 

 lowing the trail closely. 



9 :30 A.M. The ants are not yet following the trail on the upper 

 side. 



io:io A.M. The ants still wandering on the upper side, but oc- 

 casionally one follows the trail. Trail closely followed on the lower 

 side. 



11:05 A.M. More ants are following the trail, but they still 

 wander about considerably on the upper surface. 



11:55 A.M. The ants are now following the trail on both sur- 

 faces. 



February 2. — 4:00 P.M. The last few days I have been using 

 new disks, C and D. I remove the top disk, D, and replace it with 

 a fresh one, E. 



February j. — 8:00 A.M. I remove disk C and replace disk D. 

 D has been removed 16 hours. The ants can still distinguish the trail 

 and some of them follow it, sometimes turning and retracing their 

 steps, sometimes wandering out to the side and then back, a few of 

 them, however, following it with very little or no hesitation. 



9 :30 A.M. The ants are following the trail as though' nothing 

 had happened. 



3 :oo P.M. I remove disk E. 



February _/. — 8 :oo A.M. I replace disk C. It has been removed 

 24 hours. The ants begin to follow the trail with about the same read- 

 iness that they did the one yesterday that w-as removed for 16 hours. 

 There seems to be even less confusion, but this is probably due to 

 the fact that not nearly so many ants are passing this morning. 



2 :30 P.M. I remove disk D. 



5 :30 P.M. I replace disk E. It has been removed 26^ hours. I 

 can not make out positively whether any of the ants recognize the 

 trail or not. I had placed a piece of fresh meat on the bottle in the 

 afternoon, and a much larger number of ants are passing than usual. 

 A great many ants are scattered over the surface of the disk. Some 

 of them seem to follow the trail for a little way and then lose it, but 

 I can not be sure that they do not just happen to follow the trail 

 for a short distance. More of the ants pass from one surface of the 

 disk to the other at or very near where the trail goes over the edge 

 than at any other place. I watch them until 6 :oo p. m. but can not 

 tell whether they are going to follow the trail or not. 



