449 



8 :oo P.M. The ants are not using the old trail. They are still 

 wandering a great deal, but seem to be following a trail at an angle 

 of about 15 degrees to the right of the old one and 75 degrees to the 

 left of the trail on the lower disk. 



8:45 P.M. The new trail is now fairly definite. 



February p. — 2 :oo P.M. I remove disk E. 



February 10. — 3:15 P.M. I remove disk C and replace disk E. 

 Disk E has been removed 25 hours and 15 minutes. Most of the ants 

 do not recognize the trail, but a few of them seem to do so. 



3 130 P.M. A great many ants are scattered over the disk. Now 

 and then an ant seems to recognize the trail and follows it for a short 

 distance, five or six of them following it over both surfaces. 



4:00 P.M. Ants still wandering about on the disk, but occasionally 

 one seems to follow the trail. 



4 40 P.M. The ants are now following the trail with very little 

 wandering. 



February 11. — 5 130 P.M. I replace disk C. It has been removed 

 26 hours and 15 minutes. I can not see that the first ants that reach 

 the disk recognize the trail. I watch them for 10 minutes; most of 

 them do not follow the trail but wander about on both surfaces. A 

 few of them, on the lower surface, seem to recognize the trail and 

 several pass over the edge at or near the place where the trail passes 

 over. 



February 12. — 10:00 A.M. The ants are following the old trail. 



February 16. — i 145 P.M. I remove disk C. 



February ly. — 5 :oo P.M. I replace disk C. It has been re- 

 moved 27 hours and 1 5 minutes. The first ants that reach the disk do 

 not seem to recognize any trail. Some start back to the nest or the 

 food, and some wander about on the disk. 



5:10 P.M. I notice two ants follow the trail on the lower sur- 

 face, go over the edge, and then wander about on the upper surface. 

 A great many ants are wandering about on the upper surface of each 

 disk. 



5 :20 P.M. Now and then an ant follows the trail on the lower 

 surface and loses it on the upper surface. 



February 18. — 8:00 A.M. The ants have formed a new trail, 

 about 65 degrees to the left of the old one and about 15 degrees to 

 the right of the one on the lower disk. 



The above experiments show that a trail formed over cardboard 

 by M. pharaonis may be recognized after it has ceased to be used for 

 26 hours and 15 minutes. No doubt factors such as the material over 



