33 



the right and the lower to the left until there was a difference of 

 1 80 degrees in the direction of the trails on the two papers. The 

 ants still followed the trail. I continued turning the papers until 

 both trails again led the same way but exactly opposite to their first 

 direction, with the same result. Then I tried turning the papers 

 through an angle of 90 degrees and even 180 degrees at one turn, 

 but always with the same result. The first ants that reached the 

 l>aper after turning it through so large an angle, were a little con- 

 fused by the slight break in the trail, and sometimes a. few of them 

 would get lost and wander about for a while, until, striking the 

 trail, they would start off in a straight line. 



The above experiment I repeated a great many times and always 

 with the same result ; the ants followed the trail absolutely without 

 regard to change of direction. This shows that, at least after the 

 trail is formed, the ants, if they do possess a sense of direction, are 

 not guided by it in finding their way back to the nest, but slavishly 

 adhere to their trails, although the fact that the trails were formed 

 on the side of the bottle and towards the edges of the paper nearest 

 the nest indicates that in forming their trails a sense of direction 

 may play some part. Later on I repeated the experiment, using cir- 

 cular cardboard disks, 4 inches in diameter, instead of square pieces 

 of paper, and foimd that the trails were formed in the same way, 

 although quite often there was a difference of a few degrees in the 

 direction of the trails on the two disks, and in some places they 

 even extended in opposite directions. Usually, however, tliey ex- 

 tended in nearly the same direction. 



EXPERIMENT NO. 2 



To determine whether the direction from which the light comes 

 influences the ants in finding their way. 



In some of the foregoing tests the apparatus was sitting near a 

 window, so that when the disks were turned through an angle of 

 180 degrees the relation of the light to the trail was exactly reversed. 

 This, however, made absolutely no difference in the behavior of the 

 ants. 



In order to make another test, one evening, at 7 :30, I placed an 

 incandescent light 2 feet from one side of the apparatus. At 8 45 

 p. m. I changed it to about the same distance from the opposite side. 

 So far as I could judge from their behavior, the ants did not even 

 notice the change. I repeated this experiment many times, and al- 

 ways with the same result. 



