IMPORTANCE OF SCENT. 



25d 



Fig. 19. 



then twisted as shown in Fig. 19. The bricks and tunnel 

 being also rearranged so that they were exactly in the 

 same direction as before, but the board having been moved, 

 the line d e was now outside them. This change, ho wever, 

 did not at all discom- 

 pose the ants ; but 

 instead of going, as 

 before, through the 

 tunnel and between 

 the rows of bricks 

 to a, they walked 

 exactly along the 

 old path to e. 



I then arranged 

 matters as before, 



but without the tunnel and with only three pairs of 

 bricks (Fig. 20). WTien an ant had got quite used to the 

 path d to e, I altered 

 the position of the 

 bricks and food, as 

 shown in Fig, 21, mak- 

 ing a difference of 8 

 inches in the position 

 of the latter. The ant 

 came as before, walked 

 up to the first brick, 

 touched it with her antenna, but then followed her old 

 line to a. »om there she veered towards the food, and 

 very soon found it. When she was gone, I altered it 



(! 2 



