EXPERIMENTS. 261 
soon as she came to the end of the bridge she turned 
round. 
I then modified the arrangement, placing between 
the nest and the food three similar pieces of wood. 
Then when the ant was on the middle piece, I trans- 
posed the other two. To my surprise this did not at 
all disconcert them. 
I then tried the arrangement shown in Fig. 24. 
Fig. 24. 
= 
a 
eO 
a is a paper bridge leading tothe nest; 6 is a board 
about 22 inches long by 13 broad, on which is a disk of 
white paper fastened at the centre by a pin d; ¢ is 
some food. When the ants had come to know their way 
so that they passed straight over the paper disk on their 
way from a toe, I moved the disk round with an ant 
on it, so that f came to g andg tof. As before, the 
ants turned round with the paper. 
As it might be possible that the ants turned 
round on account of the changed relative position 
of external objects, I next substituted a circular 
box 12 inches in diameter, open at the top, and 
