268 EFFECT OF LIGHT. 



little surprised ; but after walking once round the cup, 

 started off along the paper bridge straight home. 

 When she returned to the cup I again half rotated the 

 table. This time she went back quite straight. When 

 she had come again, I once more half rotated the table ; 

 she returned quite straight. Again the same happened. 

 A second ant then came : I half rotated the table as 

 before. She went wrong for about an inch and a half, 

 but then turned round and went straight home. 



I was working by the light of two candles which were 

 on the side of the table towards the nest. The next time 

 the two ants came I half rotated the table as before, and 

 moved the candles to the far side. This time the ants 

 were deceived, and followed the paper bridge to the end 

 of the table furthest from the nest. This I repeated a 

 second time, with the same result. I then turned the 

 table as before without altering the lights, and the 

 ants (four of them) went back all right. I then again 

 turned the table, altering the lights, and the ant went 

 wrong. 



I then altered the lights without rotating the table : 

 the first ant went wrong ; the second right ; the third 

 wrong ; the fourth wrong ; the fifth hesitated some 

 seconds, and then went wrong ; the sixth right ; the 

 seventh went all but to the edge the wrong way, but, 

 after various wanderings, at last went right. When, 

 therefore, the direction of the light was changed, but 

 everything else left as before, out of seven ants, five 

 were deceived and went in the wrong direction. 



After an interval of a week, on March 25, I arranged 



