90 ON THE HABITS OF ANTS. [LECT. 



to be very good. In order to test how far they are guided 

 by vision, I made the following experiments. I placed 

 a common lead-pencil on a board, fastening it upright, 

 so as to serve as a landmark. At the base I placed 

 a glass containing food, and put a L. niger to the 

 food ; when she knew her way from the glass to the nest 

 and back again perfectly well, she went quite straight 

 backwards and forwards. I then took an opportunity 

 when the ant was on the glass, and moved the glass 

 with the ant on it about three inches. Now, under 

 such circumstances, if she had been much guided by 

 sight, she could not of course have had any difficulty 

 in finding her way to the nest. As a matter of fact, 

 however, she was entirely at sea, and after wandering 

 about for some time, got back to the nest by another 

 and very roundabout route. I then again varied the 

 experiment as follows. I placed the food in a small 

 china cup on the top of the pencil, which thus formed 

 a column seven and a half inches high. When the 

 ant once knew her way, she went very straight to and 

 from the food. I then moved the pencil six inches. This 

 puzzled her very much : she went over and over the 

 spot where the pencil had previously stood, retraced 

 her steps several times almost to the nest, and then 

 returned along the whole line, showing great persever- 

 ance, if not much power of vision. She found it at last, 

 but only after many meanderings. 



I repeated the observation on three other ants with 

 the same result : the second was seven minutes before she 

 found the pencil, and at last seemed to do so accidentally ; 

 the third actually wandered about for no less than half 

 an hour, returning up the paper bridge several times. 



