250 INGENUITY IN BUILDING NESTS. 



me as very ingenious. The same expedient was, more- 

 over, repeated under similar circumstances by the 

 slaves belonging to my nest of Polyergus. 



The facility or difficulty with which ants find their 

 way, while it partly falls within the section of the 

 subject dealing with their organs of sense, is also 

 closely connected with the question of their general 

 intelligence. 



Partly, then, in order to test how far they are 

 guided by sight, partly to test their intelligence, I 

 made various observations and experiments, the ac- 

 companying woodcuts being reduced copies of tracings 

 of some of the routes followed by the ants during the 

 course of the observations. 



I may here note that the diagrams Figs. 12-17 are 

 careful reductions of large tracings made during the 

 experiments. Though not absolutely correct in every 

 minute detail of contour, they are exact for all practical 

 purposes. As the ants pursued their way, pencil-mark- 

 ings in certain instances, and coloiued lines in others, 

 were made so as to follow consecutively the paths 

 pursued. 



Exper'iment 1. — February. On a table communi- 

 cating with one of my nests (see Fig. 12)1 placed upright 

 a common cylindrical lead pencil ^ inch in diameter 

 and 7 inches long, fastened with sealing-wax to a 

 penny piece. Close to the base of the pencil (a) I 

 brought the end of a paper bridge (b) leading to the 

 nest, and then placed a shallow glass with larvae at c, 



