VI INSTANCES OF INTELLIGENCE IN ANTS 287 



he was carried down by the current, and therefore could not 

 reach a particular place on the opposite bank which was 

 suitable for landing. He therefore used to go along the 

 shore some distance up the river before he jumped into the 

 water, and so swimming straight forwards, and being carried 

 down by the stream at the same time, he crossed in a slant- 

 ing direction to the landing-place. This was intelligent 

 reflection, not instinct. 



Professor Leuckart observed a highly remarkable example 

 of intelligence in ants. The insects were crawling up the 

 trunk of a tree in order to reach some aphides. Leuckart 

 painted a ring of tar half-way up the trunk to see what the 

 insects would do. They could not go either up or down 

 across the sticky obstacle. For a time they ran up and 

 down restlessly, but at last those who were below the ring 

 descended to the ground. After a time they came back 

 each with a grain of earth between her jaws; one after the 

 other placed her morsel of earth on the tar, so that gradually 

 a bridge was formed across it, over which the insects passed 

 in safety. That they should have recourse to an expedient 

 so remarkable was not instinct but intelligence ; but if they 

 intended to rescue the ants on the upper side of the ring, then 

 they acted by reason. However, it is known that ants in 

 such cases know how to help themselves by dropping from 

 the branches to the ground. 



Father Gredler of Bozen records the following observation, 

 made in his monastery : ^ " One of my colleagues had for some 

 months placed food on his window-sill for the benefit of a com- 

 munity of ants (Formica aliena, Foerst.), which held regular 

 processions from the garden to the window of his room. When 

 I described to him the experiments made long ago by Gleditsch, 

 and recently by more modern students of ants, the amusing 

 idea occurred to him to fasten an empty ink-bottle by a thread 



•'■ Zoologischer Garten, vol. xv. p. 434, 



