PREVIOUS OBSERVERS. 239 
Dr. Biichner records the following instance on the 
authority of a friend (M. Theuerkauf) :— 
‘A maple tree standing on the ground of the 
manufacturer, Vollbaum, of Elbing (now of Dantzic) 
swarmed with aphides and ants. In order to check 
the mischief, the proprietor smeared about a foot width 
of the ground round the tree with tar. The first ants 
who wanted to cross naturally stuck fast. But what 
did the next? They turned back to the tree and 
carried down aphides, which they stuck down on the 
tar one after another until they had made a bridge, over 
which they could cross the tar-ring without danger. 
The above-named merchant, Vollbaum, is the guarantor 
of this story, which I received from his own mouth on 
the very spot whereat it occurred.”! 
In this case I confess I have my doubts as to the 
interpretation of the fact. Is it not possible that as 
the ants descended the tree, carrying the aphides, the 
latter naturally stuck to the tar, and would certainly 
be left there. In the same way I have seen hundreds 
of bits of earth deposited on the honey with which I 
fed my ants. 
On one occasion Belt observed? a community of 
leaf-cutting ants (’codoma), which was in the process 
of moving from one nest to another. ‘ Between the 
old burrows and the new one was a steep slope. In- 
stead of descending this with their burdens, they cast 
1 Mind in Animals, by Prof. Ludwig Biichner, p. 120. 
2 Naturalist in Nicaragua, O. Belt, p. 76. 
