in.] ENGINEERING. 81 



supplies off to the nest, and when they had got to 

 know the way thoroughly, I poured some fine mould in 

 front of the hole, so as to cover it up to a depth of about 

 half an inch. I then took out the ants which were 

 actually in the box. As soon as they had recovered from 

 the shock of this unexpected proceeding on my part, they 

 began to run all round and about the box, looking for 

 some other place of entrance. Finding none, however, 

 after a while they dug down into the earth just over the 

 hole, carrying off the grains of earth one by one, and 

 depositing them, without any order, all round at a 

 distance of from half an inch to six inches, until they 

 had excavated down to the doorway, when they 

 again began carrying off the food as before. This 

 experiment I repeated several times, always with the 

 same result. 



Again, I suspended some honey over a nest of Lasius 

 jlavus, at a height of about half an inch, and accessible 

 only by a paper bridge more than 10 feet long. Under 

 the glass I then placed a small heap of earth. The ants 

 soon swarmed over the earth on to the glass, and began 

 feeding on the honey. I then removed a little of the earth, 

 so that there was an interval of about one-third of an inch 

 between the glass and the earth ; but, though the dis^ 

 tance was so small, the ants would not jump down, but 

 preferred to go round by the long bridge. They tried in 

 vain to stretch up from the earth to the glass, which, 

 however, was just out of their reach, though they could 

 touch it with their antennae ; but it did not occur to 

 them to heap the earth up a little ; though, if they 

 had moved only half a dozen particles, they would 

 have secured for themselves direct access to the food. 



S. E. 



