I put some provisions in a shallow box with a glass top and a single hole in one side; I then put some specimens of _Lasius niger_ to the food, and soon a stream of ants was at work busily carrying supplies off to the nest. When they had got to know their way thoroughly, and from thirty to forty were so occupied, I poured some fine mould in front of the hole, so as to cover it to a depth of about 1/2 an inch. I then took out the ants which were actually in the box. As soon as the ants 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, they began digging 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 1/2 to 6 inches, until they had excavated down to the doorway, when they again began carrying off the food as before. This experiment was several times repeated on _L. niger_ and on _L. flavus_, always with the same result. Thus, then, we may conclude that the reasoning power of these ants, although shown by the first experiments to be almost _nil_, is shown by this experiment to be not quite _nil_; for the attempt to meet the exigencies of the case by first going round the box to seek another entrance, before taking the labour to remove the earth from the known entrance, implies a certain rudimentary degree of adaptive capacity which belongs to the category of the rational. Another point of considerable interest, as bearing on the general intelligence of ants, is one that was brought out as the result of a laborious series of hourly observations, extending without intermission from 6.30 A.M. to 10 P.M. for a period of three months. The object of these observations was to ascertain whether the principle of the division of labour is practised by the ants. The result of these observations was to show that during the winter-time, when the ants are not active, certain individuals are told off to forage for supplies, and that when any casualty overtakes these individuals, others are told off to supply their places. Thus, in the words of Sir John Lubbock's analysis of his lengthy tables,--