They had noticed the paper; that was plain enough, but did they notice the redness? To test this, we left things as they were for two days, and then substituted blue paper for the red. Again the confusion, the swarming of fervent legions, the noisy expostulations, the descent of one after another; but this time they settled down to their ordinary routine in a little more than two hours. On the following day we removed the blue paper, leaving the grass around the nest exposed; and this proved a new source of mystification, but not so serious as the others. At the end of an hour twenty–five or thirty were still buzzing about, needing the guidance of the blue paper to get inside, and entering at once when it was replaced. As we tried new colors from day to day a few of the wasps became entirely reconciled to our interference, and paid no attention to the changes, while the others grew more or less accustomed to the idea of mutability, and were but little disturbed, although they still showed their consciousness of each alteration by making a few circles before going in. We once placed some dark red nasturtiums on light yellow paper near the nest, and found that more than one third of the homecoming wasps flew to them and hovered over them before entering. When light yellow nasturtiums, nearly matching the paper in color, were substituted, only one out of thirty–six noticed them; and as the odor was as strong in one case as the other, it would seem that the color was the attracting force. Our final color experiment was to let the blue paper remain for a day or two, giving time for all the wasps to become familiar with it, and then to leave it on the ground a foot and a half away, while replacing it with yellow. This gave a false nest surrounded by the color that they had been associating with the entrance, and a true nest surrounded by a new color. In the next ten minutes two hundred and seventy wasps came home, and every one of them went to the false nest. Many circled above it, others entered the hole in the paper, and some began to excavate, and made quite a depression in the ground; but gradually they found their way home. Three hours later seventy–six wasps entered the false nest in five minutes, and at evening they were still visiting it in goodly numbers; but on the next day we saw only two that were deceived.