It gives us at least an insight into the brain-life of these animals. Better than any generalisations, a good example will show what I mean. Plateau had maintained that when Dahlia blossoms are covered with green leaves, bees nevertheless return to them at once. At first he concealed his Dahlias incompletely (i. e., only their ray-florets), afterwards completely, but still in an unsatisfactory manner, and inferred from the results that bees are attracted by odor and not by sight. _a._ In a Dahlia bed visited by many bees and comprising about forty-three floral heads of different colors, I covered first seventeen and then eight at 2.15 P. M., September 10th, with grape-leaves bent around them and fastened with pins. _b._ Of four I covered only the yellow disc; _c._ Of one, on the other hand, I covered only the outer ray-florets, leaving the disc visible. So many bees were visiting the Dahlias that at times there were two or three to a flower. Result: Immediately all the completely covered flowers ceased to be visited by the bees. Dahlia (_c_) continued to be visited like those completely visible. The bees often flew to Dahlias (_b_) but at once abandoned them; a few, however, succeeded in finding the disc beneath the leaves. Then as soon as I removed the covering from a red Dahlia the bees at once flew to it; and soon a poorly concealed specimen was detected and visited. Later an inquisitive bee discovered the entrance to a covered Dahlia from the side or from below. Thenceforth this bee, but only this one, returned to this same covered flower. Nevertheless several bees seemed to be seeking the Dahlias which had so suddenly disappeared. Towards 5.30 o’clock some of them had detected the covered flowers. Thenceforth these insects were rapidly imitated by the other bees, and in a short time the hidden flowers were again being visited. As soon as a bee had discovered my imposition and found the entrance to a hidden flower, she flew in her subsequent journeys, without hesitation to the concealed opening of the grape-leaf. As long as a bee had merely made the discovery by herself, she remained unnoticed by the others. When this was accomplished by several, however, (usually by four or five,) the others followed their example. Plateau, therefore, conducted his experiments in a faulty manner and obtained erroneous results. The bees still saw the Dahlias which he at first incompletely concealed. Then, by the time he had covered them up completely, but only from above, they had already detected the fraud and saw the Dahlias also from the side. Plateau had failed to take into consideration the bee’s memory and attention.