Ought I to go or to wait a little while? I took the latter decision. Out of malice, and without any idea of trying a control experiment to the admirable observations which science owes to the naturalist of Sérignan, of whom I was not thinking at all, I cut close to the sand the stalk of the swallow–wort and planted it a little nearer the mill, moving it about two feet, and being careful to put in place of the plant a little fragment of a bottle which I found in the mill. I seated myself in the shade and waited. Twenty minutes later the wasp dropped straight on to the place where I had cut the plant, that is to say, it deviated from its nest by a distance about equal to the displacement to which I had subjected the swallow–wort. It walked right and left, agitating its antennæ, appearing confused as to the locality. I followed these goings and comings for two or three minutes. Several times it flew away and then returned, always searching about. Pitying it and desiring, since I was now relieved of the fatigue which the heat had caused me, to go back to breakfast, I took my net and drawing near, made as if to catch it, swinging the pocket rapidly about. It veered away with a quick jerk of the wings. I then took up the swallow–wort, lifting the fragment which marked its original place, and replanted it in the sand. I again looked at my watch to see whether I could consecrate yet a few more minutes to curiosity without making my kind host, my friend Dr. M^[ce] Rivron, and his wife, who honored me with the charming hospitality of Kursac, wait too long. It was only half past eleven; we usually did not breakfast until about noon; it would take only a quarter of an hour to traverse the distance from the mill of Caudan to the house. I could then, without fear of being chided, dispose of fifteen minutes. This lapse of time would perhaps suffice to show me whether my _bestiole_ would this time find the way to her nest without hesitation. I waited a little; five minutes had not passed when my Bembex, coming like an arrow, alighted on the sand near the plant, still holding the prey which I had noticed when she departed at my chasing her, after her vain attempts to find the entrance to her nest; but this time she did not hunt long. She felt about a little to right and left, but soon turned directly toward the entrance to the tunnel, distant scarcely two inches from the place where she had settled. My Bembex had a memory.