Before considering the inferences to be drawn from this odd behaviour, we will record an even more striking experiment, also made at the Pelopæus’ expense. I have described how, when the group of cells is completed, the insect plasters its nest, covering it with a thick rind of mud under which all the elegance of the pottery disappears. I surprise a Pelopæus at the moment when she is spreading her first pellets to form an outer casing. The nest is fastened to a wall coated with mortar. The idea occurs to me to take it away, in the vague hope of beholding something new. And something new there is, nay more, something so absurd that one would never have dared to foresee it. Let me begin by explaining that naught remains of the nest, when I have removed it and put it in my pocket, except a thin, broken line, marking the circumference of the clod of mud. Within this ring, save for a few fragments of mud, the wall has resumed the whiteness of its coat of mortar, a very different colour from that of the nest, which is an ashen grey. The Pelopæus arrives with her load of clay. Without any hesitation that I can perceive, she alights on the deserted spot and deposits her pellet there, spreading it slightly. The operation would have been conducted no differently on the nest itself. Judging by the quiet and zealous way in which the Wasp is working, there is no doubt but that she really believes herself to be plastering her house, whereas she is merely plastering its uncovered support. The new colour of the site and its flat surface, replacing the prominence of the vanished clod, fail to apprise her that the nest is gone. Can this be a temporary distraction, a blunder due to the Wasp’s excessive eagerness for work? She will change her mind, no doubt, perceive her mistake and discontinue her futile labours. But no: I see her coming back thirty times in succession. At each trip she brings a globule of mud, which she applies, without making a single error, inside the circumference formed by the line of clay which the base of the nest has left on the wall. Her memory, which tells her nothing of the colour, shape or prominence of the nest, is surprisingly faithful in matters of topographical detail: it knows nothing of essentials but is thoroughly acquainted with accessories; topographically speaking, the nest is there; the structure, it is true, is missing, but there is the supporting base; and that, it appears, is enough; at any rate, the Pelopæus is lavish of her exertions in bringing mud to plaster the surface on which the structure no longer stands.