In the afternoon, the study has become an odious laboratory in which the penetrating aroma of lavender-oil and the foul stench of sulphuretted hydrogen predominate. Remember that I smoke in this room and plentifully at that. Will the concentrated odours of a gas-works, a smoker’s divan, a scent-shop, an oil-well and a chemical factory succeed in putting off the Monk? Not at all. A little before three, the Moths arrive, as numerous as ever. They go to the cage, which I have taken pains to cover with a thick kitchen-cloth, so as to increase the difficulty. Though they see nothing after they have entered, though they are steeped in a foreign atmosphere in which any subtle fragrance should have been annihilated, they fly towards the prisoner and try to get at her by slipping under the folds of the cloth. My artifices are fruitless. After this reverse, so definite in its results, which repeats what my naphthaline experiment with the Great Peacock taught me, I ought, logically speaking, to give up the theory that odorous effluvia serve as a guide to the Moths invited to the nuptial feast. That I did not do so was due to a casual observation. The unexpected, the fortuitous, often provides us with one of those surprises which show us the road to the truth, hitherto sought in vain. One afternoon, trying to discover whether sight plays any part in the search, once that the Moths have entered the room, I place the female in a glass bell-jar and give her a little oak-branch, with withered leaves, as a perch. The apparatus is put on a table, opposite the open window. On entering, the Moths cannot fail to see the prisoner, standing as she does where they are bound to pass. The pan with its layer of sand, in which the female spent the previous night and the morning under a wire-gauze cover, is in my way. I put it, without premeditation, on the floor at the other end of the room, in a corner which is only dimly lighted. It is seven yards from the window. The result of these preparations upsets all my ideas. Of the Moths arriving, none stops at the glass bell, where the female is plainly visible, in the full light. They pass by with utter indifference. Not a glance in her direction, not an enquiry. They all fly right to the far end of the room, to the dusky corner where I placed the tray and the cage. They alight on the trellised top and explore it at length, flapping their wings and hustling one another a little. All the afternoon, until sunset, they dance around the deserted dome the same saraband to which the actual presence of the female would give rise. At last they fly away, but not all of them. There are persistent ones who refuse to go, rooted to the spot by some magic attraction.