After this set-back, so obvious in its consequences, which only repeated the lesson of the experiments made with naphthaline when my subject was the Great Peacock, I ought logically to have abandoned the theory that the moths are guided to their wedding festivities by means of strongly scented effluvia.  That I did not do so was due to a fortuitous observation.  Chance often has a surprise in store which sets us on the right road when we have been seeking it in vain.

One afternoon, while trying to determine whether sight plays any part in the search for the female once the males had entered the room, I placed the female in a bell-glass and gave her a slender twig of oak with withered leaves as a support.  The glass was set upon a table facing the open window.  Upon entering the room the moths could not fail to see the prisoner, as she stood directly in the way.  The tray, containing a layer of sand, on which the female had passed the preceding day and night, covered with a wire-gauze dish-cover, was in my way.  Without premeditation I placed it at the other end of the room on the floor, in a corner where there was but little light.  It was a dozen yards away from the window.

The result of these preparations entirely upset my preconceived ideas.  None of the arrivals stopped at the bell-glass, where the female was plainly to be seen, the light falling full upon her prison.  Not a glance, not an inquiry.  They all flew to the further end of the room, into the dark corner where I had placed the tray and the empty dish-cover.

They alighted on the wire dome, explored it persistently, beating their wings and jostling one another.  All the afternoon, until sunset, the moths danced about the empty cage the same saraband that the actual presence of the female had previously evoked.  Finally they departed:  not all, for there were some that would not go, held by some magical attractive force.

Truly a strange result!  The moths collected where there was apparently nothing to attract them, and remained there, unpersuaded by the sense of sight; they passed the bell-glass actually containing the female without halting for a moment, although she must have been seen by many of the moths both going and coming.  Maddened by a lure, they paid no attention to the reality.

What was the lure that so deceived them?  All the preceding night and all the morning the female had remained under the wire-gauze cover; sometimes clinging to the wire-work, sometimes resting on the sand in the tray.  Whatever she touched—­above all, apparently, with her distended abdomen—­was impregnated, as a result of long contact, with a certain emanation.  This was her lure, her love-philtre; this it was that revolutionised the Oak Eggar world.  The sand retained it for some time and diffused the effluvium in turn.

They passed by the glass prison in which the female was then confined and hastened to the meshes of wire and the sand on which the magic philtre had been poured; they crowded round the deserted chamber where nothing of the magician remained but the odorous testimony of her sojourn.