The memory of places has no part in the finding of the female.  For instance, the day before the cage was installed in a certain room.  The males visited the room and fluttered about the cage for a couple of hours, and some even passed the night there.  On the following day, at sunset, when I moved the cage, all were out of doors.  Although their lives are so ephemeral, the youngest were ready to resume their nocturnal expeditions a second and even a third time.  Where did they first go, these veterans of a day?

They knew precisely where the cage had been the night before.  One would have expected them to return to it, guided by memory; and that not finding it they would go out to continue their search elsewhere.  No; contrary to my expectation, nothing of the kind appeared.  None came to the spot which had been so crowded the night before; none paid even a passing visit.  The room was recognised as an empty room, with no previous examination, such as would apparently be necessary to contradict the memory of the place.  A more positive guide than memory called them elsewhere.

Hitherto the female was always visible, behind the meshes of the wire-gauze cover.  The visitors, seeing plainly in the dark night, must have been able to see her by the vague luminosity of what for us is the dark.  What would happen if I imprisoned her in an opaque receptacle?  Would not such a receptacle arrest or set free the informing effluvia according to its nature?

Practical physics has given us wireless telegraphy by means of the Hertzian vibrations of the ether.  Had the Great Peacock butterfly outstripped and anticipated mankind in this direction?  In order to disturb the whole surrounding neighbourhood, to warn pretenders at a distance of a mile or more, does the newly emerged female make use of electric or magnetic waves, known or unknown, that a screen of one material would arrest while another would allow them to pass?  In a word, does she, after her fashion, employ a system of wireless telegraphy?  I see nothing impossible in this; insects are responsible for many inventions equally marvellous.

Accordingly I lodged the female in boxes of various materials; boxes of tin-plate, wood, and cardboard.  All were hermetically closed, even sealed with a greasy paste.  I also used a glass bell resting upon a base-plate of glass.

Under these conditions not a male arrived; not one, though the warmth and quiet of the evening were propitious.  Whatever its nature, whether of glass, metal, card, or wood, the closed receptacle was evidently an insuperable obstacle to the warning effluvia.

A layer of cotton-wool two fingers in thickness had the same result.  I placed the female in a large glass jar, and laced a piece of thin cotton batting over the mouth for a cover; this again guarded the secret of my laboratory.  Not a male appeared.