op by a closed door.

These data show us that the visitors to the wedding-feast did not go
straight to their goal as they would have done were they attracted by
any kind of luminous radiations, whether known or unknown to our
physical science. Something other than radiant energy warned them at a
distance, led them to the neighbourhood of the precise spot, and left
the final discovery to be made after a vague and hesitating search. The
senses of hearing and smell warn us very much in this way; they are not
precise guides when we try to determine exactly the point of origin of a
sound or smell.

What sense is it that informs this great butterfly of the whereabouts of
his mate, and leads him wandering through the night? What organ does
this sense affect? One suspects the antennae; in the male butterfly they
actually seem to be sounding, interrogating empty space with their long
feathery plumes. Are these splendid plumes merely items of finery, or do
they really play a part in the perception of the effluvia which guide
the lover? It seemed easy, on the occasion I spoke of, to devise a
conclusive experiment.

On the morrow of the invasion I found in my study eight of my nocturnal
visitors. They were perched, motionless, upon the cross-mouldings of the
second window, which had remained closed. The others, having concluded
their ballet by about ten o'clock at night, had left as they had
entered, by the other window, which was left open night and day. These
eight persevering lovers were just what I required for my experiment.

With a sharp pair of scissors, and without otherwise touching the
butterflies, I cut off their antennae near the base. The victims barely
noticed the operation. None moved; there was scarcely a flutter of the
wings. Their condition was excellent; the wound did not seem to be in
the least serious. They were not perturbed by physical suffering, and
would therefore be all the better adapted to my designs. They passed the
rest of the day in placid immobility on the cross-bars of the window.

A few other arrangements were still to be made. In particular it was
necessary to change the scene; not to leave the female under the eyes of
the mutilated butterflies at the moment of resuming their nocturnal
flight; the difficulty of the search must not be lessened. I therefore
removed the cage and its captive, and placed it under a porch on the
other side of the house, at a distance of some fifty paces from my
stu