eggs are emitted for
nearly half an hour. The layer, utterly absorbed in her serious
business, remains stationary and impassive and is easily observed
through my lens. A movement on my part would doubtless scare her; but
my restful presence gives her no anxiety. I am nothing to her.

The discharge does not go on continuously until the ovaries are
exhausted; it is intermittent and performed in so many packets. Several
times over, the Fly leaves the bird's beak and comes to take a rest
upon the wire-gauze, where she brushes her hind-legs one against the
other. In particular, before using it again, she cleans, smooths and
polishes her laying-tool, the probe that places the eggs. Then, feeling
her womb still teeming, she returns to the same spot at the joint of
the beak. The delivery is resumed, to cease presently and then begin
anew. A couple of hours are thus spent in alternate standing near the
eye and resting on the wire-gauze.

At last it is over. The Fly does not go back to the bird, a proof that
her ovaries are exhausted. The next day she is dead. The eggs are
dabbed in a continuous layer, at the entrance to the throat, at the
root of the tongue, on the membrane of the palate. Their number appears
considerable; the whole inside of the gullet is white with them. I fix
a little wooden prop between the two mandibles of the beak, to keep
them open and enable me to see what happens.

I learn in this way that the hatching takes place in a couple of days.
As soon as they are born, the young vermin, a swarming mass, leave the
place where they are and disappear down the throat.

The beak of the bird invaded was closed at the start, as far as the
natural contact of the mandibles allowed. There remained a narrow slit
at the base, sufficient at most to admit the passage of a horse-hair.
It was through this that the laying was performed. Lengthening her
ovipositor like a telescope, the mother inserted the point of her
implement, a point slightly hardened with a horny armour. The fineness
of the probe equals the fineness of the aperture. But, if the beak were
entirely closed, where would the eggs be laid then?

With a tied thread I keep the two mandibles in absolute contact; and I
place a second Bluebottle in the presence of the Linnet, whom the
colonists have already entered by the beak. This time the laying takes
place on one of the eyes, between the lid and the eyeball. At the
hatching, which again occurs a couple of days