The Mason-bee of the Walls shows us, under another form, a similar
repetition of an act which is useless in itself, but which is the
compulsory preface to the act that follows. When arriving with her
provisions, the Bee performs a twofold operation of storing. First,
she dives head foremost into the cell, to disgorge the contents of her
crop; next, she comes out and at once goes in again backwards, to
brush her abdomen and rub off the load of pollen. At the moment when
the insect is about to enter the cell tail first, I push her aside
gently with a straw. The second act is thus prevented. The Bee now
begins the whole performance over again, that is to say, she once more
dives head first to the bottom of the cell, though she has nothing
left to disgorge, as her crop has just been emptied. When this is
done, it is the belly's turn. I instantly push her aside again. The
insect repeats its proceedings, still entering head first; I also
repeat my touch of the straw. And this can go on as long as the
observer pleases. Pushed aside at the moment when she is about to
insert her abdomen into the cell, the Bee goes back to the opening and
persists in going down head first to begin with. Sometimes, she
descends to the bottom, sometimes only half-way, sometimes again she
only pretends to descend, just bending her head into the aperture;
but, whether completed or not, this action, for which there is no
longer any motive, since the honey has already been disgorged,
invariably precedes the entrance backwards to deposit the pollen. It
is almost the movement of a machine whose works are only set going
when the driving-wheel begins to revolve.


CHAPTER 4. MORE ENQUIRIES INTO MASON-BEES.

This chapter was to have taken the form of a letter addressed to