xperiment, the strings of cocoons are arranged
differently in different tubes. In some of them, the heads of the
cocoons are turned downwards, towards the opening; in others, they are
turned upwards, towards the closed end; in others again, the cocoons
alternate in direction, that is to say, they are placed head to head and
rear to rear, turn and turn about. I need not say that the separating
floors are of sorghum.

The result is identical in all these tubes. If the Osmiae have their
heads pointing upwards, they attack the partition above them, as happens
under normal conditions; if their heads point downwards, they turn round
in their cells and set to work as usual. In short, the general outward
trend is towards the top, in whatever position the cocoon be placed.

We here see manifestly at work the influence of gravity, which warns
the insect of its reversed position and makes it turn round, even as it
would warn us if we ourselves happened to be hanging head downwards.
In natural conditions, the insect has but to follow the counsels of
gravity, which tells it to dig upwards, and it will infallibly reach the
exit-door situated at the upper end. But, in my apparatus, these same
counsels betray it: it goes towards the top, where there is no outlet.
Thus misled by my artifices, the Osmiae perish, heaped up on the higher
floors and buried in the ruins.

It nevertheless happens that attempts are made to clear a road
downwards. But it is rare for the work to lead to anything in this
direction, especially in the case of the middle or upper cells. The
insect is little inclined for this progress, the opposite to that to
which it is accustomed; besides, a serious difficulty arises in
the course of this reversed boring. As the Bee flings the excavated
materials behind her, these fall back of their own weight under
her mandibles; the clearance has to be begun anew. Exhausted by her
Sisyphean task, distrustful of this new and unfamiliar method, the Osmia
resigns herself and expires in her cell. I am bound to add, however,
that the Osmiae in the lower storeys, those nearest the exit--sometimes
one, sometimes two or three--do succeed in escaping. In that case, they
unhesitatingly attack the partitions below them, while their companions,
who form the great majority, persist and perish in the upper cells.

It was easy to repeat the experiment without changing anything in the
natural conditions, except the direction of the cocoons: a