to ask
workers equipped with tools for cutting clay as hard as granite to cut
a piece of gauze does not strike me as a happy inspiration; you
cannot expect a navvy's pick-axe to do the same work as a dressmaker's
scissors. Secondly, the transparent glass prison seems to me ill-chosen.
As soon as the insect has made a passage through the thickness of its
earthen dome, it finds itself in broad daylight; and to it daylight
means the final deliverance, means liberty. It strikes against an
invisible obstacle, the glass; and to it glass is nothing at all and yet
an obstruction. On the far side, it sees free space, bathed in sunshine.
It wears itself out in efforts to fly there, unable to understand the
futile nature of its attempts against that strange barrier which
it cannot see. It perishes, at last, of exhaustion, without, in its
obstinacy, giving a glance at the gauze closing the conical chimney. The
experiment must be renewed under better conditions.

The obstacle which I select is ordinary brown paper, stout enough
to keep the insect in the dark and thin enough not to offer serious
resistance to the prisoner's efforts. As there is a great difference, in
so far as the actual nature of the barrier is concerned, between a paper
partition and a clay ceiling, let us begin by enquiring if the Mason-bee
of the Walls knows how or rather is able to make her way through one
of these partitions. The mandibles are pickaxes suitable for breaking
through hard mortar: are they also scissors capable of cutting a thin
membrane? This is the point to look into first of all.

In February, by which time the insect is in its perfect state, I take a
certain number of cocoons, without damaging them, from their cells and
insert them each in a separate stump of reed, closed at one end by the
natural wall of the node and open at the other. These pieces of reed
represent the cells of the nest. The cocoons are introduced with the
insect's head turned towards the opening. Lastly, my artificial cells
are closed in different ways. Some receive a stopper of kneaded clay,
which, when dry, will correspond in thickness and consistency with the
mortar ceiling of the natural nest. Others are plugged with a cylinder
of sorghum, at least a centimetre (.39 inch--Translator's Note.) thick;
and the remainder with a disk of brown paper solidly fastened by the
edge. All these bits of reed are placed side by side in a box, standing
upright, with the roof of my mak