still in position in the lower
rooms, left no doubt as to this eccentric mode of exit. The same fact,
moreover, was repeated, in several bramble-stumps, in the case of Osmia
tridentata; it was likewise repeated in the case of Anthidium scapulare.
The observation was worth confirming by experiment.

I select a bramble-stem with the thinnest rind possible, so as to
facilitate the Osmiae's work. I split it in half, thus obtaining a
smooth-sided trough which will enable me to judge better of future
exits. The cocoons are next laid out in one of the troughs. I separate
them with disks of sorghum, covering both surfaces of the disk with a
generous layer of sealing-wax, a material which the Osmia's mandibles
are not able to attack. The two troughs are then placed together and
fastened. A little putty does away with the joint and prevents the
least ray of light from penetrating. Lastly, the apparatus is hung up
perpendicularly, with the cocoons' heads up. We have now only to wait.
None of the Osmiae can get out in the usual manner, because each of them
is confined between two partitions coated with sealing-wax. There is but
one resource left to them if they would emerge into the light of day,
that is, for each of them to open a side-window, provided always that
they possess the instinct and the power to do so.

In July, the result is as follows: of twenty Osmiae thus immured, six
succeed in boring a round hole through the wall and making their way
out; the others perish in their cells, without managing to release
themselves. But, when I open the cylinder, when I separate the two
wooden troughs, I realize that all have attempted to escape through the
side, for the wall of each cell bears traces of gnawing concentrated
upon one spot. All, therefore, have acted in the same way as their more
fortunate sisters; they did not succeed, because their strength failed
them. Lastly, in my glass tubes, part-lined with a thick piece of
packing-paper, I often see attempts at making a window in the side of
the cell: the paper is pierced right through with a round hole.

This then is yet another result which I am glad to record in the history
of the bramble-dwellers. When the Osmia, the Anthidium and probably
others are unable to emerge through the customary outlet, they take
an heroic decision and perforate the side of the shaft. It is the last
resource, resolved upon after other methods have been tried in vain. The
brave, the strong succee