herself a passage through the string of those cocoons would mean to
exterminate the remainder of the brood; the deliverance of one would
mean the destruction of all the rest. Insects are notoriously
obstinate in their actions and unscrupulous in their methods. If the
Bee at the bottom of the shaft wants to leave her lodging, will she
spare those who bar her road?

The difficulty is great, obviously; it seems insuperable. Thereupon
we become suspicious: we begin to wonder if the emergence from the
cocoon, that is to say, the hatching, really takes place in the order
of primogeniture. Might it not be--by a very singular exception, it
is true, but one which is necessary in such circumstances--that the
youngest of the Osmiae bursts her cocoon first and the oldest last;
in short, that the hatching proceeds from one chamber to the next in
the inverse direction to that which the age of the occupants would
lead us to presume? In that case, the whole difficulty would be
removed: each Osmia, as she rent her silken prison, would find a
clear road in front of her, the Osmiae nearer the outlet having gone
out before her. But is this really how things happen? Our theories
very often do not agree with the insect's practice; even where our
reasoning seems most logical, we should be more prudent to see what
happens before venturing on any positive statements. Leon Dufour was
not so prudent when he, the first in the field, took this little
problem in hand. He describes to us the habits of an Odynerus
(Odynerus rubicola, DUF.) who piles up clay cells in the shaft of a
dry bramble-stalk; and, full of enthusiasm for his industrious Wasp,
he goes on to say:

'Picture a string of eight cement shells, placed end to end and
closely wedged inside a wooden sheath. The lowest was undeniably made