Might not this intercourse tend to cheer them and encourage them to
patience? Meanwhile, slowly, doors are opening here and there through
the separating walls; the road is cleared by sections; and a moment
arrives when the leader of the file walks out. The others follow, if
ready; but there are always laggards who keep the rear-ranks waiting
until they are gone.

To sum up, first, the hatching of the larvae takes place without any
order; secondly, the exodus proceeds regularly from summit to base,
but only in consequence of the insect's inability to move forward so
long as the upper cells are not vacated. We have here not an
exceptional evolution, in the inverse ratio to age, but the simple
impossibility of emerging otherwise. Should a chance occur of going
out before its turn, the insect does not fail to seize it, as we can
see by the lateral movements which send the impatient ones a few
ranks ahead and even release the more favoured altogether. The only
remarkable thing that I perceive is the scrupulous respect shown to
the as yet unopened neighbouring cocoon. However eager to come out,
the Osmia is most careful not to touch it with his mandibles: it is
taboo. He will demolish the partition, he will gnaw the side-wall
fiercely, even though there be nothing left but wood, he will reduce
everything around him to dust; but touch a cocoon that obstructs his
way? Never! He will not make himself an outlet by breaking up his
sisters' cradles.

It may happen that the Osmia's patience is in vain and that the
barricade that blocks the way never disappears at all. Sometimes, the
egg in a cell does not mature; and the unconsumed provisions dry up
and become a compact, sticky, mildewed plug, through which the
occupants of the floors below could never clear themselves a passage.