e arranged.

It is not possible to ascertain the chronological order of a laying,
except by going to suitably-chosen species. Fortunately there are a few
species in which we do not find this difficulty: these are the Bees who
keep to one gallery and build their cells in storeys. Among the number
are the different inhabitants of the bramble-stumps, notably the
Three-pronged Osmiae, who form an excellent subject for observation,
partly because they are of imposing size--bigger than any other
bramble-dwellers in my neighbourhood--partly because they are so
plentiful.

Let us briefly recall the Osmia's habits. Amid the tangle of a hedge, a
bramble-stalk is selected, still standing, but a mere withered stump.
In this the insect digs a more or less deep tunnel, an easy piece of
work owing to the abundance of soft pith. Provisions are heaped up
right at the bottom of the tunnel and an egg is laid on the surface of
the food: that is the first-born of the family. At a height of some
twelve millimetres (About half an inch.--Translator's Note.), a
partition is fixed. This gives a second storey, which in its turn
receives provisions and an egg, the second in order of primogeniture.
And so it goes on, storey by storey, until the cylinder is full. Then
the thick plug of the same green material of which the partitions are
formed closes the home and keeps out marauders.

In this common cradle, the chronological order of births is perfectly
clear. The first-born of the family is at the bottom of the series; the
last-born is at the top, near the closed door. The others follow from
bottom to top in the same order in which they followed in point of
time. The laying is numbered automatically; each cocoon tells us its
respective age by the place which it occupies.

A number of eggs bordering on fifteen represents the entire family of
an Osmia, and my observations enable me to state that the distribution
of the sexes is not governed by any rule. All that I can say in general
is that the complete series begins with females and nearly always ends
with males. The incomplete series--those which the insect has laid in
various places--can teach us nothing in this respect, for they are only
fragments starting we know not whence; and it is impossible to tell
whether they should be ascribed to the beginning, to the end, or to an
intermediate period of the laying. To sum up: in the laying of the
Three-pronged Osmia, no order governs the succession