oon begins. These cells are
cemented to the surface of the nest, which thus increases in thickness
every year. The edifice of cells is not built all at once: mortar and
honey alternate repeatedly. The masonry starts with a sort of little
swallow's nest, a half-cup or thimble, whose circumference is completed
by the wall against which it rests. Picture the cup of an acorn cut in
two and stuck to the surface of the nest: there you have the receptacle
in a stage sufficiently advanced to take a first instalment of honey.

The Bee thereupon leaves the mortar and busies herself with harvesting.
After a few foraging-trips, the work of building is resumed; and some
new rows of bricks raise the edge of the basin, which becomes capable
of receiving a larger stock of provisions. Then comes another change of
business: the mason once more becomes a harvester. A little later, the
harvester is again a mason; and these alternations continue until the
cell is of the regulation height and holds the amount of honey required
for the larva's food. Thus come, turn and turn about, more or less
numerous according to the occupation in hand, journeys to the dry and
barren path, where the cement is gathered and mixed, and journeys to
the flowers, where the Bee's crop is crammed with honey and her belly
powdered with pollen.

At last comes the time for laying. We see the Bee arrive with a pellet
of mortar. She gives a glance at the cell to enquire if everything is in
order; she inserts her abdomen; and the egg is laid. Then and there
the mother seals up the home: with her pellet of cement she closes the
orifice and manages so well with the material that the lid receives its
permanent form at this first sitting; it has only to be thickened and
strengthened with fresh layers, a work which is less urgent and will
be done by and by. What does appear to be an urgent necessity is the
closing of the cell immediately after the egg has been religiously
deposited therein, so that there may be no danger from evilly-disposed
visitors during the mother's absence. The Bee must have serious reasons
for thus hurrying on the closing of the cell. What would happen if,
after laying her egg, she left the house open and went to the cement-pit
to fetch the wherewithal to block the door? Some thief might drop in
and substitute her own egg for the Mason-bee's. We shall see that our
suspicions are not uncalled-for. One thing is certain, that the Mason
never lays without