ely tried by my
experiments; they have taught me much and can teach me more. Alien
colonies, picked up more or less everywhere, provide me with my booty.
With my lens in one hand and my forceps in the other, I go through my
collection on the same day, with the prudence and care which only the
laboratory-table permits. The results at first fall far short of my
expectations. I see nothing that I have not seen before. I make fresh
expeditions, after a few days' interval; I bring back fresh loads of
lumps of mortar, until at last fortune smiles upon me.

Reason was not at fault. Each thrust means the laying of an egg when the
probe reaches the cell. Here is a cocoon of the Mason-bee of the Pebbles
with an egg side by side with the Chalicodoma-grub. But what a curious
egg! Never have my eyes beheld the like; and then is it really the egg
of the Leucopsis? Great was my apprehension. But I breathed again when
I found, a couple of weeks later, that the egg had become the larva with
which I was familiar. Those cocoons with a single egg are as numerous as
I can wish; they exceed my wishes: my little glass receptacles are too
few to hold them.

And here are others, more precious ones still, with manifold layings.
I find plenty with two eggs; I find some with three or four; the
best-colonised offer me as many as five. And, to crown my delight, the
joy of the seeker to whom success comes at the last moment, when he is
on the verge of despair, here again, duly furnished with an egg, is a
sterile cocoon, that is to say, one containing only a shrivelled and
decaying larva. All my suspicions are confirmed, down to the most
inconsequent: the egg housed with a mass of putrefaction.

The nests of the Mason-bee of the Walls are the more regular in
structure and are easier to examine, because their base is wide open
once it is separated from the supporting pebble; and it was these which
supplied me with by far the greater part of my information. Those of the
Mason-bee of the Sheds have to be chipped away with a hammer before one
can inspect their cells, which are heaped up anyhow; and they do not
lend themselves anything like so well to delicate investigations, as
they suffer both from the shock and the ill-treatment.

And now the thing is done: it remains certain that the Leucopsis' laying
is exposed to very exceptional dangers. She can entrust the egg to
sterile cells, without provisions fit to use; she can establish several
in the sam