f instinct that cannot be explained by mechanics; I submit it
to the consideration of science; and I pass on.

The Silky Leaf-cutter (Megachile sericans, FONSCOL.; M. Dufourii, LEP.)
makes her nests in the disused galleries of the Anthophorae. I know
her to occupy another dwelling which is more elegant and affords a more
roomy installation: I mean the old dwelling of the fat Capricorn, the
denizen of the oaks. The metamorphosis is effected in a spacious chamber
lined with soft felt. When the long-horned Beetle reaches the adult
stage, he releases himself and emerges from the tree by following a
vestibule which the larva's powerful tools have prepared beforehand.
When the deserted cabin, owing to its position, remains wholesome and
there is no sign of any running from its walls, no brown stuff smelling
of the tan-yard, it is soon visited by the Silky Megachile, who finds in
it the most sumptuous of the apartments inhabited by the Leaf-cutters.
It combines every condition of comfort: perfect safety, an even
temperature, freedom from damp, ample room; and so the mother who is
fortunate enough to become the possessor of such a lodging uses it
entirely, vestibule and drawing-room alike. Accommodation is found for
all her family of eggs; at least, I have nowhere seen nests as populous
as here.

One of them provides me with seventeen cells, the highest number
appearing in my census of the Megachile clan. Most of them are lodged in
the nymphal chamber of the Capricorn; and, as the spacious recess is too
wide for a single row, the cells are arranged in three parallel series.
The remainder, in a single string, occupy the vestibule, which is
completed and filled up by the terminal barricade. In the materials
employed, hawthorn-and paliurus-leaves predominate. The pieces, both
in the cells and in the barrier, vary in size. It is true that the
hawthorn-leaves, with their deep indentations, do not lend themselves to
the cutting of neat oval pieces. The insect seems to have detached each
morsel without troubling overmuch about the shape of the piece, so long
as it was big enough. Nor has it been very particular about arranging
the pieces according to the nature of the leaf: after a few bits of
paliurus come bits of vine and hawthorn; and these again are followed by
bits of bramble and paliurus. The Bee has collected her pieces anyhow,
taking a bit here and there, just as her fancy dictated. Nevertheless,
paliurus is the commonest, pe