r, thanks to the
huge number of layers.

Let us leave the Leaf-cutter to finish depositing her eggs in other
galleries, which will be colonized in the same manner, and consider for
a moment her skill as a cutter. Her edifices consist of a multitude of
fragments belonging to three categories: oval pieces for the sides
of the cells; round pieces for the lids; and irregular pieces for the
barricades at the front and back. The last present no difficulty: the
Bee obtains them by removing from the leaf some projecting portion,
as it stands, a serrate lobe which, owing to its notches, shortens the
insect's task and lends itself better to scissor-work. So far, there
is nothing to deserve attention: it is unskilled labour, in which an
inexperienced apprentice might excel.

With the oval pieces, it becomes another matter. What model has the
Megachile when cutting her neat ellipses out of the delicate material
for her wallets, the robinia-leaves? What mental pattern guides her
scissors? What system of measurement tells her the dimensions? One would
like to picture the insect as a living pair of compasses, capable of
tracing an elliptic curve by a certain natural inflexion of its body,
even as our arm traces a circle by swinging from the shoulder. A
blind mechanism, the mere outcome of its organization, would alone be
responsible for its geometry. This explanation would tempt me if the
large oval pieces were not accompanied by much smaller ones, also oval,
which are used to fill the empty spaces. A pair of compasses which
changes its radius of its own accord and alters the curve according to
the plan before it appears to me an instrument somewhat difficult to
believe in. There must be something better than that. The circular
pieces of the lid suggest it to us.

If, by the mere flexion inherent in her structure, the Leaf-cutter
succeeds in cutting out ovals, how does she succeed in cutting out
rounds? Can we admit the presence of other wheels in the machinery for
the new pattern, so different in shape and size? Besides, the real point
of the difficulty does not lie there. These rounds, for the most part,
fit the mouth of the jar with almost exact precision. When the cell
is finished, the Bee flies hundreds of yards away to make the lid. She
arrives at the leaf from which the disk is to be cut. What picture, what
recollection has she of the pot to be covered? Why, none at all: she has
never seen it; she does her work underground,