ine. All curves are banished from the Spiders' work; nothing is
used but the straight line and its combinations. All that is aimed at is
a polygonal line drawn in a curve as geometry understands it. To this
polygonal line, a work destined to disappear as the real toils are woven,
I will give the name of the 'auxiliary spiral.' Its object is to supply
cross-bars, supporting rungs, especially in the outer zone, where the
radii are too distant from one another to afford a suitable groundwork.
Its object is also to guide the Epeira in the extremely delicate business
which she is now about to undertake.

But, before that, one last task becomes essential. The area occupied by
the spokes is very irregular, being marked out by the supports of the
branch, which are infinitely variable. There are angular niches which,
if skirted too closely, would disturb the symmetry of the web about to be
constructed. The Epeira needs an exact space wherein gradually to lay
her spiral thread. Moreover, she must not leave any gaps through which
her prey might find an outlet.

An expert in these matters, the Spider soon knows the corners that have
to be filled up. With an alternating movement, first in this direction,
then in that, she lays, upon the support of the radii, a thread that
forms two acute angles at the lateral boundaries of the faulty part and
describes a zigzag line not wholly unlike the ornament known as the fret.

The sharp corners have now been filled with frets on every side; the time
has come to work at the essential part, the snaring-web for which all the
rest is but a support. Clinging on the one hand to the radii, on the
other to the chords of the auxiliary spiral, the Epeira covers the same
ground as when laying the spiral, but in the opposite direction:
formerly, she moved away from the centre; now she moves towards it and
with closer and more numerous circles. She starts from the base of the
auxiliary spiral, near the frame.

What follows is difficult to observe, for the movements are very quick
and spasmodic, consisting of a series of sudden little rushes, sways and
bends that bewilder the eye. It needs continuous attention and repeated
examination to distinguish the progress of the work however slightly.

The two hind-legs, the weaving implements, keep going constantly. Let us
name them according to their position on the work-floor. I call the leg
that faces the centre of the coil, when the animal moves