Lastly, the hind legs, of medium length, afford a support when the
others are busy.

The caddis worm, I was saying, with the piece which it has removed
held crosswise to its chest, retreats a little way along its
suspended hammock until the spinneret is level with the support
furnished by the close tangle of rootlets. With a quick movement,
it shifts its burden, gets it as nearly by the middle as it can, so
that the two ends stick out equally on either side, and chooses the
spot to place it, whereupon the spinneret sets to work at once,
while the little fore legs hold the scrap of root motionless in its
transversal position. The soldering is effected with a touch of
silk in the middle of the bit and along a certain distance to the
right and left, as far as the bending of the head permits.

Without delay, other sticks are speared in like manner at a
distance, cut off and placed in position. As the immediate
neighborhood is stripped, the material is gathered at a yet greater
distance and the caddis worm bends even farther from its support,
which now holds only its last few segments. It is a curious
gymnastic display, that of this soft, hanging spine turning and
swaying, while the grapnels feel in every direction for a thread.

All this labor results in a sort of casing of little white cords.
The work lacks firmness and regularity. Nevertheless, judging by
the builder's methods, I can see that the building would not be
devoid of merit if the materials gave it a better chance. The
caddis worm estimates the size of its pieces very fairly; it cuts
them all to nearly the same length; it always arranges them
crosswise on the margin of the case; it fixes them by the middle.