regular polygon as an opening. Then how comes it that
the cylinder of bits of root is so confused, so clumsily fashioned? The
reason is this: the worker possesses talent, but the materials do not
lend themselves to accurate work. The rootlets supply stumps of very
uneven shape and thickness. They include big and small ones, straight
and bent, simple and ramified. To combine all these dissimilar pieces
into an orderly whole is hardly possible, all the more so as the caddis
worm does not appear to attach very much importance to its cylinder,
which is a temporary work, hurriedly constructed to afford a speedy
shelter. Matters are urgent; and very soft fibers, clipped with a bite
of the mandibles, are more quickly gathered and more easily put together
than joists, which require the patient work of the saw. The inaccurate
cylinder, in short, held in position by numerous guy ropes, is a base
upon which a solid and definite structure will rise before long. Soon,
the original work will crumble to ruins and disappear, whereas the new
one, a permanent structure, will even outlast the owner.

The insects reared in a tumbler show yet another method of building the
first dwelling. This time, the caddis worm is given a few very leafy
stalks of pond weed (Potamogeton densum) and a bundle of small dry
twigs. It perches on a leaf, which the nippers of the mandibles cut half
across. The portion left untouched will act as a lanyard and give the
necessary steadiness to the early operations.

From an adjoining leaf a section is cut out entirely, an angular and
good sized piece. There is plenty of material and no need for economy.
The piece is soldered with silk to the strip which was not wholly cut
off. The result of three or four similar operations is to surround
the Caddis worm with a conical bag, whose wide mouth is scalloped with
pointed and very irregular notches. The work of the nippers continues;
fresh pieces are fixed, from one to another, inside the funnel, not far
from the edge, so that the bag lengthens, tapers and ends by wrapping
the animal in a light and floating drapery.

Thus clad for the time being, either in the fine silk of the pond weed
or in the linsey-woolsey supplied by the roots of the watercress, the
caddis worm begins to think of building a more solid sheath. The present
casing will serve as a foundation for the stronger building. But the
necessary materials are seldom near at hand: you have to go and fetch
them,