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