ge later a
full-grown moth.

When spinning, the caterpillar begins by sending out the end of a thread
which is quite soft and sticky. This immediately sticks to the object to
which it is attached. This done, every movement of the caterpillar's
head draws a fresh piece of the silk thread from its mouth. When
spinning a cocoon, the thread is made to form a long, oval, egg-shaped
case around the body of the caterpillar. But sometimes, as in the case
of those caterpillars which live in companies, it is used to form a
sheet or tent within which the tent-makers dwell. Other caterpillars use
the power of weaving silk as a means of escape from enemies. When in
danger they let themselves down on to the ground by attaching the end of
a thread to a leaf or twig, and then dropping off, leaving the thread to
be drawn from the mouth by the weight of the body as it falls.

Under the microscope each thread of silk is seen to be double: the total
length of the thread when unwound from the cocoon is over a thousand
feet. Over four hundred different kinds of silk-producing caterpillars
are known.

The spinning glands of the spider are placed at the tail end of the
body, but the threads spun therefrom, though strong, are of little use
for commercial purposes. Silk fabrics have, however, been made from
spider webs, but these are only curiosities.

The silk, or, as we may call them, the spinning glands, consist of from
two to four pairs of organs, or 'spinnerets,' placed together in a small
cluster. The threads which they form are made, as in the case of the
silk of the caterpillar, of a sticky fluid, which, when drawn out
through the tiny holes of the spinnerets, and exposed to the air, form
fine threads, and these combining together form the silky thread with
which we are familiar.

One of the principal uses of the silk threads is to form nets to catch
small insects. These nets are often--as is the case of the garden
spider, for example--very beautiful. In their construction the greatest
skill is shown. The method is briefly as follows: First of all a large
five-sided frame is formed; then long threads, which are rather like the
spokes of a wheel, are added. These harden at once, and to them are
attached the cross-threads, which form the delicate network of the
complete web. But if the web be examined with a strong magnifying glass,
there will be found, among the network, a number of threads bearing
little drops of a sticky substance