e cocoons is
fastened to stems of grass or other objects, and partially hidden by a
few withered leaves. "For the purpose of securing their prey," says
Mr. Blackwall, the author of a splendid work on 'British Spiders,'
"spiders have recourse to divers expedients. Numerous species run
rapidly about in quest of those objects which constitute their food;
others, approaching their victims with great circumspection, spring
upon them from a distance; some lie concealed in flowers or among
leaves, seizing such insects as come within their reach; and many
species procure a supply of nutriment by means of complicated snares
of their own fabrication." Of these snares the most beautiful, as I
said, are the "wheel within wheel" nets of the various species of the
family _Epeiridae_. "What are those spider-like things," asked Willy,
"with long thin bodies, you often see skating along the water? they
are something like the spiders." They are not spiders at all, but
insects called "water-measurers," from their peculiar habit of taking
a short skate on the surface of the water and then stopping; having
measured that distance, off they go again. However, many spiders do
run along on the surface of the water, and you know there is one, the
great water-spider, that lives habitually in it. Some years ago I had
one of these water-spiders in a glass vessel of water, and saw it spin
its curious dome-shaped web which it attached to the sides of the
glass and some weeds. These domes are formed of closely woven white
silk, in the form of a diving bell or half a pigeon's egg, as De Geer
has said, with the opening below. It looks like a half-ball of silver;
this appearance is due to a quantity of air. It is, in fact, a huge
air-bubble surrounded by a covering of white silk, and, as you may
suppose, a very interesting and pretty object. Within this silver dome
the spider places her eggs, perhaps a hundred or more in number, which
are enveloped in a cocoon, this being attached to the inner side of
the dome. "But how," said Jack, "is the bubble formed? Where does the
air come from?" You have asked a very interesting question, and one
which can be answered; for the question was set at rest by Mr. Bell,
an excellent observer and well-known naturalist, about twelve years
ago, if I remember rightly. He found that the old spider actually took
the air down with her from the surface of the water, and deposited it
in her domed house. I shall now quote Mr. Bell