web, I gather a series of
lime-threads which remain fixed in parallel lines. I cover this sheet
with a bell-jar standing in a depth of water. Soon, in this atmosphere
saturated with humidity, the threads become enveloped in a watery
sheath, which gradually increases and begins to flow. The twisted shape
has by this time disappeared; and the channel of the thread reveals a
chaplet of translucent orbs, that is to say, a series of extremely fine
drops.
In twenty-four hours the threads have lost their contents and are
reduced to almost invisible streaks. If I then lay a drop of water on
the glass, I get a sticky solution similar to that which a particle of
gum arabic might yield. The conclusion is evident: the Epeira's glue is
a substance that absorbs moisture freely. In an atmosphere with a high
degree of humidity, it becomes saturated and percolates by sweating
through the side of the tubular threads.
These data explain certain facts relating to the work of the net. The
Epeirae weave at very early hours, long before dawn. Should the air
turn misty, they sometimes leave that part of the task unfinished: they
build the general framework, they lay the spokes, they even draw the
auxiliary spiral, for all these parts are unaffected by excess of
moisture; but they are very careful not to work at the lime-threads,
which, if soaked by the fog, would dissolve into sticky shreds and lose
their efficacy by being wetted. The net that was started will be
finished to-morrow, if the atmosphere be favourable.
While the highly-absorbent character of the snaring-thread has its
drawbacks, it also has compensating advantages. The Epeirae, when
hunting by day, affect those hot places, exposed to the fierce rays of
the sun, wherein the Crickets delight. In the torrid heats of the
dog-days, therefore, the lime-threads, but for special provisions,
would be liable to dry up, to shrivel into stiff and lifeless
filaments. But the very opposite happens. At the most scorching times
of the day they continue supple, elastic and more and more adhesive.
How is this brought about? By their very powers of absorption. The
moisture of which the air is never deprived penetrates them slowly; it
dilutes the thick contents of their tubes to the requisite degree and
causes it to ooze through, as and when the earlier stickiness
decreases. What bird-catcher could vie with the Garden Spider in the
art of laying lime-snares? And all this industry and cunning
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